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Commit | Line | Data |
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021b6e45 JH |
1 | /* |
2 | * Copyright (c) 2005, Junio C Hamano | |
3 | */ | |
021b6e45 | 4 | #include "cache.h" |
4a16d072 | 5 | #include "sigchain.h" |
021b6e45 JH |
6 | |
7 | static struct lock_file *lock_file_list; | |
5e7f56ac | 8 | static const char *alternate_index_output; |
021b6e45 JH |
9 | |
10 | static void remove_lock_file(void) | |
11 | { | |
5e635e39 JH |
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); | |
021b6e45 | 19 | unlink(lock_file_list->filename); |
4723ee99 | 20 | } |
021b6e45 JH |
21 | lock_file_list = lock_file_list->next; |
22 | } | |
23 | } | |
24 | ||
25 | static void remove_lock_file_on_signal(int signo) | |
26 | { | |
27 | remove_lock_file(); | |
4a16d072 | 28 | sigchain_pop(signo); |
021b6e45 JH |
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 | */ | |
38 | static 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 | ||
80 | static 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 | */ | |
112 | char *r = (char*)last_path_elm(p); | |
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 | 125 | static int lock_file(struct lock_file *lk, const char *path, int flags) |
021b6e45 | 126 | { |
acd3b9ec JH |
127 | if (strlen(path) >= sizeof(lk->filename)) |
128 | return -1; | |
5d5a7a67 BS |
129 | strcpy(lk->filename, path); |
130 | /* | |
131 | * subtract 5 from size to make sure there's room for adding | |
132 | * ".lock" for the lock file name | |
133 | */ | |
acd3b9ec JH |
134 | if (!(flags & LOCK_NODEREF)) |
135 | resolve_symlink(lk->filename, sizeof(lk->filename)-5); | |
5d5a7a67 | 136 | strcat(lk->filename, ".lock"); |
4723ee99 JS |
137 | lk->fd = open(lk->filename, O_RDWR | O_CREAT | O_EXCL, 0666); |
138 | if (0 <= lk->fd) { | |
9a4cbdca | 139 | if (!lock_file_list) { |
57b235a4 | 140 | sigchain_push_common(remove_lock_file_on_signal); |
9a4cbdca SV |
141 | atexit(remove_lock_file); |
142 | } | |
5e635e39 | 143 | lk->owner = getpid(); |
1084b845 | 144 | if (!lk->on_list) { |
138086a7 JH |
145 | lk->next = lock_file_list; |
146 | lock_file_list = lk; | |
1084b845 JH |
147 | lk->on_list = 1; |
148 | } | |
138086a7 JH |
149 | if (adjust_shared_perm(lk->filename)) |
150 | return error("cannot fix permission bits on %s", | |
151 | lk->filename); | |
021b6e45 | 152 | } |
1084b845 JH |
153 | else |
154 | lk->filename[0] = 0; | |
4723ee99 | 155 | return lk->fd; |
021b6e45 JH |
156 | } |
157 | ||
e43a6fd3 MM |
158 | |
159 | NORETURN void unable_to_lock_index_die(const char *path, int err) | |
160 | { | |
161 | if (errno == EEXIST) { | |
162 | die("Unable to create '%s.lock': %s.\n\n" | |
163 | "If no other git process is currently running, this probably means a\n" | |
164 | "git process crashed in this repository earlier. Make sure no other git\n" | |
165 | "process is running and remove the file manually to continue.", | |
166 | path, strerror(err)); | |
167 | } else { | |
168 | die("Unable to create '%s.lock': %s", path, strerror(err)); | |
169 | } | |
170 | } | |
171 | ||
acd3b9ec | 172 | int hold_lock_file_for_update(struct lock_file *lk, const char *path, int flags) |
40aaae88 | 173 | { |
acd3b9ec JH |
174 | int fd = lock_file(lk, path, flags); |
175 | if (fd < 0 && (flags & LOCK_DIE_ON_ERROR)) | |
e43a6fd3 | 176 | unable_to_lock_index_die(path, errno); |
40aaae88 JH |
177 | return fd; |
178 | } | |
179 | ||
acd3b9ec | 180 | int hold_lock_file_for_append(struct lock_file *lk, const char *path, int flags) |
ea3cd5c7 DB |
181 | { |
182 | int fd, orig_fd; | |
183 | ||
acd3b9ec | 184 | fd = lock_file(lk, path, flags); |
ea3cd5c7 | 185 | if (fd < 0) { |
acd3b9ec | 186 | if (flags & LOCK_DIE_ON_ERROR) |
ea3cd5c7 DB |
187 | die("unable to create '%s.lock': %s", path, strerror(errno)); |
188 | return fd; | |
189 | } | |
190 | ||
191 | orig_fd = open(path, O_RDONLY); | |
192 | if (orig_fd < 0) { | |
193 | if (errno != ENOENT) { | |
acd3b9ec | 194 | if (flags & LOCK_DIE_ON_ERROR) |
ea3cd5c7 DB |
195 | die("cannot open '%s' for copying", path); |
196 | close(fd); | |
197 | return error("cannot open '%s' for copying", path); | |
198 | } | |
199 | } else if (copy_fd(orig_fd, fd)) { | |
acd3b9ec | 200 | if (flags & LOCK_DIE_ON_ERROR) |
ea3cd5c7 DB |
201 | exit(128); |
202 | close(fd); | |
203 | return -1; | |
204 | } | |
205 | return fd; | |
206 | } | |
207 | ||
d6cf61bf BC |
208 | int close_lock_file(struct lock_file *lk) |
209 | { | |
210 | int fd = lk->fd; | |
211 | lk->fd = -1; | |
212 | return close(fd); | |
213 | } | |
214 | ||
021b6e45 JH |
215 | int commit_lock_file(struct lock_file *lk) |
216 | { | |
217 | char result_file[PATH_MAX]; | |
d6cf61bf BC |
218 | size_t i; |
219 | if (lk->fd >= 0 && close_lock_file(lk)) | |
220 | return -1; | |
021b6e45 JH |
221 | strcpy(result_file, lk->filename); |
222 | i = strlen(result_file) - 5; /* .lock */ | |
223 | result_file[i] = 0; | |
d6cf61bf BC |
224 | if (rename(lk->filename, result_file)) |
225 | return -1; | |
021b6e45 | 226 | lk->filename[0] = 0; |
d6cf61bf | 227 | return 0; |
021b6e45 JH |
228 | } |
229 | ||
30ca07a2 JH |
230 | int hold_locked_index(struct lock_file *lk, int die_on_error) |
231 | { | |
acd3b9ec JH |
232 | return hold_lock_file_for_update(lk, get_index_file(), |
233 | die_on_error | |
234 | ? LOCK_DIE_ON_ERROR | |
235 | : 0); | |
30ca07a2 JH |
236 | } |
237 | ||
5e7f56ac JH |
238 | void set_alternate_index_output(const char *name) |
239 | { | |
240 | alternate_index_output = name; | |
241 | } | |
242 | ||
30ca07a2 JH |
243 | int commit_locked_index(struct lock_file *lk) |
244 | { | |
5e7f56ac | 245 | if (alternate_index_output) { |
d6cf61bf BC |
246 | if (lk->fd >= 0 && close_lock_file(lk)) |
247 | return -1; | |
248 | if (rename(lk->filename, alternate_index_output)) | |
249 | return -1; | |
30ca07a2 | 250 | lk->filename[0] = 0; |
d6cf61bf | 251 | return 0; |
30ca07a2 JH |
252 | } |
253 | else | |
254 | return commit_lock_file(lk); | |
255 | } | |
256 | ||
021b6e45 JH |
257 | void rollback_lock_file(struct lock_file *lk) |
258 | { | |
4723ee99 | 259 | if (lk->filename[0]) { |
d6cf61bf BC |
260 | if (lk->fd >= 0) |
261 | close(lk->fd); | |
021b6e45 | 262 | unlink(lk->filename); |
4723ee99 | 263 | } |
021b6e45 JH |
264 | lk->filename[0] = 0; |
265 | } |