perf machine: Introduce machine__findnew_dso() method

[mirror_ubuntu-artful-kernel.git] / tools / perf / util / header.c

#include "util.h"
#include <sys/types.h>
#include <byteswap.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <linux/list.h>
#include <linux/kernel.h>
#include <linux/bitops.h>
#include <sys/utsname.h>

#include "evlist.h"
#include "evsel.h"
#include "header.h"
#include "../perf.h"
#include "trace-event.h"
#include "session.h"
#include "symbol.h"
#include "debug.h"
#include "cpumap.h"
#include "pmu.h"
#include "vdso.h"
#include "strbuf.h"
#include "build-id.h"
#include "data.h"

static u32 header_argc;
static const char **header_argv;

/*
 * magic2 = "PERFILE2"
 * must be a numerical value to let the endianness
 * determine the memory layout. That way we are able
 * to detect endianness when reading the perf.data file
 * back.
 *
 * we check for legacy (PERFFILE) format.
 */
static const char *__perf_magic1 = "PERFFILE";
static const u64 __perf_magic2    = 0x32454c4946524550ULL;
static const u64 __perf_magic2_sw = 0x50455246494c4532ULL;

#define PERF_MAGIC      __perf_magic2

struct perf_file_attr {
        struct perf_event_attr  attr;
        struct perf_file_section        ids;
};

void perf_header__set_feat(struct perf_header *header, int feat)
{
        set_bit(feat, header->adds_features);
}

void perf_header__clear_feat(struct perf_header *header, int feat)
{
        clear_bit(feat, header->adds_features);
}

bool perf_header__has_feat(const struct perf_header *header, int feat)
{
        return test_bit(feat, header->adds_features);
}

static int do_write(int fd, const void *buf, size_t size)
{
        while (size) {
                int ret = write(fd, buf, size);

                if (ret < 0)
                        return -errno;

                size -= ret;
                buf += ret;
        }

        return 0;
}

int write_padded(int fd, const void *bf, size_t count, size_t count_aligned)
{
        static const char zero_buf[NAME_ALIGN];
        int err = do_write(fd, bf, count);

        if (!err)
                err = do_write(fd, zero_buf, count_aligned - count);

        return err;
}

static int do_write_string(int fd, const char *str)
{
        u32 len, olen;
        int ret;

        olen = strlen(str) + 1;
        len = PERF_ALIGN(olen, NAME_ALIGN);

        /* write len, incl. \0 */
        ret = do_write(fd, &len, sizeof(len));
        if (ret < 0)
                return ret;

        return write_padded(fd, str, olen, len);
}

static char *do_read_string(int fd, struct perf_header *ph)
{
        ssize_t sz, ret;
        u32 len;
        char *buf;

        sz = readn(fd, &len, sizeof(len));
        if (sz < (ssize_t)sizeof(len))
                return NULL;

        if (ph->needs_swap)
                len = bswap_32(len);

        buf = malloc(len);
        if (!buf)
                return NULL;

        ret = readn(fd, buf, len);
        if (ret == (ssize_t)len) {
                /*
                 * strings are padded by zeroes
                 * thus the actual strlen of buf
                 * may be less than len
                 */
                return buf;
        }

        free(buf);
        return NULL;
}

int
perf_header__set_cmdline(int argc, const char **argv)
{
        int i;

        /*
         * If header_argv has already been set, do not override it.
         * This allows a command to set the cmdline, parse args and
         * then call another builtin function that implements a
         * command -- e.g, cmd_kvm calling cmd_record.
         */
        if (header_argv)
                return 0;

        header_argc = (u32)argc;

        /* do not include NULL termination */
        header_argv = calloc(argc, sizeof(char *));
        if (!header_argv)
                return -ENOMEM;

        /*
         * must copy argv contents because it gets moved
         * around during option parsing
         */
        for (i = 0; i < argc ; i++)
                header_argv[i] = argv[i];

        return 0;
}

static int write_tracing_data(int fd, struct perf_header *h __maybe_unused,
                            struct perf_evlist *evlist)
{
        return read_tracing_data(fd, &evlist->entries);
}


static int write_build_id(int fd, struct perf_header *h,
                          struct perf_evlist *evlist __maybe_unused)
{
        struct perf_session *session;
        int err;

        session = container_of(h, struct perf_session, header);

        if (!perf_session__read_build_ids(session, true))
                return -1;

        err = perf_session__write_buildid_table(session, fd);
        if (err < 0) {
                pr_debug("failed to write buildid table\n");
                return err;
        }
        perf_session__cache_build_ids(session);

        return 0;
}

static int write_hostname(int fd, struct perf_header *h __maybe_unused,
                          struct perf_evlist *evlist __maybe_unused)
{
        struct utsname uts;
        int ret;

        ret = uname(&uts);
        if (ret < 0)
                return -1;

        return do_write_string(fd, uts.nodename);
}

static int write_osrelease(int fd, struct perf_header *h __maybe_unused,
                           struct perf_evlist *evlist __maybe_unused)
{
        struct utsname uts;
        int ret;

        ret = uname(&uts);
        if (ret < 0)
                return -1;

        return do_write_string(fd, uts.release);
}

static int write_arch(int fd, struct perf_header *h __maybe_unused,
                      struct perf_evlist *evlist __maybe_unused)
{
        struct utsname uts;
        int ret;

        ret = uname(&uts);
        if (ret < 0)
                return -1;

        return do_write_string(fd, uts.machine);
}

static int write_version(int fd, struct perf_header *h __maybe_unused,
                         struct perf_evlist *evlist __maybe_unused)
{
        return do_write_string(fd, perf_version_string);
}

static int __write_cpudesc(int fd, const char *cpuinfo_proc)
{
        FILE *file;
        char *buf = NULL;
        char *s, *p;
        const char *search = cpuinfo_proc;
        size_t len = 0;
        int ret = -1;

        if (!search)
                return -1;

        file = fopen("/proc/cpuinfo", "r");
        if (!file)
                return -1;

        while (getline(&buf, &len, file) > 0) {
                ret = strncmp(buf, search, strlen(search));
                if (!ret)
                        break;
        }

        if (ret) {
                ret = -1;
                goto done;
        }

        s = buf;

        p = strchr(buf, ':');
        if (p && *(p+1) == ' ' && *(p+2))
                s = p + 2;
        p = strchr(s, '\n');
        if (p)
                *p = '\0';

        /* squash extra space characters (branding string) */
        p = s;
        while (*p) {
                if (isspace(*p)) {
                        char *r = p + 1;
                        char *q = r;
                        *p = ' ';
                        while (*q && isspace(*q))
                                q++;
                        if (q != (p+1))
                                while ((*r++ = *q++));
                }
                p++;
        }
        ret = do_write_string(fd, s);
done:
        free(buf);
        fclose(file);
        return ret;
}

static int write_cpudesc(int fd, struct perf_header *h __maybe_unused,
                       struct perf_evlist *evlist __maybe_unused)
{
#ifndef CPUINFO_PROC
#define CPUINFO_PROC {"model name", }
#endif
        const char *cpuinfo_procs[] = CPUINFO_PROC;
        unsigned int i;

        for (i = 0; i < ARRAY_SIZE(cpuinfo_procs); i++) {
                int ret;
                ret = __write_cpudesc(fd, cpuinfo_procs[i]);
                if (ret >= 0)
                        return ret;
        }
        return -1;
}


static int write_nrcpus(int fd, struct perf_header *h __maybe_unused,
                        struct perf_evlist *evlist __maybe_unused)
{
        long nr;
        u32 nrc, nra;
        int ret;

        nr = sysconf(_SC_NPROCESSORS_CONF);
        if (nr < 0)
                return -1;

        nrc = (u32)(nr & UINT_MAX);

        nr = sysconf(_SC_NPROCESSORS_ONLN);
        if (nr < 0)
                return -1;

        nra = (u32)(nr & UINT_MAX);

        ret = do_write(fd, &nrc, sizeof(nrc));
        if (ret < 0)
                return ret;

        return do_write(fd, &nra, sizeof(nra));
}

static int write_event_desc(int fd, struct perf_header *h __maybe_unused,
                            struct perf_evlist *evlist)
{
        struct perf_evsel *evsel;
        u32 nre, nri, sz;
        int ret;

        nre = evlist->nr_entries;

        /*
         * write number of events
         */
        ret = do_write(fd, &nre, sizeof(nre));
        if (ret < 0)
                return ret;

        /*
         * size of perf_event_attr struct
         */
        sz = (u32)sizeof(evsel->attr);
        ret = do_write(fd, &sz, sizeof(sz));
        if (ret < 0)
                return ret;

        evlist__for_each(evlist, evsel) {
                ret = do_write(fd, &evsel->attr, sz);
                if (ret < 0)
                        return ret;
                /*
                 * write number of unique id per event
                 * there is one id per instance of an event
                 *
                 * copy into an nri to be independent of the
                 * type of ids,
                 */
                nri = evsel->ids;
                ret = do_write(fd, &nri, sizeof(nri));
                if (ret < 0)
                        return ret;

                /*
                 * write event string as passed on cmdline
                 */
                ret = do_write_string(fd, perf_evsel__name(evsel));
                if (ret < 0)
                        return ret;
                /*
                 * write unique ids for this event
                 */
                ret = do_write(fd, evsel->id, evsel->ids * sizeof(u64));
                if (ret < 0)
                        return ret;
        }
        return 0;
}

static int write_cmdline(int fd, struct perf_header *h __maybe_unused,
                         struct perf_evlist *evlist __maybe_unused)
{
        char buf[MAXPATHLEN];
        char proc[32];
        u32 i, n;
        int ret;

        /*
         * actual atual path to perf binary
         */
        sprintf(proc, "/proc/%d/exe", getpid());
        ret = readlink(proc, buf, sizeof(buf));
        if (ret <= 0)
                return -1;

        /* readlink() does not add null termination */
        buf[ret] = '\0';

        /* account for binary path */
        n = header_argc + 1;

        ret = do_write(fd, &n, sizeof(n));
        if (ret < 0)
                return ret;

        ret = do_write_string(fd, buf);
        if (ret < 0)
                return ret;

        for (i = 0 ; i < header_argc; i++) {
                ret = do_write_string(fd, header_argv[i]);
                if (ret < 0)
                        return ret;
        }
        return 0;
}

#define CORE_SIB_FMT \
        "/sys/devices/system/cpu/cpu%d/topology/core_siblings_list"
#define THRD_SIB_FMT \
        "/sys/devices/system/cpu/cpu%d/topology/thread_siblings_list"

struct cpu_topo {
        u32 core_sib;
        u32 thread_sib;
        char **core_siblings;
        char **thread_siblings;
};

static int build_cpu_topo(struct cpu_topo *tp, int cpu)
{
        FILE *fp;
        char filename[MAXPATHLEN];
        char *buf = NULL, *p;
        size_t len = 0;
        ssize_t sret;
        u32 i = 0;
        int ret = -1;

        sprintf(filename, CORE_SIB_FMT, cpu);
        fp = fopen(filename, "r");
        if (!fp)
                goto try_threads;

        sret = getline(&buf, &len, fp);
        fclose(fp);
        if (sret <= 0)
                goto try_threads;

        p = strchr(buf, '\n');
        if (p)
                *p = '\0';

        for (i = 0; i < tp->core_sib; i++) {
                if (!strcmp(buf, tp->core_siblings[i]))
                        break;
        }
        if (i == tp->core_sib) {
                tp->core_siblings[i] = buf;
                tp->core_sib++;
                buf = NULL;
                len = 0;
        }
        ret = 0;

try_threads:
        sprintf(filename, THRD_SIB_FMT, cpu);
        fp = fopen(filename, "r");
        if (!fp)
                goto done;

        if (getline(&buf, &len, fp) <= 0)
                goto done;

        p = strchr(buf, '\n');
        if (p)
                *p = '\0';

        for (i = 0; i < tp->thread_sib; i++) {
                if (!strcmp(buf, tp->thread_siblings[i]))
                        break;
        }
        if (i == tp->thread_sib) {
                tp->thread_siblings[i] = buf;
                tp->thread_sib++;
                buf = NULL;
        }
        ret = 0;
done:
        if(fp)
                fclose(fp);
        free(buf);
        return ret;
}

static void free_cpu_topo(struct cpu_topo *tp)
{
        u32 i;

        if (!tp)
                return;

        for (i = 0 ; i < tp->core_sib; i++)
                zfree(&tp->core_siblings[i]);

        for (i = 0 ; i < tp->thread_sib; i++)
                zfree(&tp->thread_siblings[i]);

        free(tp);
}

static struct cpu_topo *build_cpu_topology(void)
{
        struct cpu_topo *tp;
        void *addr;
        u32 nr, i;
        size_t sz;
        long ncpus;
        int ret = -1;

        ncpus = sysconf(_SC_NPROCESSORS_CONF);
        if (ncpus < 0)
                return NULL;

        nr = (u32)(ncpus & UINT_MAX);

        sz = nr * sizeof(char *);

        addr = calloc(1, sizeof(*tp) + 2 * sz);
        if (!addr)
                return NULL;

        tp = addr;

        addr += sizeof(*tp);
        tp->core_siblings = addr;
        addr += sz;
        tp->thread_siblings = addr;

        for (i = 0; i < nr; i++) {
                ret = build_cpu_topo(tp, i);
                if (ret < 0)
                        break;
        }
        if (ret) {
                free_cpu_topo(tp);
                tp = NULL;
        }
        return tp;
}

static int write_cpu_topology(int fd, struct perf_header *h __maybe_unused,
                          struct perf_evlist *evlist __maybe_unused)
{
        struct cpu_topo *tp;
        u32 i;
        int ret;

        tp = build_cpu_topology();
        if (!tp)
                return -1;

        ret = do_write(fd, &tp->core_sib, sizeof(tp->core_sib));
        if (ret < 0)
                goto done;

        for (i = 0; i < tp->core_sib; i++) {
                ret = do_write_string(fd, tp->core_siblings[i]);
                if (ret < 0)
                        goto done;
        }
        ret = do_write(fd, &tp->thread_sib, sizeof(tp->thread_sib));
        if (ret < 0)
                goto done;

        for (i = 0; i < tp->thread_sib; i++) {
                ret = do_write_string(fd, tp->thread_siblings[i]);
                if (ret < 0)
                        break;
        }
done:
        free_cpu_topo(tp);
        return ret;
}



static int write_total_mem(int fd, struct perf_header *h __maybe_unused,
                          struct perf_evlist *evlist __maybe_unused)
{
        char *buf = NULL;
        FILE *fp;
        size_t len = 0;
        int ret = -1, n;
        uint64_t mem;

        fp = fopen("/proc/meminfo", "r");
        if (!fp)
                return -1;

        while (getline(&buf, &len, fp) > 0) {
                ret = strncmp(buf, "MemTotal:", 9);
                if (!ret)
                        break;
        }
        if (!ret) {
                n = sscanf(buf, "%*s %"PRIu64, &mem);
                if (n == 1)
                        ret = do_write(fd, &mem, sizeof(mem));
        } else
                ret = -1;
        free(buf);
        fclose(fp);
        return ret;
}

static int write_topo_node(int fd, int node)
{
        char str[MAXPATHLEN];
        char field[32];
        char *buf = NULL, *p;
        size_t len = 0;
        FILE *fp;
        u64 mem_total, mem_free, mem;
        int ret = -1;

        sprintf(str, "/sys/devices/system/node/node%d/meminfo", node);
        fp = fopen(str, "r");
        if (!fp)
                return -1;

        while (getline(&buf, &len, fp) > 0) {
                /* skip over invalid lines */
                if (!strchr(buf, ':'))
                        continue;
                if (sscanf(buf, "%*s %*d %31s %"PRIu64, field, &mem) != 2)
                        goto done;
                if (!strcmp(field, "MemTotal:"))
                        mem_total = mem;
                if (!strcmp(field, "MemFree:"))
                        mem_free = mem;
        }

        fclose(fp);
        fp = NULL;

        ret = do_write(fd, &mem_total, sizeof(u64));
        if (ret)
                goto done;

        ret = do_write(fd, &mem_free, sizeof(u64));
        if (ret)
                goto done;

        ret = -1;
        sprintf(str, "/sys/devices/system/node/node%d/cpulist", node);

        fp = fopen(str, "r");
        if (!fp)
                goto done;

        if (getline(&buf, &len, fp) <= 0)
                goto done;

        p = strchr(buf, '\n');
        if (p)
                *p = '\0';

        ret = do_write_string(fd, buf);
done:
        free(buf);
        if (fp)
                fclose(fp);
        return ret;
}

static int write_numa_topology(int fd, struct perf_header *h __maybe_unused,
                          struct perf_evlist *evlist __maybe_unused)
{
        char *buf = NULL;
        size_t len = 0;
        FILE *fp;
        struct cpu_map *node_map = NULL;
        char *c;
        u32 nr, i, j;
        int ret = -1;

        fp = fopen("/sys/devices/system/node/online", "r");
        if (!fp)
                return -1;

        if (getline(&buf, &len, fp) <= 0)
                goto done;

        c = strchr(buf, '\n');
        if (c)
                *c = '\0';

        node_map = cpu_map__new(buf);
        if (!node_map)
                goto done;

        nr = (u32)node_map->nr;

        ret = do_write(fd, &nr, sizeof(nr));
        if (ret < 0)
                goto done;

        for (i = 0; i < nr; i++) {
                j = (u32)node_map->map[i];
                ret = do_write(fd, &j, sizeof(j));
                if (ret < 0)
                        break;

                ret = write_topo_node(fd, i);
                if (ret < 0)
                        break;
        }
done:
        free(buf);
        fclose(fp);
        free(node_map);
        return ret;
}

/*
 * File format:
 *
 * struct pmu_mappings {
 *      u32     pmu_num;
 *      struct pmu_map {
 *              u32     type;
 *              char    name[];
 *      }[pmu_num];
 * };
 */

static int write_pmu_mappings(int fd, struct perf_header *h __maybe_unused,
                              struct perf_evlist *evlist __maybe_unused)
{
        struct perf_pmu *pmu = NULL;
        off_t offset = lseek(fd, 0, SEEK_CUR);
        __u32 pmu_num = 0;
        int ret;

        /* write real pmu_num later */
        ret = do_write(fd, &pmu_num, sizeof(pmu_num));
        if (ret < 0)
                return ret;

        while ((pmu = perf_pmu__scan(pmu))) {
                if (!pmu->name)
                        continue;
                pmu_num++;

                ret = do_write(fd, &pmu->type, sizeof(pmu->type));
                if (ret < 0)
                        return ret;

                ret = do_write_string(fd, pmu->name);
                if (ret < 0)
                        return ret;
        }

        if (pwrite(fd, &pmu_num, sizeof(pmu_num), offset) != sizeof(pmu_num)) {
                /* discard all */
                lseek(fd, offset, SEEK_SET);
                return -1;
        }

        return 0;
}

/*
 * File format:
 *
 * struct group_descs {
 *      u32     nr_groups;
 *      struct group_desc {
 *              char    name[];
 *              u32     leader_idx;
 *              u32     nr_members;
 *      }[nr_groups];
 * };
 */
static int write_group_desc(int fd, struct perf_header *h __maybe_unused,
                            struct perf_evlist *evlist)
{
        u32 nr_groups = evlist->nr_groups;
        struct perf_evsel *evsel;
        int ret;

        ret = do_write(fd, &nr_groups, sizeof(nr_groups));
        if (ret < 0)
                return ret;

        evlist__for_each(evlist, evsel) {
                if (perf_evsel__is_group_leader(evsel) &&
                    evsel->nr_members > 1) {
                        const char *name = evsel->group_name ?: "{anon_group}";
                        u32 leader_idx = evsel->idx;
                        u32 nr_members = evsel->nr_members;

                        ret = do_write_string(fd, name);
                        if (ret < 0)
                                return ret;

                        ret = do_write(fd, &leader_idx, sizeof(leader_idx));
                        if (ret < 0)
                                return ret;

                        ret = do_write(fd, &nr_members, sizeof(nr_members));
                        if (ret < 0)
                                return ret;
                }
        }
        return 0;
}

/*
 * default get_cpuid(): nothing gets recorded
 * actual implementation must be in arch/$(ARCH)/util/header.c
 */
int __attribute__ ((weak)) get_cpuid(char *buffer __maybe_unused,
                                     size_t sz __maybe_unused)
{
        return -1;
}

static int write_cpuid(int fd, struct perf_header *h __maybe_unused,
                       struct perf_evlist *evlist __maybe_unused)
{
        char buffer[64];
        int ret;

        ret = get_cpuid(buffer, sizeof(buffer));
        if (!ret)
                goto write_it;

        return -1;
write_it:
        return do_write_string(fd, buffer);
}

static int write_branch_stack(int fd __maybe_unused,
                              struct perf_header *h __maybe_unused,
                       struct perf_evlist *evlist __maybe_unused)
{
        return 0;
}

static int write_auxtrace(int fd, struct perf_header *h,
                          struct perf_evlist *evlist __maybe_unused)
{
        struct perf_session *session;
        int err;

        session = container_of(h, struct perf_session, header);

        err = auxtrace_index__write(fd, &session->auxtrace_index);
        if (err < 0)
                pr_err("Failed to write auxtrace index\n");
        return err;
}

static void print_hostname(struct perf_header *ph, int fd __maybe_unused,
                           FILE *fp)
{
        fprintf(fp, "# hostname : %s\n", ph->env.hostname);
}

static void print_osrelease(struct perf_header *ph, int fd __maybe_unused,
                            FILE *fp)
{
        fprintf(fp, "# os release : %s\n", ph->env.os_release);
}

static void print_arch(struct perf_header *ph, int fd __maybe_unused, FILE *fp)
{
        fprintf(fp, "# arch : %s\n", ph->env.arch);
}

static void print_cpudesc(struct perf_header *ph, int fd __maybe_unused,
                          FILE *fp)
{
        fprintf(fp, "# cpudesc : %s\n", ph->env.cpu_desc);
}

static void print_nrcpus(struct perf_header *ph, int fd __maybe_unused,
                         FILE *fp)
{
        fprintf(fp, "# nrcpus online : %u\n", ph->env.nr_cpus_online);
        fprintf(fp, "# nrcpus avail : %u\n", ph->env.nr_cpus_avail);
}

static void print_version(struct perf_header *ph, int fd __maybe_unused,
                          FILE *fp)
{
        fprintf(fp, "# perf version : %s\n", ph->env.version);
}

static void print_cmdline(struct perf_header *ph, int fd __maybe_unused,
                          FILE *fp)
{
        int nr, i;
        char *str;

        nr = ph->env.nr_cmdline;
        str = ph->env.cmdline;

        fprintf(fp, "# cmdline : ");

        for (i = 0; i < nr; i++) {
                fprintf(fp, "%s ", str);
                str += strlen(str) + 1;
        }
        fputc('\n', fp);
}

static void print_cpu_topology(struct perf_header *ph, int fd __maybe_unused,
                               FILE *fp)
{
        int nr, i;
        char *str;

        nr = ph->env.nr_sibling_cores;
        str = ph->env.sibling_cores;

        for (i = 0; i < nr; i++) {
                fprintf(fp, "# sibling cores   : %s\n", str);
                str += strlen(str) + 1;
        }

        nr = ph->env.nr_sibling_threads;
        str = ph->env.sibling_threads;

        for (i = 0; i < nr; i++) {
                fprintf(fp, "# sibling threads : %s\n", str);
                str += strlen(str) + 1;
        }
}

static void free_event_desc(struct perf_evsel *events)
{
        struct perf_evsel *evsel;

        if (!events)
                return;

        for (evsel = events; evsel->attr.size; evsel++) {
                zfree(&evsel->name);
                zfree(&evsel->id);
        }

        free(events);
}

static struct perf_evsel *
read_event_desc(struct perf_header *ph, int fd)
{
        struct perf_evsel *evsel, *events = NULL;
        u64 *id;
        void *buf = NULL;
        u32 nre, sz, nr, i, j;
        ssize_t ret;
        size_t msz;

        /* number of events */
        ret = readn(fd, &nre, sizeof(nre));
        if (ret != (ssize_t)sizeof(nre))
                goto error;

        if (ph->needs_swap)
                nre = bswap_32(nre);

        ret = readn(fd, &sz, sizeof(sz));
        if (ret != (ssize_t)sizeof(sz))
                goto error;

        if (ph->needs_swap)
                sz = bswap_32(sz);

        /* buffer to hold on file attr struct */
        buf = malloc(sz);
        if (!buf)
                goto error;

        /* the last event terminates with evsel->attr.size == 0: */
        events = calloc(nre + 1, sizeof(*events));
        if (!events)
                goto error;

        msz = sizeof(evsel->attr);
        if (sz < msz)
                msz = sz;

        for (i = 0, evsel = events; i < nre; evsel++, i++) {
                evsel->idx = i;

                /*
                 * must read entire on-file attr struct to
                 * sync up with layout.
                 */
                ret = readn(fd, buf, sz);
                if (ret != (ssize_t)sz)
                        goto error;

                if (ph->needs_swap)
                        perf_event__attr_swap(buf);

                memcpy(&evsel->attr, buf, msz);

                ret = readn(fd, &nr, sizeof(nr));
                if (ret != (ssize_t)sizeof(nr))
                        goto error;

                if (ph->needs_swap) {
                        nr = bswap_32(nr);
                        evsel->needs_swap = true;
                }

                evsel->name = do_read_string(fd, ph);

                if (!nr)
                        continue;

                id = calloc(nr, sizeof(*id));
                if (!id)
                        goto error;
                evsel->ids = nr;
                evsel->id = id;

                for (j = 0 ; j < nr; j++) {
                        ret = readn(fd, id, sizeof(*id));
                        if (ret != (ssize_t)sizeof(*id))
                                goto error;
                        if (ph->needs_swap)
                                *id = bswap_64(*id);
                        id++;
                }
        }
out:
        free(buf);
        return events;
error:
        if (events)
                free_event_desc(events);
        events = NULL;
        goto out;
}

static int __desc_attr__fprintf(FILE *fp, const char *name, const char *val,
                                void *priv __attribute__((unused)))
{
        return fprintf(fp, ", %s = %s", name, val);
}

static void print_event_desc(struct perf_header *ph, int fd, FILE *fp)
{
        struct perf_evsel *evsel, *events = read_event_desc(ph, fd);
        u32 j;
        u64 *id;

        if (!events) {
                fprintf(fp, "# event desc: not available or unable to read\n");
                return;
        }

        for (evsel = events; evsel->attr.size; evsel++) {
                fprintf(fp, "# event : name = %s, ", evsel->name);

                if (evsel->ids) {
                        fprintf(fp, ", id = {");
                        for (j = 0, id = evsel->id; j < evsel->ids; j++, id++) {
                                if (j)
                                        fputc(',', fp);
                                fprintf(fp, " %"PRIu64, *id);
                        }
                        fprintf(fp, " }");
                }

                perf_event_attr__fprintf(fp, &evsel->attr, __desc_attr__fprintf, NULL);

                fputc('\n', fp);
        }

        free_event_desc(events);
}

static void print_total_mem(struct perf_header *ph, int fd __maybe_unused,
                            FILE *fp)
{
        fprintf(fp, "# total memory : %Lu kB\n", ph->env.total_mem);
}

static void print_numa_topology(struct perf_header *ph, int fd __maybe_unused,
                                FILE *fp)
{
        u32 nr, c, i;
        char *str, *tmp;
        uint64_t mem_total, mem_free;

        /* nr nodes */
        nr = ph->env.nr_numa_nodes;
        str = ph->env.numa_nodes;

        for (i = 0; i < nr; i++) {
                /* node number */
                c = strtoul(str, &tmp, 0);
                if (*tmp != ':')
                        goto error;

                str = tmp + 1;
                mem_total = strtoull(str, &tmp, 0);
                if (*tmp != ':')
                        goto error;

                str = tmp + 1;
                mem_free = strtoull(str, &tmp, 0);
                if (*tmp != ':')
                        goto error;

                fprintf(fp, "# node%u meminfo  : total = %"PRIu64" kB,"
                            " free = %"PRIu64" kB\n",
                        c, mem_total, mem_free);

                str = tmp + 1;
                fprintf(fp, "# node%u cpu list : %s\n", c, str);

                str += strlen(str) + 1;
        }
        return;
error:
        fprintf(fp, "# numa topology : not available\n");
}

static void print_cpuid(struct perf_header *ph, int fd __maybe_unused, FILE *fp)
{
        fprintf(fp, "# cpuid : %s\n", ph->env.cpuid);
}

static void print_branch_stack(struct perf_header *ph __maybe_unused,
                               int fd __maybe_unused, FILE *fp)
{
        fprintf(fp, "# contains samples with branch stack\n");
}

static void print_auxtrace(struct perf_header *ph __maybe_unused,
                           int fd __maybe_unused, FILE *fp)
{
        fprintf(fp, "# contains AUX area data (e.g. instruction trace)\n");
}

static void print_pmu_mappings(struct perf_header *ph, int fd __maybe_unused,
                               FILE *fp)
{
        const char *delimiter = "# pmu mappings: ";
        char *str, *tmp;
        u32 pmu_num;
        u32 type;

        pmu_num = ph->env.nr_pmu_mappings;
        if (!pmu_num) {
                fprintf(fp, "# pmu mappings: not available\n");
                return;
        }

        str = ph->env.pmu_mappings;

        while (pmu_num) {
                type = strtoul(str, &tmp, 0);
                if (*tmp != ':')
                        goto error;

                str = tmp + 1;
                fprintf(fp, "%s%s = %" PRIu32, delimiter, str, type);

                delimiter = ", ";
                str += strlen(str) + 1;
                pmu_num--;
        }

        fprintf(fp, "\n");

        if (!pmu_num)
                return;
error:
        fprintf(fp, "# pmu mappings: unable to read\n");
}

static void print_group_desc(struct perf_header *ph, int fd __maybe_unused,
                             FILE *fp)
{
        struct perf_session *session;
        struct perf_evsel *evsel;
        u32 nr = 0;

        session = container_of(ph, struct perf_session, header);

        evlist__for_each(session->evlist, evsel) {
                if (perf_evsel__is_group_leader(evsel) &&
                    evsel->nr_members > 1) {
                        fprintf(fp, "# group: %s{%s", evsel->group_name ?: "",
                                perf_evsel__name(evsel));

                        nr = evsel->nr_members - 1;
                } else if (nr) {
                        fprintf(fp, ",%s", perf_evsel__name(evsel));

                        if (--nr == 0)
                                fprintf(fp, "}\n");
                }
        }
}

static int __event_process_build_id(struct build_id_event *bev,
                                    char *filename,
                                    struct perf_session *session)
{
        int err = -1;
        struct machine *machine;
        u16 misc;
        struct dso *dso;
        enum dso_kernel_type dso_type;

        machine = perf_session__findnew_machine(session, bev->pid);
        if (!machine)
                goto out;

        misc = bev->header.misc & PERF_RECORD_MISC_CPUMODE_MASK;

        switch (misc) {
        case PERF_RECORD_MISC_KERNEL:
                dso_type = DSO_TYPE_KERNEL;
                break;
        case PERF_RECORD_MISC_GUEST_KERNEL:
                dso_type = DSO_TYPE_GUEST_KERNEL;
                break;
        case PERF_RECORD_MISC_USER:
        case PERF_RECORD_MISC_GUEST_USER:
                dso_type = DSO_TYPE_USER;
                break;
        default:
                goto out;
        }

        dso = machine__findnew_dso(machine, filename);
        if (dso != NULL) {
                char sbuild_id[BUILD_ID_SIZE * 2 + 1];

                dso__set_build_id(dso, &bev->build_id);

                if (!is_kernel_module(filename))
                        dso->kernel = dso_type;

                build_id__sprintf(dso->build_id, sizeof(dso->build_id),
                                  sbuild_id);
                pr_debug("build id event received for %s: %s\n",
                         dso->long_name, sbuild_id);
        }

        err = 0;
out:
        return err;
}

static int perf_header__read_build_ids_abi_quirk(struct perf_header *header,
                                                 int input, u64 offset, u64 size)
{
        struct perf_session *session = container_of(header, struct perf_session, header);
        struct {
                struct perf_event_header   header;
                u8                         build_id[PERF_ALIGN(BUILD_ID_SIZE, sizeof(u64))];
                char                       filename[0];
        } old_bev;
        struct build_id_event bev;
        char filename[PATH_MAX];
        u64 limit = offset + size;

        while (offset < limit) {
                ssize_t len;

                if (readn(input, &old_bev, sizeof(old_bev)) != sizeof(old_bev))
                        return -1;

                if (header->needs_swap)
                        perf_event_header__bswap(&old_bev.header);

                len = old_bev.header.size - sizeof(old_bev);
                if (readn(input, filename, len) != len)
                        return -1;

                bev.header = old_bev.header;

                /*
                 * As the pid is the missing value, we need to fill
                 * it properly. The header.misc value give us nice hint.
                 */
                bev.pid = HOST_KERNEL_ID;
                if (bev.header.misc == PERF_RECORD_MISC_GUEST_USER ||
                    bev.header.misc == PERF_RECORD_MISC_GUEST_KERNEL)
                        bev.pid = DEFAULT_GUEST_KERNEL_ID;

                memcpy(bev.build_id, old_bev.build_id, sizeof(bev.build_id));
                __event_process_build_id(&bev, filename, session);

                offset += bev.header.size;
        }

        return 0;
}

static int perf_header__read_build_ids(struct perf_header *header,
                                       int input, u64 offset, u64 size)
{
        struct perf_session *session = container_of(header, struct perf_session, header);
        struct build_id_event bev;
        char filename[PATH_MAX];
        u64 limit = offset + size, orig_offset = offset;
        int err = -1;

        while (offset < limit) {
                ssize_t len;

                if (readn(input, &bev, sizeof(bev)) != sizeof(bev))
                        goto out;

                if (header->needs_swap)
                        perf_event_header__bswap(&bev.header);

                len = bev.header.size - sizeof(bev);
                if (readn(input, filename, len) != len)
                        goto out;
                /*
                 * The a1645ce1 changeset:
                 *
                 * "perf: 'perf kvm' tool for monitoring guest performance from host"
                 *
                 * Added a field to struct build_id_event that broke the file
                 * format.
                 *
                 * Since the kernel build-id is the first entry, process the
                 * table using the old format if the well known
                 * '[kernel.kallsyms]' string for the kernel build-id has the
                 * first 4 characters chopped off (where the pid_t sits).
                 */
                if (memcmp(filename, "nel.kallsyms]", 13) == 0) {
                        if (lseek(input, orig_offset, SEEK_SET) == (off_t)-1)
                                return -1;
                        return perf_header__read_build_ids_abi_quirk(header, input, offset, size);
                }

                __event_process_build_id(&bev, filename, session);

                offset += bev.header.size;
        }
        err = 0;
out:
        return err;
}

static int process_tracing_data(struct perf_file_section *section __maybe_unused,
                                struct perf_header *ph __maybe_unused,
                                int fd, void *data)
{
        ssize_t ret = trace_report(fd, data, false);
        return ret < 0 ? -1 : 0;
}

static int process_build_id(struct perf_file_section *section,
                            struct perf_header *ph, int fd,
                            void *data __maybe_unused)
{
        if (perf_header__read_build_ids(ph, fd, section->offset, section->size))
                pr_debug("Failed to read buildids, continuing...\n");
        return 0;
}

static int process_hostname(struct perf_file_section *section __maybe_unused,
                            struct perf_header *ph, int fd,
                            void *data __maybe_unused)
{
        ph->env.hostname = do_read_string(fd, ph);
        return ph->env.hostname ? 0 : -ENOMEM;
}

static int process_osrelease(struct perf_file_section *section __maybe_unused,
                             struct perf_header *ph, int fd,
                             void *data __maybe_unused)
{
        ph->env.os_release = do_read_string(fd, ph);
        return ph->env.os_release ? 0 : -ENOMEM;
}

static int process_version(struct perf_file_section *section __maybe_unused,
                           struct perf_header *ph, int fd,
                           void *data __maybe_unused)
{
        ph->env.version = do_read_string(fd, ph);
        return ph->env.version ? 0 : -ENOMEM;
}

static int process_arch(struct perf_file_section *section __maybe_unused,
                        struct perf_header *ph, int fd,
                        void *data __maybe_unused)
{
        ph->env.arch = do_read_string(fd, ph);
        return ph->env.arch ? 0 : -ENOMEM;
}

static int process_nrcpus(struct perf_file_section *section __maybe_unused,
                          struct perf_header *ph, int fd,
                          void *data __maybe_unused)
{
        ssize_t ret;
        u32 nr;

        ret = readn(fd, &nr, sizeof(nr));
        if (ret != sizeof(nr))
                return -1;

        if (ph->needs_swap)
                nr = bswap_32(nr);

        ph->env.nr_cpus_online = nr;

        ret = readn(fd, &nr, sizeof(nr));
        if (ret != sizeof(nr))
                return -1;

        if (ph->needs_swap)
                nr = bswap_32(nr);

        ph->env.nr_cpus_avail = nr;
        return 0;
}

static int process_cpudesc(struct perf_file_section *section __maybe_unused,
                           struct perf_header *ph, int fd,
                           void *data __maybe_unused)
{
        ph->env.cpu_desc = do_read_string(fd, ph);
        return ph->env.cpu_desc ? 0 : -ENOMEM;
}

static int process_cpuid(struct perf_file_section *section __maybe_unused,
                         struct perf_header *ph,  int fd,
                         void *data __maybe_unused)
{
        ph->env.cpuid = do_read_string(fd, ph);
        return ph->env.cpuid ? 0 : -ENOMEM;
}

static int process_total_mem(struct perf_file_section *section __maybe_unused,
                             struct perf_header *ph, int fd,
                             void *data __maybe_unused)
{
        uint64_t mem;
        ssize_t ret;

        ret = readn(fd, &mem, sizeof(mem));
        if (ret != sizeof(mem))
                return -1;

        if (ph->needs_swap)
                mem = bswap_64(mem);

        ph->env.total_mem = mem;
        return 0;
}

static struct perf_evsel *
perf_evlist__find_by_index(struct perf_evlist *evlist, int idx)
{
        struct perf_evsel *evsel;

        evlist__for_each(evlist, evsel) {
                if (evsel->idx == idx)
                        return evsel;
        }

        return NULL;
}

static void
perf_evlist__set_event_name(struct perf_evlist *evlist,
                            struct perf_evsel *event)
{
        struct perf_evsel *evsel;

        if (!event->name)
                return;

        evsel = perf_evlist__find_by_index(evlist, event->idx);
        if (!evsel)
                return;

        if (evsel->name)
                return;

        evsel->name = strdup(event->name);
}

static int
process_event_desc(struct perf_file_section *section __maybe_unused,
                   struct perf_header *header, int fd,
                   void *data __maybe_unused)
{
        struct perf_session *session;
        struct perf_evsel *evsel, *events = read_event_desc(header, fd);

        if (!events)
                return 0;

        session = container_of(header, struct perf_session, header);
        for (evsel = events; evsel->attr.size; evsel++)
                perf_evlist__set_event_name(session->evlist, evsel);

        free_event_desc(events);

        return 0;
}

static int process_cmdline(struct perf_file_section *section __maybe_unused,
                           struct perf_header *ph, int fd,
                           void *data __maybe_unused)
{
        ssize_t ret;
        char *str;
        u32 nr, i;
        struct strbuf sb;

        ret = readn(fd, &nr, sizeof(nr));
        if (ret != sizeof(nr))
                return -1;

        if (ph->needs_swap)
                nr = bswap_32(nr);

        ph->env.nr_cmdline = nr;
        strbuf_init(&sb, 128);

        for (i = 0; i < nr; i++) {
                str = do_read_string(fd, ph);
                if (!str)
                        goto error;

                /* include a NULL character at the end */
                strbuf_add(&sb, str, strlen(str) + 1);
                free(str);
        }
        ph->env.cmdline = strbuf_detach(&sb, NULL);
        return 0;

error:
        strbuf_release(&sb);
        return -1;
}

static int process_cpu_topology(struct perf_file_section *section __maybe_unused,
                                struct perf_header *ph, int fd,
                                void *data __maybe_unused)
{
        ssize_t ret;
        u32 nr, i;
        char *str;
        struct strbuf sb;

        ret = readn(fd, &nr, sizeof(nr));
        if (ret != sizeof(nr))
                return -1;

        if (ph->needs_swap)
                nr = bswap_32(nr);

        ph->env.nr_sibling_cores = nr;
        strbuf_init(&sb, 128);

        for (i = 0; i < nr; i++) {
                str = do_read_string(fd, ph);
                if (!str)
                        goto error;

                /* include a NULL character at the end */
                strbuf_add(&sb, str, strlen(str) + 1);
                free(str);
        }
        ph->env.sibling_cores = strbuf_detach(&sb, NULL);

        ret = readn(fd, &nr, sizeof(nr));
        if (ret != sizeof(nr))
                return -1;

        if (ph->needs_swap)
                nr = bswap_32(nr);

        ph->env.nr_sibling_threads = nr;

        for (i = 0; i < nr; i++) {
                str = do_read_string(fd, ph);
                if (!str)
                        goto error;

                /* include a NULL character at the end */
                strbuf_add(&sb, str, strlen(str) + 1);
                free(str);
        }
        ph->env.sibling_threads = strbuf_detach(&sb, NULL);
        return 0;

error:
        strbuf_release(&sb);
        return -1;
}

static int process_numa_topology(struct perf_file_section *section __maybe_unused,
                                 struct perf_header *ph, int fd,
                                 void *data __maybe_unused)
{
        ssize_t ret;
        u32 nr, node, i;
        char *str;
        uint64_t mem_total, mem_free;
        struct strbuf sb;

        /* nr nodes */
        ret = readn(fd, &nr, sizeof(nr));
        if (ret != sizeof(nr))
                goto error;

        if (ph->needs_swap)
                nr = bswap_32(nr);

        ph->env.nr_numa_nodes = nr;
        strbuf_init(&sb, 256);

        for (i = 0; i < nr; i++) {
                /* node number */
                ret = readn(fd, &node, sizeof(node));
                if (ret != sizeof(node))
                        goto error;

                ret = readn(fd, &mem_total, sizeof(u64));
                if (ret != sizeof(u64))
                        goto error;

                ret = readn(fd, &mem_free, sizeof(u64));
                if (ret != sizeof(u64))
                        goto error;

                if (ph->needs_swap) {
                        node = bswap_32(node);
                        mem_total = bswap_64(mem_total);
                        mem_free = bswap_64(mem_free);
                }

                strbuf_addf(&sb, "%u:%"PRIu64":%"PRIu64":",
                            node, mem_total, mem_free);

                str = do_read_string(fd, ph);
                if (!str)
                        goto error;

                /* include a NULL character at the end */
                strbuf_add(&sb, str, strlen(str) + 1);
                free(str);
        }
        ph->env.numa_nodes = strbuf_detach(&sb, NULL);
        return 0;

error:
        strbuf_release(&sb);
        return -1;
}

static int process_pmu_mappings(struct perf_file_section *section __maybe_unused,
                                struct perf_header *ph, int fd,
                                void *data __maybe_unused)
{
        ssize_t ret;
        char *name;
        u32 pmu_num;
        u32 type;
        struct strbuf sb;

        ret = readn(fd, &pmu_num, sizeof(pmu_num));
        if (ret != sizeof(pmu_num))
                return -1;

        if (ph->needs_swap)
                pmu_num = bswap_32(pmu_num);

        if (!pmu_num) {
                pr_debug("pmu mappings not available\n");
                return 0;
        }

        ph->env.nr_pmu_mappings = pmu_num;
        strbuf_init(&sb, 128);

        while (pmu_num) {
                if (readn(fd, &type, sizeof(type)) != sizeof(type))
                        goto error;
                if (ph->needs_swap)
                        type = bswap_32(type);

                name = do_read_string(fd, ph);
                if (!name)
                        goto error;

                strbuf_addf(&sb, "%u:%s", type, name);
                /* include a NULL character at the end */
                strbuf_add(&sb, "", 1);

                free(name);
                pmu_num--;
        }
        ph->env.pmu_mappings = strbuf_detach(&sb, NULL);
        return 0;

error:
        strbuf_release(&sb);
        return -1;
}

static int process_group_desc(struct perf_file_section *section __maybe_unused,
                              struct perf_header *ph, int fd,
                              void *data __maybe_unused)
{
        size_t ret = -1;
        u32 i, nr, nr_groups;
        struct perf_session *session;
        struct perf_evsel *evsel, *leader = NULL;
        struct group_desc {
                char *name;
                u32 leader_idx;
                u32 nr_members;
        } *desc;

        if (readn(fd, &nr_groups, sizeof(nr_groups)) != sizeof(nr_groups))
                return -1;

        if (ph->needs_swap)
                nr_groups = bswap_32(nr_groups);

        ph->env.nr_groups = nr_groups;
        if (!nr_groups) {
                pr_debug("group desc not available\n");
                return 0;
        }

        desc = calloc(nr_groups, sizeof(*desc));
        if (!desc)
                return -1;

        for (i = 0; i < nr_groups; i++) {
                desc[i].name = do_read_string(fd, ph);
                if (!desc[i].name)
                        goto out_free;

                if (readn(fd, &desc[i].leader_idx, sizeof(u32)) != sizeof(u32))
                        goto out_free;

                if (readn(fd, &desc[i].nr_members, sizeof(u32)) != sizeof(u32))
                        goto out_free;

                if (ph->needs_swap) {
                        desc[i].leader_idx = bswap_32(desc[i].leader_idx);
                        desc[i].nr_members = bswap_32(desc[i].nr_members);
                }
        }

        /*
         * Rebuild group relationship based on the group_desc
         */
        session = container_of(ph, struct perf_session, header);
        session->evlist->nr_groups = nr_groups;

        i = nr = 0;
        evlist__for_each(session->evlist, evsel) {
                if (evsel->idx == (int) desc[i].leader_idx) {
                        evsel->leader = evsel;
                        /* {anon_group} is a dummy name */
                        if (strcmp(desc[i].name, "{anon_group}")) {
                                evsel->group_name = desc[i].name;
                                desc[i].name = NULL;
                        }
                        evsel->nr_members = desc[i].nr_members;

                        if (i >= nr_groups || nr > 0) {
                                pr_debug("invalid group desc\n");
                                goto out_free;
                        }

                        leader = evsel;
                        nr = evsel->nr_members - 1;
                        i++;
                } else if (nr) {
                        /* This is a group member */
                        evsel->leader = leader;

                        nr--;
                }
        }

        if (i != nr_groups || nr != 0) {
                pr_debug("invalid group desc\n");
                goto out_free;
        }

        ret = 0;
out_free:
        for (i = 0; i < nr_groups; i++)
                zfree(&desc[i].name);
        free(desc);

        return ret;
}

static int process_auxtrace(struct perf_file_section *section,
                            struct perf_header *ph, int fd,
                            void *data __maybe_unused)
{
        struct perf_session *session;
        int err;

        session = container_of(ph, struct perf_session, header);

        err = auxtrace_index__process(fd, section->size, session,
                                      ph->needs_swap);
        if (err < 0)
                pr_err("Failed to process auxtrace index\n");
        return err;
}

struct feature_ops {
        int (*write)(int fd, struct perf_header *h, struct perf_evlist *evlist);
        void (*print)(struct perf_header *h, int fd, FILE *fp);
        int (*process)(struct perf_file_section *section,
                       struct perf_header *h, int fd, void *data);
        const char *name;
        bool full_only;
};

#define FEAT_OPA(n, func) \
        [n] = { .name = #n, .write = write_##func, .print = print_##func }
#define FEAT_OPP(n, func) \
        [n] = { .name = #n, .write = write_##func, .print = print_##func, \
                .process = process_##func }
#define FEAT_OPF(n, func) \
        [n] = { .name = #n, .write = write_##func, .print = print_##func, \
                .process = process_##func, .full_only = true }

/* feature_ops not implemented: */
#define print_tracing_data      NULL
#define print_build_id          NULL

static const struct feature_ops feat_ops[HEADER_LAST_FEATURE] = {
        FEAT_OPP(HEADER_TRACING_DATA,   tracing_data),
        FEAT_OPP(HEADER_BUILD_ID,       build_id),
        FEAT_OPP(HEADER_HOSTNAME,       hostname),
        FEAT_OPP(HEADER_OSRELEASE,      osrelease),
        FEAT_OPP(HEADER_VERSION,        version),
        FEAT_OPP(HEADER_ARCH,           arch),
        FEAT_OPP(HEADER_NRCPUS,         nrcpus),
        FEAT_OPP(HEADER_CPUDESC,        cpudesc),
        FEAT_OPP(HEADER_CPUID,          cpuid),
        FEAT_OPP(HEADER_TOTAL_MEM,      total_mem),
        FEAT_OPP(HEADER_EVENT_DESC,     event_desc),
        FEAT_OPP(HEADER_CMDLINE,        cmdline),
        FEAT_OPF(HEADER_CPU_TOPOLOGY,   cpu_topology),
        FEAT_OPF(HEADER_NUMA_TOPOLOGY,  numa_topology),
        FEAT_OPA(HEADER_BRANCH_STACK,   branch_stack),
        FEAT_OPP(HEADER_PMU_MAPPINGS,   pmu_mappings),
        FEAT_OPP(HEADER_GROUP_DESC,     group_desc),
        FEAT_OPP(HEADER_AUXTRACE,       auxtrace),
};

struct header_print_data {
        FILE *fp;
        bool full; /* extended list of headers */
};

static int perf_file_section__fprintf_info(struct perf_file_section *section,
                                           struct perf_header *ph,
                                           int feat, int fd, void *data)
{
        struct header_print_data *hd = data;

        if (lseek(fd, section->offset, SEEK_SET) == (off_t)-1) {
                pr_debug("Failed to lseek to %" PRIu64 " offset for feature "
                                "%d, continuing...\n", section->offset, feat);
                return 0;
        }
        if (feat >= HEADER_LAST_FEATURE) {
                pr_warning("unknown feature %d\n", feat);
                return 0;
        }
        if (!feat_ops[feat].print)
                return 0;

        if (!feat_ops[feat].full_only || hd->full)
                feat_ops[feat].print(ph, fd, hd->fp);
        else
                fprintf(hd->fp, "# %s info available, use -I to display\n",
                        feat_ops[feat].name);

        return 0;
}

int perf_header__fprintf_info(struct perf_session *session, FILE *fp, bool full)
{
        struct header_print_data hd;
        struct perf_header *header = &session->header;
        int fd = perf_data_file__fd(session->file);
        hd.fp = fp;
        hd.full = full;

        perf_header__process_sections(header, fd, &hd,
                                      perf_file_section__fprintf_info);
        return 0;
}

static int do_write_feat(int fd, struct perf_header *h, int type,
                         struct perf_file_section **p,
                         struct perf_evlist *evlist)
{
        int err;
        int ret = 0;

        if (perf_header__has_feat(h, type)) {
                if (!feat_ops[type].write)
                        return -1;

                (*p)->offset = lseek(fd, 0, SEEK_CUR);

                err = feat_ops[type].write(fd, h, evlist);
                if (err < 0) {
                        pr_debug("failed to write feature %d\n", type);

                        /* undo anything written */
                        lseek(fd, (*p)->offset, SEEK_SET);

                        return -1;
                }
                (*p)->size = lseek(fd, 0, SEEK_CUR) - (*p)->offset;
                (*p)++;
        }
        return ret;
}

static int perf_header__adds_write(struct perf_header *header,
                                   struct perf_evlist *evlist, int fd)
{
        int nr_sections;
        struct perf_file_section *feat_sec, *p;
        int sec_size;
        u64 sec_start;
        int feat;
        int err;

        nr_sections = bitmap_weight(header->adds_features, HEADER_FEAT_BITS);
        if (!nr_sections)
                return 0;

        feat_sec = p = calloc(nr_sections, sizeof(*feat_sec));
        if (feat_sec == NULL)
                return -ENOMEM;

        sec_size = sizeof(*feat_sec) * nr_sections;

        sec_start = header->feat_offset;
        lseek(fd, sec_start + sec_size, SEEK_SET);

        for_each_set_bit(feat, header->adds_features, HEADER_FEAT_BITS) {
                if (do_write_feat(fd, header, feat, &p, evlist))
                        perf_header__clear_feat(header, feat);
        }

        lseek(fd, sec_start, SEEK_SET);
        /*
         * may write more than needed due to dropped feature, but
         * this is okay, reader will skip the mising entries
         */
        err = do_write(fd, feat_sec, sec_size);
        if (err < 0)
                pr_debug("failed to write feature section\n");
        free(feat_sec);
        return err;
}

int perf_header__write_pipe(int fd)
{
        struct perf_pipe_file_header f_header;
        int err;

        f_header = (struct perf_pipe_file_header){
                .magic     = PERF_MAGIC,
                .size      = sizeof(f_header),
        };

        err = do_write(fd, &f_header, sizeof(f_header));
        if (err < 0) {
                pr_debug("failed to write perf pipe header\n");
                return err;
        }

        return 0;
}

int perf_session__write_header(struct perf_session *session,
                               struct perf_evlist *evlist,
                               int fd, bool at_exit)
{
        struct perf_file_header f_header;
        struct perf_file_attr   f_attr;
        struct perf_header *header = &session->header;
        struct perf_evsel *evsel;
        u64 attr_offset;
        int err;

        lseek(fd, sizeof(f_header), SEEK_SET);

        evlist__for_each(session->evlist, evsel) {
                evsel->id_offset = lseek(fd, 0, SEEK_CUR);
                err = do_write(fd, evsel->id, evsel->ids * sizeof(u64));
                if (err < 0) {
                        pr_debug("failed to write perf header\n");
                        return err;
                }
        }

        attr_offset = lseek(fd, 0, SEEK_CUR);

        evlist__for_each(evlist, evsel) {
                f_attr = (struct perf_file_attr){
                        .attr = evsel->attr,
                        .ids  = {
                                .offset = evsel->id_offset,
                                .size   = evsel->ids * sizeof(u64),
                        }
                };
                err = do_write(fd, &f_attr, sizeof(f_attr));
                if (err < 0) {
                        pr_debug("failed to write perf header attribute\n");
                        return err;
                }
        }

        if (!header->data_offset)
                header->data_offset = lseek(fd, 0, SEEK_CUR);
        header->feat_offset = header->data_offset + header->data_size;

        if (at_exit) {
                err = perf_header__adds_write(header, evlist, fd);
                if (err < 0)
                        return err;
        }

        f_header = (struct perf_file_header){
                .magic     = PERF_MAGIC,
                .size      = sizeof(f_header),
                .attr_size = sizeof(f_attr),
                .attrs = {
                        .offset = attr_offset,
                        .size   = evlist->nr_entries * sizeof(f_attr),
                },
                .data = {
                        .offset = header->data_offset,
                        .size   = header->data_size,
                },
                /* event_types is ignored, store zeros */
        };

        memcpy(&f_header.adds_features, &header->adds_features, sizeof(header->adds_features));

        lseek(fd, 0, SEEK_SET);
        err = do_write(fd, &f_header, sizeof(f_header));
        if (err < 0) {
                pr_debug("failed to write perf header\n");
                return err;
        }
        lseek(fd, header->data_offset + header->data_size, SEEK_SET);

        return 0;
}

static int perf_header__getbuffer64(struct perf_header *header,
                                    int fd, void *buf, size_t size)
{
        if (readn(fd, buf, size) <= 0)
                return -1;

        if (header->needs_swap)
                mem_bswap_64(buf, size);

        return 0;
}

int perf_header__process_sections(struct perf_header *header, int fd,
                                  void *data,
                                  int (*process)(struct perf_file_section *section,
                                                 struct perf_header *ph,
                                                 int feat, int fd, void *data))
{
        struct perf_file_section *feat_sec, *sec;
        int nr_sections;
        int sec_size;
        int feat;
        int err;

        nr_sections = bitmap_weight(header->adds_features, HEADER_FEAT_BITS);
        if (!nr_sections)
                return 0;

        feat_sec = sec = calloc(nr_sections, sizeof(*feat_sec));
        if (!feat_sec)
                return -1;

        sec_size = sizeof(*feat_sec) * nr_sections;

        lseek(fd, header->feat_offset, SEEK_SET);

        err = perf_header__getbuffer64(header, fd, feat_sec, sec_size);
        if (err < 0)
                goto out_free;

        for_each_set_bit(feat, header->adds_features, HEADER_LAST_FEATURE) {
                err = process(sec++, header, feat, fd, data);
                if (err < 0)
                        goto out_free;
        }
        err = 0;
out_free:
        free(feat_sec);
        return err;
}

static const int attr_file_abi_sizes[] = {
        [0] = PERF_ATTR_SIZE_VER0,
        [1] = PERF_ATTR_SIZE_VER1,
        [2] = PERF_ATTR_SIZE_VER2,
        [3] = PERF_ATTR_SIZE_VER3,
        [4] = PERF_ATTR_SIZE_VER4,
        0,
};

/*
 * In the legacy file format, the magic number is not used to encode endianness.
 * hdr_sz was used to encode endianness. But given that hdr_sz can vary based
 * on ABI revisions, we need to try all combinations for all endianness to
 * detect the endianness.
 */
static int try_all_file_abis(uint64_t hdr_sz, struct perf_header *ph)
{
        uint64_t ref_size, attr_size;
        int i;

        for (i = 0 ; attr_file_abi_sizes[i]; i++) {
                ref_size = attr_file_abi_sizes[i]
                         + sizeof(struct perf_file_section);
                if (hdr_sz != ref_size) {
                        attr_size = bswap_64(hdr_sz);
                        if (attr_size != ref_size)
                                continue;

                        ph->needs_swap = true;
                }
                pr_debug("ABI%d perf.data file detected, need_swap=%d\n",
                         i,
                         ph->needs_swap);
                return 0;
        }
        /* could not determine endianness */
        return -1;
}

#define PERF_PIPE_HDR_VER0      16

static const size_t attr_pipe_abi_sizes[] = {
        [0] = PERF_PIPE_HDR_VER0,
        0,
};

/*
 * In the legacy pipe format, there is an implicit assumption that endiannesss
 * between host recording the samples, and host parsing the samples is the
 * same. This is not always the case given that the pipe output may always be
 * redirected into a file and analyzed on a different machine with possibly a
 * different endianness and perf_event ABI revsions in the perf tool itself.
 */
static int try_all_pipe_abis(uint64_t hdr_sz, struct perf_header *ph)
{
        u64 attr_size;
        int i;

        for (i = 0 ; attr_pipe_abi_sizes[i]; i++) {
                if (hdr_sz != attr_pipe_abi_sizes[i]) {
                        attr_size = bswap_64(hdr_sz);
                        if (attr_size != hdr_sz)
                                continue;

                        ph->needs_swap = true;
                }
                pr_debug("Pipe ABI%d perf.data file detected\n", i);
                return 0;
        }
        return -1;
}

bool is_perf_magic(u64 magic)
{
        if (!memcmp(&magic, __perf_magic1, sizeof(magic))
                || magic == __perf_magic2
                || magic == __perf_magic2_sw)
                return true;

        return false;
}

static int check_magic_endian(u64 magic, uint64_t hdr_sz,
                              bool is_pipe, struct perf_header *ph)
{
        int ret;

        /* check for legacy format */
        ret = memcmp(&magic, __perf_magic1, sizeof(magic));
        if (ret == 0) {
                ph->version = PERF_HEADER_VERSION_1;
                pr_debug("legacy perf.data format\n");
                if (is_pipe)
                        return try_all_pipe_abis(hdr_sz, ph);

                return try_all_file_abis(hdr_sz, ph);
        }
        /*
         * the new magic number serves two purposes:
         * - unique number to identify actual perf.data files
         * - encode endianness of file
         */
        ph->version = PERF_HEADER_VERSION_2;

        /* check magic number with one endianness */
        if (magic == __perf_magic2)
                return 0;

        /* check magic number with opposite endianness */
        if (magic != __perf_magic2_sw)
                return -1;

        ph->needs_swap = true;

        return 0;
}

int perf_file_header__read(struct perf_file_header *header,
                           struct perf_header *ph, int fd)
{
        ssize_t ret;

        lseek(fd, 0, SEEK_SET);

        ret = readn(fd, header, sizeof(*header));
        if (ret <= 0)
                return -1;

        if (check_magic_endian(header->magic,
                               header->attr_size, false, ph) < 0) {
                pr_debug("magic/endian check failed\n");
                return -1;
        }

        if (ph->needs_swap) {
                mem_bswap_64(header, offsetof(struct perf_file_header,
                             adds_features));
        }

        if (header->size != sizeof(*header)) {
                /* Support the previous format */
                if (header->size == offsetof(typeof(*header), adds_features))
                        bitmap_zero(header->adds_features, HEADER_FEAT_BITS);
                else
                        return -1;
        } else if (ph->needs_swap) {
                /*
                 * feature bitmap is declared as an array of unsigned longs --
                 * not good since its size can differ between the host that
                 * generated the data file and the host analyzing the file.
                 *
                 * We need to handle endianness, but we don't know the size of
                 * the unsigned long where the file was generated. Take a best
                 * guess at determining it: try 64-bit swap first (ie., file
                 * created on a 64-bit host), and check if the hostname feature
                 * bit is set (this feature bit is forced on as of fbe96f2).
                 * If the bit is not, undo the 64-bit swap and try a 32-bit
                 * swap. If the hostname bit is still not set (e.g., older data
                 * file), punt and fallback to the original behavior --
                 * clearing all feature bits and setting buildid.
                 */
                mem_bswap_64(&header->adds_features,
                            BITS_TO_U64(HEADER_FEAT_BITS));

                if (!test_bit(HEADER_HOSTNAME, header->adds_features)) {
                        /* unswap as u64 */
                        mem_bswap_64(&header->adds_features,
                                    BITS_TO_U64(HEADER_FEAT_BITS));

                        /* unswap as u32 */
                        mem_bswap_32(&header->adds_features,
                                    BITS_TO_U32(HEADER_FEAT_BITS));
                }

                if (!test_bit(HEADER_HOSTNAME, header->adds_features)) {
                        bitmap_zero(header->adds_features, HEADER_FEAT_BITS);
                        set_bit(HEADER_BUILD_ID, header->adds_features);
                }
        }

        memcpy(&ph->adds_features, &header->adds_features,
               sizeof(ph->adds_features));

        ph->data_offset  = header->data.offset;
        ph->data_size    = header->data.size;
        ph->feat_offset  = header->data.offset + header->data.size;
        return 0;
}

static int perf_file_section__process(struct perf_file_section *section,
                                      struct perf_header *ph,
                                      int feat, int fd, void *data)
{
        if (lseek(fd, section->offset, SEEK_SET) == (off_t)-1) {
                pr_debug("Failed to lseek to %" PRIu64 " offset for feature "
                          "%d, continuing...\n", section->offset, feat);
                return 0;
        }

        if (feat >= HEADER_LAST_FEATURE) {
                pr_debug("unknown feature %d, continuing...\n", feat);
                return 0;
        }

        if (!feat_ops[feat].process)
                return 0;

        return feat_ops[feat].process(section, ph, fd, data);
}

static int perf_file_header__read_pipe(struct perf_pipe_file_header *header,
                                       struct perf_header *ph, int fd,
                                       bool repipe)
{
        ssize_t ret;

        ret = readn(fd, header, sizeof(*header));
        if (ret <= 0)
                return -1;

        if (check_magic_endian(header->magic, header->size, true, ph) < 0) {
                pr_debug("endian/magic failed\n");
                return -1;
        }

        if (ph->needs_swap)
                header->size = bswap_64(header->size);

        if (repipe && do_write(STDOUT_FILENO, header, sizeof(*header)) < 0)
                return -1;

        return 0;
}

static int perf_header__read_pipe(struct perf_session *session)
{
        struct perf_header *header = &session->header;
        struct perf_pipe_file_header f_header;

        if (perf_file_header__read_pipe(&f_header, header,
                                        perf_data_file__fd(session->file),
                                        session->repipe) < 0) {
                pr_debug("incompatible file format\n");
                return -EINVAL;
        }

        return 0;
}

static int read_attr(int fd, struct perf_header *ph,
                     struct perf_file_attr *f_attr)
{
        struct perf_event_attr *attr = &f_attr->attr;
        size_t sz, left;
        size_t our_sz = sizeof(f_attr->attr);
        ssize_t ret;

        memset(f_attr, 0, sizeof(*f_attr));

        /* read minimal guaranteed structure */
        ret = readn(fd, attr, PERF_ATTR_SIZE_VER0);
        if (ret <= 0) {
                pr_debug("cannot read %d bytes of header attr\n",
                         PERF_ATTR_SIZE_VER0);
                return -1;
        }

        /* on file perf_event_attr size */
        sz = attr->size;

        if (ph->needs_swap)
                sz = bswap_32(sz);

        if (sz == 0) {
                /* assume ABI0 */
                sz =  PERF_ATTR_SIZE_VER0;
        } else if (sz > our_sz) {
                pr_debug("file uses a more recent and unsupported ABI"
                         " (%zu bytes extra)\n", sz - our_sz);
                return -1;
        }
        /* what we have not yet read and that we know about */
        left = sz - PERF_ATTR_SIZE_VER0;
        if (left) {
                void *ptr = attr;
                ptr += PERF_ATTR_SIZE_VER0;

                ret = readn(fd, ptr, left);
        }
        /* read perf_file_section, ids are read in caller */
        ret = readn(fd, &f_attr->ids, sizeof(f_attr->ids));

        return ret <= 0 ? -1 : 0;
}

static int perf_evsel__prepare_tracepoint_event(struct perf_evsel *evsel,
                                                struct pevent *pevent)
{
        struct event_format *event;
        char bf[128];

        /* already prepared */
        if (evsel->tp_format)
                return 0;

        if (pevent == NULL) {
                pr_debug("broken or missing trace data\n");
                return -1;
        }

        event = pevent_find_event(pevent, evsel->attr.config);
        if (event == NULL)
                return -1;

        if (!evsel->name) {
                snprintf(bf, sizeof(bf), "%s:%s", event->system, event->name);
                evsel->name = strdup(bf);
                if (evsel->name == NULL)
                        return -1;
        }

        evsel->tp_format = event;
        return 0;
}

static int perf_evlist__prepare_tracepoint_events(struct perf_evlist *evlist,
                                                  struct pevent *pevent)
{
        struct perf_evsel *pos;

        evlist__for_each(evlist, pos) {
                if (pos->attr.type == PERF_TYPE_TRACEPOINT &&
                    perf_evsel__prepare_tracepoint_event(pos, pevent))
                        return -1;
        }

        return 0;
}

int perf_session__read_header(struct perf_session *session)
{
        struct perf_data_file *file = session->file;
        struct perf_header *header = &session->header;
        struct perf_file_header f_header;
        struct perf_file_attr   f_attr;
        u64                     f_id;
        int nr_attrs, nr_ids, i, j;
        int fd = perf_data_file__fd(file);

        session->evlist = perf_evlist__new();
        if (session->evlist == NULL)
                return -ENOMEM;

        if (perf_data_file__is_pipe(file))
                return perf_header__read_pipe(session);

        if (perf_file_header__read(&f_header, header, fd) < 0)
                return -EINVAL;

        /*
         * Sanity check that perf.data was written cleanly; data size is
         * initialized to 0 and updated only if the on_exit function is run.
         * If data size is still 0 then the file contains only partial
         * information.  Just warn user and process it as much as it can.
         */
        if (f_header.data.size == 0) {
                pr_warning("WARNING: The %s file's data size field is 0 which is unexpected.\n"
                           "Was the 'perf record' command properly terminated?\n",
                           file->path);
        }

        nr_attrs = f_header.attrs.size / f_header.attr_size;
        lseek(fd, f_header.attrs.offset, SEEK_SET);

        for (i = 0; i < nr_attrs; i++) {
                struct perf_evsel *evsel;
                off_t tmp;

                if (read_attr(fd, header, &f_attr) < 0)
                        goto out_errno;

                if (header->needs_swap) {
                        f_attr.ids.size   = bswap_64(f_attr.ids.size);
                        f_attr.ids.offset = bswap_64(f_attr.ids.offset);
                        perf_event__attr_swap(&f_attr.attr);
                }

                tmp = lseek(fd, 0, SEEK_CUR);
                evsel = perf_evsel__new(&f_attr.attr);

                if (evsel == NULL)
                        goto out_delete_evlist;

                evsel->needs_swap = header->needs_swap;
                /*
                 * Do it before so that if perf_evsel__alloc_id fails, this
                 * entry gets purged too at perf_evlist__delete().
                 */
                perf_evlist__add(session->evlist, evsel);

                nr_ids = f_attr.ids.size / sizeof(u64);
                /*
                 * We don't have the cpu and thread maps on the header, so
                 * for allocating the perf_sample_id table we fake 1 cpu and
                 * hattr->ids threads.
                 */
                if (perf_evsel__alloc_id(evsel, 1, nr_ids))
                        goto out_delete_evlist;

                lseek(fd, f_attr.ids.offset, SEEK_SET);

                for (j = 0; j < nr_ids; j++) {
                        if (perf_header__getbuffer64(header, fd, &f_id, sizeof(f_id)))
                                goto out_errno;

                        perf_evlist__id_add(session->evlist, evsel, 0, j, f_id);
                }

                lseek(fd, tmp, SEEK_SET);
        }

        symbol_conf.nr_events = nr_attrs;

        perf_header__process_sections(header, fd, &session->tevent,
                                      perf_file_section__process);

        if (perf_evlist__prepare_tracepoint_events(session->evlist,
                                                   session->tevent.pevent))
                goto out_delete_evlist;

        return 0;
out_errno:
        return -errno;

out_delete_evlist:
        perf_evlist__delete(session->evlist);
        session->evlist = NULL;
        return -ENOMEM;
}

int perf_event__synthesize_attr(struct perf_tool *tool,
                                struct perf_event_attr *attr, u32 ids, u64 *id,
                                perf_event__handler_t process)
{
        union perf_event *ev;
        size_t size;
        int err;

        size = sizeof(struct perf_event_attr);
        size = PERF_ALIGN(size, sizeof(u64));
        size += sizeof(struct perf_event_header);
        size += ids * sizeof(u64);

        ev = malloc(size);

        if (ev == NULL)
                return -ENOMEM;

        ev->attr.attr = *attr;
        memcpy(ev->attr.id, id, ids * sizeof(u64));

        ev->attr.header.type = PERF_RECORD_HEADER_ATTR;
        ev->attr.header.size = (u16)size;

        if (ev->attr.header.size == size)
                err = process(tool, ev, NULL, NULL);
        else
                err = -E2BIG;

        free(ev);

        return err;
}

int perf_event__synthesize_attrs(struct perf_tool *tool,
                                   struct perf_session *session,
                                   perf_event__handler_t process)
{
        struct perf_evsel *evsel;
        int err = 0;

        evlist__for_each(session->evlist, evsel) {
                err = perf_event__synthesize_attr(tool, &evsel->attr, evsel->ids,
                                                  evsel->id, process);
                if (err) {
                        pr_debug("failed to create perf header attribute\n");
                        return err;
                }
        }

        return err;
}

int perf_event__process_attr(struct perf_tool *tool __maybe_unused,
                             union perf_event *event,
                             struct perf_evlist **pevlist)
{
        u32 i, ids, n_ids;
        struct perf_evsel *evsel;
        struct perf_evlist *evlist = *pevlist;

        if (evlist == NULL) {
                *pevlist = evlist = perf_evlist__new();
                if (evlist == NULL)
                        return -ENOMEM;
        }

        evsel = perf_evsel__new(&event->attr.attr);
        if (evsel == NULL)
                return -ENOMEM;

        perf_evlist__add(evlist, evsel);

        ids = event->header.size;
        ids -= (void *)&event->attr.id - (void *)event;
        n_ids = ids / sizeof(u64);
        /*
         * We don't have the cpu and thread maps on the header, so
         * for allocating the perf_sample_id table we fake 1 cpu and
         * hattr->ids threads.
         */
        if (perf_evsel__alloc_id(evsel, 1, n_ids))
                return -ENOMEM;

        for (i = 0; i < n_ids; i++) {
                perf_evlist__id_add(evlist, evsel, 0, i, event->attr.id[i]);
        }

        symbol_conf.nr_events = evlist->nr_entries;

        return 0;
}

int perf_event__synthesize_tracing_data(struct perf_tool *tool, int fd,
                                        struct perf_evlist *evlist,
                                        perf_event__handler_t process)
{
        union perf_event ev;
        struct tracing_data *tdata;
        ssize_t size = 0, aligned_size = 0, padding;
        int err __maybe_unused = 0;

        /*
         * We are going to store the size of the data followed
         * by the data contents. Since the fd descriptor is a pipe,
         * we cannot seek back to store the size of the data once
         * we know it. Instead we:
         *
         * - write the tracing data to the temp file
         * - get/write the data size to pipe
         * - write the tracing data from the temp file
         *   to the pipe
         */
        tdata = tracing_data_get(&evlist->entries, fd, true);
        if (!tdata)
                return -1;

        memset(&ev, 0, sizeof(ev));

        ev.tracing_data.header.type = PERF_RECORD_HEADER_TRACING_DATA;
        size = tdata->size;
        aligned_size = PERF_ALIGN(size, sizeof(u64));
        padding = aligned_size - size;
        ev.tracing_data.header.size = sizeof(ev.tracing_data);
        ev.tracing_data.size = aligned_size;

        process(tool, &ev, NULL, NULL);

        /*
         * The put function will copy all the tracing data
         * stored in temp file to the pipe.
         */
        tracing_data_put(tdata);

        write_padded(fd, NULL, 0, padding);

        return aligned_size;
}

int perf_event__process_tracing_data(struct perf_tool *tool __maybe_unused,
                                     union perf_event *event,
                                     struct perf_session *session)
{
        ssize_t size_read, padding, size = event->tracing_data.size;
        int fd = perf_data_file__fd(session->file);
        off_t offset = lseek(fd, 0, SEEK_CUR);
        char buf[BUFSIZ];

        /* setup for reading amidst mmap */
        lseek(fd, offset + sizeof(struct tracing_data_event),
              SEEK_SET);

        size_read = trace_report(fd, &session->tevent,
                                 session->repipe);
        padding = PERF_ALIGN(size_read, sizeof(u64)) - size_read;

        if (readn(fd, buf, padding) < 0) {
                pr_err("%s: reading input file", __func__);
                return -1;
        }
        if (session->repipe) {
                int retw = write(STDOUT_FILENO, buf, padding);
                if (retw <= 0 || retw != padding) {
                        pr_err("%s: repiping tracing data padding", __func__);
                        return -1;
                }
        }

        if (size_read + padding != size) {
                pr_err("%s: tracing data size mismatch", __func__);
                return -1;
        }

        perf_evlist__prepare_tracepoint_events(session->evlist,
                                               session->tevent.pevent);

        return size_read + padding;
}

int perf_event__synthesize_build_id(struct perf_tool *tool,
                                    struct dso *pos, u16 misc,
                                    perf_event__handler_t process,
                                    struct machine *machine)
{
        union perf_event ev;
        size_t len;
        int err = 0;

        if (!pos->hit)
                return err;

        memset(&ev, 0, sizeof(ev));

        len = pos->long_name_len + 1;
        len = PERF_ALIGN(len, NAME_ALIGN);
        memcpy(&ev.build_id.build_id, pos->build_id, sizeof(pos->build_id));
        ev.build_id.header.type = PERF_RECORD_HEADER_BUILD_ID;
        ev.build_id.header.misc = misc;
        ev.build_id.pid = machine->pid;
        ev.build_id.header.size = sizeof(ev.build_id) + len;
        memcpy(&ev.build_id.filename, pos->long_name, pos->long_name_len);

        err = process(tool, &ev, NULL, machine);

        return err;
}

int perf_event__process_build_id(struct perf_tool *tool __maybe_unused,
                                 union perf_event *event,
                                 struct perf_session *session)
{
        __event_process_build_id(&event->build_id,
                                 event->build_id.filename,
                                 session);
        return 0;
}