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