refs.c

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