src/lxc/utils.h

   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 #ifndef __LXC_UTILS_H
  24 #define __LXC_UTILS_H
  25
  26 /* Properly support loop devices on 32bit systems. */
  27 #define _FILE_OFFSET_BITS 64
  28
  29 #include "config.h"
  30
  31 #include <errno.h>
  32 #include <stdarg.h>
  33 #include <stdio.h>
  34 #include <stdbool.h>
  35 #include <unistd.h>
  36 #include <linux/loop.h>
  37 #include <linux/magic.h>
  38 #include <sys/syscall.h>
  39 #include <sys/types.h>
  40 #include <sys/vfs.h>
  41
  42 #ifdef HAVE_LINUX_MEMFD_H
  43 #include <linux/memfd.h>
  44 #endif
  45
  46 #include "initutils.h"
  47
  48 /* Define __S_ISTYPE if missing from the C library. */
  49 #ifndef __S_ISTYPE
  50 #define __S_ISTYPE(mode, mask) (((mode)&S_IFMT) == (mask))
  51 #endif
  52
  53 /* Useful macros */
  54 /* Maximum number for 64 bit integer is a string with 21 digits: 2^64 - 1 = 21 */
  55 #define LXC_NUMSTRLEN64 21
  56 #define LXC_LINELEN 4096
  57 #define LXC_IDMAPLEN 4096
  58
  59 /* returns 1 on success, 0 if there were any failures */
  60 extern int lxc_rmdir_onedev(char *path, const char *exclude);
  61 extern int get_u16(unsigned short *val, const char *arg, int base);
  62 extern int mkdir_p(const char *dir, mode_t mode);
  63 extern char *get_rundir(void);
  64
  65 /* Define getline() if missing from the C library */
  66 #ifndef HAVE_GETLINE
  67 #ifdef HAVE_FGETLN
  68 #include <../include/getline.h>
  69 #endif
  70 #endif
  71
  72 /* Define setns() if missing from the C library */
  73 #ifndef HAVE_SETNS
  74 static inline int setns(int fd, int nstype)
  75 {
  76 #ifdef __NR_setns
  77         return syscall(__NR_setns, fd, nstype);
  78 #elif defined(__NR_set_ns)
  79         return syscall(__NR_set_ns, fd, nstype);
  80 #else
  81         errno = ENOSYS;
  82         return -1;
  83 #endif
  84 }
  85 #endif
  86
  87 /* Define unshare() if missing from the C library */
  88 #ifndef HAVE_UNSHARE
  89 static inline int unshare(int flags)
  90 {
  91 #ifdef __NR_unshare
  92         return syscall(__NR_unshare, flags);
  93 #else
  94         errno = ENOSYS;
  95         return -1;
  96 #endif
  97 }
  98 #else
  99 extern int unshare(int);
 100 #endif
 101
 102 /* Define signalfd() if missing from the C library */
 103 #ifdef HAVE_SYS_SIGNALFD_H
 104 #  include <sys/signalfd.h>
 105 #else
 106 /* assume kernel headers are too old */
 107 #include <stdint.h>
 108 struct signalfd_siginfo
 109 {
 110         uint32_t ssi_signo;
 111         int32_t ssi_errno;
 112         int32_t ssi_code;
 113         uint32_t ssi_pid;
 114         uint32_t ssi_uid;
 115         int32_t ssi_fd;
 116         uint32_t ssi_tid;
 117         uint32_t ssi_band;
 118         uint32_t ssi_overrun;
 119         uint32_t ssi_trapno;
 120         int32_t ssi_status;
 121         int32_t ssi_int;
 122         uint64_t ssi_ptr;
 123         uint64_t ssi_utime;
 124         uint64_t ssi_stime;
 125         uint64_t ssi_addr;
 126         uint8_t __pad[48];
 127 };
 128
 129 #  ifndef __NR_signalfd4
 130 /* assume kernel headers are too old */
 131 #    if __i386__
 132 #      define __NR_signalfd4 327
 133 #    elif __x86_64__
 134 #      define __NR_signalfd4 289
 135 #    elif __powerpc__
 136 #      define __NR_signalfd4 313
 137 #    elif __s390x__
 138 #      define __NR_signalfd4 322
 139 #    elif __arm__
 140 #      define __NR_signalfd4 355
 141 #    elif __mips__ && _MIPS_SIM == _ABIO32
 142 #      define __NR_signalfd4 4324
 143 #    elif __mips__ && _MIPS_SIM == _ABI64
 144 #      define __NR_signalfd4 5283
 145 #    elif __mips__ && _MIPS_SIM == _ABIN32
 146 #      define __NR_signalfd4 6287
 147 #    endif
 148 #endif
 149
 150 #  ifndef __NR_signalfd
 151 /* assume kernel headers are too old */
 152 #    if __i386__
 153 #      define __NR_signalfd 321
 154 #    elif __x86_64__
 155 #      define __NR_signalfd 282
 156 #    elif __powerpc__
 157 #      define __NR_signalfd 305
 158 #    elif __s390x__
 159 #      define __NR_signalfd 316
 160 #    elif __arm__
 161 #      define __NR_signalfd 349
 162 #    elif __mips__ && _MIPS_SIM == _ABIO32
 163 #      define __NR_signalfd 4317
 164 #    elif __mips__ && _MIPS_SIM == _ABI64
 165 #      define __NR_signalfd 5276
 166 #    elif __mips__ && _MIPS_SIM == _ABIN32
 167 #      define __NR_signalfd 6280
 168 #    endif
 169 #endif
 170
 171 static inline int signalfd(int fd, const sigset_t *mask, int flags)
 172 {
 173         int retval;
 174
 175         retval = syscall (__NR_signalfd4, fd, mask, _NSIG / 8, flags);
 176         if (errno == ENOSYS && flags == 0)
 177                 retval = syscall (__NR_signalfd, fd, mask, _NSIG / 8);
 178         return retval;
 179 }
 180 #endif
 181
 182 /* loop devices */
 183 #ifndef LO_FLAGS_AUTOCLEAR
 184 #define LO_FLAGS_AUTOCLEAR 4
 185 #endif
 186
 187 #ifndef LOOP_CTL_GET_FREE
 188 #define LOOP_CTL_GET_FREE 0x4C82
 189 #endif
 190
 191 /* memfd_create() */
 192 #ifndef MFD_CLOEXEC
 193 #define MFD_CLOEXEC 0x0001U
 194 #endif
 195
 196 #ifndef MFD_ALLOW_SEALING
 197 #define MFD_ALLOW_SEALING 0x0002U
 198 #endif
 199
 200 #ifndef HAVE_MEMFD_CREATE
 201 static inline int memfd_create(const char *name, unsigned int flags) {
 202         #ifndef __NR_memfd_create
 203                 #if defined __i386__
 204                         #define __NR_memfd_create 356
 205                 #elif defined __x86_64__
 206                         #define __NR_memfd_create 319
 207                 #elif defined __arm__
 208                         #define __NR_memfd_create 385
 209                 #elif defined __aarch64__
 210                         #define __NR_memfd_create 279
 211                 #elif defined __s390__
 212                         #define __NR_memfd_create 350
 213                 #elif defined __powerpc__
 214                         #define __NR_memfd_create 360
 215                 #elif defined __sparc__
 216                         #define __NR_memfd_create 348
 217                 #elif defined __blackfin__
 218                         #define __NR_memfd_create 390
 219                 #elif defined __ia64__
 220                         #define __NR_memfd_create 1340
 221                 #elif defined _MIPS_SIM
 222                         #if _MIPS_SIM == _MIPS_SIM_ABI32
 223                                 #define __NR_memfd_create 4354
 224                         #endif
 225                         #if _MIPS_SIM == _MIPS_SIM_NABI32
 226                                 #define __NR_memfd_create 6318
 227                         #endif
 228                         #if _MIPS_SIM == _MIPS_SIM_ABI64
 229                                 #define __NR_memfd_create 5314
 230                         #endif
 231                 #endif
 232         #endif
 233         #ifdef __NR_memfd_create
 234         return syscall(__NR_memfd_create, name, flags);
 235         #else
 236         errno = ENOSYS;
 237         return -1;
 238         #endif
 239 }
 240 #else
 241 extern int memfd_create(const char *name, unsigned int flags);
 242 #endif
 243
 244 static inline int lxc_set_cloexec(int fd)
 245 {
 246         return fcntl(fd, F_SETFD, FD_CLOEXEC);
 247 }
 248
 249 /* Struct to carry child pid from lxc_popen() to lxc_pclose().
 250  * Not an opaque struct to allow direct access to the underlying FILE *
 251  * (i.e., struct lxc_popen_FILE *file; fgets(buf, sizeof(buf), file->f))
 252  * without additional wrappers.
 253  */
 254 struct lxc_popen_FILE {
 255         int pipe;
 256         FILE *f;
 257         pid_t child_pid;
 258 };
 259
 260 /* popen(command, "re") replacement that restores default signal mask
 261  * via sigprocmask(2) (unblocks all signals) after fork(2) but prior to calling exec(3).
 262  * In short, popen(command, "re") does pipe() + fork()                 + exec()
 263  * while lxc_popen(command)       does pipe() + fork() + sigprocmask() + exec().
 264  * Returns pointer to struct lxc_popen_FILE, that should be freed with lxc_pclose().
 265  * On error returns NULL.
 266  */
 267 extern struct lxc_popen_FILE *lxc_popen(const char *command);
 268
 269 /* pclose() replacement to be used on struct lxc_popen_FILE *,
 270  * returned by lxc_popen().
 271  * Waits for associated process to terminate, returns its exit status and
 272  * frees resources, pointed to by struct lxc_popen_FILE *.
 273  */
 274 extern int lxc_pclose(struct lxc_popen_FILE *fp);
 275
 276 /**
 277  * BUILD_BUG_ON - break compile if a condition is true.
 278  * @condition: the condition which the compiler should know is false.
 279  *
 280  * If you have some code which relies on certain constants being equal, or
 281  * other compile-time-evaluated condition, you should use BUILD_BUG_ON to
 282  * detect if someone changes it.
 283  *
 284  * The implementation uses gcc's reluctance to create a negative array, but
 285  * gcc (as of 4.4) only emits that error for obvious cases (eg. not arguments
 286  * to inline functions).  So as a fallback we use the optimizer; if it can't
 287  * prove the condition is false, it will cause a link error on the undefined
 288  * "__build_bug_on_failed".  This error message can be harder to track down
 289  * though, hence the two different methods.
 290  */
 291 #ifndef __OPTIMIZE__
 292 #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
 293 #else
 294 extern int __build_bug_on_failed;
 295 #define BUILD_BUG_ON(condition)                                 \
 296         do {                                                    \
 297                 ((void)sizeof(char[1 - 2*!!(condition)]));      \
 298                 if (condition) __build_bug_on_failed = 1;       \
 299         } while(0)
 300 #endif
 301
 302 /*
 303  * wait on a child we forked
 304  */
 305 extern int wait_for_pid(pid_t pid);
 306 extern int lxc_wait_for_pid_status(pid_t pid);
 307
 308 /* send and receive buffers completely */
 309 extern ssize_t lxc_write_nointr(int fd, const void* buf, size_t count);
 310 extern ssize_t lxc_read_nointr(int fd, void* buf, size_t count);
 311 extern ssize_t lxc_read_nointr_expect(int fd, void *buf, size_t count,
 312                                       const void *expected_buf);
 313 #if HAVE_LIBGNUTLS
 314 #define SHA_DIGEST_LENGTH 20
 315 extern int sha1sum_file(char *fnam, unsigned char *md_value);
 316 #endif
 317
 318 /* read and write whole files */
 319 extern int lxc_write_to_file(const char *filename, const void *buf,
 320                              size_t count, bool add_newline);
 321 extern int lxc_read_from_file(const char *filename, void* buf, size_t count);
 322
 323 /* convert variadic argument lists to arrays (for execl type argument lists) */
 324 extern char** lxc_va_arg_list_to_argv(va_list ap, size_t skip, int do_strdup);
 325 extern const char** lxc_va_arg_list_to_argv_const(va_list ap, size_t skip);
 326
 327 /* Some simple string functions; if they return pointers, they are allocated
 328  * buffers.
 329  */
 330 extern char *lxc_string_replace(const char *needle, const char *replacement,
 331                                 const char *haystack);
 332 extern bool lxc_string_in_array(const char *needle, const char **haystack);
 333 extern char *lxc_string_join(const char *sep, const char **parts,
 334                              bool use_as_prefix);
 335 /* Normalize and split path: Leading and trailing / are removed, multiple
 336  * / are compactified, .. and . are resolved (.. on the top level is considered
 337  * identical to .).
 338  * Examples:
 339  *     /            ->   { NULL }
 340  *     foo/../bar   ->   { bar, NULL }
 341  *     ../../       ->   { NULL }
 342  *     ./bar/baz/.. ->   { bar, NULL }
 343  *     foo//bar     ->   { foo, bar, NULL }
 344  */
 345 extern char **lxc_normalize_path(const char *path);
 346 /* remove multiple slashes from the path, e.g. ///foo//bar -> /foo/bar */
 347 extern char *lxc_deslashify(const char *path);
 348 extern char *lxc_append_paths(const char *first, const char *second);
 349 /* Note: the following two functions use strtok(), so they will never
 350  *       consider an empty element, even if two delimiters are next to
 351  *       each other.
 352  */
 353 extern bool lxc_string_in_list(const char *needle, const char *haystack,
 354                                char sep);
 355 extern char **lxc_string_split(const char *string, char sep);
 356 extern char **lxc_string_split_and_trim(const char *string, char sep);
 357 extern char **lxc_string_split_quoted(char *string);
 358 /* Append string to NULL-terminated string array. */
 359 extern int lxc_append_string(char ***list, char *entry);
 360
 361 /* some simple array manipulation utilities */
 362 typedef void (*lxc_free_fn)(void *);
 363 typedef void *(*lxc_dup_fn)(void *);
 364 extern int lxc_grow_array(void ***array, size_t *capacity, size_t new_size,
 365                           size_t capacity_increment);
 366 extern void lxc_free_array(void **array, lxc_free_fn element_free_fn);
 367 extern size_t lxc_array_len(void **array);
 368
 369 extern void **lxc_append_null_to_array(void **array, size_t count);
 370
 371 /* mmap() wrapper. lxc_strmmap() will take care to \0-terminate files so that
 372  * normal string-handling functions can be used on the buffer. */
 373 extern void *lxc_strmmap(void *addr, size_t length, int prot, int flags, int fd,
 374                          off_t offset);
 375 /* munmap() wrapper. Use it to free memory mmap()ed with lxc_strmmap(). */
 376 extern int lxc_strmunmap(void *addr, size_t length);
 377
 378 /* initialize rand with urandom */
 379 extern int randseed(bool);
 380
 381 inline static bool am_unpriv(void) {
 382         return geteuid() != 0;
 383 }
 384
 385 /*
 386  * parse /proc/self/uid_map to find what @orig maps to
 387  */
 388 extern uid_t get_ns_uid(uid_t orig);
 389
 390 extern bool dir_exists(const char *path);
 391
 392 #define FNV1A_64_INIT ((uint64_t)0xcbf29ce484222325ULL)
 393 extern uint64_t fnv_64a_buf(void *buf, size_t len, uint64_t hval);
 394
 395 extern int detect_shared_rootfs(void);
 396 extern bool detect_ramfs_rootfs(void);
 397 extern char *on_path(const char *cmd, const char *rootfs);
 398 extern bool file_exists(const char *f);
 399 extern bool cgns_supported(void);
 400 extern char *choose_init(const char *rootfs);
 401 extern int print_to_file(const char *file, const char *content);
 402 extern bool switch_to_ns(pid_t pid, const char *ns);
 403 extern int is_dir(const char *path);
 404 extern char *get_template_path(const char *t);
 405 extern int safe_mount(const char *src, const char *dest, const char *fstype,
 406                       unsigned long flags, const void *data,
 407                       const char *rootfs);
 408 extern int lxc_mount_proc_if_needed(const char *rootfs);
 409 extern int open_devnull(void);
 410 extern int set_stdfds(int fd);
 411 extern int null_stdfds(void);
 412 extern int lxc_count_file_lines(const char *fn);
 413 extern int lxc_preserve_ns(const int pid, const char *ns);
 414
 415 /* Check whether a signal is blocked by a process. */
 416 extern bool task_blocking_signal(pid_t pid, int signal);
 417
 418 /* Helper functions to parse numbers. */
 419 extern int lxc_safe_uint(const char *numstr, unsigned int *converted);
 420 extern int lxc_safe_int(const char *numstr, int *converted);
 421 extern int lxc_safe_long(const char *numstr, long int *converted);
 422 extern int lxc_safe_ulong(const char *numstr, unsigned long *converted);
 423
 424 /* Switch to a new uid and gid. */
 425 extern int lxc_switch_uid_gid(uid_t uid, gid_t gid);
 426 extern int lxc_setgroups(int size, gid_t list[]);
 427
 428 /* Find an unused loop device and associate it with source. */
 429 extern int lxc_prepare_loop_dev(const char *source, char *loop_dev, int flags);
 430
 431 /* Clear all mounts on a given node.
 432  * >= 0 successfully cleared. The number returned is the number of umounts
 433  *      performed.
 434  * < 0  error umounting. Return -errno.
 435  */
 436 extern int lxc_unstack_mountpoint(const char *path, bool lazy);
 437
 438 /*
 439  * run_command runs a command and collect it's std{err,out} output in buf.
 440  *
 441  * @param[out] buf     The buffer where the commands std{err,out] output will be
 442  *                     read into. If no output was produced, buf will be memset
 443  *                     to 0.
 444  * @param[in] buf_size The size of buf. This function will reserve one byte for
 445  *                     \0-termination.
 446  * @param[in] child_fn The function to be run in the child process. This
 447  *                     function must exec.
 448  * @param[in] args     Arguments to be passed to child_fn.
 449  */
 450 extern int run_command(char *buf, size_t buf_size, int (*child_fn)(void *),
 451                        void *args);
 452
 453 /* Concatenate all passed-in strings into one path. Do not fail. If any piece
 454  * is not prefixed with '/', add a '/'.
 455  */
 456 extern char *must_make_path(const char *first, ...) __attribute__((sentinel));
 457
 458 /* return copy of string @entry;  do not fail. */
 459 extern char *must_copy_string(const char *entry);
 460
 461 /* Re-alllocate a pointer, do not fail */
 462 extern void *must_realloc(void *orig, size_t sz);
 463
 464 /* __typeof__ should be safe to use with all compilers. */
 465 typedef __typeof__(((struct statfs *)NULL)->f_type) fs_type_magic;
 466 extern bool has_fs_type(const char *path, fs_type_magic magic_val);
 467 extern bool is_fs_type(const struct statfs *fs, fs_type_magic magic_val);
 468 extern bool lxc_nic_exists(char *nic);
 469 extern int lxc_make_tmpfile(char *template, bool rm);
 470 extern uint64_t lxc_getpagesize(void);
 471
 472 #endif /* __LXC_UTILS_H */