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;
  72         char *hex;
  73
  74         if (safe_create_leading_directories(path))
  75                 die("unable to create leading directory for %s", ref->name);
  76         fd = open(path, O_CREAT | O_EXCL | O_WRONLY, 0666);
  77         if (fd < 0)
  78                 die("unable to create ref %s", ref->name);
  79         hex = sha1_to_hex(ref->sha1);
  80         hex[40] = '\n';
  81         if (write(fd, hex, 41) != 41)
  82                 die("unable to write ref %s", ref->name);
  83         close(fd);
  84 }
  85
  86 static void write_refs(struct ref *ref)
  87 {
  88         struct ref *head = NULL, *head_ptr, *master_ref;
  89         char *head_path;
  90
  91         if (!strcmp(ref->name, "HEAD")) {
  92                 head = ref;
  93                 ref = ref->next;
  94         }
  95         head_ptr = NULL;
  96         master_ref = NULL;
  97         while (ref) {
  98                 if (is_master(ref))
  99                         master_ref = ref;
 100                 if (head && !memcmp(ref->sha1, head->sha1, 20)) {
 101                         if (!head_ptr || ref == master_ref)
 102                                 head_ptr = ref;
 103                 }
 104                 write_one_ref(ref);
 105                 ref = ref->next;
 106         }
 107         if (!head)
 108                 return;
 109
 110         head_path = git_path("HEAD");
 111         if (!head_ptr) {
 112                 /*
 113                  * If we had a master ref, and it wasn't HEAD, we need to undo the
 114                  * symlink, and write a standalone HEAD. Give a warning, because that's
 115                  * really really wrong.
 116                  */
 117                 if (master_ref) {
 118                         error("HEAD doesn't point to any refs! Making standalone HEAD");
 119                         unlink(head_path);
 120                 }
 121                 write_one_ref(head);
 122                 return;
 123         }
 124
 125         /* We reset to the master branch if it's available */
 126         if (master_ref)
 127                 return;
 128
 129         /*
 130          * Uhhuh. Other end didn't have master. We start HEAD off with
 131          * the first branch with the same value.
 132          */
 133         unlink(head_path);
 134         if (symlink(head_ptr->name, head_path) < 0)
 135                 die("unable to link HEAD to %s", head_ptr->name);
 136 }
 137
 138 static int clone_pack(int fd[2], int nr_match, char **match)
 139 {
 140         struct ref *refs;
 141         int status;
 142         pid_t pid;
 143
 144         refs = get_remote_refs(fd[0], nr_match, match);
 145         if (!refs) {
 146                 packet_flush(fd[1]);
 147                 die("no matching remote head");
 148         }
 149         clone_handshake(fd, refs);
 150         pid = fork();
 151         if (pid < 0)
 152                 die("git-clone-pack: unable to fork off git-unpack-objects");
 153         if (!pid) {
 154                 close(fd[1]);
 155                 dup2(fd[0], 0);
 156                 close(fd[0]);
 157                 execlp("git-unpack-objects", "git-unpack-objects", NULL);
 158                 die("git-unpack-objects exec failed");
 159         }
 160         close(fd[0]);
 161         close(fd[1]);
 162         while (waitpid(pid, &status, 0) < 0) {
 163                 if (errno != EINTR)
 164                         die("waiting for git-unpack-objects: %s", strerror(errno));
 165         }
 166         if (WIFEXITED(status)) {
 167                 int code = WEXITSTATUS(status);
 168                 if (code)
 169                         die("git-unpack-objects died with error code %d", code);
 170                 write_refs(refs);
 171                 return 0;
 172         }
 173         if (WIFSIGNALED(status)) {
 174                 int sig = WTERMSIG(status);
 175                 die("git-unpack-objects died of signal %d", sig);
 176         }
 177         die("Sherlock Holmes! git-unpack-objects died of unnatural causes %d!", status);
 178 }
 179
 180 int main(int argc, char **argv)
 181 {
 182         int i, ret, nr_heads;
 183         char *dest = NULL, **heads;
 184         int fd[2];
 185         pid_t pid;
 186
 187         nr_heads = 0;
 188         heads = NULL;
 189         for (i = 1; i < argc; i++) {
 190                 char *arg = argv[i];
 191
 192                 if (*arg == '-') {
 193                         /* Arguments go here */
 194                         usage(clone_pack_usage);
 195                 }
 196                 dest = arg;
 197                 heads = argv + i + 1;
 198                 nr_heads = argc - i - 1;
 199                 break;
 200         }
 201         if (!dest)
 202                 usage(clone_pack_usage);
 203         pid = git_connect(fd, dest, exec);
 204         if (pid < 0)
 205                 return 1;
 206         ret = clone_pack(fd, nr_heads, heads);
 207         close(fd[0]);
 208         close(fd[1]);
 209         finish_connect(pid);
 210         return ret;
 211 }