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_remote_heads(int fd, int nr_match, char **match, unsigned char *result)
  74 {
  75         int count = 0;
  76
  77         for (;;) {
  78                 static char line[1000];
  79                 unsigned char sha1[20];
  80                 char *refname;
  81                 int len;
  82
  83                 len = packet_read_line(fd, line, sizeof(line));
  84                 if (!len)
  85                         break;
  86                 if (line[len-1] == '\n')
  87                         line[--len] = 0;
  88                 if (len < 42 || get_sha1_hex(line, sha1))
  89                         die("git-fetch-pack: protocol error - expected ref descriptor, got '%s¤'", line);
  90                 refname = line+41;
  91                 if (nr_match && !path_match(refname, nr_match, match))
  92                         continue;
  93                 count++;
  94                 memcpy(result, sha1, 20);
  95         }
  96         return count;
  97 }
  98
  99 static int fetch_pack(int fd[2], int nr_match, char **match)
 100 {
 101         unsigned char sha1[20], remote[20];
 102         int heads, status;
 103         pid_t pid;
 104
 105         heads = get_remote_heads(fd[0], nr_match, match, remote);
 106         if (heads != 1) {
 107                 packet_flush(fd[1]);
 108                 die(heads ? "multiple remote heads" : "no matching remote head");
 109         }
 110         if (find_common(fd, sha1, remote) < 0)
 111                 die("git-fetch-pack: no common commits");
 112         pid = fork();
 113         if (pid < 0)
 114                 die("git-fetch-pack: unable to fork off git-unpack-objects");
 115         if (!pid) {
 116                 close(fd[1]);
 117                 dup2(fd[0], 0);
 118                 close(fd[0]);
 119                 execlp("git-unpack-objects", "git-unpack-objects", NULL);
 120                 die("git-unpack-objects exec failed");
 121         }
 122         close(fd[0]);
 123         close(fd[1]);
 124         while (waitpid(pid, &status, 0) < 0) {
 125                 if (errno != EINTR)
 126                         die("waiting for git-unpack-objects: %s", strerror(errno));
 127         }
 128         if (WIFEXITED(status)) {
 129                 int code = WEXITSTATUS(status);
 130                 if (code)
 131                         die("git-unpack-objects died with error code %d", code);
 132                 puts(sha1_to_hex(remote));
 133                 return 0;
 134         }
 135         if (WIFSIGNALED(status)) {
 136                 int sig = WTERMSIG(status);
 137                 die("git-unpack-objects died of signal %d", sig);
 138         }
 139         die("Sherlock Holmes! git-unpack-objects died of unnatural causes %d!", status);
 140 }
 141
 142 int main(int argc, char **argv)
 143 {
 144         int i, ret, nr_heads;
 145         char *dest = NULL, **heads;
 146         int fd[2];
 147         pid_t pid;
 148
 149         nr_heads = 0;
 150         heads = NULL;
 151         for (i = 1; i < argc; i++) {
 152                 char *arg = argv[i];
 153
 154                 if (*arg == '-') {
 155                         /* Arguments go here */
 156                         usage(fetch_pack_usage);
 157                 }
 158                 dest = arg;
 159                 heads = argv + i + 1;
 160                 nr_heads = argc - i - 1;
 161                 break;
 162         }
 163         if (!dest)
 164                 usage(fetch_pack_usage);
 165         pid = git_connect(fd, dest, exec);
 166         if (pid < 0)
 167                 return 1;
 168         ret = fetch_pack(fd, nr_heads, heads);
 169         close(fd[0]);
 170         close(fd[1]);
 171         finish_connect(pid);
 172         return ret;
 173 }