lockfile.c

   1 /*
   2  * Copyright (c) 2005, Junio C Hamano
   3  */
   4 #include "cache.h"
   5
   6 static struct lock_file *lock_file_list;
   7 static const char *alternate_index_output;
   8
   9 static void remove_lock_file(void)
  10 {
  11         while (lock_file_list) {
  12                 if (lock_file_list->filename[0]) {
  13                         close(lock_file_list->fd);
  14                         unlink(lock_file_list->filename);
  15                 }
  16                 lock_file_list = lock_file_list->next;
  17         }
  18 }
  19
  20 static void remove_lock_file_on_signal(int signo)
  21 {
  22         remove_lock_file();
  23         signal(SIGINT, SIG_DFL);
  24         raise(signo);
  25 }
  26
  27 static int lock_file(struct lock_file *lk, const char *path)
  28 {
  29         sprintf(lk->filename, "%s.lock", path);
  30         lk->fd = open(lk->filename, O_RDWR | O_CREAT | O_EXCL, 0666);
  31         if (0 <= lk->fd) {
  32                 if (!lk->on_list) {
  33                         lk->next = lock_file_list;
  34                         lock_file_list = lk;
  35                         lk->on_list = 1;
  36                 }
  37                 if (lock_file_list) {
  38                         signal(SIGINT, remove_lock_file_on_signal);
  39                         atexit(remove_lock_file);
  40                 }
  41                 if (adjust_shared_perm(lk->filename))
  42                         return error("cannot fix permission bits on %s",
  43                                      lk->filename);
  44         }
  45         else
  46                 lk->filename[0] = 0;
  47         return lk->fd;
  48 }
  49
  50 int hold_lock_file_for_update(struct lock_file *lk, const char *path, int die_on_error)
  51 {
  52         int fd = lock_file(lk, path);
  53         if (fd < 0 && die_on_error)
  54                 die("unable to create '%s.lock': %s", path, strerror(errno));
  55         return fd;
  56 }
  57
  58 int commit_lock_file(struct lock_file *lk)
  59 {
  60         char result_file[PATH_MAX];
  61         int i;
  62         close(lk->fd);
  63         strcpy(result_file, lk->filename);
  64         i = strlen(result_file) - 5; /* .lock */
  65         result_file[i] = 0;
  66         unlink(result_file);
  67         i = rename(lk->filename, result_file);
  68         lk->filename[0] = 0;
  69         return i;
  70 }
  71
  72 int hold_locked_index(struct lock_file *lk, int die_on_error)
  73 {
  74         return hold_lock_file_for_update(lk, get_index_file(), die_on_error);
  75 }
  76
  77 void set_alternate_index_output(const char *name)
  78 {
  79         alternate_index_output = name;
  80 }
  81
  82 int commit_locked_index(struct lock_file *lk)
  83 {
  84         if (alternate_index_output) {
  85                 int result = rename(lk->filename, alternate_index_output);
  86                 lk->filename[0] = 0;
  87                 return result;
  88         }
  89         else
  90                 return commit_lock_file(lk);
  91 }
  92
  93 void rollback_lock_file(struct lock_file *lk)
  94 {
  95         if (lk->filename[0]) {
  96                 close(lk->fd);
  97                 unlink(lk->filename);
  98         }
  99         lk->filename[0] = 0;
 100 }
 101