receive-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 receive_pack_usage[] = "git-receive-pack <git-dir>";
   7
   8 static const char *unpacker = "git-unpack-objects";
   9
  10 static int show_ref(const char *path, const unsigned char *sha1)
  11 {
  12         packet_write(1, "%s %s\n", sha1_to_hex(sha1), path);
  13         return 0;
  14 }
  15
  16 static void write_head_info(void)
  17 {
  18         for_each_ref(show_ref);
  19 }
  20
  21 struct command {
  22         struct command *next;
  23         unsigned char old_sha1[20];
  24         unsigned char new_sha1[20];
  25         char ref_name[0];
  26 };
  27
  28 static struct command *commands = NULL;
  29
  30 static int is_all_zeroes(const char *hex)
  31 {
  32         int i;
  33         for (i = 0; i < 40; i++)
  34                 if (*hex++ != '0')
  35                         return 0;
  36         return 1;
  37 }
  38
  39 static int verify_old_ref(const char *name, char *hex_contents)
  40 {
  41         int fd, ret;
  42         char buffer[60];
  43
  44         if (is_all_zeroes(hex_contents))
  45                 return 0;
  46         fd = open(name, O_RDONLY);
  47         if (fd < 0)
  48                 return -1;
  49         ret = read(fd, buffer, 40);
  50         close(fd);
  51         if (ret != 40)
  52                 return -1;
  53         if (memcmp(buffer, hex_contents, 40))
  54                 return -1;
  55         return 0;
  56 }
  57
  58 static void update(const char *name, unsigned char *old_sha1, unsigned char *new_sha1)
  59 {
  60         char new_hex[60], *old_hex, *lock_name;
  61         int newfd, namelen, written;
  62
  63         namelen = strlen(name);
  64         lock_name = xmalloc(namelen + 10);
  65         memcpy(lock_name, name, namelen);
  66         memcpy(lock_name + namelen, ".lock", 6);
  67
  68         strcpy(new_hex, sha1_to_hex(new_sha1));
  69         old_hex = sha1_to_hex(old_sha1);
  70         if (!has_sha1_file(new_sha1))
  71                 die("unpack should have generated %s, but I can't find it!", new_hex);
  72
  73         newfd = open(lock_name, O_CREAT | O_EXCL | O_WRONLY, 0666);
  74         if (newfd < 0)
  75                 die("unable to create %s (%s)", lock_name, strerror(errno));
  76
  77         /* Write the ref with an ending '\n' */
  78         new_hex[40] = '\n';
  79         new_hex[41] = 0;
  80         written = write(newfd, new_hex, 41);
  81         /* Remove the '\n' again */
  82         new_hex[40] = 0;
  83
  84         close(newfd);
  85         if (written != 41) {
  86                 unlink(lock_name);
  87                 die("unable to write %s", lock_name);
  88         }
  89         if (verify_old_ref(name, old_hex) < 0) {
  90                 unlink(lock_name);
  91                 die("%s changed during push", name);
  92         }
  93         if (rename(lock_name, name) < 0) {
  94                 unlink(lock_name);
  95                 die("unable to replace %s", name);
  96         }
  97         fprintf(stderr, "%s: %s -> %s\n", name, old_hex, new_hex);
  98 }
  99
 100
 101 /*
 102  * This gets called after(if) we've successfully
 103  * unpacked the data payload.
 104  */
 105 static void execute_commands(void)
 106 {
 107         struct command *cmd = commands;
 108
 109         while (cmd) {
 110                 update(cmd->ref_name, cmd->old_sha1, cmd->new_sha1);
 111                 cmd = cmd->next;
 112         }
 113 }
 114
 115 static void read_head_info(void)
 116 {
 117         struct command **p = &commands;
 118         for (;;) {
 119                 static char line[1000];
 120                 unsigned char old_sha1[20], new_sha1[20];
 121                 struct command *cmd;
 122                 int len;
 123
 124                 len = packet_read_line(0, line, sizeof(line));
 125                 if (!len)
 126                         break;
 127                 if (line[len-1] == '\n')
 128                         line[--len] = 0;
 129                 if (len < 83 ||
 130                     line[40] != ' ' ||
 131                     line[81] != ' ' ||
 132                     get_sha1_hex(line, old_sha1) ||
 133                     get_sha1_hex(line + 41, new_sha1))
 134                         die("protocol error: expected old/new/ref, got '%s'", line);
 135                 cmd = xmalloc(sizeof(struct command) + len - 80);
 136                 memcpy(cmd->old_sha1, old_sha1, 20);
 137                 memcpy(cmd->new_sha1, new_sha1, 20);
 138                 memcpy(cmd->ref_name, line + 82, len - 81);
 139                 cmd->next = NULL;
 140                 *p = cmd;
 141                 p = &cmd->next;
 142         }
 143 }
 144
 145 static void unpack(void)
 146 {
 147         pid_t pid = fork();
 148
 149         if (pid < 0)
 150                 die("unpack fork failed");
 151         if (!pid) {
 152                 execlp(unpacker, unpacker, NULL);
 153                 die("unpack execute failed");
 154         }
 155
 156         for (;;) {
 157                 int status, code;
 158                 int retval = waitpid(pid, &status, 0);
 159
 160                 if (retval < 0) {
 161                         if (errno == EINTR)
 162                                 continue;
 163                         die("waitpid failed (%s)", strerror(retval));
 164                 }
 165                 if (retval != pid)
 166                         die("waitpid is confused");
 167                 if (WIFSIGNALED(status))
 168                         die("%s died of signal %d", unpacker, WTERMSIG(status));
 169                 if (!WIFEXITED(status))
 170                         die("%s died out of really strange complications", unpacker);
 171                 code = WEXITSTATUS(status);
 172                 if (code)
 173                         die("%s exited with error code %d", unpacker, code);
 174                 return;
 175         }
 176 }
 177
 178 int main(int argc, char **argv)
 179 {
 180         int i;
 181         const char *dir = NULL;
 182
 183         argv++;
 184         for (i = 1; i < argc; i++) {
 185                 const char *arg = *argv++;
 186
 187                 if (*arg == '-') {
 188                         /* Do flag handling here */
 189                         usage(receive_pack_usage);
 190                 }
 191                 if (dir)
 192                         usage(receive_pack_usage);
 193                 dir = arg;
 194         }
 195         if (!dir)
 196                 usage(receive_pack_usage);
 197
 198         /* chdir to the directory. If that fails, try appending ".git" */
 199         if (chdir(dir) < 0) {
 200                 static char path[PATH_MAX];
 201                 snprintf(path, sizeof(path), "%s.git", dir);
 202                 if (chdir(path) < 0)
 203                         die("unable to cd to %s", dir);
 204         }
 205
 206         /* If we have a ".git" directory, chdir to it */
 207         chdir(".git");
 208         setenv("GIT_DIR", ".", 1);
 209
 210         if (access("objects", X_OK) < 0 || access("refs/heads", X_OK) < 0)
 211                 die("%s doesn't appear to be a git directory", dir);
 212         write_head_info();
 213
 214         /* EOF */
 215         packet_flush(1);
 216
 217         read_head_info();
 218         if (commands) {
 219                 unpack();
 220                 execute_commands();
 221         }
 222         return 0;
 223 }