fetch-pack.c

   1 #include "cache.h"
   2 #include "refs.h"
   3 #include "pkt-line.h"
   4 #include <sys/wait.h>
   5
   6 static const char fetch_pack_usage[] = "git-fetch-pack [host:]directory [heads]* < mycommitlist";
   7 static const char *exec = "git-upload-pack";
   8
   9 static int get_ack(int fd, unsigned char *result_sha1)
  10 {
  11         static char line[1000];
  12         int len = packet_read_line(fd, line, sizeof(line));
  13
  14         if (!len)
  15                 die("git-fetch-pack: expected ACK/NAK, got EOF");
  16         if (line[len-1] == '\n')
  17                 line[--len] = 0;
  18         if (!strcmp(line, "NAK"))
  19                 return 0;
  20         if (!strncmp(line, "ACK ", 3)) {
  21                 if (!get_sha1_hex(line+4, result_sha1))
  22                         return 1;
  23         }
  24         die("git-fetch_pack: expected ACK/NAK, got '%s'", line);
  25 }
  26
  27 static int find_common(int fd[2], unsigned char *result_sha1, unsigned char *remote)
  28 {
  29         static char line[1000];
  30         int count = 0, flushes = 0, retval;
  31         FILE *revs;
  32
  33         revs = popen("git-rev-list $(git-rev-parse --all)", "r");
  34         if (!revs)
  35                 die("unable to run 'git-rev-list'");
  36         packet_write(fd[1], "want %s\n", sha1_to_hex(remote));
  37         packet_flush(fd[1]);
  38         flushes = 1;
  39         retval = -1;
  40         while (fgets(line, sizeof(line), revs) != NULL) {
  41                 unsigned char sha1[20];
  42                 if (get_sha1_hex(line, sha1))
  43                         die("git-fetch-pack: expected object name, got crud");
  44                 packet_write(fd[1], "have %s\n", sha1_to_hex(sha1));
  45                 if (!(31 & ++count)) {
  46                         packet_flush(fd[1]);
  47                         flushes++;
  48
  49                         /*
  50                          * We keep one window "ahead" of the other side, and
  51                          * will wait for an ACK only on the next one
  52                          */
  53                         if (count == 32)
  54                                 continue;
  55                         if (get_ack(fd[0], result_sha1)) {
  56                                 flushes = 0;
  57                                 retval = 0;
  58                                 break;
  59                         }
  60                         flushes--;
  61                 }
  62         }
  63         pclose(revs);
  64         packet_write(fd[1], "done\n");
  65         while (flushes) {
  66                 flushes--;
  67                 if (get_ack(fd[0], result_sha1))
  68                         return 0;
  69         }
  70         return retval;
  71 }
  72
  73 static int get_old_sha1(const char *refname, unsigned char *sha1)
  74 {
  75         int fd, ret;
  76
  77         fd = open(git_path("%s", refname), O_RDONLY);
  78         ret = -1;
  79         if (fd >= 0) {
  80                 char buffer[60];
  81                 if (read(fd, buffer, sizeof(buffer)) >= 40)
  82                         ret = get_sha1_hex(buffer, sha1);
  83                 close(fd);
  84         }
  85         return ret;
  86 }
  87
  88 static int check_ref(const char *refname, const unsigned char *sha1)
  89 {
  90         unsigned char mysha1[20];
  91         char oldhex[41];
  92
  93         if (get_old_sha1(refname, mysha1) < 0)
  94                 memset(mysha1, 0, 20);
  95
  96         if (!memcmp(sha1, mysha1, 20)) {
  97                 fprintf(stderr, "%s: unchanged\n", refname);
  98                 return 0;
  99         }
 100
 101         memcpy(oldhex, sha1_to_hex(mysha1), 41);
 102         fprintf(stderr, "%s: %s (%s)\n", refname, sha1_to_hex(sha1), oldhex);
 103         return 1;
 104 }
 105
 106 static int get_remote_heads(int fd, int nr_match, char **match, unsigned char *result)
 107 {
 108         int count = 0;
 109
 110         for (;;) {
 111                 static char line[1000];
 112                 unsigned char sha1[20];
 113                 char *refname;
 114                 int len;
 115
 116                 len = packet_read_line(fd, line, sizeof(line));
 117                 if (!len)
 118                         break;
 119                 if (line[len-1] == '\n')
 120                         line[--len] = 0;
 121                 if (len < 42 || get_sha1_hex(line, sha1))
 122                         die("git-fetch-pack: protocol error - expected ref descriptor, got '%sä'", line);
 123                 refname = line+41;
 124                 if (nr_match && !path_match(refname, nr_match, match))
 125                         continue;
 126                 if (check_ref(refname, sha1)) {
 127                         count++;
 128                         memcpy(result, sha1, 20);
 129                 }
 130         }
 131         return count;
 132 }
 133
 134 static int fetch_pack(int fd[2], int nr_match, char **match)
 135 {
 136         unsigned char sha1[20], remote[20];
 137         int heads, status;
 138         pid_t pid;
 139
 140         heads = get_remote_heads(fd[0], nr_match, match, remote);
 141         if (heads != 1) {
 142                 packet_flush(fd[1]);
 143                 die(heads ? "multiple remote heads" : "no matching remote head");
 144         }
 145         if (find_common(fd, sha1, remote) < 0)
 146                 die("git-fetch-pack: no common commits");
 147         pid = fork();
 148         if (pid < 0)
 149                 die("git-fetch-pack: unable to fork off git-unpack-objects");
 150         if (!pid) {
 151                 close(fd[1]);
 152                 dup2(fd[0], 0);
 153                 close(fd[0]);
 154                 execlp("git-unpack-objects", "git-unpack-objects", NULL);
 155                 die("git-unpack-objects exec failed");
 156         }
 157         close(fd[0]);
 158         close(fd[1]);
 159         while (waitpid(pid, &status, 0) < 0) {
 160                 if (errno != EINTR)
 161                         die("waiting for git-unpack-objects: %s", strerror(errno));
 162         }
 163         if (WIFEXITED(status)) {
 164                 int code = WEXITSTATUS(status);
 165                 if (code)
 166                         die("git-unpack-objects died with error code %d", code);
 167                 puts(sha1_to_hex(remote));
 168                 return 0;
 169         }
 170         if (WIFSIGNALED(status)) {
 171                 int sig = WTERMSIG(status);
 172                 die("git-unpack-objects died of signal %d", sig);
 173         }
 174         die("Sherlock Holmes! git-unpack-objects died of unnatural causes %d!", status);
 175 }
 176
 177 int main(int argc, char **argv)
 178 {
 179         int i, ret, nr_heads;
 180         char *dest = NULL, **heads;
 181         int fd[2];
 182         pid_t pid;
 183
 184         nr_heads = 0;
 185         heads = NULL;
 186         for (i = 1; i < argc; i++) {
 187                 char *arg = argv[i];
 188
 189                 if (*arg == '-') {
 190                         /* Arguments go here */
 191                         usage(fetch_pack_usage);
 192                 }
 193                 dest = arg;
 194                 heads = argv + i + 1;
 195                 nr_heads = argc - i - 1;
 196                 break;
 197         }
 198         if (!dest)
 199                 usage(fetch_pack_usage);
 200         pid = git_connect(fd, dest, exec);
 201         if (pid < 0)
 202                 return 1;
 203         ret = fetch_pack(fd, nr_heads, heads);
 204         close(fd[0]);
 205         close(fd[1]);
 206         finish_connect(pid);
 207         return ret;
 208 }