utils-lib.c

   1 #include "kerncompat.h"
   2 #include <unistd.h>
   3 #include <stdlib.h>
   4 #include <limits.h>
   5 #include <sys/ioctl.h>
   6 #include <ioctl.h>
   7
   8 #if BTRFS_FLAT_INCLUDES
   9 #include "ctree.h"
  10 #else
  11 #include <btrfs/ctree.h>
  12 #endif /* BTRFS_FLAT_INCLUDES */
  13
  14 /*
  15  * This function should be only used when parsing command arg, it won't return
  16  * error to its caller and rather exit directly just like usage().
  17  */
  18 u64 arg_strtou64(const char *str)
  19 {
  20         u64 value;
  21         char *ptr_parse_end = NULL;
  22
  23         value = strtoull(str, &ptr_parse_end, 0);
  24         if (ptr_parse_end && *ptr_parse_end != '\0') {
  25                 fprintf(stderr, "ERROR: %s is not a valid numeric value.\n",
  26                         str);
  27                 exit(1);
  28         }
  29
  30         /*
  31          * if we pass a negative number to strtoull, it will return an
  32          * unexpected number to us, so let's do the check ourselves.
  33          */
  34         if (str[0] == '-') {
  35                 fprintf(stderr, "ERROR: %s: negative value is invalid.\n",
  36                         str);
  37                 exit(1);
  38         }
  39         if (value == ULLONG_MAX) {
  40                 fprintf(stderr, "ERROR: %s is too large.\n", str);
  41                 exit(1);
  42         }
  43         return value;
  44 }
  45
  46 /*
  47  * For a given:
  48  * - file or directory return the containing tree root id
  49  * - subvolume return its own tree id
  50  * - BTRFS_EMPTY_SUBVOL_DIR_OBJECTID (directory with ino == 2) the result is
  51  *   undefined and function returns -1
  52  */
  53 int lookup_path_rootid(int fd, u64 *rootid)
  54 {
  55         struct btrfs_ioctl_ino_lookup_args args;
  56         int ret;
  57
  58         memset(&args, 0, sizeof(args));
  59         args.treeid = 0;
  60         args.objectid = BTRFS_FIRST_FREE_OBJECTID;
  61
  62         ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &args);
  63         if (ret < 0)
  64                 return -errno;
  65
  66         *rootid = args.treeid;
  67
  68         return 0;
  69 }
  70