2 * State diagram and cleanup
3 * -------------------------
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
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.
15 * The possible states of a `tempfile` object are as follows:
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.
22 * - Active, file open (after `create_tempfile()` or
23 * `reopen_tempfile()`). In this state:
25 * - the temporary file exists
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
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`.
37 * - Inactive (after `delete_tempfile()`, `rename_tempfile()`, or a
38 * failed attempt to create a temporary file). In this state:
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
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.
58 static struct tempfile
*volatile tempfile_list
;
60 static void remove_tempfiles(int skip_fclose
)
64 while (tempfile_list
) {
65 if (tempfile_list
->owner
== me
) {
66 /* fclose() is not safe to call in a signal handler */
68 tempfile_list
->fp
= NULL
;
69 delete_tempfile(tempfile_list
);
71 tempfile_list
= tempfile_list
->next
;
75 static void remove_tempfiles_on_exit(void)
80 static void remove_tempfiles_on_signal(int signo
)
88 * Initialize *tempfile if necessary and add it to tempfile_list.
90 static void prepare_tempfile_object(struct tempfile
*tempfile
)
93 /* One-time initialization */
94 sigchain_push_common(remove_tempfiles_on_signal
);
95 atexit(remove_tempfiles_on_exit
);
98 if (is_tempfile_active(tempfile
))
99 BUG("prepare_tempfile_object called for active object");
100 if (!tempfile
->on_list
) {
101 /* Initialize *tempfile and add it to tempfile_list: */
104 tempfile
->active
= 0;
106 strbuf_init(&tempfile
->filename
, 0);
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. */
112 BUG("prepare_tempfile_object called for improperly-reset object");
116 /* Make sure errno contains a meaningful value on error */
117 int create_tempfile(struct tempfile
*tempfile
, const char *path
)
119 prepare_tempfile_object(tempfile
);
121 strbuf_add_absolute_path(&tempfile
->filename
, path
);
122 tempfile
->fd
= open(tempfile
->filename
.buf
,
123 O_RDWR
| O_CREAT
| O_EXCL
| O_CLOEXEC
, 0666);
124 if (O_CLOEXEC
&& tempfile
->fd
< 0 && errno
== EINVAL
)
125 /* Try again w/o O_CLOEXEC: the kernel might not support it */
126 tempfile
->fd
= open(tempfile
->filename
.buf
,
127 O_RDWR
| O_CREAT
| O_EXCL
, 0666);
128 if (tempfile
->fd
< 0) {
129 strbuf_reset(&tempfile
->filename
);
132 tempfile
->owner
= getpid();
133 tempfile
->active
= 1;
134 if (adjust_shared_perm(tempfile
->filename
.buf
)) {
135 int save_errno
= errno
;
136 error("cannot fix permission bits on %s", tempfile
->filename
.buf
);
137 delete_tempfile(tempfile
);
144 void register_tempfile(struct tempfile
*tempfile
, const char *path
)
146 prepare_tempfile_object(tempfile
);
147 strbuf_add_absolute_path(&tempfile
->filename
, path
);
148 tempfile
->owner
= getpid();
149 tempfile
->active
= 1;
152 int mks_tempfile_sm(struct tempfile
*tempfile
,
153 const char *template, int suffixlen
, int mode
)
155 prepare_tempfile_object(tempfile
);
157 strbuf_add_absolute_path(&tempfile
->filename
, template);
158 tempfile
->fd
= git_mkstemps_mode(tempfile
->filename
.buf
, suffixlen
, mode
);
159 if (tempfile
->fd
< 0) {
160 strbuf_reset(&tempfile
->filename
);
163 tempfile
->owner
= getpid();
164 tempfile
->active
= 1;
168 int mks_tempfile_tsm(struct tempfile
*tempfile
,
169 const char *template, int suffixlen
, int mode
)
173 prepare_tempfile_object(tempfile
);
175 tmpdir
= getenv("TMPDIR");
179 strbuf_addf(&tempfile
->filename
, "%s/%s", tmpdir
, template);
180 tempfile
->fd
= git_mkstemps_mode(tempfile
->filename
.buf
, suffixlen
, mode
);
181 if (tempfile
->fd
< 0) {
182 strbuf_reset(&tempfile
->filename
);
185 tempfile
->owner
= getpid();
186 tempfile
->active
= 1;
190 int xmks_tempfile_m(struct tempfile
*tempfile
, const char *template, int mode
)
193 struct strbuf full_template
= STRBUF_INIT
;
195 strbuf_add_absolute_path(&full_template
, template);
196 fd
= mks_tempfile_m(tempfile
, full_template
.buf
, mode
);
198 die_errno("Unable to create temporary file '%s'",
201 strbuf_release(&full_template
);
205 FILE *fdopen_tempfile(struct tempfile
*tempfile
, const char *mode
)
207 if (!is_tempfile_active(tempfile
))
208 BUG("fdopen_tempfile() called for inactive object");
210 BUG("fdopen_tempfile() called for open object");
212 tempfile
->fp
= fdopen(tempfile
->fd
, mode
);
216 const char *get_tempfile_path(struct tempfile
*tempfile
)
218 if (!is_tempfile_active(tempfile
))
219 BUG("get_tempfile_path() called for inactive object");
220 return tempfile
->filename
.buf
;
223 int get_tempfile_fd(struct tempfile
*tempfile
)
225 if (!is_tempfile_active(tempfile
))
226 BUG("get_tempfile_fd() called for inactive object");
230 FILE *get_tempfile_fp(struct tempfile
*tempfile
)
232 if (!is_tempfile_active(tempfile
))
233 BUG("get_tempfile_fp() called for inactive object");
237 int close_tempfile_gently(struct tempfile
*tempfile
)
243 if (!is_tempfile_active(tempfile
) || tempfile
->fd
< 0)
265 int reopen_tempfile(struct tempfile
*tempfile
)
267 if (!is_tempfile_active(tempfile
))
268 BUG("reopen_tempfile called for an inactive object");
269 if (0 <= tempfile
->fd
)
270 BUG("reopen_tempfile called for an open object");
271 tempfile
->fd
= open(tempfile
->filename
.buf
, O_WRONLY
);
275 int rename_tempfile(struct tempfile
*tempfile
, const char *path
)
277 if (!is_tempfile_active(tempfile
))
278 BUG("rename_tempfile called for inactive object");
280 if (close_tempfile_gently(tempfile
)) {
281 delete_tempfile(tempfile
);
285 if (rename(tempfile
->filename
.buf
, path
)) {
286 int save_errno
= errno
;
287 delete_tempfile(tempfile
);
292 tempfile
->active
= 0;
293 strbuf_reset(&tempfile
->filename
);
297 void delete_tempfile(struct tempfile
*tempfile
)
299 if (!is_tempfile_active(tempfile
))
302 close_tempfile_gently(tempfile
);
303 unlink_or_warn(tempfile
->filename
.buf
);
304 tempfile
->active
= 0;
305 strbuf_reset(&tempfile
->filename
);