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Commit | Line | Data |
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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 | * | |
33 | * - Active, file closed (after `close_tempfile_gently()`). Same | |
34 | * as the previous state, except that the temporary file is closed, | |
35 | * `fd` is -1, and `fp` is `NULL`. | |
36 | * | |
37 | * - Inactive (after `delete_tempfile()`, `rename_tempfile()`, or a | |
38 | * failed attempt to create a temporary file). In this state: | |
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 removed from `tempfile_list` (but could be used again) | |
46 | * | |
47 | * A temporary file is owned by the process that created it. The | |
48 | * `tempfile` has an `owner` field that records the owner's PID. This | |
49 | * field is used to prevent a forked process from deleting a temporary | |
50 | * file created by its parent. | |
51 | */ | |
52 | ||
53 | #include "cache.h" | |
54 | #include "tempfile.h" | |
55 | #include "sigchain.h" | |
56 | ||
57 | static VOLATILE_LIST_HEAD(tempfile_list); | |
58 | ||
59 | static void remove_tempfiles(int in_signal_handler) | |
60 | { | |
61 | pid_t me = getpid(); | |
62 | volatile struct volatile_list_head *pos; | |
63 | ||
64 | list_for_each(pos, &tempfile_list) { | |
65 | struct tempfile *p = list_entry(pos, struct tempfile, list); | |
66 | ||
67 | if (!is_tempfile_active(p) || p->owner != me) | |
68 | continue; | |
69 | ||
70 | if (p->fd >= 0) | |
71 | close(p->fd); | |
72 | ||
73 | if (in_signal_handler) | |
74 | unlink(p->filename.buf); | |
75 | else | |
76 | unlink_or_warn(p->filename.buf); | |
77 | ||
78 | p->active = 0; | |
79 | } | |
80 | } | |
81 | ||
82 | static void remove_tempfiles_on_exit(void) | |
83 | { | |
84 | remove_tempfiles(0); | |
85 | } | |
86 | ||
87 | static void remove_tempfiles_on_signal(int signo) | |
88 | { | |
89 | remove_tempfiles(1); | |
90 | sigchain_pop(signo); | |
91 | raise(signo); | |
92 | } | |
93 | ||
94 | static struct tempfile *new_tempfile(void) | |
95 | { | |
96 | struct tempfile *tempfile = xmalloc(sizeof(*tempfile)); | |
97 | tempfile->fd = -1; | |
98 | tempfile->fp = NULL; | |
99 | tempfile->active = 0; | |
100 | tempfile->owner = 0; | |
101 | INIT_LIST_HEAD(&tempfile->list); | |
102 | strbuf_init(&tempfile->filename, 0); | |
103 | return tempfile; | |
104 | } | |
105 | ||
106 | static void activate_tempfile(struct tempfile *tempfile) | |
107 | { | |
108 | static int initialized; | |
109 | ||
110 | if (is_tempfile_active(tempfile)) | |
111 | BUG("activate_tempfile called for active object"); | |
112 | ||
113 | if (!initialized) { | |
114 | sigchain_push_common(remove_tempfiles_on_signal); | |
115 | atexit(remove_tempfiles_on_exit); | |
116 | initialized = 1; | |
117 | } | |
118 | ||
119 | volatile_list_add(&tempfile->list, &tempfile_list); | |
120 | tempfile->owner = getpid(); | |
121 | tempfile->active = 1; | |
122 | } | |
123 | ||
124 | static void deactivate_tempfile(struct tempfile *tempfile) | |
125 | { | |
126 | tempfile->active = 0; | |
127 | strbuf_release(&tempfile->filename); | |
128 | volatile_list_del(&tempfile->list); | |
129 | free(tempfile); | |
130 | } | |
131 | ||
132 | /* Make sure errno contains a meaningful value on error */ | |
133 | struct tempfile *create_tempfile(const char *path) | |
134 | { | |
135 | struct tempfile *tempfile = new_tempfile(); | |
136 | ||
137 | strbuf_add_absolute_path(&tempfile->filename, path); | |
138 | tempfile->fd = open(tempfile->filename.buf, | |
139 | O_RDWR | O_CREAT | O_EXCL | O_CLOEXEC, 0666); | |
140 | if (O_CLOEXEC && tempfile->fd < 0 && errno == EINVAL) | |
141 | /* Try again w/o O_CLOEXEC: the kernel might not support it */ | |
142 | tempfile->fd = open(tempfile->filename.buf, | |
143 | O_RDWR | O_CREAT | O_EXCL, 0666); | |
144 | if (tempfile->fd < 0) { | |
145 | deactivate_tempfile(tempfile); | |
146 | return NULL; | |
147 | } | |
148 | activate_tempfile(tempfile); | |
149 | if (adjust_shared_perm(tempfile->filename.buf)) { | |
150 | int save_errno = errno; | |
151 | error("cannot fix permission bits on %s", tempfile->filename.buf); | |
152 | delete_tempfile(&tempfile); | |
153 | errno = save_errno; | |
154 | return NULL; | |
155 | } | |
156 | ||
157 | return tempfile; | |
158 | } | |
159 | ||
160 | struct tempfile *register_tempfile(const char *path) | |
161 | { | |
162 | struct tempfile *tempfile = new_tempfile(); | |
163 | strbuf_add_absolute_path(&tempfile->filename, path); | |
164 | activate_tempfile(tempfile); | |
165 | return tempfile; | |
166 | } | |
167 | ||
168 | struct tempfile *mks_tempfile_sm(const char *filename_template, int suffixlen, int mode) | |
169 | { | |
170 | struct tempfile *tempfile = new_tempfile(); | |
171 | ||
172 | strbuf_add_absolute_path(&tempfile->filename, filename_template); | |
173 | tempfile->fd = git_mkstemps_mode(tempfile->filename.buf, suffixlen, mode); | |
174 | if (tempfile->fd < 0) { | |
175 | deactivate_tempfile(tempfile); | |
176 | return NULL; | |
177 | } | |
178 | activate_tempfile(tempfile); | |
179 | return tempfile; | |
180 | } | |
181 | ||
182 | struct tempfile *mks_tempfile_tsm(const char *filename_template, int suffixlen, int mode) | |
183 | { | |
184 | struct tempfile *tempfile = new_tempfile(); | |
185 | const char *tmpdir; | |
186 | ||
187 | tmpdir = getenv("TMPDIR"); | |
188 | if (!tmpdir) | |
189 | tmpdir = "/tmp"; | |
190 | ||
191 | strbuf_addf(&tempfile->filename, "%s/%s", tmpdir, filename_template); | |
192 | tempfile->fd = git_mkstemps_mode(tempfile->filename.buf, suffixlen, mode); | |
193 | if (tempfile->fd < 0) { | |
194 | deactivate_tempfile(tempfile); | |
195 | return NULL; | |
196 | } | |
197 | activate_tempfile(tempfile); | |
198 | return tempfile; | |
199 | } | |
200 | ||
201 | struct tempfile *xmks_tempfile_m(const char *filename_template, int mode) | |
202 | { | |
203 | struct tempfile *tempfile; | |
204 | struct strbuf full_template = STRBUF_INIT; | |
205 | ||
206 | strbuf_add_absolute_path(&full_template, filename_template); | |
207 | tempfile = mks_tempfile_m(full_template.buf, mode); | |
208 | if (!tempfile) | |
209 | die_errno("Unable to create temporary file '%s'", | |
210 | full_template.buf); | |
211 | ||
212 | strbuf_release(&full_template); | |
213 | return tempfile; | |
214 | } | |
215 | ||
216 | FILE *fdopen_tempfile(struct tempfile *tempfile, const char *mode) | |
217 | { | |
218 | if (!is_tempfile_active(tempfile)) | |
219 | BUG("fdopen_tempfile() called for inactive object"); | |
220 | if (tempfile->fp) | |
221 | BUG("fdopen_tempfile() called for open object"); | |
222 | ||
223 | tempfile->fp = fdopen(tempfile->fd, mode); | |
224 | return tempfile->fp; | |
225 | } | |
226 | ||
227 | const char *get_tempfile_path(struct tempfile *tempfile) | |
228 | { | |
229 | if (!is_tempfile_active(tempfile)) | |
230 | BUG("get_tempfile_path() called for inactive object"); | |
231 | return tempfile->filename.buf; | |
232 | } | |
233 | ||
234 | int get_tempfile_fd(struct tempfile *tempfile) | |
235 | { | |
236 | if (!is_tempfile_active(tempfile)) | |
237 | BUG("get_tempfile_fd() called for inactive object"); | |
238 | return tempfile->fd; | |
239 | } | |
240 | ||
241 | FILE *get_tempfile_fp(struct tempfile *tempfile) | |
242 | { | |
243 | if (!is_tempfile_active(tempfile)) | |
244 | BUG("get_tempfile_fp() called for inactive object"); | |
245 | return tempfile->fp; | |
246 | } | |
247 | ||
248 | int close_tempfile_gently(struct tempfile *tempfile) | |
249 | { | |
250 | int fd; | |
251 | FILE *fp; | |
252 | int err; | |
253 | ||
254 | if (!is_tempfile_active(tempfile) || tempfile->fd < 0) | |
255 | return 0; | |
256 | ||
257 | fd = tempfile->fd; | |
258 | fp = tempfile->fp; | |
259 | tempfile->fd = -1; | |
260 | if (fp) { | |
261 | tempfile->fp = NULL; | |
262 | if (ferror(fp)) { | |
263 | err = -1; | |
264 | if (!fclose(fp)) | |
265 | errno = EIO; | |
266 | } else { | |
267 | err = fclose(fp); | |
268 | } | |
269 | } else { | |
270 | err = close(fd); | |
271 | } | |
272 | ||
273 | return err ? -1 : 0; | |
274 | } | |
275 | ||
276 | int reopen_tempfile(struct tempfile *tempfile) | |
277 | { | |
278 | if (!is_tempfile_active(tempfile)) | |
279 | BUG("reopen_tempfile called for an inactive object"); | |
280 | if (0 <= tempfile->fd) | |
281 | BUG("reopen_tempfile called for an open object"); | |
282 | tempfile->fd = open(tempfile->filename.buf, O_WRONLY|O_TRUNC); | |
283 | return tempfile->fd; | |
284 | } | |
285 | ||
286 | int rename_tempfile(struct tempfile **tempfile_p, const char *path) | |
287 | { | |
288 | struct tempfile *tempfile = *tempfile_p; | |
289 | ||
290 | if (!is_tempfile_active(tempfile)) | |
291 | BUG("rename_tempfile called for inactive object"); | |
292 | ||
293 | if (close_tempfile_gently(tempfile)) { | |
294 | delete_tempfile(tempfile_p); | |
295 | return -1; | |
296 | } | |
297 | ||
298 | if (rename(tempfile->filename.buf, path)) { | |
299 | int save_errno = errno; | |
300 | delete_tempfile(tempfile_p); | |
301 | errno = save_errno; | |
302 | return -1; | |
303 | } | |
304 | ||
305 | deactivate_tempfile(tempfile); | |
306 | *tempfile_p = NULL; | |
307 | return 0; | |
308 | } | |
309 | ||
310 | void delete_tempfile(struct tempfile **tempfile_p) | |
311 | { | |
312 | struct tempfile *tempfile = *tempfile_p; | |
313 | ||
314 | if (!is_tempfile_active(tempfile)) | |
315 | return; | |
316 | ||
317 | close_tempfile_gently(tempfile); | |
318 | unlink_or_warn(tempfile->filename.buf); | |
319 | deactivate_tempfile(tempfile); | |
320 | *tempfile_p = NULL; | |
321 | } |