clone-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 clone_pack_usage[] = "git-clone-pack [host:]directory [heads]*";
   7 static const char *exec = "git-upload-pack";
   8
   9 struct ref {
  10         struct ref *next;
  11         unsigned char sha1[20];
  12         char name[0];
  13 };
  14
  15 struct ref *get_remote_refs(int fd, int nr_match, char **match)
  16 {
  17         struct ref *ref_list = NULL, **next_ref = &ref_list;
  18
  19         for (;;) {
  20                 static char line[1000];
  21                 unsigned char sha1[20];
  22                 struct ref *ref;
  23                 char *refname;
  24                 int len;
  25
  26                 len = packet_read_line(fd, line, sizeof(line));
  27                 if (!len)
  28                         break;
  29                 if (line[len-1] == '\n')
  30                         line[--len] = 0;
  31                 if (len < 42 || get_sha1_hex(line, sha1))
  32                         die("git-fetch-pack: protocol error - expected ref descriptor, got '%s¤'", line);
  33                 refname = line+41;
  34                 len = len-40;
  35                 if (nr_match && !path_match(refname, nr_match, match))
  36                         continue;
  37                 ref = xmalloc(sizeof(struct ref) + len);
  38                 ref->next = NULL;
  39                 memcpy(ref->sha1, sha1, 20);
  40                 memcpy(ref->name, refname, len);
  41                 *next_ref = ref;
  42                 next_ref = &ref->next;
  43         }
  44         return ref_list;
  45 }
  46
  47 static void clone_handshake(int fd[2], struct ref *ref)
  48 {
  49         unsigned char sha1[20];
  50
  51         while (ref) {
  52                 packet_write(fd[1], "want %s\n", sha1_to_hex(ref->sha1));
  53                 ref = ref->next;
  54         }
  55         packet_flush(fd[1]);
  56
  57         /* We don't have nuttin' */
  58         packet_write(fd[1], "done\n");
  59         if (get_ack(fd[0], sha1))
  60                 error("Huh! git-clone-pack got positive ack for %s", sha1_to_hex(sha1));
  61 }
  62
  63 static int is_master(struct ref *ref)
  64 {
  65         return !strcmp(ref->name, "refs/heads/master");
  66 }
  67
  68 static void write_one_ref(struct ref *ref)
  69 {
  70         char *path = git_path(ref->name);
  71         int fd = open(path, O_CREAT | O_EXCL | O_WRONLY, 0666);
  72         char *hex;
  73
  74         if (fd < 0)
  75                 die("unable to create ref %s", ref->name);
  76         hex = sha1_to_hex(ref->sha1);
  77         hex[40] = '\n';
  78         if (write(fd, hex, 41) != 41)
  79                 die("unable to write ref %s", ref->name);
  80         close(fd);
  81 }
  82
  83 static void write_refs(struct ref *ref)
  84 {
  85         struct ref *head = NULL, *head_ptr, *master_ref;
  86         char *head_path;
  87
  88         if (!strcmp(ref->name, "HEAD")) {
  89                 head = ref;
  90                 ref = ref->next;
  91         }
  92         head_ptr = NULL;
  93         master_ref = NULL;
  94         while (ref) {
  95                 if (is_master(ref))
  96                         master_ref = ref;
  97                 if (head && !memcmp(ref->sha1, head->sha1, 20)) {
  98                         if (!head_ptr || ref == master_ref)
  99                                 head_ptr = ref;
 100                 }
 101                 write_one_ref(ref);
 102                 ref = ref->next;
 103         }
 104         if (!head)
 105                 return;
 106
 107         head_path = git_path("HEAD");
 108         if (!head_ptr) {
 109                 /*
 110                  * If we had a master ref, and it wasn't HEAD, we need to undo the
 111                  * symlink, and write a standalone HEAD. Give a warning, because that's
 112                  * really really wrong.
 113                  */
 114                 if (master_ref) {
 115                         error("HEAD doesn't point to any refs! Making standalone HEAD");
 116                         unlink(head_path);
 117                 }
 118                 write_one_ref(head);
 119                 return;
 120         }
 121
 122         /* We reset to the master branch if it's available */
 123         if (master_ref)
 124                 return;
 125
 126         /*
 127          * Uhhuh. Other end didn't have master. We start HEAD off with
 128          * the first branch with the same value.
 129          */
 130         unlink(head_path);
 131         if (symlink(head_ptr->name, head_path) < 0)
 132                 die("unable to link HEAD to %s", head_ptr->name);
 133 }
 134
 135 static int clone_pack(int fd[2], int nr_match, char **match)
 136 {
 137         struct ref *refs;
 138         int status;
 139         pid_t pid;
 140
 141         refs = get_remote_refs(fd[0], nr_match, match);
 142         if (!refs) {
 143                 packet_flush(fd[1]);
 144                 die("no matching remote head");
 145         }
 146         clone_handshake(fd, refs);
 147         pid = fork();
 148         if (pid < 0)
 149                 die("git-clone-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                 write_refs(refs);
 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(clone_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(clone_pack_usage);
 200         pid = git_connect(fd, dest, exec);
 201         if (pid < 0)
 202                 return 1;
 203         ret = clone_pack(fd, nr_heads, heads);
 204         close(fd[0]);
 205         close(fd[1]);
 206         finish_connect(pid);
 207         return ret;
 208 }