tempfile: remove deactivated list entries
[git/git.git] / tempfile.c
CommitLineData
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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 *
49bd0fc2 33 * - Active, file closed (after `close_tempfile_gently()`). Same
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34 * as the previous state, except that the temporary file is closed,
35 * `fd` is -1, and `fp` is `NULL`.
36 *
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37 * - Inactive (after `delete_tempfile()`, `rename_tempfile()`, or a
38 * failed attempt to create a temporary file). In this state:
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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`
422a21c6 45 * - the object is removed from `tempfile_list` (but could be used again)
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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
24d82185 57static VOLATILE_LIST_HEAD(tempfile_list);
1a9d15db 58
6b935066 59static void remove_tempfiles(int in_signal_handler)
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60{
61 pid_t me = getpid();
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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);
1a9d15db 66
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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;
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79 }
80}
81
82static void remove_tempfiles_on_exit(void)
83{
84 remove_tempfiles(0);
85}
86
87static void remove_tempfiles_on_signal(int signo)
88{
89 remove_tempfiles(1);
90 sigchain_pop(signo);
91 raise(signo);
92}
93
7eba6ce5 94static void prepare_tempfile_object(struct tempfile *tempfile)
1a9d15db 95{
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96 tempfile->fd = -1;
97 tempfile->fp = NULL;
98 tempfile->active = 0;
99 tempfile->owner = 0;
100 INIT_LIST_HEAD(&tempfile->list);
101 strbuf_init(&tempfile->filename, 0);
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102}
103
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104static void activate_tempfile(struct tempfile *tempfile)
105{
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106 static int initialized;
107
108 if (is_tempfile_active(tempfile))
109 BUG("activate_tempfile called for active object");
110
111 if (!initialized) {
112 sigchain_push_common(remove_tempfiles_on_signal);
113 atexit(remove_tempfiles_on_exit);
114 initialized = 1;
115 }
116
117 volatile_list_add(&tempfile->list, &tempfile_list);
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118 tempfile->owner = getpid();
119 tempfile->active = 1;
120}
121
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122static void deactivate_tempfile(struct tempfile *tempfile)
123{
124 tempfile->active = 0;
102cf7a6 125 strbuf_release(&tempfile->filename);
422a21c6 126 volatile_list_del(&tempfile->list);
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127}
128
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129/* Make sure errno contains a meaningful value on error */
130int create_tempfile(struct tempfile *tempfile, const char *path)
131{
132 prepare_tempfile_object(tempfile);
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133
134 strbuf_add_absolute_path(&tempfile->filename, path);
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135 tempfile->fd = open(tempfile->filename.buf,
136 O_RDWR | O_CREAT | O_EXCL | O_CLOEXEC, 0666);
137 if (O_CLOEXEC && tempfile->fd < 0 && errno == EINVAL)
138 /* Try again w/o O_CLOEXEC: the kernel might not support it */
139 tempfile->fd = open(tempfile->filename.buf,
140 O_RDWR | O_CREAT | O_EXCL, 0666);
1a9d15db 141 if (tempfile->fd < 0) {
b5f4dcb5 142 deactivate_tempfile(tempfile);
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143 return -1;
144 }
2933ebba 145 activate_tempfile(tempfile);
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146 if (adjust_shared_perm(tempfile->filename.buf)) {
147 int save_errno = errno;
148 error("cannot fix permission bits on %s", tempfile->filename.buf);
149 delete_tempfile(tempfile);
150 errno = save_errno;
151 return -1;
152 }
153 return tempfile->fd;
154}
155
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156void register_tempfile(struct tempfile *tempfile, const char *path)
157{
158 prepare_tempfile_object(tempfile);
159 strbuf_add_absolute_path(&tempfile->filename, path);
2933ebba 160 activate_tempfile(tempfile);
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161}
162
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163int mks_tempfile_sm(struct tempfile *tempfile,
164 const char *template, int suffixlen, int mode)
165{
166 prepare_tempfile_object(tempfile);
167
168 strbuf_add_absolute_path(&tempfile->filename, template);
169 tempfile->fd = git_mkstemps_mode(tempfile->filename.buf, suffixlen, mode);
170 if (tempfile->fd < 0) {
b5f4dcb5 171 deactivate_tempfile(tempfile);
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172 return -1;
173 }
2933ebba 174 activate_tempfile(tempfile);
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175 return tempfile->fd;
176}
177
178int mks_tempfile_tsm(struct tempfile *tempfile,
179 const char *template, int suffixlen, int mode)
180{
181 const char *tmpdir;
182
183 prepare_tempfile_object(tempfile);
184
185 tmpdir = getenv("TMPDIR");
186 if (!tmpdir)
187 tmpdir = "/tmp";
188
189 strbuf_addf(&tempfile->filename, "%s/%s", tmpdir, template);
190 tempfile->fd = git_mkstemps_mode(tempfile->filename.buf, suffixlen, mode);
191 if (tempfile->fd < 0) {
b5f4dcb5 192 deactivate_tempfile(tempfile);
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193 return -1;
194 }
2933ebba 195 activate_tempfile(tempfile);
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196 return tempfile->fd;
197}
198
199int xmks_tempfile_m(struct tempfile *tempfile, const char *template, int mode)
200{
201 int fd;
202 struct strbuf full_template = STRBUF_INIT;
203
204 strbuf_add_absolute_path(&full_template, template);
205 fd = mks_tempfile_m(tempfile, full_template.buf, mode);
206 if (fd < 0)
207 die_errno("Unable to create temporary file '%s'",
208 full_template.buf);
209
210 strbuf_release(&full_template);
211 return fd;
212}
213
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214FILE *fdopen_tempfile(struct tempfile *tempfile, const char *mode)
215{
e6fc2673 216 if (!is_tempfile_active(tempfile))
9b028aa4 217 BUG("fdopen_tempfile() called for inactive object");
1a9d15db 218 if (tempfile->fp)
9b028aa4 219 BUG("fdopen_tempfile() called for open object");
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220
221 tempfile->fp = fdopen(tempfile->fd, mode);
222 return tempfile->fp;
223}
224
225const char *get_tempfile_path(struct tempfile *tempfile)
226{
e6fc2673 227 if (!is_tempfile_active(tempfile))
9b028aa4 228 BUG("get_tempfile_path() called for inactive object");
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229 return tempfile->filename.buf;
230}
231
232int get_tempfile_fd(struct tempfile *tempfile)
233{
e6fc2673 234 if (!is_tempfile_active(tempfile))
9b028aa4 235 BUG("get_tempfile_fd() called for inactive object");
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236 return tempfile->fd;
237}
238
239FILE *get_tempfile_fp(struct tempfile *tempfile)
240{
e6fc2673 241 if (!is_tempfile_active(tempfile))
9b028aa4 242 BUG("get_tempfile_fp() called for inactive object");
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243 return tempfile->fp;
244}
245
49bd0fc2 246int close_tempfile_gently(struct tempfile *tempfile)
1a9d15db 247{
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248 int fd;
249 FILE *fp;
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250 int err;
251
f5b4dc76 252 if (!is_tempfile_active(tempfile) || tempfile->fd < 0)
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253 return 0;
254
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255 fd = tempfile->fd;
256 fp = tempfile->fp;
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257 tempfile->fd = -1;
258 if (fp) {
259 tempfile->fp = NULL;
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260 if (ferror(fp)) {
261 err = -1;
262 if (!fclose(fp))
263 errno = EIO;
264 } else {
265 err = fclose(fp);
266 }
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267 } else {
268 err = close(fd);
269 }
270
49bd0fc2 271 return err ? -1 : 0;
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272}
273
274int reopen_tempfile(struct tempfile *tempfile)
275{
e6fc2673 276 if (!is_tempfile_active(tempfile))
9b028aa4 277 BUG("reopen_tempfile called for an inactive object");
f5b4dc76 278 if (0 <= tempfile->fd)
9b028aa4 279 BUG("reopen_tempfile called for an open object");
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280 tempfile->fd = open(tempfile->filename.buf, O_WRONLY);
281 return tempfile->fd;
282}
283
284int rename_tempfile(struct tempfile *tempfile, const char *path)
285{
e6fc2673 286 if (!is_tempfile_active(tempfile))
9b028aa4 287 BUG("rename_tempfile called for inactive object");
1a9d15db 288
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289 if (close_tempfile_gently(tempfile)) {
290 delete_tempfile(tempfile);
1a9d15db 291 return -1;
49bd0fc2 292 }
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293
294 if (rename(tempfile->filename.buf, path)) {
295 int save_errno = errno;
296 delete_tempfile(tempfile);
297 errno = save_errno;
298 return -1;
299 }
300
b5f4dcb5 301 deactivate_tempfile(tempfile);
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302 return 0;
303}
304
305void delete_tempfile(struct tempfile *tempfile)
306{
e6fc2673 307 if (!is_tempfile_active(tempfile))
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308 return;
309
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310 close_tempfile_gently(tempfile);
311 unlink_or_warn(tempfile->filename.buf);
b5f4dcb5 312 deactivate_tempfile(tempfile);
1a9d15db 313}