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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 JH |
14 | if (lock_file_list->owner == me && |
15 | lock_file_list->filename[0]) | |
021b6e45 JH |
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 | ||
5d5a7a67 BS |
28 | /* |
29 | * p = absolute or relative path name | |
30 | * | |
31 | * Return a pointer into p showing the beginning of the last path name | |
32 | * element. If p is empty or the root directory ("/"), just return p. | |
33 | */ | |
34 | static char *last_path_elm(char *p) | |
35 | { | |
36 | /* r starts pointing to null at the end of the string */ | |
37 | char *r = strchr(p, '\0'); | |
38 | ||
39 | if (r == p) | |
40 | return p; /* just return empty string */ | |
41 | ||
42 | r--; /* back up to last non-null character */ | |
43 | ||
44 | /* back up past trailing slashes, if any */ | |
45 | while (r > p && *r == '/') | |
46 | r--; | |
47 | ||
48 | /* | |
49 | * then go backwards until I hit a slash, or the beginning of | |
50 | * the string | |
51 | */ | |
52 | while (r > p && *(r-1) != '/') | |
53 | r--; | |
54 | return r; | |
55 | } | |
56 | ||
57 | ||
58 | /* We allow "recursive" symbolic links. Only within reason, though */ | |
59 | #define MAXDEPTH 5 | |
60 | ||
61 | /* | |
62 | * p = path that may be a symlink | |
63 | * s = full size of p | |
64 | * | |
65 | * If p is a symlink, attempt to overwrite p with a path to the real | |
66 | * file or directory (which may or may not exist), following a chain of | |
67 | * symlinks if necessary. Otherwise, leave p unmodified. | |
68 | * | |
69 | * This is a best-effort routine. If an error occurs, p will either be | |
70 | * left unmodified or will name a different symlink in a symlink chain | |
71 | * that started with p's initial contents. | |
72 | * | |
73 | * Always returns p. | |
74 | */ | |
75 | ||
76 | static char *resolve_symlink(char *p, size_t s) | |
77 | { | |
78 | int depth = MAXDEPTH; | |
79 | ||
80 | while (depth--) { | |
81 | char link[PATH_MAX]; | |
82 | int link_len = readlink(p, link, sizeof(link)); | |
83 | if (link_len < 0) { | |
84 | /* not a symlink anymore */ | |
85 | return p; | |
86 | } | |
87 | else if (link_len < sizeof(link)) | |
88 | /* readlink() never null-terminates */ | |
89 | link[link_len] = '\0'; | |
90 | else { | |
91 | warning("%s: symlink too long", p); | |
92 | return p; | |
93 | } | |
94 | ||
95 | if (link[0] == '/') { | |
96 | /* absolute path simply replaces p */ | |
97 | if (link_len < s) | |
98 | strcpy(p, link); | |
99 | else { | |
100 | warning("%s: symlink too long", p); | |
101 | return p; | |
102 | } | |
103 | } else { | |
104 | /* | |
105 | * link is a relative path, so I must replace the | |
106 | * last element of p with it. | |
107 | */ | |
108 | char *r = (char*)last_path_elm(p); | |
109 | if (r - p + link_len < s) | |
110 | strcpy(r, link); | |
111 | else { | |
112 | warning("%s: symlink too long", p); | |
113 | return p; | |
114 | } | |
115 | } | |
116 | } | |
117 | return p; | |
118 | } | |
119 | ||
120 | ||
40aaae88 | 121 | static int lock_file(struct lock_file *lk, const char *path) |
021b6e45 JH |
122 | { |
123 | int fd; | |
5d5a7a67 BS |
124 | |
125 | if (strlen(path) >= sizeof(lk->filename)) return -1; | |
126 | strcpy(lk->filename, path); | |
127 | /* | |
128 | * subtract 5 from size to make sure there's room for adding | |
129 | * ".lock" for the lock file name | |
130 | */ | |
131 | resolve_symlink(lk->filename, sizeof(lk->filename)-5); | |
132 | strcat(lk->filename, ".lock"); | |
021b6e45 | 133 | fd = open(lk->filename, O_RDWR | O_CREAT | O_EXCL, 0666); |
138086a7 | 134 | if (0 <= fd) { |
9a4cbdca SV |
135 | if (!lock_file_list) { |
136 | signal(SIGINT, remove_lock_file_on_signal); | |
137 | atexit(remove_lock_file); | |
138 | } | |
5e635e39 | 139 | lk->owner = getpid(); |
1084b845 | 140 | if (!lk->on_list) { |
138086a7 JH |
141 | lk->next = lock_file_list; |
142 | lock_file_list = lk; | |
1084b845 JH |
143 | lk->on_list = 1; |
144 | } | |
138086a7 JH |
145 | if (adjust_shared_perm(lk->filename)) |
146 | return error("cannot fix permission bits on %s", | |
147 | lk->filename); | |
021b6e45 | 148 | } |
1084b845 JH |
149 | else |
150 | lk->filename[0] = 0; | |
021b6e45 JH |
151 | return fd; |
152 | } | |
153 | ||
40aaae88 JH |
154 | int hold_lock_file_for_update(struct lock_file *lk, const char *path, int die_on_error) |
155 | { | |
156 | int fd = lock_file(lk, path); | |
157 | if (fd < 0 && die_on_error) | |
f9e8a43a | 158 | die("unable to create '%s.lock': %s", path, strerror(errno)); |
40aaae88 JH |
159 | return fd; |
160 | } | |
161 | ||
021b6e45 JH |
162 | int commit_lock_file(struct lock_file *lk) |
163 | { | |
164 | char result_file[PATH_MAX]; | |
165 | int i; | |
166 | strcpy(result_file, lk->filename); | |
167 | i = strlen(result_file) - 5; /* .lock */ | |
168 | result_file[i] = 0; | |
169 | i = rename(lk->filename, result_file); | |
170 | lk->filename[0] = 0; | |
171 | return i; | |
172 | } | |
173 | ||
30ca07a2 JH |
174 | int hold_locked_index(struct lock_file *lk, int die_on_error) |
175 | { | |
176 | return hold_lock_file_for_update(lk, get_index_file(), die_on_error); | |
177 | } | |
178 | ||
5e7f56ac JH |
179 | void set_alternate_index_output(const char *name) |
180 | { | |
181 | alternate_index_output = name; | |
182 | } | |
183 | ||
30ca07a2 JH |
184 | int commit_locked_index(struct lock_file *lk) |
185 | { | |
5e7f56ac JH |
186 | if (alternate_index_output) { |
187 | int result = rename(lk->filename, alternate_index_output); | |
30ca07a2 JH |
188 | lk->filename[0] = 0; |
189 | return result; | |
190 | } | |
191 | else | |
192 | return commit_lock_file(lk); | |
193 | } | |
194 | ||
021b6e45 JH |
195 | void rollback_lock_file(struct lock_file *lk) |
196 | { | |
197 | if (lk->filename[0]) | |
198 | unlink(lk->filename); | |
199 | lk->filename[0] = 0; | |
200 | } |