Import branch 'git-p4' of git://repo.or.cz/fast-export
[git] / 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                 lk->owner = getpid();
35                 if (!lk->on_list) {
36                         lk->next = lock_file_list;
37                         lock_file_list = lk;
38                         lk->on_list = 1;
39                 }
40                 if (lock_file_list) {
41                         signal(SIGINT, remove_lock_file_on_signal);
42                         atexit(remove_lock_file);
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 }