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