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 head_ref(int (*fn)(const char *path, const unsigned char *sha1))
  72 {
  73         unsigned char sha1[20];
  74         const char *headpath = git_path("HEAD");
  75         if (!read_ref(headpath, sha1))
  76                 return fn(headpath, sha1);
  77         return 0;
  78 }
  79
  80 int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
  81 {
  82         return do_for_each_ref(get_refs_directory(), fn);
  83 }
  84
  85 static char *ref_file_name(const char *ref)
  86 {
  87         char *base = get_refs_directory();
  88         int baselen = strlen(base);
  89         int reflen = strlen(ref);
  90         char *ret = xmalloc(baselen + 2 + reflen);
  91         sprintf(ret, "%s/%s", base, ref);
  92         return ret;
  93 }
  94
  95 static char *ref_lock_file_name(const char *ref)
  96 {
  97         char *base = get_refs_directory();
  98         int baselen = strlen(base);
  99         int reflen = strlen(ref);
 100         char *ret = xmalloc(baselen + 7 + reflen);
 101         sprintf(ret, "%s/%s.lock", base, ref);
 102         return ret;
 103 }
 104
 105 static int read_ref_file(const char *filename, unsigned char *sha1) {
 106         int fd = open(filename, O_RDONLY);
 107         char hex[41];
 108         if (fd < 0) {
 109                 return error("Couldn't open %s\n", filename);
 110         }
 111         if ((read(fd, hex, 41) < 41) ||
 112             (hex[40] != '\n') ||
 113             get_sha1_hex(hex, sha1)) {
 114                 error("Couldn't read a hash from %s\n", filename);
 115                 close(fd);
 116                 return -1;
 117         }
 118         close(fd);
 119         return 0;
 120 }
 121
 122 int get_ref_sha1(const char *ref, unsigned char *sha1)
 123 {
 124         char *filename;
 125         int retval;
 126         if (check_ref_format(ref))
 127                 return -1;
 128         filename = ref_file_name(ref);
 129         retval = read_ref_file(filename, sha1);
 130         free(filename);
 131         return retval;
 132 }
 133
 134 static int lock_ref_file(const char *filename, const char *lock_filename,
 135                          const unsigned char *old_sha1)
 136 {
 137         int fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 138         unsigned char current_sha1[20];
 139         int retval;
 140         if (fd < 0) {
 141                 return error("Couldn't open lock file for %s: %s",
 142                              filename, strerror(errno));
 143         }
 144         retval = read_ref_file(filename, current_sha1);
 145         if (old_sha1) {
 146                 if (retval) {
 147                         close(fd);
 148                         unlink(lock_filename);
 149                         return error("Could not read the current value of %s",
 150                                      filename);
 151                 }
 152                 if (memcmp(current_sha1, old_sha1, 20)) {
 153                         close(fd);
 154                         unlink(lock_filename);
 155                         error("The current value of %s is %s",
 156                               filename, sha1_to_hex(current_sha1));
 157                         return error("Expected %s",
 158                                      sha1_to_hex(old_sha1));
 159                 }
 160         } else {
 161                 if (!retval) {
 162                         close(fd);
 163                         unlink(lock_filename);
 164                         return error("Unexpectedly found a value of %s for %s",
 165                                      sha1_to_hex(current_sha1), filename);
 166                 }
 167         }
 168         return fd;
 169 }
 170
 171 int lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 172 {
 173         char *filename;
 174         char *lock_filename;
 175         int retval;
 176         if (check_ref_format(ref))
 177                 return -1;
 178         filename = ref_file_name(ref);
 179         lock_filename = ref_lock_file_name(ref);
 180         retval = lock_ref_file(filename, lock_filename, old_sha1);
 181         free(filename);
 182         free(lock_filename);
 183         return retval;
 184 }
 185
 186 static int write_ref_file(const char *filename,
 187                           const char *lock_filename, int fd,
 188                           const unsigned char *sha1)
 189 {
 190         char *hex = sha1_to_hex(sha1);
 191         char term = '\n';
 192         if (write(fd, hex, 40) < 40 ||
 193             write(fd, &term, 1) < 1) {
 194                 error("Couldn't write %s\n", filename);
 195                 close(fd);
 196                 return -1;
 197         }
 198         close(fd);
 199         rename(lock_filename, filename);
 200         return 0;
 201 }
 202
 203 int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1)
 204 {
 205         char *filename;
 206         char *lock_filename;
 207         int retval;
 208         if (fd < 0)
 209                 return -1;
 210         if (check_ref_format(ref))
 211                 return -1;
 212         filename = ref_file_name(ref);
 213         lock_filename = ref_lock_file_name(ref);
 214         retval = write_ref_file(filename, lock_filename, fd, sha1);
 215         free(filename);
 216         free(lock_filename);
 217         return retval;
 218 }
 219
 220 int check_ref_format(const char *ref)
 221 {
 222         char *middle;
 223         if (ref[0] == '.' || ref[0] == '/')
 224                 return -1;
 225         middle = strchr(ref, '/');
 226         if (!middle || !middle[1])
 227                 return -1;
 228         if (strchr(middle + 1, '/'))
 229                 return -1;
 230         return 0;
 231 }
 232
 233 int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1)
 234 {
 235         char *filename;
 236         char *lock_filename;
 237         int fd;
 238         int retval;
 239         if (check_ref_format(ref))
 240                 return -1;
 241         filename = ref_file_name(ref);
 242         lock_filename = ref_lock_file_name(ref);
 243         fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 244         if (fd < 0) {
 245                 error("Writing %s", lock_filename);
 246                 perror("Open");
 247         }
 248         retval = write_ref_file(filename, lock_filename, fd, sha1);
 249         free(filename);
 250         free(lock_filename);
 251         return retval;
 252 }