refs.c

   1 #include "refs.h"
   2 #include "cache.h"
   3
   4 #include <errno.h>
   5 #include <ctype.h>
   6
   7 /* We allow "recursive" symbolic refs. Only within reason, though */
   8 #define MAXDEPTH 5
   9
  10 int read_ref(const char *filename, unsigned char *sha1)
  11 {
  12         int depth = 0;
  13         int ret = -1, fd;
  14
  15         while ((fd = open(filename, O_RDONLY)) >= 0) {
  16                 char buffer[256];
  17                 int len = read(fd, buffer, sizeof(buffer)-1);
  18
  19                 close(fd);
  20                 if (len < 0)
  21                         break;
  22
  23                 buffer[len] = 0;
  24                 while (len && isspace(buffer[len-1]))
  25                         buffer[--len] = 0;
  26
  27                 if (!strncmp(buffer, "ref:", 4)) {
  28                         char *buf;
  29                         if (depth > MAXDEPTH)
  30                                 break;
  31                         depth++;
  32                         buf = buffer + 4;
  33                         len -= 4;
  34                         while (len && isspace(*buf))
  35                                 buf++, len--;
  36                         filename = git_path("%.*s", len, buf);
  37                         continue;
  38                 }
  39                 if (len >= 40)
  40                         ret = get_sha1_hex(buffer, sha1);
  41                 break;
  42         }
  43         return ret;
  44 }
  45
  46 static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1))
  47 {
  48         int retval = 0;
  49         DIR *dir = opendir(git_path("%s", base));
  50
  51         if (dir) {
  52                 struct dirent *de;
  53                 int baselen = strlen(base);
  54                 char *path = xmalloc(baselen + 257);
  55
  56                 if (!strncmp(base, "./", 2)) {
  57                         base += 2;
  58                         baselen -= 2;
  59                 }
  60                 memcpy(path, base, baselen);
  61                 if (baselen && base[baselen-1] != '/')
  62                         path[baselen++] = '/';
  63
  64                 while ((de = readdir(dir)) != NULL) {
  65                         unsigned char sha1[20];
  66                         struct stat st;
  67                         int namelen;
  68
  69                         if (de->d_name[0] == '.')
  70                                 continue;
  71                         namelen = strlen(de->d_name);
  72                         if (namelen > 255)
  73                                 continue;
  74                         memcpy(path + baselen, de->d_name, namelen+1);
  75                         if (stat(git_path("%s", path), &st) < 0)
  76                                 continue;
  77                         if (S_ISDIR(st.st_mode)) {
  78                                 retval = do_for_each_ref(path, fn);
  79                                 if (retval)
  80                                         break;
  81                                 continue;
  82                         }
  83                         if (read_ref(git_path("%s", path), sha1) < 0)
  84                                 continue;
  85                         if (!has_sha1_file(sha1))
  86                                 continue;
  87                         retval = fn(path, sha1);
  88                         if (retval)
  89                                 break;
  90                 }
  91                 free(path);
  92                 closedir(dir);
  93         }
  94         return retval;
  95 }
  96
  97 int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
  98 {
  99         unsigned char sha1[20];
 100         if (!read_ref(git_path("HEAD"), sha1))
 101                 return fn("HEAD", sha1);
 102         return 0;
 103 }
 104
 105 int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
 106 {
 107         return do_for_each_ref("refs", fn);
 108 }
 109
 110 static char *ref_file_name(const char *ref)
 111 {
 112         char *base = get_refs_directory();
 113         int baselen = strlen(base);
 114         int reflen = strlen(ref);
 115         char *ret = xmalloc(baselen + 2 + reflen);
 116         sprintf(ret, "%s/%s", base, ref);
 117         return ret;
 118 }
 119
 120 static char *ref_lock_file_name(const char *ref)
 121 {
 122         char *base = get_refs_directory();
 123         int baselen = strlen(base);
 124         int reflen = strlen(ref);
 125         char *ret = xmalloc(baselen + 7 + reflen);
 126         sprintf(ret, "%s/%s.lock", base, ref);
 127         return ret;
 128 }
 129
 130 int get_ref_sha1(const char *ref, unsigned char *sha1)
 131 {
 132         const char *filename;
 133
 134         if (check_ref_format(ref))
 135                 return -1;
 136         filename = git_path("refs/%s", ref);
 137         return read_ref(filename, sha1);
 138 }
 139
 140 static int lock_ref_file(const char *filename, const char *lock_filename,
 141                          const unsigned char *old_sha1)
 142 {
 143         int fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 144         unsigned char current_sha1[20];
 145         int retval;
 146         if (fd < 0) {
 147                 return error("Couldn't open lock file for %s: %s",
 148                              filename, strerror(errno));
 149         }
 150         retval = read_ref(filename, current_sha1);
 151         if (old_sha1) {
 152                 if (retval) {
 153                         close(fd);
 154                         unlink(lock_filename);
 155                         return error("Could not read the current value of %s",
 156                                      filename);
 157                 }
 158                 if (memcmp(current_sha1, old_sha1, 20)) {
 159                         close(fd);
 160                         unlink(lock_filename);
 161                         error("The current value of %s is %s",
 162                               filename, sha1_to_hex(current_sha1));
 163                         return error("Expected %s",
 164                                      sha1_to_hex(old_sha1));
 165                 }
 166         } else {
 167                 if (!retval) {
 168                         close(fd);
 169                         unlink(lock_filename);
 170                         return error("Unexpectedly found a value of %s for %s",
 171                                      sha1_to_hex(current_sha1), filename);
 172                 }
 173         }
 174         return fd;
 175 }
 176
 177 int lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 178 {
 179         char *filename;
 180         char *lock_filename;
 181         int retval;
 182         if (check_ref_format(ref))
 183                 return -1;
 184         filename = ref_file_name(ref);
 185         lock_filename = ref_lock_file_name(ref);
 186         retval = lock_ref_file(filename, lock_filename, old_sha1);
 187         free(filename);
 188         free(lock_filename);
 189         return retval;
 190 }
 191
 192 static int write_ref_file(const char *filename,
 193                           const char *lock_filename, int fd,
 194                           const unsigned char *sha1)
 195 {
 196         char *hex = sha1_to_hex(sha1);
 197         char term = '\n';
 198         if (write(fd, hex, 40) < 40 ||
 199             write(fd, &term, 1) < 1) {
 200                 error("Couldn't write %s\n", filename);
 201                 close(fd);
 202                 return -1;
 203         }
 204         close(fd);
 205         rename(lock_filename, filename);
 206         return 0;
 207 }
 208
 209 int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1)
 210 {
 211         char *filename;
 212         char *lock_filename;
 213         int retval;
 214         if (fd < 0)
 215                 return -1;
 216         if (check_ref_format(ref))
 217                 return -1;
 218         filename = ref_file_name(ref);
 219         lock_filename = ref_lock_file_name(ref);
 220         retval = write_ref_file(filename, lock_filename, fd, sha1);
 221         free(filename);
 222         free(lock_filename);
 223         return retval;
 224 }
 225
 226 int check_ref_format(const char *ref)
 227 {
 228         char *middle;
 229         if (ref[0] == '.' || ref[0] == '/')
 230                 return -1;
 231         middle = strchr(ref, '/');
 232         if (!middle || !middle[1])
 233                 return -1;
 234         if (strchr(middle + 1, '/'))
 235                 return -1;
 236         return 0;
 237 }
 238
 239 int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1)
 240 {
 241         char *filename;
 242         char *lock_filename;
 243         int fd;
 244         int retval;
 245         if (check_ref_format(ref))
 246                 return -1;
 247         filename = ref_file_name(ref);
 248         lock_filename = ref_lock_file_name(ref);
 249         fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 250         if (fd < 0) {
 251                 error("Writing %s", lock_filename);
 252                 perror("Open");
 253         }
 254         retval = write_ref_file(filename, lock_filename, fd, sha1);
 255         free(filename);
 256         free(lock_filename);
 257         return retval;
 258 }