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