2 * Copyright (C) 2008 - 2016 The Geeqie Team
4 * Author: Laurent Monin
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License along
17 * with this program; if not, write to the Free Software Foundation, Inc.,
18 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
22 #include <glib/gprintf.h>
23 #include <glib/gstdio.h>
27 #include "secure_save.h"
32 * ABOUT SECURE SAVE \n
33 * This code was borrowed from the ELinks project (http://elinks.cz)
34 * It was originally written by me (Laurent Monin aka Zas) and heavily
35 * modified and improved by all ELinks contributors.
36 * This code was released under the GPLv2 licence.
37 * It was modified to be included in geeqie on 2008/04/05
38 * If ssi->secure_save is TRUE:
40 * A call to secure_open("/home/me/.confdir/filename", mask) will open a file
41 * named "filename.tmp_XXXXXX" in /home/me/.confdir/ and return a pointer to a
42 * structure SecureSaveInfo on success or NULL on error.
44 * filename.tmp_XXXXXX can't conflict with any file since it's created using
45 * mkstemp(). XXXXXX is a random string.
47 * Subsequent write operations are done using returned SecureSaveInfo FILE *
50 * If an error is encountered, SecureSaveInfo int field named err is set
51 * (automatically if using secure_fp*() functions or by programmer)
53 * When secure_close() is called, "filename.tmp_XXXXXX" is flushed and closed,
54 * and if SecureSaveInfo err field has a value of zero, "filename.tmp_XXXXXX"
55 * is renamed to "filename". If this succeeded, then secure_close() returns 0.
57 * WARNING: since rename() is used, any symlink called "filename" may be
58 * replaced by a regular file. If destination file isn't a regular file,
59 * then secsave is disabled for that file.
61 * If ssi->secure_save is FALSE:
63 * No temporary file is created, "filename" is truncated, all operations are
64 * done on it, no rename nor flush occur, symlinks are preserved.
68 * Access rights are affected by secure_open() mask parameter.
71 /* FIXME: locking system on files about to be rewritten ? */
72 /* FIXME: Low risk race conditions about ssi->file_name. */
74 SecureSaveErrno secsave_errno = SS_ERR_NONE;
77 /** Open a file for writing in a secure way. @returns a pointer to a
78 * structure secure_save_info on success, or NULL on failure. */
79 static SecureSaveInfo *
80 secure_open_umask(const gchar *file_name)
85 secsave_errno = SS_ERR_NONE;
87 ssi = g_new0(SecureSaveInfo, 1);
89 secsave_errno = SS_ERR_OUT_OF_MEM;
93 ssi->secure_save = TRUE;
94 ssi->preserve_perms = TRUE;
95 ssi->unlink_on_error = TRUE;
97 ssi->file_name = g_strdup(file_name);
98 if (!ssi->file_name) {
99 secsave_errno = SS_ERR_OUT_OF_MEM;
103 /* Check properties of final file. */
104 #ifndef NO_UNIX_SOFTLINKS
105 if (lstat(ssi->file_name, &st)) {
107 if (stat(ssi->file_name, &st)) {
109 /* We ignore error caused by file inexistence. */
110 if (errno != ENOENT) {
113 secsave_errno = SS_ERR_STAT;
117 if (!S_ISREG(st.st_mode)) {
118 /* Not a regular file, secure_save is disabled. */
119 ssi->secure_save = FALSE;
122 /* XXX: access() do not work with setuid programs. */
123 if (access(ssi->file_name, R_OK | W_OK) < 0) {
125 secsave_errno = SS_ERR_ACCESS;
131 /* We still have a race condition here between
132 * [l]stat() and fopen() */
134 f1 = fopen(ssi->file_name, "rb+");
139 secsave_errno = SS_ERR_OPEN_READ;
146 if (ssi->secure_save) {
147 /* We use a random name for temporary file, mkstemp() opens
148 * the file and return a file descriptor named fd, which is
149 * then converted to FILE * using fdopen().
152 gchar *randname = g_strconcat(ssi->file_name, ".tmp_XXXXXX", NULL);
155 secsave_errno = SS_ERR_OUT_OF_MEM;
159 /* No need to use safe_mkstemp() here. --Zas */
160 fd = g_mkstemp(randname);
162 secsave_errno = SS_ERR_MKSTEMP;
167 ssi->fp = fdopen(fd, "wb");
169 secsave_errno = SS_ERR_OPEN_WRITE;
175 ssi->tmp_file_name = randname;
177 /* No need to create a temporary file here. */
178 ssi->fp = fopen(ssi->file_name, "wb");
180 secsave_errno = SS_ERR_OPEN_WRITE;
189 g_free(ssi->file_name);
190 ssi->file_name = NULL;
201 secure_open(const gchar *file_name)
205 #ifdef CONFIG_OS_WIN32
206 /* There is neither S_IRWXG nor S_IRWXO under crossmingw32-gcc */
207 const mode_t mask = 0177;
209 const mode_t mask = S_IXUSR | S_IRWXG | S_IRWXO;
212 saved_mask = umask(mask);
213 ssi = secure_open_umask(file_name);
219 /** Close a file opened with secure_open(). Rreturns 0 on success,
220 * errno or -1 on failure.
223 secure_close(SecureSaveInfo *ssi)
227 if (!ssi) return ret;
228 if (!ssi->fp) goto free;
230 if (ssi->err) { /* Keep previous errno. */
232 fclose(ssi->fp); /* Close file */
236 /* Ensure data is effectively written to disk, we first flush libc buffers
237 * using fflush(), then fsync() to flush kernel buffers, and finally call
238 * fclose() (which call fflush() again, but the first one is needed since
239 * it doesn't make much sense to flush kernel buffers and then libc buffers,
240 * while closing file releases file descriptor we need to call fsync(). */
241 #if defined(HAVE_FFLUSH) || defined(HAVE_FSYNC)
242 if (ssi->secure_save) {
243 gboolean fail = FALSE;
246 fail = (fflush(ssi->fp) == EOF);
250 if (!fail) fail = fsync(fileno(ssi->fp));
255 secsave_errno = SS_ERR_OTHER;
257 fclose(ssi->fp); /* Close file, ignore errors. */
264 if (fclose(ssi->fp) == EOF) {
266 secsave_errno = SS_ERR_OTHER;
270 if (ssi->secure_save && ssi->file_name && ssi->tmp_file_name) {
273 /* FIXME: Race condition on ssi->file_name. The file
274 * named ssi->file_name may have changed since
275 * secure_open() call (where we stat() file and
277 #ifndef NO_UNIX_SOFTLINKS
278 if (lstat(ssi->file_name, &st) == 0)
280 if (stat(ssi->file_name, &st) == 0)
283 /* set the dest file attributes to that of source (ignoring errors) */
284 if (ssi->preserve_perms)
286 if (chown(ssi->tmp_file_name, st.st_uid, st.st_gid) != 0) log_printf("chown('%s', %d, %d) failed", ssi->tmp_file_name, st.st_uid, st.st_gid);
287 if (chmod(ssi->tmp_file_name, st.st_mode) != 0) log_printf("chmod('%s', %o) failed", ssi->tmp_file_name, st.st_mode);
290 if (ssi->preserve_mtime)
294 tb.actime = st.st_atime;
295 tb.modtime = st.st_mtime;
296 utime(ssi->tmp_file_name, &tb);
299 if (rename(ssi->tmp_file_name, ssi->file_name) == -1) {
301 secsave_errno = SS_ERR_RENAME;
306 ret = 0; /* Success. */
309 if (ssi->tmp_file_name)
311 if (ret && ssi->unlink_on_error) unlink(ssi->tmp_file_name);
312 g_free(ssi->tmp_file_name);
314 if (ssi->file_name) g_free(ssi->file_name);
315 if (ssi) g_free(ssi);
321 /** fputs() wrapper, set ssi->err to errno on error. If ssi->err is set when
322 * called, it immediately returns EOF.
325 secure_fputs(SecureSaveInfo *ssi, const gchar *s)
329 if (!ssi || !ssi->fp || ssi->err) return EOF;
331 ret = fputs(s, ssi->fp);
333 secsave_errno = SS_ERR_OTHER;
341 /** fputc() wrapper, set ssi->err to errno on error. If ssi->err is set when
342 * called, it immediately returns EOF.
345 secure_fputc(SecureSaveInfo *ssi, gint c)
349 if (!ssi || !ssi->fp || ssi->err) return EOF;
351 ret = fputc(c, ssi->fp);
354 secsave_errno = SS_ERR_OTHER;
360 /** fprintf() wrapper, set ssi->err to errno on error and return a negative
361 * value. If ssi->err is set when called, it immediately returns -1.
364 secure_fprintf(SecureSaveInfo *ssi, const gchar *format, ...)
369 if (!ssi || !ssi->fp || ssi->err) return -1;
371 va_start(ap, format);
372 ret = g_vfprintf(ssi->fp, format, ap);
378 /** fwrite() wrapper, set ssi->err to errno on error and return a value less than
379 * the number of elements to write. If ssi->err is set when called, it immediately returns 0.
382 secure_fwrite(gconstpointer ptr, size_t size, size_t nmemb, SecureSaveInfo *ssi)
386 if (!ssi || !ssi->fp || ssi->err) return 0;
388 ret = fwrite(ptr, size, nmemb, ssi->fp);
392 secsave_errno = SS_ERR_OTHER;
399 secsave_strerror(SecureSaveErrno secsave_error)
401 switch (secsave_error) {
402 case SS_ERR_OPEN_READ:
403 return _("Cannot read the file");
405 return _("Cannot get file status");
407 return _("Cannot access the file");
409 return _("Cannot create temp file");
411 return _("Cannot rename the file");
412 case SS_ERR_DISABLED:
413 return _("File saving disabled by option");
414 case SS_ERR_OUT_OF_MEM:
415 return _("Out of memory");
416 case SS_ERR_OPEN_WRITE:
417 return _("Cannot write the file");
418 case SS_ERR_NONE: /* Impossible. */
421 return _("Secure file saving error");
424 /* vim: set shiftwidth=8 softtabstop=0 cindent cinoptions={1s: */