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