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, const char **argv UNUSED, const char *prefix)
  16 {
  17         char buffer[HEADERSIZE];
  18         struct ustar_header *header = (struct ustar_header *)buffer;
  19         char *content = buffer + RECORDSIZE;
  20         const char *comment;
  21         ssize_t n;
  22         long len;
  23         char *end;
  24
  25         BUG_ON_NON_EMPTY_PREFIX(prefix);
  26
  27         if (argc != 1)
  28                 usage(builtin_get_tar_commit_id_usage);
  29
  30         n = read_in_full(0, buffer, HEADERSIZE);
  31         if (n < 0)
  32                 die_errno("git get-tar-commit-id: read error");
  33         if (n != HEADERSIZE)
  34                 die_errno("git get-tar-commit-id: EOF before reading tar header");
  35         if (header->typeflag[0] != TYPEFLAG_GLOBAL_HEADER)
  36                 return 1;
  37
  38         len = strtol(content, &end, 10);
  39         if (errno == ERANGE || end == content || len < 0)
  40                 return 1;
  41         if (!skip_prefix(end, " comment=", &comment))
  42                 return 1;
  43         len -= comment - content;
  44         if (len < 1 || !(len % 2) ||
  45             hash_algo_by_length((len - 1) / 2) == GIT_HASH_UNKNOWN)
  46                 return 1;
  47
  48         if (write_in_full(1, comment, len) < 0)
  49                 die_errno("git get-tar-commit-id: write error");
  50
  51         return 0;
  52 }