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Commit | Line | Data |
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021b6e45 JH |
1 | /* |
2 | * Copyright (c) 2005, Junio C Hamano | |
3 | */ | |
021b6e45 JH |
4 | #include "cache.h" |
5 | ||
6 | static struct lock_file *lock_file_list; | |
5e7f56ac | 7 | static const char *alternate_index_output; |
021b6e45 JH |
8 | |
9 | static void remove_lock_file(void) | |
10 | { | |
5e635e39 JH |
11 | pid_t me = getpid(); |
12 | ||
021b6e45 | 13 | while (lock_file_list) { |
5e635e39 | 14 | if (lock_file_list->owner == me && |
4723ee99 | 15 | lock_file_list->filename[0]) { |
d6cf61bf BC |
16 | if (lock_file_list->fd >= 0) |
17 | close(lock_file_list->fd); | |
021b6e45 | 18 | unlink(lock_file_list->filename); |
4723ee99 | 19 | } |
021b6e45 JH |
20 | lock_file_list = lock_file_list->next; |
21 | } | |
22 | } | |
23 | ||
24 | static void remove_lock_file_on_signal(int signo) | |
25 | { | |
26 | remove_lock_file(); | |
a1292939 | 27 | signal(signo, SIG_DFL); |
021b6e45 JH |
28 | raise(signo); |
29 | } | |
30 | ||
5d5a7a67 BS |
31 | /* |
32 | * p = absolute or relative path name | |
33 | * | |
34 | * Return a pointer into p showing the beginning of the last path name | |
35 | * element. If p is empty or the root directory ("/"), just return p. | |
36 | */ | |
37 | static char *last_path_elm(char *p) | |
38 | { | |
39 | /* r starts pointing to null at the end of the string */ | |
40 | char *r = strchr(p, '\0'); | |
41 | ||
42 | if (r == p) | |
43 | return p; /* just return empty string */ | |
44 | ||
45 | r--; /* back up to last non-null character */ | |
46 | ||
47 | /* back up past trailing slashes, if any */ | |
48 | while (r > p && *r == '/') | |
49 | r--; | |
50 | ||
51 | /* | |
52 | * then go backwards until I hit a slash, or the beginning of | |
53 | * the string | |
54 | */ | |
55 | while (r > p && *(r-1) != '/') | |
56 | r--; | |
57 | return r; | |
58 | } | |
59 | ||
60 | ||
61 | /* We allow "recursive" symbolic links. Only within reason, though */ | |
62 | #define MAXDEPTH 5 | |
63 | ||
64 | /* | |
65 | * p = path that may be a symlink | |
66 | * s = full size of p | |
67 | * | |
68 | * If p is a symlink, attempt to overwrite p with a path to the real | |
69 | * file or directory (which may or may not exist), following a chain of | |
70 | * symlinks if necessary. Otherwise, leave p unmodified. | |
71 | * | |
72 | * This is a best-effort routine. If an error occurs, p will either be | |
73 | * left unmodified or will name a different symlink in a symlink chain | |
74 | * that started with p's initial contents. | |
75 | * | |
76 | * Always returns p. | |
77 | */ | |
78 | ||
79 | static char *resolve_symlink(char *p, size_t s) | |
80 | { | |
81 | int depth = MAXDEPTH; | |
82 | ||
83 | while (depth--) { | |
84 | char link[PATH_MAX]; | |
85 | int link_len = readlink(p, link, sizeof(link)); | |
86 | if (link_len < 0) { | |
87 | /* not a symlink anymore */ | |
88 | return p; | |
89 | } | |
90 | else if (link_len < sizeof(link)) | |
91 | /* readlink() never null-terminates */ | |
92 | link[link_len] = '\0'; | |
93 | else { | |
94 | warning("%s: symlink too long", p); | |
95 | return p; | |
96 | } | |
97 | ||
ecf4831d | 98 | if (is_absolute_path(link)) { |
5d5a7a67 BS |
99 | /* absolute path simply replaces p */ |
100 | if (link_len < s) | |
101 | strcpy(p, link); | |
102 | else { | |
103 | warning("%s: symlink too long", p); | |
104 | return p; | |
105 | } | |
106 | } else { | |
107 | /* | |
108 | * link is a relative path, so I must replace the | |
109 | * last element of p with it. | |
110 | */ | |
111 | char *r = (char*)last_path_elm(p); | |
112 | if (r - p + link_len < s) | |
113 | strcpy(r, link); | |
114 | else { | |
115 | warning("%s: symlink too long", p); | |
116 | return p; | |
117 | } | |
118 | } | |
119 | } | |
120 | return p; | |
121 | } | |
122 | ||
123 | ||
acd3b9ec | 124 | static int lock_file(struct lock_file *lk, const char *path, int flags) |
021b6e45 | 125 | { |
acd3b9ec JH |
126 | if (strlen(path) >= sizeof(lk->filename)) |
127 | return -1; | |
5d5a7a67 BS |
128 | strcpy(lk->filename, path); |
129 | /* | |
130 | * subtract 5 from size to make sure there's room for adding | |
131 | * ".lock" for the lock file name | |
132 | */ | |
acd3b9ec JH |
133 | if (!(flags & LOCK_NODEREF)) |
134 | resolve_symlink(lk->filename, sizeof(lk->filename)-5); | |
5d5a7a67 | 135 | strcat(lk->filename, ".lock"); |
4723ee99 JS |
136 | lk->fd = open(lk->filename, O_RDWR | O_CREAT | O_EXCL, 0666); |
137 | if (0 <= lk->fd) { | |
9a4cbdca SV |
138 | if (!lock_file_list) { |
139 | signal(SIGINT, remove_lock_file_on_signal); | |
ad5fa3cc PB |
140 | signal(SIGHUP, remove_lock_file_on_signal); |
141 | signal(SIGTERM, remove_lock_file_on_signal); | |
142 | signal(SIGQUIT, remove_lock_file_on_signal); | |
0693f9dd | 143 | signal(SIGPIPE, remove_lock_file_on_signal); |
9a4cbdca SV |
144 | atexit(remove_lock_file); |
145 | } | |
5e635e39 | 146 | lk->owner = getpid(); |
1084b845 | 147 | if (!lk->on_list) { |
138086a7 JH |
148 | lk->next = lock_file_list; |
149 | lock_file_list = lk; | |
1084b845 JH |
150 | lk->on_list = 1; |
151 | } | |
138086a7 JH |
152 | if (adjust_shared_perm(lk->filename)) |
153 | return error("cannot fix permission bits on %s", | |
154 | lk->filename); | |
021b6e45 | 155 | } |
1084b845 JH |
156 | else |
157 | lk->filename[0] = 0; | |
4723ee99 | 158 | return lk->fd; |
021b6e45 JH |
159 | } |
160 | ||
e43a6fd3 MM |
161 | |
162 | NORETURN void unable_to_lock_index_die(const char *path, int err) | |
163 | { | |
164 | if (errno == EEXIST) { | |
165 | die("Unable to create '%s.lock': %s.\n\n" | |
166 | "If no other git process is currently running, this probably means a\n" | |
167 | "git process crashed in this repository earlier. Make sure no other git\n" | |
168 | "process is running and remove the file manually to continue.", | |
169 | path, strerror(err)); | |
170 | } else { | |
171 | die("Unable to create '%s.lock': %s", path, strerror(err)); | |
172 | } | |
173 | } | |
174 | ||
acd3b9ec | 175 | int hold_lock_file_for_update(struct lock_file *lk, const char *path, int flags) |
40aaae88 | 176 | { |
acd3b9ec JH |
177 | int fd = lock_file(lk, path, flags); |
178 | if (fd < 0 && (flags & LOCK_DIE_ON_ERROR)) | |
e43a6fd3 | 179 | unable_to_lock_index_die(path, errno); |
40aaae88 JH |
180 | return fd; |
181 | } | |
182 | ||
acd3b9ec | 183 | int hold_lock_file_for_append(struct lock_file *lk, const char *path, int flags) |
ea3cd5c7 DB |
184 | { |
185 | int fd, orig_fd; | |
186 | ||
acd3b9ec | 187 | fd = lock_file(lk, path, flags); |
ea3cd5c7 | 188 | if (fd < 0) { |
acd3b9ec | 189 | if (flags & LOCK_DIE_ON_ERROR) |
ea3cd5c7 DB |
190 | die("unable to create '%s.lock': %s", path, strerror(errno)); |
191 | return fd; | |
192 | } | |
193 | ||
194 | orig_fd = open(path, O_RDONLY); | |
195 | if (orig_fd < 0) { | |
196 | if (errno != ENOENT) { | |
acd3b9ec | 197 | if (flags & LOCK_DIE_ON_ERROR) |
ea3cd5c7 DB |
198 | die("cannot open '%s' for copying", path); |
199 | close(fd); | |
200 | return error("cannot open '%s' for copying", path); | |
201 | } | |
202 | } else if (copy_fd(orig_fd, fd)) { | |
acd3b9ec | 203 | if (flags & LOCK_DIE_ON_ERROR) |
ea3cd5c7 DB |
204 | exit(128); |
205 | close(fd); | |
206 | return -1; | |
207 | } | |
208 | return fd; | |
209 | } | |
210 | ||
d6cf61bf BC |
211 | int close_lock_file(struct lock_file *lk) |
212 | { | |
213 | int fd = lk->fd; | |
214 | lk->fd = -1; | |
215 | return close(fd); | |
216 | } | |
217 | ||
021b6e45 JH |
218 | int commit_lock_file(struct lock_file *lk) |
219 | { | |
220 | char result_file[PATH_MAX]; | |
d6cf61bf BC |
221 | size_t i; |
222 | if (lk->fd >= 0 && close_lock_file(lk)) | |
223 | return -1; | |
021b6e45 JH |
224 | strcpy(result_file, lk->filename); |
225 | i = strlen(result_file) - 5; /* .lock */ | |
226 | result_file[i] = 0; | |
d6cf61bf BC |
227 | if (rename(lk->filename, result_file)) |
228 | return -1; | |
021b6e45 | 229 | lk->filename[0] = 0; |
d6cf61bf | 230 | return 0; |
021b6e45 JH |
231 | } |
232 | ||
30ca07a2 JH |
233 | int hold_locked_index(struct lock_file *lk, int die_on_error) |
234 | { | |
acd3b9ec JH |
235 | return hold_lock_file_for_update(lk, get_index_file(), |
236 | die_on_error | |
237 | ? LOCK_DIE_ON_ERROR | |
238 | : 0); | |
30ca07a2 JH |
239 | } |
240 | ||
5e7f56ac JH |
241 | void set_alternate_index_output(const char *name) |
242 | { | |
243 | alternate_index_output = name; | |
244 | } | |
245 | ||
30ca07a2 JH |
246 | int commit_locked_index(struct lock_file *lk) |
247 | { | |
5e7f56ac | 248 | if (alternate_index_output) { |
d6cf61bf BC |
249 | if (lk->fd >= 0 && close_lock_file(lk)) |
250 | return -1; | |
251 | if (rename(lk->filename, alternate_index_output)) | |
252 | return -1; | |
30ca07a2 | 253 | lk->filename[0] = 0; |
d6cf61bf | 254 | return 0; |
30ca07a2 JH |
255 | } |
256 | else | |
257 | return commit_lock_file(lk); | |
258 | } | |
259 | ||
021b6e45 JH |
260 | void rollback_lock_file(struct lock_file *lk) |
261 | { | |
4723ee99 | 262 | if (lk->filename[0]) { |
d6cf61bf BC |
263 | if (lk->fd >= 0) |
264 | close(lk->fd); | |
021b6e45 | 265 | unlink(lk->filename); |
4723ee99 | 266 | } |
021b6e45 JH |
267 | lk->filename[0] = 0; |
268 | } |