refs.c

   1 #include "refs.h"
   2 #include "cache.h"
   3
   4 #include <errno.h>
   5
   6 static int read_ref(const char *refname, unsigned char *sha1)
   7 {
   8         int ret = -1;
   9         int fd = open(git_path(refname), 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(git_path(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(git_path(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 head_ref(int (*fn)(const char *path, const unsigned char *sha1))
  72 {
  73         unsigned char sha1[20];
  74         if (!read_ref("HEAD", sha1))
  75                 return fn("HEAD", sha1);
  76         return 0;
  77 }
  78
  79 int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
  80 {
  81         return do_for_each_ref("refs", fn);
  82 }
  83
  84 static char *ref_file_name(const char *ref)
  85 {
  86         char *base = get_refs_directory();
  87         int baselen = strlen(base);
  88         int reflen = strlen(ref);
  89         char *ret = xmalloc(baselen + 2 + reflen);
  90         sprintf(ret, "%s/%s", base, ref);
  91         return ret;
  92 }
  93
  94 static char *ref_lock_file_name(const char *ref)
  95 {
  96         char *base = get_refs_directory();
  97         int baselen = strlen(base);
  98         int reflen = strlen(ref);
  99         char *ret = xmalloc(baselen + 7 + reflen);
 100         sprintf(ret, "%s/%s.lock", base, ref);
 101         return ret;
 102 }
 103
 104 static int read_ref_file(const char *filename, unsigned char *sha1) {
 105         int fd = open(filename, O_RDONLY);
 106         char hex[41];
 107         if (fd < 0) {
 108                 return error("Couldn't open %s\n", filename);
 109         }
 110         if ((read(fd, hex, 41) < 41) ||
 111             (hex[40] != '\n') ||
 112             get_sha1_hex(hex, sha1)) {
 113                 error("Couldn't read a hash from %s\n", filename);
 114                 close(fd);
 115                 return -1;
 116         }
 117         close(fd);
 118         return 0;
 119 }
 120
 121 int get_ref_sha1(const char *ref, unsigned char *sha1)
 122 {
 123         char *filename;
 124         int retval;
 125         if (check_ref_format(ref))
 126                 return -1;
 127         filename = ref_file_name(ref);
 128         retval = read_ref_file(filename, sha1);
 129         free(filename);
 130         return retval;
 131 }
 132
 133 static int lock_ref_file(const char *filename, const char *lock_filename,
 134                          const unsigned char *old_sha1)
 135 {
 136         int fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 137         unsigned char current_sha1[20];
 138         int retval;
 139         if (fd < 0) {
 140                 return error("Couldn't open lock file for %s: %s",
 141                              filename, strerror(errno));
 142         }
 143         retval = read_ref_file(filename, current_sha1);
 144         if (old_sha1) {
 145                 if (retval) {
 146                         close(fd);
 147                         unlink(lock_filename);
 148                         return error("Could not read the current value of %s",
 149                                      filename);
 150                 }
 151                 if (memcmp(current_sha1, old_sha1, 20)) {
 152                         close(fd);
 153                         unlink(lock_filename);
 154                         error("The current value of %s is %s",
 155                               filename, sha1_to_hex(current_sha1));
 156                         return error("Expected %s",
 157                                      sha1_to_hex(old_sha1));
 158                 }
 159         } else {
 160                 if (!retval) {
 161                         close(fd);
 162                         unlink(lock_filename);
 163                         return error("Unexpectedly found a value of %s for %s",
 164                                      sha1_to_hex(current_sha1), filename);
 165                 }
 166         }
 167         return fd;
 168 }
 169
 170 int lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 171 {
 172         char *filename;
 173         char *lock_filename;
 174         int retval;
 175         if (check_ref_format(ref))
 176                 return -1;
 177         filename = ref_file_name(ref);
 178         lock_filename = ref_lock_file_name(ref);
 179         retval = lock_ref_file(filename, lock_filename, old_sha1);
 180         free(filename);
 181         free(lock_filename);
 182         return retval;
 183 }
 184
 185 static int write_ref_file(const char *filename,
 186                           const char *lock_filename, int fd,
 187                           const unsigned char *sha1)
 188 {
 189         char *hex = sha1_to_hex(sha1);
 190         char term = '\n';
 191         if (write(fd, hex, 40) < 40 ||
 192             write(fd, &term, 1) < 1) {
 193                 error("Couldn't write %s\n", filename);
 194                 close(fd);
 195                 return -1;
 196         }
 197         close(fd);
 198         rename(lock_filename, filename);
 199         return 0;
 200 }
 201
 202 int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1)
 203 {
 204         char *filename;
 205         char *lock_filename;
 206         int retval;
 207         if (fd < 0)
 208                 return -1;
 209         if (check_ref_format(ref))
 210                 return -1;
 211         filename = ref_file_name(ref);
 212         lock_filename = ref_lock_file_name(ref);
 213         retval = write_ref_file(filename, lock_filename, fd, sha1);
 214         free(filename);
 215         free(lock_filename);
 216         return retval;
 217 }
 218
 219 int check_ref_format(const char *ref)
 220 {
 221         char *middle;
 222         if (ref[0] == '.' || ref[0] == '/')
 223                 return -1;
 224         middle = strchr(ref, '/');
 225         if (!middle || !middle[1])
 226                 return -1;
 227         if (strchr(middle + 1, '/'))
 228                 return -1;
 229         return 0;
 230 }
 231
 232 int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1)
 233 {
 234         char *filename;
 235         char *lock_filename;
 236         int fd;
 237         int retval;
 238         if (check_ref_format(ref))
 239                 return -1;
 240         filename = ref_file_name(ref);
 241         lock_filename = ref_lock_file_name(ref);
 242         fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 243         if (fd < 0) {
 244                 error("Writing %s", lock_filename);
 245                 perror("Open");
 246         }
 247         retval = write_ref_file(filename, lock_filename, fd, sha1);
 248         free(filename);
 249         free(lock_filename);
 250         return retval;
 251 }