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         static char pathname[PATH_MAX];
  76         const char *git_dir;
  77         int fd, ret;
  78
  79         git_dir = gitenv(GIT_DIR_ENVIRONMENT) ? : DEFAULT_GIT_DIR_ENVIRONMENT;
  80         snprintf(pathname, sizeof(pathname), "%s/%s", git_dir, refname);
  81         fd = open(pathname, O_RDONLY);
  82         ret = -1;
  83         if (fd >= 0) {
  84                 char buffer[60];
  85                 if (read(fd, buffer, sizeof(buffer)) >= 40)
  86                         ret = get_sha1_hex(buffer, sha1);
  87                 close(fd);
  88         }
  89         return ret;
  90 }
  91
  92 static int check_ref(const char *refname, const unsigned char *sha1)
  93 {
  94         unsigned char mysha1[20];
  95         char oldhex[41];
  96
  97         if (get_old_sha1(refname, mysha1) < 0)
  98                 memset(mysha1, 0, 20);
  99
 100         if (!memcmp(sha1, mysha1, 20)) {
 101                 fprintf(stderr, "%s: unchanged\n", refname);
 102                 return 0;
 103         }
 104
 105         memcpy(oldhex, sha1_to_hex(mysha1), 41);
 106         fprintf(stderr, "%s: %s (%s)\n", refname, sha1_to_hex(sha1), oldhex);
 107         return 1;
 108 }
 109
 110 static int get_remote_heads(int fd, int nr_match, char **match, unsigned char *result)
 111 {
 112         int count = 0;
 113
 114         for (;;) {
 115                 static char line[1000];
 116                 unsigned char sha1[20];
 117                 char *refname;
 118                 int len;
 119
 120                 len = packet_read_line(fd, line, sizeof(line));
 121                 if (!len)
 122                         break;
 123                 if (line[len-1] == '\n')
 124                         line[--len] = 0;
 125                 if (len < 42 || get_sha1_hex(line, sha1))
 126                         die("git-fetch-pack: protocol error - expected ref descriptor, got '%sä'", line);
 127                 refname = line+41;
 128                 if (nr_match && !path_match(refname, nr_match, match))
 129                         continue;
 130                 if (check_ref(refname, sha1)) {
 131                         count++;
 132                         memcpy(result, sha1, 20);
 133                 }
 134         }
 135         return count;
 136 }
 137
 138 static int fetch_pack(int fd[2], int nr_match, char **match)
 139 {
 140         unsigned char sha1[20], remote[20];
 141         int heads, status;
 142         pid_t pid;
 143
 144         heads = get_remote_heads(fd[0], nr_match, match, remote);
 145         if (heads != 1) {
 146                 packet_flush(fd[1]);
 147                 die(heads ? "multiple remote heads" : "no matching remote head");
 148         }
 149         if (find_common(fd, sha1, remote) < 0)
 150                 die("git-fetch-pack: no common commits");
 151         pid = fork();
 152         if (pid < 0)
 153                 die("git-fetch-pack: unable to fork off git-unpack-objects");
 154         if (!pid) {
 155                 close(fd[1]);
 156                 dup2(fd[0], 0);
 157                 close(fd[0]);
 158                 execlp("git-unpack-objects", "git-unpack-objects", NULL);
 159                 die("git-unpack-objects exec failed");
 160         }
 161         close(fd[0]);
 162         close(fd[1]);
 163         while (waitpid(pid, &status, 0) < 0) {
 164                 if (errno != EINTR)
 165                         die("waiting for git-unpack-objects: %s", strerror(errno));
 166         }
 167         if (WIFEXITED(status)) {
 168                 int code = WEXITSTATUS(status);
 169                 if (code)
 170                         die("git-unpack-objects died with error code %d", code);
 171                 puts(sha1_to_hex(remote));
 172                 return 0;
 173         }
 174         if (WIFSIGNALED(status)) {
 175                 int sig = WTERMSIG(status);
 176                 die("git-unpack-objects died of signal %d", sig);
 177         }
 178         die("Sherlock Holmes! git-unpack-objects died of unnatural causes %d!", status);
 179 }
 180
 181 int main(int argc, char **argv)
 182 {
 183         int i, ret, nr_heads;
 184         char *dest = NULL, **heads;
 185         int fd[2];
 186         pid_t pid;
 187
 188         nr_heads = 0;
 189         heads = NULL;
 190         for (i = 1; i < argc; i++) {
 191                 char *arg = argv[i];
 192
 193                 if (*arg == '-') {
 194                         /* Arguments go here */
 195                         usage(fetch_pack_usage);
 196                 }
 197                 dest = arg;
 198                 heads = argv + i + 1;
 199                 nr_heads = argc - i - 1;
 200                 break;
 201         }
 202         if (!dest)
 203                 usage(fetch_pack_usage);
 204         pid = git_connect(fd, dest, exec);
 205         if (pid < 0)
 206                 return 1;
 207         ret = fetch_pack(fd, nr_heads, heads);
 208         close(fd[0]);
 209         close(fd[1]);
 210         finish_connect(pid);
 211         return ret;
 212 }