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Commit | Line | Data |
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1a9d15db MH |
1 | /* |
2 | * State diagram and cleanup | |
3 | * ------------------------- | |
4 | * | |
5 | * If the program exits while a temporary file is active, we want to | |
6 | * make sure that we remove it. This is done by remembering the active | |
7 | * temporary files in a linked list, `tempfile_list`. An `atexit(3)` | |
8 | * handler and a signal handler are registered, to clean up any active | |
9 | * temporary files. | |
10 | * | |
11 | * Because the signal handler can run at any time, `tempfile_list` and | |
12 | * the `tempfile` objects that comprise it must be kept in | |
13 | * self-consistent states at all times. | |
14 | * | |
15 | * The possible states of a `tempfile` object are as follows: | |
16 | * | |
17 | * - Uninitialized. In this state the object's `on_list` field must be | |
18 | * zero but the rest of its contents need not be initialized. As | |
19 | * soon as the object is used in any way, it is irrevocably | |
20 | * registered in `tempfile_list`, and `on_list` is set. | |
21 | * | |
22 | * - Active, file open (after `create_tempfile()` or | |
23 | * `reopen_tempfile()`). In this state: | |
24 | * | |
25 | * - the temporary file exists | |
26 | * - `active` is set | |
27 | * - `filename` holds the filename of the temporary file | |
28 | * - `fd` holds a file descriptor open for writing to it | |
29 | * - `fp` holds a pointer to an open `FILE` object if and only if | |
30 | * `fdopen_tempfile()` has been called on the object | |
31 | * - `owner` holds the PID of the process that created the file | |
32 | * | |
49bd0fc2 | 33 | * - Active, file closed (after `close_tempfile_gently()`). Same |
1a9d15db MH |
34 | * as the previous state, except that the temporary file is closed, |
35 | * `fd` is -1, and `fp` is `NULL`. | |
36 | * | |
49bd0fc2 JK |
37 | * - Inactive (after `delete_tempfile()`, `rename_tempfile()`, or a |
38 | * failed attempt to create a temporary file). In this state: | |
1a9d15db MH |
39 | * |
40 | * - `active` is unset | |
41 | * - `filename` is empty (usually, though there are transitory | |
42 | * states in which this condition doesn't hold). Client code should | |
43 | * *not* rely on the filename being empty in this state. | |
44 | * - `fd` is -1 and `fp` is `NULL` | |
45 | * - the object is left registered in the `tempfile_list`, and | |
46 | * `on_list` is set. | |
47 | * | |
48 | * A temporary file is owned by the process that created it. The | |
49 | * `tempfile` has an `owner` field that records the owner's PID. This | |
50 | * field is used to prevent a forked process from deleting a temporary | |
51 | * file created by its parent. | |
52 | */ | |
53 | ||
54 | #include "cache.h" | |
55 | #include "tempfile.h" | |
56 | #include "sigchain.h" | |
57 | ||
58 | static struct tempfile *volatile tempfile_list; | |
59 | ||
60 | static void remove_tempfiles(int skip_fclose) | |
61 | { | |
62 | pid_t me = getpid(); | |
63 | ||
64 | while (tempfile_list) { | |
65 | if (tempfile_list->owner == me) { | |
66 | /* fclose() is not safe to call in a signal handler */ | |
67 | if (skip_fclose) | |
68 | tempfile_list->fp = NULL; | |
69 | delete_tempfile(tempfile_list); | |
70 | } | |
71 | tempfile_list = tempfile_list->next; | |
72 | } | |
73 | } | |
74 | ||
75 | static void remove_tempfiles_on_exit(void) | |
76 | { | |
77 | remove_tempfiles(0); | |
78 | } | |
79 | ||
80 | static void remove_tempfiles_on_signal(int signo) | |
81 | { | |
82 | remove_tempfiles(1); | |
83 | sigchain_pop(signo); | |
84 | raise(signo); | |
85 | } | |
86 | ||
7eba6ce5 MH |
87 | /* |
88 | * Initialize *tempfile if necessary and add it to tempfile_list. | |
89 | */ | |
90 | static void prepare_tempfile_object(struct tempfile *tempfile) | |
1a9d15db | 91 | { |
1a9d15db MH |
92 | if (!tempfile_list) { |
93 | /* One-time initialization */ | |
94 | sigchain_push_common(remove_tempfiles_on_signal); | |
95 | atexit(remove_tempfiles_on_exit); | |
96 | } | |
97 | ||
e6fc2673 | 98 | if (is_tempfile_active(tempfile)) |
9b028aa4 | 99 | BUG("prepare_tempfile_object called for active object"); |
1a9d15db MH |
100 | if (!tempfile->on_list) { |
101 | /* Initialize *tempfile and add it to tempfile_list: */ | |
102 | tempfile->fd = -1; | |
103 | tempfile->fp = NULL; | |
104 | tempfile->active = 0; | |
105 | tempfile->owner = 0; | |
7eba6ce5 | 106 | strbuf_init(&tempfile->filename, 0); |
1a9d15db MH |
107 | tempfile->next = tempfile_list; |
108 | tempfile_list = tempfile; | |
109 | tempfile->on_list = 1; | |
110 | } else if (tempfile->filename.len) { | |
111 | /* This shouldn't happen, but better safe than sorry. */ | |
9b028aa4 | 112 | BUG("prepare_tempfile_object called for improperly-reset object"); |
1a9d15db | 113 | } |
7eba6ce5 MH |
114 | } |
115 | ||
2933ebba JK |
116 | static void activate_tempfile(struct tempfile *tempfile) |
117 | { | |
118 | tempfile->owner = getpid(); | |
119 | tempfile->active = 1; | |
120 | } | |
121 | ||
7eba6ce5 MH |
122 | /* Make sure errno contains a meaningful value on error */ |
123 | int create_tempfile(struct tempfile *tempfile, const char *path) | |
124 | { | |
125 | prepare_tempfile_object(tempfile); | |
1a9d15db MH |
126 | |
127 | strbuf_add_absolute_path(&tempfile->filename, path); | |
05d1ed61 BW |
128 | tempfile->fd = open(tempfile->filename.buf, |
129 | O_RDWR | O_CREAT | O_EXCL | O_CLOEXEC, 0666); | |
130 | if (O_CLOEXEC && tempfile->fd < 0 && errno == EINVAL) | |
131 | /* Try again w/o O_CLOEXEC: the kernel might not support it */ | |
132 | tempfile->fd = open(tempfile->filename.buf, | |
133 | O_RDWR | O_CREAT | O_EXCL, 0666); | |
1a9d15db MH |
134 | if (tempfile->fd < 0) { |
135 | strbuf_reset(&tempfile->filename); | |
136 | return -1; | |
137 | } | |
2933ebba | 138 | activate_tempfile(tempfile); |
1a9d15db MH |
139 | if (adjust_shared_perm(tempfile->filename.buf)) { |
140 | int save_errno = errno; | |
141 | error("cannot fix permission bits on %s", tempfile->filename.buf); | |
142 | delete_tempfile(tempfile); | |
143 | errno = save_errno; | |
144 | return -1; | |
145 | } | |
146 | return tempfile->fd; | |
147 | } | |
148 | ||
99397152 MH |
149 | void register_tempfile(struct tempfile *tempfile, const char *path) |
150 | { | |
151 | prepare_tempfile_object(tempfile); | |
152 | strbuf_add_absolute_path(&tempfile->filename, path); | |
2933ebba | 153 | activate_tempfile(tempfile); |
99397152 MH |
154 | } |
155 | ||
354ab112 MH |
156 | int mks_tempfile_sm(struct tempfile *tempfile, |
157 | const char *template, int suffixlen, int mode) | |
158 | { | |
159 | prepare_tempfile_object(tempfile); | |
160 | ||
161 | strbuf_add_absolute_path(&tempfile->filename, template); | |
162 | tempfile->fd = git_mkstemps_mode(tempfile->filename.buf, suffixlen, mode); | |
163 | if (tempfile->fd < 0) { | |
164 | strbuf_reset(&tempfile->filename); | |
165 | return -1; | |
166 | } | |
2933ebba | 167 | activate_tempfile(tempfile); |
354ab112 MH |
168 | return tempfile->fd; |
169 | } | |
170 | ||
171 | int mks_tempfile_tsm(struct tempfile *tempfile, | |
172 | const char *template, int suffixlen, int mode) | |
173 | { | |
174 | const char *tmpdir; | |
175 | ||
176 | prepare_tempfile_object(tempfile); | |
177 | ||
178 | tmpdir = getenv("TMPDIR"); | |
179 | if (!tmpdir) | |
180 | tmpdir = "/tmp"; | |
181 | ||
182 | strbuf_addf(&tempfile->filename, "%s/%s", tmpdir, template); | |
183 | tempfile->fd = git_mkstemps_mode(tempfile->filename.buf, suffixlen, mode); | |
184 | if (tempfile->fd < 0) { | |
185 | strbuf_reset(&tempfile->filename); | |
186 | return -1; | |
187 | } | |
2933ebba | 188 | activate_tempfile(tempfile); |
354ab112 MH |
189 | return tempfile->fd; |
190 | } | |
191 | ||
192 | int xmks_tempfile_m(struct tempfile *tempfile, const char *template, int mode) | |
193 | { | |
194 | int fd; | |
195 | struct strbuf full_template = STRBUF_INIT; | |
196 | ||
197 | strbuf_add_absolute_path(&full_template, template); | |
198 | fd = mks_tempfile_m(tempfile, full_template.buf, mode); | |
199 | if (fd < 0) | |
200 | die_errno("Unable to create temporary file '%s'", | |
201 | full_template.buf); | |
202 | ||
203 | strbuf_release(&full_template); | |
204 | return fd; | |
205 | } | |
206 | ||
1a9d15db MH |
207 | FILE *fdopen_tempfile(struct tempfile *tempfile, const char *mode) |
208 | { | |
e6fc2673 | 209 | if (!is_tempfile_active(tempfile)) |
9b028aa4 | 210 | BUG("fdopen_tempfile() called for inactive object"); |
1a9d15db | 211 | if (tempfile->fp) |
9b028aa4 | 212 | BUG("fdopen_tempfile() called for open object"); |
1a9d15db MH |
213 | |
214 | tempfile->fp = fdopen(tempfile->fd, mode); | |
215 | return tempfile->fp; | |
216 | } | |
217 | ||
218 | const char *get_tempfile_path(struct tempfile *tempfile) | |
219 | { | |
e6fc2673 | 220 | if (!is_tempfile_active(tempfile)) |
9b028aa4 | 221 | BUG("get_tempfile_path() called for inactive object"); |
1a9d15db MH |
222 | return tempfile->filename.buf; |
223 | } | |
224 | ||
225 | int get_tempfile_fd(struct tempfile *tempfile) | |
226 | { | |
e6fc2673 | 227 | if (!is_tempfile_active(tempfile)) |
9b028aa4 | 228 | BUG("get_tempfile_fd() called for inactive object"); |
1a9d15db MH |
229 | return tempfile->fd; |
230 | } | |
231 | ||
232 | FILE *get_tempfile_fp(struct tempfile *tempfile) | |
233 | { | |
e6fc2673 | 234 | if (!is_tempfile_active(tempfile)) |
9b028aa4 | 235 | BUG("get_tempfile_fp() called for inactive object"); |
1a9d15db MH |
236 | return tempfile->fp; |
237 | } | |
238 | ||
49bd0fc2 | 239 | int close_tempfile_gently(struct tempfile *tempfile) |
1a9d15db | 240 | { |
f5b4dc76 JK |
241 | int fd; |
242 | FILE *fp; | |
1a9d15db MH |
243 | int err; |
244 | ||
f5b4dc76 | 245 | if (!is_tempfile_active(tempfile) || tempfile->fd < 0) |
1a9d15db MH |
246 | return 0; |
247 | ||
f5b4dc76 JK |
248 | fd = tempfile->fd; |
249 | fp = tempfile->fp; | |
1a9d15db MH |
250 | tempfile->fd = -1; |
251 | if (fp) { | |
252 | tempfile->fp = NULL; | |
7e8c9355 JK |
253 | if (ferror(fp)) { |
254 | err = -1; | |
255 | if (!fclose(fp)) | |
256 | errno = EIO; | |
257 | } else { | |
258 | err = fclose(fp); | |
259 | } | |
1a9d15db MH |
260 | } else { |
261 | err = close(fd); | |
262 | } | |
263 | ||
49bd0fc2 | 264 | return err ? -1 : 0; |
1a9d15db MH |
265 | } |
266 | ||
267 | int reopen_tempfile(struct tempfile *tempfile) | |
268 | { | |
e6fc2673 | 269 | if (!is_tempfile_active(tempfile)) |
9b028aa4 | 270 | BUG("reopen_tempfile called for an inactive object"); |
f5b4dc76 | 271 | if (0 <= tempfile->fd) |
9b028aa4 | 272 | BUG("reopen_tempfile called for an open object"); |
1a9d15db MH |
273 | tempfile->fd = open(tempfile->filename.buf, O_WRONLY); |
274 | return tempfile->fd; | |
275 | } | |
276 | ||
277 | int rename_tempfile(struct tempfile *tempfile, const char *path) | |
278 | { | |
e6fc2673 | 279 | if (!is_tempfile_active(tempfile)) |
9b028aa4 | 280 | BUG("rename_tempfile called for inactive object"); |
1a9d15db | 281 | |
49bd0fc2 JK |
282 | if (close_tempfile_gently(tempfile)) { |
283 | delete_tempfile(tempfile); | |
1a9d15db | 284 | return -1; |
49bd0fc2 | 285 | } |
1a9d15db MH |
286 | |
287 | if (rename(tempfile->filename.buf, path)) { | |
288 | int save_errno = errno; | |
289 | delete_tempfile(tempfile); | |
290 | errno = save_errno; | |
291 | return -1; | |
292 | } | |
293 | ||
294 | tempfile->active = 0; | |
295 | strbuf_reset(&tempfile->filename); | |
296 | return 0; | |
297 | } | |
298 | ||
299 | void delete_tempfile(struct tempfile *tempfile) | |
300 | { | |
e6fc2673 | 301 | if (!is_tempfile_active(tempfile)) |
1a9d15db MH |
302 | return; |
303 | ||
49bd0fc2 JK |
304 | close_tempfile_gently(tempfile); |
305 | unlink_or_warn(tempfile->filename.buf); | |
306 | tempfile->active = 0; | |
307 | strbuf_reset(&tempfile->filename); | |
1a9d15db | 308 | } |