builtin/get-tar-commit-id.c

   1 /*
   2  * Copyright (c) 2005, 2006 Rene Scharfe
   3  */
   4 #include "builtin.h"
   5 #include "commit.h"
   6 #include "tar.h"
   7
   8 static const char builtin_get_tar_commit_id_usage[] =
   9 "git get-tar-commit-id";
  10
  11 /* ustar header + extended global header content */
  12 #define RECORDSIZE      (512)
  13 #define HEADERSIZE (2 * RECORDSIZE)
  14
  15 int cmd_get_tar_commit_id(int argc,
  16                           const char **argv,
  17                           const char *prefix,
  18                           struct repository *repo UNUSED)
  19 {
  20         char buffer[HEADERSIZE];
  21         struct ustar_header *header = (struct ustar_header *)buffer;
  22         char *content = buffer + RECORDSIZE;
  23         const char *comment;
  24         ssize_t n;
  25         long len;
  26         char *end;
  27
  28         BUG_ON_NON_EMPTY_PREFIX(prefix);
  29
  30         show_usage_if_asked(argc, argv, builtin_get_tar_commit_id_usage);
  31
  32         if (argc != 1)
  33                 usage(builtin_get_tar_commit_id_usage);
  34
  35         n = read_in_full(0, buffer, HEADERSIZE);
  36         if (n < 0)
  37                 die_errno("git get-tar-commit-id: read error");
  38         if (n != HEADERSIZE)
  39                 die_errno("git get-tar-commit-id: EOF before reading tar header");
  40         if (header->typeflag[0] != TYPEFLAG_GLOBAL_HEADER)
  41                 return 1;
  42
  43         errno = 0;
  44         len = strtol(content, &end, 10);
  45         if (errno == ERANGE || end == content || len < 0)
  46                 return 1;
  47         if (!skip_prefix(end, " comment=", &comment))
  48                 return 1;
  49         len -= comment - content;
  50         if (len < 1 || !(len % 2) ||
  51             hash_algo_by_length((len - 1) / 2) == GIT_HASH_UNKNOWN)
  52                 return 1;
  53
  54         if (write_in_full(1, comment, len) < 0)
  55                 die_errno("git get-tar-commit-id: write error");
  56
  57         return 0;
  58 }