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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(); | |
27 | signal(SIGINT, SIG_DFL); | |
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 | ||
40aaae88 | 124 | static int lock_file(struct lock_file *lk, const char *path) |
021b6e45 | 125 | { |
5d5a7a67 BS |
126 | if (strlen(path) >= sizeof(lk->filename)) return -1; |
127 | strcpy(lk->filename, path); | |
128 | /* | |
129 | * subtract 5 from size to make sure there's room for adding | |
130 | * ".lock" for the lock file name | |
131 | */ | |
132 | resolve_symlink(lk->filename, sizeof(lk->filename)-5); | |
133 | strcat(lk->filename, ".lock"); | |
4723ee99 JS |
134 | lk->fd = open(lk->filename, O_RDWR | O_CREAT | O_EXCL, 0666); |
135 | if (0 <= lk->fd) { | |
9a4cbdca SV |
136 | if (!lock_file_list) { |
137 | signal(SIGINT, remove_lock_file_on_signal); | |
138 | atexit(remove_lock_file); | |
139 | } | |
5e635e39 | 140 | lk->owner = getpid(); |
1084b845 | 141 | if (!lk->on_list) { |
138086a7 JH |
142 | lk->next = lock_file_list; |
143 | lock_file_list = lk; | |
1084b845 JH |
144 | lk->on_list = 1; |
145 | } | |
138086a7 JH |
146 | if (adjust_shared_perm(lk->filename)) |
147 | return error("cannot fix permission bits on %s", | |
148 | lk->filename); | |
021b6e45 | 149 | } |
1084b845 JH |
150 | else |
151 | lk->filename[0] = 0; | |
4723ee99 | 152 | return lk->fd; |
021b6e45 JH |
153 | } |
154 | ||
40aaae88 JH |
155 | int hold_lock_file_for_update(struct lock_file *lk, const char *path, int die_on_error) |
156 | { | |
157 | int fd = lock_file(lk, path); | |
158 | if (fd < 0 && die_on_error) | |
f9e8a43a | 159 | die("unable to create '%s.lock': %s", path, strerror(errno)); |
40aaae88 JH |
160 | return fd; |
161 | } | |
162 | ||
d6cf61bf BC |
163 | int close_lock_file(struct lock_file *lk) |
164 | { | |
165 | int fd = lk->fd; | |
166 | lk->fd = -1; | |
167 | return close(fd); | |
168 | } | |
169 | ||
021b6e45 JH |
170 | int commit_lock_file(struct lock_file *lk) |
171 | { | |
172 | char result_file[PATH_MAX]; | |
d6cf61bf BC |
173 | size_t i; |
174 | if (lk->fd >= 0 && close_lock_file(lk)) | |
175 | return -1; | |
021b6e45 JH |
176 | strcpy(result_file, lk->filename); |
177 | i = strlen(result_file) - 5; /* .lock */ | |
178 | result_file[i] = 0; | |
d6cf61bf BC |
179 | if (rename(lk->filename, result_file)) |
180 | return -1; | |
021b6e45 | 181 | lk->filename[0] = 0; |
d6cf61bf | 182 | return 0; |
021b6e45 JH |
183 | } |
184 | ||
30ca07a2 JH |
185 | int hold_locked_index(struct lock_file *lk, int die_on_error) |
186 | { | |
187 | return hold_lock_file_for_update(lk, get_index_file(), die_on_error); | |
188 | } | |
189 | ||
5e7f56ac JH |
190 | void set_alternate_index_output(const char *name) |
191 | { | |
192 | alternate_index_output = name; | |
193 | } | |
194 | ||
30ca07a2 JH |
195 | int commit_locked_index(struct lock_file *lk) |
196 | { | |
5e7f56ac | 197 | if (alternate_index_output) { |
d6cf61bf BC |
198 | if (lk->fd >= 0 && close_lock_file(lk)) |
199 | return -1; | |
200 | if (rename(lk->filename, alternate_index_output)) | |
201 | return -1; | |
30ca07a2 | 202 | lk->filename[0] = 0; |
d6cf61bf | 203 | return 0; |
30ca07a2 JH |
204 | } |
205 | else | |
206 | return commit_lock_file(lk); | |
207 | } | |
208 | ||
021b6e45 JH |
209 | void rollback_lock_file(struct lock_file *lk) |
210 | { | |
4723ee99 | 211 | if (lk->filename[0]) { |
d6cf61bf BC |
212 | if (lk->fd >= 0) |
213 | close(lk->fd); | |
021b6e45 | 214 | unlink(lk->filename); |
4723ee99 | 215 | } |
021b6e45 JH |
216 | lk->filename[0] = 0; |
217 | } |