receive-pack.c

   1 #include "cache.h"
   2 #include <sys/wait.h>
   3
   4 static const char receive_pack_usage[] = "git-receive-pack [--unpack=executable] <git-dir> [heads]";
   5
   6 static const char *unpacker = "git-unpack-objects";
   7
   8 static int path_match(const char *path, int nr, char **match)
   9 {
  10         int i;
  11         int pathlen = strlen(path);
  12
  13         for (i = 0; i < nr; i++) {
  14                 char *s = match[i];
  15                 int len = strlen(s);
  16
  17                 if (!len || len > pathlen)
  18                         continue;
  19                 if (memcmp(path + pathlen - len, s, len))
  20                         continue;
  21                 if (pathlen > len && path[pathlen - len - 1] != '/')
  22                         continue;
  23                 *s = 0;
  24                 return 1;
  25         }
  26         return 0;
  27 }
  28
  29 static void safe_write(int fd, const void *buf, unsigned n)
  30 {
  31         while (n) {
  32                 int ret = write(fd, buf, n);
  33                 if (ret > 0) {
  34                         buf += ret;
  35                         n -= ret;
  36                         continue;
  37                 }
  38                 if (!ret)
  39                         die("write error (disk full?)");
  40                 if (errno == EAGAIN || errno == EINTR)
  41                         continue;
  42                 die("write error (%s)", strerror(errno));
  43         }
  44 }
  45
  46 /*
  47  * If we buffered things up above (we don't, but we should),
  48  * we'd flush it here
  49  */
  50 static void flush_safe(int fd)
  51 {
  52 }
  53
  54 /*
  55  * Write a packetized stream, where each line is preceded by
  56  * its length (including the header) as a 4-byte hex number.
  57  * A length of 'zero' means end of stream (and a length of 1-3
  58  * would be an error).
  59  */
  60 #define hex(a) (hexchar[(a) & 15])
  61 static void packet_write(const char *fmt, ...)
  62 {
  63         static char buffer[1000];
  64         static char hexchar[] = "0123456789abcdef";
  65         va_list args;
  66         unsigned n;
  67
  68         va_start(args, fmt);
  69         n = vsnprintf(buffer + 4, sizeof(buffer) - 4, fmt, args);
  70         va_end(args);
  71         if (n >= sizeof(buffer)-4)
  72                 die("protocol error: impossibly long line");
  73         n += 4;
  74         buffer[0] = hex(n >> 12);
  75         buffer[1] = hex(n >> 8);
  76         buffer[2] = hex(n >> 4);
  77         buffer[3] = hex(n);
  78         safe_write(1, buffer, n);
  79 }
  80
  81 static void show_ref(const char *path, unsigned char *sha1)
  82 {
  83         packet_write("%s %s\n", sha1_to_hex(sha1), path);
  84 }
  85
  86 static int read_ref(const char *path, unsigned char *sha1)
  87 {
  88         int ret = -1;
  89         int fd = open(path, O_RDONLY);
  90
  91         if (fd >= 0) {
  92                 char buffer[60];
  93                 if (read(fd, buffer, sizeof(buffer)) >= 40)
  94                         ret = get_sha1_hex(buffer, sha1);
  95                 close(fd);
  96         }
  97         return ret;
  98 }
  99
 100 static void write_head_info(const char *base, int nr, char **match)
 101 {
 102         DIR *dir = opendir(base);
 103
 104         if (dir) {
 105                 struct dirent *de;
 106                 int baselen = strlen(base);
 107                 char *path = xmalloc(baselen + 257);
 108                 memcpy(path, base, baselen);
 109
 110                 while ((de = readdir(dir)) != NULL) {
 111                         char sha1[20];
 112                         struct stat st;
 113                         int namelen;
 114
 115                         if (de->d_name[0] == '.')
 116                                 continue;
 117                         namelen = strlen(de->d_name);
 118                         if (namelen > 255)
 119                                 continue;
 120                         memcpy(path + baselen, de->d_name, namelen+1);
 121                         if (lstat(path, &st) < 0)
 122                                 continue;
 123                         if (S_ISDIR(st.st_mode)) {
 124                                 path[baselen + namelen] = '/';
 125                                 path[baselen + namelen + 1] = 0;
 126                                 write_head_info(path, nr, match);
 127                                 continue;
 128                         }
 129                         if (read_ref(path, sha1) < 0)
 130                                 continue;
 131                         if (nr && !path_match(path, nr, match))
 132                                 continue;
 133                         show_ref(path, sha1);
 134                 }
 135                 free(path);
 136                 closedir(dir);
 137         }
 138 }
 139
 140 /*
 141  * This is all pretty stupid, but we use this packetized line
 142  * format to make a streaming format possible without ever
 143  * over-running the read buffers. That way we'll never read
 144  * into what might be the pack data (which should go to another
 145  * process entirely).
 146  *
 147  * The writing side could use stdio, but since the reading
 148  * side can't, we stay with pure read/write interfaces.
 149  */
 150 static void safe_read(int fd, void *buffer, unsigned size)
 151 {
 152         int n = 0;
 153
 154         while (n < size) {
 155                 int ret = read(0, buffer + n, size - n);
 156                 if (ret < 0) {
 157                         if (errno == EINTR || errno == EAGAIN)
 158                                 continue;
 159                         die("read error (%s)", strerror(errno));
 160                 }
 161                 if (!ret)
 162                         die("unexpected EOF");
 163                 n += ret;
 164         }
 165 }
 166
 167 static int safe_read_line(char *buffer, unsigned size)
 168 {
 169         int n, len;
 170
 171         safe_read(0, buffer, 4);
 172
 173         len = 0;
 174         for (n = 0; n < 4; n++) {
 175                 unsigned char c = buffer[n];
 176                 len <<= 4;
 177                 if (c >= '0' && c <= '9') {
 178                         len += c - '0';
 179                         continue;
 180                 }
 181                 if (c >= 'a' && c <= 'f') {
 182                         len += c - 'a' + 10;
 183                         continue;
 184                 }
 185                 if (c >= 'A' && c <= 'F') {
 186                         len += c - 'A' + 10;
 187                         continue;
 188                 }
 189                 die("protocol error: bad line length character");
 190         }
 191         if (!len)
 192                 return 0;
 193         if (len < 4 || len >= size)
 194                 die("protocol error: bad line length %d", len);
 195         safe_read(0, buffer + 4, len - 4);
 196         buffer[len] = 0;
 197         return len;
 198 }
 199
 200 struct line {
 201         struct line *next;
 202         char data[0];
 203 };
 204
 205 struct line *commands = NULL;
 206
 207 /*
 208  * This gets called after(if) we've successfully
 209  * unpacked the data payload.
 210  */
 211 static void execute_commands(void)
 212 {
 213         struct line *line = commands;
 214
 215         while (line) {
 216                 printf("%s", line->data);
 217                 line = line->next;
 218         }
 219 }
 220
 221 static void read_head_info(void)
 222 {
 223         struct line **p = &commands;
 224         for (;;) {
 225                 static char line[1000];
 226                 int len = safe_read_line(line, sizeof(line));
 227                 struct line *n;
 228                 if (!len)
 229                         break;
 230                 n = xmalloc(sizeof(struct line) + len);
 231                 n->next = NULL;
 232                 memcpy(n->data, line + 4, len - 3);
 233                 *p = n;
 234                 p = &n->next;
 235         }
 236 }
 237
 238 static void unpack(void)
 239 {
 240         pid_t pid = fork();
 241
 242         if (pid < 0)
 243                 die("unpack fork failed");
 244         if (!pid) {
 245                 char *const envp[] = { "GIT_DIR=.", NULL };
 246                 execle(unpacker, unpacker, NULL, envp);
 247                 die("unpack execute failed");
 248         }
 249
 250         for (;;) {
 251                 int status, code;
 252                 int retval = waitpid(pid, &status, 0);
 253
 254                 if (retval < 0) {
 255                         if (errno == EINTR)
 256                                 continue;
 257                         die("waitpid failed (%s)", strerror(retval));
 258                 }
 259                 if (retval != pid)
 260                         die("waitpid is confused");
 261                 if (WIFSIGNALED(status))
 262                         die("%s died of signal %d", unpacker, WTERMSIG(status));
 263                 if (!WIFEXITED(status))
 264                         die("%s died out of really strange complications", unpacker);
 265                 code = WEXITSTATUS(status);
 266                 if (code)
 267                         die("%s exited with error code %d", unpacker, code);
 268                 return;
 269         }
 270 }
 271
 272 int main(int argc, char **argv)
 273 {
 274         int i, nr_heads = 0;
 275         const char *dir = NULL;
 276         char **heads = NULL;
 277
 278         argv++;
 279         for (i = 1; i < argc; i++) {
 280                 const char *arg = *argv++;
 281
 282                 if (*arg == '-') {
 283                         if (!strncmp(arg, "--unpack=", 9)) {
 284                                 unpacker = arg+9;
 285                                 continue;
 286                         }
 287                         /* Do flag handling here */
 288                         usage(receive_pack_usage);
 289                 }
 290                 dir = arg;
 291                 heads = argv;
 292                 nr_heads = argc - i - 1;
 293                 break;
 294         }
 295         if (!dir)
 296                 usage(receive_pack_usage);
 297
 298         /* chdir to the directory. If that fails, try appending ".git" */
 299         if (chdir(dir) < 0) {
 300                 static char path[PATH_MAX];
 301                 snprintf(path, sizeof(path), "%s.git", dir);
 302                 if (chdir(path) < 0)
 303                         die("unable to cd to %s", dir);
 304         }
 305
 306         /* If we have a ".git" directory, chdir to it */
 307         chdir(".git");
 308
 309         if (access("objects", X_OK) < 0 || access("refs/heads", X_OK) < 0)
 310                 die("%s doesn't appear to be a git directory", dir);
 311         write_head_info("refs/", nr_heads, heads);
 312
 313         /* EOF */
 314         safe_write(1, "0000", 4);
 315         flush_safe(1);
 316
 317         read_head_info();
 318         unpack();
 319         execute_commands();
 320         return 0;
 321 }