lockfile.c: add a new public function unable_to_lock_message
[git/git.git] / lockfile.c
CommitLineData
021b6e45
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1/*
2 * Copyright (c) 2005, Junio C Hamano
3 */
021b6e45 4#include "cache.h"
4a16d072 5#include "sigchain.h"
021b6e45
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6
7static struct lock_file *lock_file_list;
5e7f56ac 8static const char *alternate_index_output;
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9
10static void remove_lock_file(void)
11{
5e635e39
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12 pid_t me = getpid();
13
021b6e45 14 while (lock_file_list) {
5e635e39 15 if (lock_file_list->owner == me &&
4723ee99 16 lock_file_list->filename[0]) {
d6cf61bf
BC
17 if (lock_file_list->fd >= 0)
18 close(lock_file_list->fd);
691f1a28 19 unlink_or_warn(lock_file_list->filename);
4723ee99 20 }
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21 lock_file_list = lock_file_list->next;
22 }
23}
24
25static void remove_lock_file_on_signal(int signo)
26{
27 remove_lock_file();
4a16d072 28 sigchain_pop(signo);
021b6e45
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29 raise(signo);
30}
31
5d5a7a67
BS
32/*
33 * p = absolute or relative path name
34 *
35 * Return a pointer into p showing the beginning of the last path name
36 * element. If p is empty or the root directory ("/"), just return p.
37 */
38static char *last_path_elm(char *p)
39{
40 /* r starts pointing to null at the end of the string */
41 char *r = strchr(p, '\0');
42
43 if (r == p)
44 return p; /* just return empty string */
45
46 r--; /* back up to last non-null character */
47
48 /* back up past trailing slashes, if any */
49 while (r > p && *r == '/')
50 r--;
51
52 /*
53 * then go backwards until I hit a slash, or the beginning of
54 * the string
55 */
56 while (r > p && *(r-1) != '/')
57 r--;
58 return r;
59}
60
61
62/* We allow "recursive" symbolic links. Only within reason, though */
63#define MAXDEPTH 5
64
65/*
66 * p = path that may be a symlink
67 * s = full size of p
68 *
69 * If p is a symlink, attempt to overwrite p with a path to the real
70 * file or directory (which may or may not exist), following a chain of
71 * symlinks if necessary. Otherwise, leave p unmodified.
72 *
73 * This is a best-effort routine. If an error occurs, p will either be
74 * left unmodified or will name a different symlink in a symlink chain
75 * that started with p's initial contents.
76 *
77 * Always returns p.
78 */
79
80static char *resolve_symlink(char *p, size_t s)
81{
82 int depth = MAXDEPTH;
83
84 while (depth--) {
85 char link[PATH_MAX];
86 int link_len = readlink(p, link, sizeof(link));
87 if (link_len < 0) {
88 /* not a symlink anymore */
89 return p;
90 }
91 else if (link_len < sizeof(link))
92 /* readlink() never null-terminates */
93 link[link_len] = '\0';
94 else {
95 warning("%s: symlink too long", p);
96 return p;
97 }
98
ecf4831d 99 if (is_absolute_path(link)) {
5d5a7a67
BS
100 /* absolute path simply replaces p */
101 if (link_len < s)
102 strcpy(p, link);
103 else {
104 warning("%s: symlink too long", p);
105 return p;
106 }
107 } else {
108 /*
109 * link is a relative path, so I must replace the
110 * last element of p with it.
111 */
4b25d091 112 char *r = (char *)last_path_elm(p);
5d5a7a67
BS
113 if (r - p + link_len < s)
114 strcpy(r, link);
115 else {
116 warning("%s: symlink too long", p);
117 return p;
118 }
119 }
120 }
121 return p;
122}
123
124
acd3b9ec 125static int lock_file(struct lock_file *lk, const char *path, int flags)
021b6e45 126{
5d5a7a67
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127 /*
128 * subtract 5 from size to make sure there's room for adding
129 * ".lock" for the lock file name
130 */
2fbd4f92
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131 static const size_t max_path_len = sizeof(lk->filename) - 5;
132
133 if (strlen(path) >= max_path_len)
134 return -1;
135 strcpy(lk->filename, path);
acd3b9ec 136 if (!(flags & LOCK_NODEREF))
2fbd4f92 137 resolve_symlink(lk->filename, max_path_len);
5d5a7a67 138 strcat(lk->filename, ".lock");
4723ee99
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139 lk->fd = open(lk->filename, O_RDWR | O_CREAT | O_EXCL, 0666);
140 if (0 <= lk->fd) {
9a4cbdca 141 if (!lock_file_list) {
57b235a4 142 sigchain_push_common(remove_lock_file_on_signal);
9a4cbdca
SV
143 atexit(remove_lock_file);
144 }
5e635e39 145 lk->owner = getpid();
1084b845 146 if (!lk->on_list) {
138086a7
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147 lk->next = lock_file_list;
148 lock_file_list = lk;
1084b845
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149 lk->on_list = 1;
150 }
138086a7
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151 if (adjust_shared_perm(lk->filename))
152 return error("cannot fix permission bits on %s",
153 lk->filename);
021b6e45 154 }
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155 else
156 lk->filename[0] = 0;
4723ee99 157 return lk->fd;
021b6e45
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158}
159
6af926e8 160void unable_to_lock_message(const char *path, int err, struct strbuf *buf)
e43a6fd3 161{
bdfd739d 162 if (err == EEXIST) {
6af926e8 163 strbuf_addf(buf, "Unable to create '%s.lock': %s.\n\n"
e43a6fd3
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164 "If no other git process is currently running, this probably means a\n"
165 "git process crashed in this repository earlier. Make sure no other git\n"
166 "process is running and remove the file manually to continue.",
e2a57aac 167 absolute_path(path), strerror(err));
1b018fd9 168 } else
6af926e8 169 strbuf_addf(buf, "Unable to create '%s.lock': %s",
e2a57aac 170 absolute_path(path), strerror(err));
1b018fd9
MV
171}
172
173int unable_to_lock_error(const char *path, int err)
174{
6af926e8
RS
175 struct strbuf buf = STRBUF_INIT;
176
177 unable_to_lock_message(path, err, &buf);
178 error("%s", buf.buf);
179 strbuf_release(&buf);
1b018fd9
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180 return -1;
181}
182
183NORETURN void unable_to_lock_index_die(const char *path, int err)
184{
6af926e8
RS
185 struct strbuf buf = STRBUF_INIT;
186
187 unable_to_lock_message(path, err, &buf);
188 die("%s", buf.buf);
e43a6fd3
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189}
190
acd3b9ec 191int hold_lock_file_for_update(struct lock_file *lk, const char *path, int flags)
40aaae88 192{
acd3b9ec
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193 int fd = lock_file(lk, path, flags);
194 if (fd < 0 && (flags & LOCK_DIE_ON_ERROR))
e43a6fd3 195 unable_to_lock_index_die(path, errno);
40aaae88
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196 return fd;
197}
198
acd3b9ec 199int hold_lock_file_for_append(struct lock_file *lk, const char *path, int flags)
ea3cd5c7
DB
200{
201 int fd, orig_fd;
202
acd3b9ec 203 fd = lock_file(lk, path, flags);
ea3cd5c7 204 if (fd < 0) {
acd3b9ec 205 if (flags & LOCK_DIE_ON_ERROR)
bdfd739d 206 unable_to_lock_index_die(path, errno);
ea3cd5c7
DB
207 return fd;
208 }
209
210 orig_fd = open(path, O_RDONLY);
211 if (orig_fd < 0) {
212 if (errno != ENOENT) {
acd3b9ec 213 if (flags & LOCK_DIE_ON_ERROR)
ea3cd5c7
DB
214 die("cannot open '%s' for copying", path);
215 close(fd);
216 return error("cannot open '%s' for copying", path);
217 }
218 } else if (copy_fd(orig_fd, fd)) {
acd3b9ec 219 if (flags & LOCK_DIE_ON_ERROR)
ea3cd5c7
DB
220 exit(128);
221 close(fd);
222 return -1;
223 }
224 return fd;
225}
226
d6cf61bf
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227int close_lock_file(struct lock_file *lk)
228{
229 int fd = lk->fd;
230 lk->fd = -1;
231 return close(fd);
232}
233
021b6e45
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234int commit_lock_file(struct lock_file *lk)
235{
236 char result_file[PATH_MAX];
d6cf61bf
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237 size_t i;
238 if (lk->fd >= 0 && close_lock_file(lk))
239 return -1;
021b6e45
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240 strcpy(result_file, lk->filename);
241 i = strlen(result_file) - 5; /* .lock */
242 result_file[i] = 0;
d6cf61bf
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243 if (rename(lk->filename, result_file))
244 return -1;
021b6e45 245 lk->filename[0] = 0;
d6cf61bf 246 return 0;
021b6e45
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247}
248
30ca07a2
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249int hold_locked_index(struct lock_file *lk, int die_on_error)
250{
acd3b9ec
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251 return hold_lock_file_for_update(lk, get_index_file(),
252 die_on_error
253 ? LOCK_DIE_ON_ERROR
254 : 0);
30ca07a2
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255}
256
5e7f56ac
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257void set_alternate_index_output(const char *name)
258{
259 alternate_index_output = name;
260}
261
30ca07a2
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262int commit_locked_index(struct lock_file *lk)
263{
5e7f56ac 264 if (alternate_index_output) {
d6cf61bf
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265 if (lk->fd >= 0 && close_lock_file(lk))
266 return -1;
267 if (rename(lk->filename, alternate_index_output))
268 return -1;
30ca07a2 269 lk->filename[0] = 0;
d6cf61bf 270 return 0;
30ca07a2
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271 }
272 else
273 return commit_lock_file(lk);
274}
275
021b6e45
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276void rollback_lock_file(struct lock_file *lk)
277{
4723ee99 278 if (lk->filename[0]) {
d6cf61bf
BC
279 if (lk->fd >= 0)
280 close(lk->fd);
691f1a28 281 unlink_or_warn(lk->filename);
4723ee99 282 }
021b6e45
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283 lk->filename[0] = 0;
284}