fetch-pack.c

   1 #include "cache.h"
   2 #include "refs.h"
   3 #include "pkt-line.h"
   4
   5 static const char fetch_pack_usage[] = "git-fetch-pack [host:]directory [heads]* < mycommitlist";
   6 static const char *exec = "git-upload-pack";
   7
   8 static int get_ack(int fd, unsigned char *result_sha1)
   9 {
  10         static char line[1000];
  11         int len = packet_read_line(fd, line, sizeof(line));
  12
  13         if (!len)
  14                 die("git-fetch-pack: expected ACK/NAK, got EOF");
  15         if (line[len-1] == '\n')
  16                 line[--len] = 0;
  17         if (!strcmp(line, "NAK"))
  18                 return 0;
  19         if (!strncmp(line, "ACK ", 3)) {
  20                 if (!get_sha1_hex(line+4, result_sha1))
  21                         return 1;
  22         }
  23         die("git-fetch_pack: expected ACK/NAK, got '%s'", line);
  24 }
  25
  26 static int find_common(int fd[2], unsigned char *result_sha1, unsigned char *remote)
  27 {
  28         static char line[1000];
  29         int count = 0, flushes = 0;
  30
  31         packet_write(fd[1], "want %s\n", sha1_to_hex(remote));
  32         packet_flush(fd[1]);
  33         while (fgets(line, sizeof(line), stdin) != NULL) {
  34                 unsigned char sha1[20];
  35                 if (get_sha1_hex(line, sha1))
  36                         die("git-fetch-pack: expected object name, got crud");
  37                 packet_write(fd[1], "have %s\n", sha1_to_hex(sha1));
  38                 if (!(31 & ++count)) {
  39                         packet_flush(fd[1]);
  40                         flushes++;
  41
  42                         /*
  43                          * We keep one window "ahead" of the other side, and
  44                          * will wait for an ACK only on the next one
  45                          */
  46                         if (count == 32)
  47                                 continue;
  48                         if (get_ack(fd[0], result_sha1))
  49                                 return 0;
  50                         flushes--;
  51                 }
  52         }
  53         flushes++;
  54         packet_flush(fd[1]);
  55         while (flushes) {
  56                 flushes--;
  57                 if (get_ack(fd[0], result_sha1))
  58                         return 0;
  59         }
  60         return -1;
  61 }
  62
  63 static int get_old_sha1(const char *refname, unsigned char *sha1)
  64 {
  65         static char pathname[PATH_MAX];
  66         const char *git_dir;
  67         int fd, ret;
  68
  69         git_dir = gitenv(GIT_DIR_ENVIRONMENT) ? : DEFAULT_GIT_DIR_ENVIRONMENT;
  70         snprintf(pathname, sizeof(pathname), "%s/%s", git_dir, refname);
  71         fd = open(pathname, O_RDONLY);
  72         ret = -1;
  73         if (fd >= 0) {
  74                 char buffer[60];
  75                 if (read(fd, buffer, sizeof(buffer)) >= 40)
  76                         ret = get_sha1_hex(buffer, sha1);
  77                 close(fd);
  78         }
  79         return ret;
  80 }
  81
  82 static int check_ref(const char *refname, const unsigned char *sha1)
  83 {
  84         unsigned char mysha1[20];
  85         char oldhex[41];
  86
  87         if (get_old_sha1(refname, mysha1) < 0)
  88                 memset(mysha1, 0, 20);
  89
  90         if (!memcmp(sha1, mysha1, 20)) {
  91                 printf("%s: unchanged\n", refname);
  92                 return 0;
  93         }
  94
  95         memcpy(oldhex, sha1_to_hex(mysha1), 41);
  96         printf("%s: %s (%s)\n", refname, sha1_to_hex(sha1), oldhex);
  97         return 1;
  98 }
  99
 100 static int get_remote_heads(int fd, int nr_match, char **match, unsigned char *result)
 101 {
 102         int count = 0;
 103
 104         for (;;) {
 105                 static char line[1000];
 106                 unsigned char sha1[20];
 107                 char *refname;
 108                 int len;
 109
 110                 len = packet_read_line(fd, line, sizeof(line));
 111                 if (!len)
 112                         break;
 113                 if (line[len-1] == '\n')
 114                         line[--len] = 0;
 115                 if (len < 42 || get_sha1_hex(line, sha1))
 116                         die("git-fetch-pack: protocol error - expected ref descriptor, got '%sä'", line);
 117                 refname = line+41;
 118                 if (nr_match && !path_match(refname, nr_match, match))
 119                         continue;
 120                 if (check_ref(refname, sha1)) {
 121                         count++;
 122                         memcpy(result, sha1, 20);
 123                 }
 124         }
 125         return count;
 126 }
 127
 128 static int fetch_pack(int fd[2], int nr_match, char **match)
 129 {
 130         unsigned char sha1[20], remote[20];
 131         int heads;
 132
 133         heads = get_remote_heads(fd[0], nr_match, match, remote);
 134         if (heads != 1) {
 135                 packet_flush(fd[1]);
 136                 die(heads ? "multiple remote heads" : "no matching remote head");
 137         }
 138         if (find_common(fd, sha1, remote) < 0)
 139                 die("git-fetch-pack: no common commits");
 140         close(fd[1]);
 141         dup2(fd[0], 0);
 142         close(fd[0]);
 143         execlp("git-unpack-objects", "git-unpack-objects", NULL);
 144         die("git-unpack-objects exec failed");
 145 }
 146
 147 int main(int argc, char **argv)
 148 {
 149         int i, ret, nr_heads;
 150         char *dest = NULL, **heads;
 151         int fd[2];
 152         pid_t pid;
 153
 154         nr_heads = 0;
 155         heads = NULL;
 156         for (i = 1; i < argc; i++) {
 157                 char *arg = argv[i];
 158
 159                 if (*arg == '-') {
 160                         /* Arguments go here */
 161                         usage(fetch_pack_usage);
 162                 }
 163                 dest = arg;
 164                 heads = argv + i + 1;
 165                 nr_heads = argc - i - 1;
 166                 break;
 167         }
 168         if (!dest)
 169                 usage(fetch_pack_usage);
 170         pid = git_connect(fd, dest, exec);
 171         if (pid < 0)
 172                 return 1;
 173         ret = fetch_pack(fd, nr_heads, heads);
 174         close(fd[0]);
 175         close(fd[1]);
 176         finish_connect(pid);
 177         return ret;
 178 }