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         pid_t me = getpid();
  12
  13         while (lock_file_list) {
  14                 if (lock_file_list->owner == me &&
  15                     lock_file_list->filename[0]) {
  16                         close(lock_file_list->fd);
  17                         unlink(lock_file_list->filename);
  18                 }
  19                 lock_file_list = lock_file_list->next;
  20         }
  21 }
  22
  23 static void remove_lock_file_on_signal(int signo)
  24 {
  25         remove_lock_file();
  26         signal(SIGINT, SIG_DFL);
  27         raise(signo);
  28 }
  29
  30 static int lock_file(struct lock_file *lk, const char *path)
  31 {
  32         sprintf(lk->filename, "%s.lock", path);
  33         lk->fd = open(lk->filename, O_RDWR | O_CREAT | O_EXCL, 0666);
  34         if (0 <= lk->fd) {
  35                 if (!lock_file_list) {
  36                         signal(SIGINT, remove_lock_file_on_signal);
  37                         atexit(remove_lock_file);
  38                 }
  39                 lk->owner = getpid();
  40                 if (!lk->on_list) {
  41                         lk->next = lock_file_list;
  42                         lock_file_list = lk;
  43                         lk->on_list = 1;
  44                 }
  45                 if (adjust_shared_perm(lk->filename))
  46                         return error("cannot fix permission bits on %s",
  47                                      lk->filename);
  48         }
  49         else
  50                 lk->filename[0] = 0;
  51         return lk->fd;
  52 }
  53
  54 int hold_lock_file_for_update(struct lock_file *lk, const char *path, int die_on_error)
  55 {
  56         int fd = lock_file(lk, path);
  57         if (fd < 0 && die_on_error)
  58                 die("unable to create '%s.lock': %s", path, strerror(errno));
  59         return fd;
  60 }
  61
  62 int commit_lock_file(struct lock_file *lk)
  63 {
  64         char result_file[PATH_MAX];
  65         int i;
  66         close(lk->fd);
  67         strcpy(result_file, lk->filename);
  68         i = strlen(result_file) - 5; /* .lock */
  69         result_file[i] = 0;
  70         unlink(result_file);
  71         i = rename(lk->filename, result_file);
  72         lk->filename[0] = 0;
  73         return i;
  74 }
  75
  76 int hold_locked_index(struct lock_file *lk, int die_on_error)
  77 {
  78         return hold_lock_file_for_update(lk, get_index_file(), die_on_error);
  79 }
  80
  81 void set_alternate_index_output(const char *name)
  82 {
  83         alternate_index_output = name;
  84 }
  85
  86 int commit_locked_index(struct lock_file *lk)
  87 {
  88         if (alternate_index_output) {
  89                 int result = rename(lk->filename, alternate_index_output);
  90                 lk->filename[0] = 0;
  91                 return result;
  92         }
  93         else
  94                 return commit_lock_file(lk);
  95 }
  96
  97 void rollback_lock_file(struct lock_file *lk)
  98 {
  99         if (lk->filename[0]) {
 100                 close(lk->fd);
 101                 unlink(lk->filename);
 102         }
 103         lk->filename[0] = 0;
 104 }