src/lxc/parse.c

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2008
   5  *
   6  * Authors:
   7  * Daniel Lezcano <daniel.lezcano at free.fr>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #ifndef _GNU_SOURCE
  25 #define _GNU_SOURCE 1
  26 #endif
  27 #include <dirent.h>
  28 #include <errno.h>
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <sys/mman.h>
  33 #include <sys/sendfile.h>
  34
  35 #include "config.h"
  36 #include "file_utils.h"
  37 #include "log.h"
  38 #include "macro.h"
  39 #include "parse.h"
  40 #include "syscall_wrappers.h"
  41 #include "utils.h"
  42
  43 lxc_log_define(parse, lxc);
  44
  45 void *lxc_strmmap(void *addr, size_t length, int prot, int flags, int fd,
  46                   off_t offset)
  47 {
  48         void *tmp = NULL, *overlap = NULL;
  49
  50         /* We establish an anonymous mapping that is one byte larger than the
  51          * underlying file. The pages handed to us are zero filled. */
  52         tmp = mmap(addr, length + 1, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  53         if (tmp == MAP_FAILED)
  54                 return tmp;
  55
  56         /* Now we establish a fixed-address mapping starting at the address we
  57          * received from our anonymous mapping and replace all bytes excluding
  58          * the additional \0-byte with the file. This allows us to use normal
  59          * string-handling functions. */
  60         overlap = mmap(tmp, length, prot, MAP_FIXED | flags, fd, offset);
  61         if (overlap == MAP_FAILED)
  62                 munmap(tmp, length + 1);
  63
  64         return overlap;
  65 }
  66
  67 int lxc_strmunmap(void *addr, size_t length)
  68 {
  69         return munmap(addr, length + 1);
  70 }
  71
  72 int lxc_file_for_each_line_mmap(const char *file, lxc_file_cb callback, void *data)
  73 {
  74         int saved_errno;
  75         ssize_t ret = -1, bytes_sent;
  76         char *line;
  77         int fd = -1, memfd = -1;
  78         char *buf = NULL;
  79
  80         memfd = memfd_create(".lxc_config_file", MFD_CLOEXEC);
  81         if (memfd < 0) {
  82                 char template[] = P_tmpdir "/.lxc_config_file_XXXXXX";
  83
  84                 if (errno != ENOSYS) {
  85                         SYSERROR("Failed to create memory file");
  86                         goto on_error;
  87                 }
  88
  89                 TRACE("Failed to create in-memory file. Falling back to "
  90                       "temporary file");
  91                 memfd = lxc_make_tmpfile(template, true);
  92                 if (memfd < 0) {
  93                         SYSERROR("Failed to create temporary file \"%s\"", template);
  94                         goto on_error;
  95                 }
  96         }
  97
  98         fd = open(file, O_RDONLY | O_CLOEXEC);
  99         if (fd < 0) {
 100                 SYSERROR("Failed to open file \"%s\"", file);
 101                 return -1;
 102         }
 103
 104
 105         /* sendfile() handles up to 2GB. No config file should be that big. */
 106         bytes_sent = lxc_sendfile_nointr(memfd, fd, NULL, LXC_SENDFILE_MAX);
 107         if (bytes_sent < 0) {
 108                 SYSERROR("Failed to sendfile \"%s\"", file);
 109                 goto on_error;
 110         }
 111
 112         ret = lxc_write_nointr(memfd, "\0", 1);
 113         if (ret < 0) {
 114                 SYSERROR("Failed to append zero byte");
 115                 goto on_error;
 116         }
 117         bytes_sent++;
 118
 119         ret = lseek(memfd, 0, SEEK_SET);
 120         if (ret < 0) {
 121                 SYSERROR("Failed to lseek");
 122                 goto on_error;
 123         }
 124
 125         ret = -1;
 126         buf = mmap(NULL, bytes_sent, PROT_READ | PROT_WRITE,
 127                    MAP_SHARED | MAP_POPULATE, memfd, 0);
 128         if (buf == MAP_FAILED) {
 129                 buf = NULL;
 130                 SYSERROR("Failed to mmap");
 131                 goto on_error;
 132         }
 133
 134         ret = 0;
 135         lxc_iterate_parts(line, buf, "\n\0") {
 136                 ret = callback(line, data);
 137                 if (ret) {
 138                         /* Callback rv > 0 means stop here callback rv < 0 means
 139                          * error.
 140                          */
 141                         if (ret < 0)
 142                                 ERROR("Failed to parse config file \"%s\" at "
 143                                       "line \"%s\"", file, line);
 144                         break;
 145                 }
 146         }
 147
 148 on_error:
 149         saved_errno = errno;
 150         if (fd >= 0)
 151                 close(fd);
 152         if (memfd >= 0)
 153                 close(memfd);
 154         if (buf && munmap(buf, bytes_sent)) {
 155                 SYSERROR("Failed to unmap");
 156                 if (ret == 0)
 157                         ret = -1;
 158         }
 159         errno = saved_errno;
 160
 161         return ret;
 162 }
 163
 164 int lxc_file_for_each_line(const char *file, lxc_file_cb callback, void *data)
 165 {
 166         FILE *f;
 167         int err = 0;
 168         char *line = NULL;
 169         size_t len = 0;
 170
 171         f = fopen(file, "r");
 172         if (!f) {
 173                 SYSERROR("failed to open %s", file);
 174                 return -1;
 175         }
 176
 177         while (getline(&line, &len, f) != -1) {
 178                 err = callback(line, data);
 179                 if (err) {
 180                         /* Callback rv > 0 means stop here callback rv < 0 means
 181                          * error.
 182                          */
 183                         if (err < 0)
 184                                 ERROR("Failed to parse config: %s", line);
 185                         break;
 186                 }
 187         }
 188
 189         free(line);
 190         fclose(f);
 191         return err;
 192 }