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-rw-r--r--src/basic/tmpfile-util.c338
1 files changed, 338 insertions, 0 deletions
diff --git a/src/basic/tmpfile-util.c b/src/basic/tmpfile-util.c
new file mode 100644
index 0000000..49c3437
--- /dev/null
+++ b/src/basic/tmpfile-util.c
@@ -0,0 +1,338 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <sys/mman.h>
+
+#include "alloc-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "fs-util.h"
+#include "hexdecoct.h"
+#include "macro.h"
+#include "memfd-util.h"
+#include "missing_fcntl.h"
+#include "missing_syscall.h"
+#include "path-util.h"
+#include "process-util.h"
+#include "random-util.h"
+#include "stdio-util.h"
+#include "string-util.h"
+#include "tmpfile-util.h"
+#include "umask-util.h"
+
+int fopen_temporary(const char *path, FILE **ret_f, char **ret_temp_path) {
+ _cleanup_fclose_ FILE *f = NULL;
+ _cleanup_free_ char *t = NULL;
+ _cleanup_close_ int fd = -1;
+ int r;
+
+ if (path) {
+ r = tempfn_xxxxxx(path, NULL, &t);
+ if (r < 0)
+ return r;
+ } else {
+ const char *d;
+
+ r = tmp_dir(&d);
+ if (r < 0)
+ return r;
+
+ t = path_join(d, "XXXXXX");
+ if (!t)
+ return -ENOMEM;
+ }
+
+ fd = mkostemp_safe(t);
+ if (fd < 0)
+ return -errno;
+
+ /* This assumes that returned FILE object is short-lived and used within the same single-threaded
+ * context and never shared externally, hence locking is not necessary. */
+
+ r = take_fdopen_unlocked(&fd, "w", &f);
+ if (r < 0) {
+ (void) unlink(t);
+ return r;
+ }
+
+ if (ret_f)
+ *ret_f = TAKE_PTR(f);
+
+ if (ret_temp_path)
+ *ret_temp_path = TAKE_PTR(t);
+
+ return 0;
+}
+
+/* This is much like mkostemp() but is subject to umask(). */
+int mkostemp_safe(char *pattern) {
+ int fd = -1; /* avoid false maybe-uninitialized warning */
+
+ assert(pattern);
+
+ RUN_WITH_UMASK(0077)
+ fd = mkostemp(pattern, O_CLOEXEC);
+ if (fd < 0)
+ return -errno;
+
+ return fd;
+}
+
+int fmkostemp_safe(char *pattern, const char *mode, FILE **ret_f) {
+ _cleanup_close_ int fd = -1;
+ FILE *f;
+
+ fd = mkostemp_safe(pattern);
+ if (fd < 0)
+ return fd;
+
+ f = take_fdopen(&fd, mode);
+ if (!f)
+ return -errno;
+
+ *ret_f = f;
+ return 0;
+}
+
+int tempfn_xxxxxx(const char *p, const char *extra, char **ret) {
+ const char *fn;
+ char *t;
+
+ assert(ret);
+
+ if (isempty(p))
+ return -EINVAL;
+ if (path_equal(p, "/"))
+ return -EINVAL;
+
+ /*
+ * Turns this:
+ * /foo/bar/waldo
+ *
+ * Into this:
+ * /foo/bar/.#<extra>waldoXXXXXX
+ */
+
+ fn = basename(p);
+ if (!filename_is_valid(fn))
+ return -EINVAL;
+
+ extra = strempty(extra);
+
+ t = new(char, strlen(p) + 2 + strlen(extra) + 6 + 1);
+ if (!t)
+ return -ENOMEM;
+
+ strcpy(stpcpy(stpcpy(stpcpy(mempcpy(t, p, fn - p), ".#"), extra), fn), "XXXXXX");
+
+ *ret = path_simplify(t, false);
+ return 0;
+}
+
+int tempfn_random(const char *p, const char *extra, char **ret) {
+ const char *fn;
+ char *t, *x;
+ uint64_t u;
+ unsigned i;
+
+ assert(ret);
+
+ if (isempty(p))
+ return -EINVAL;
+ if (path_equal(p, "/"))
+ return -EINVAL;
+
+ /*
+ * Turns this:
+ * /foo/bar/waldo
+ *
+ * Into this:
+ * /foo/bar/.#<extra>waldobaa2a261115984a9
+ */
+
+ fn = basename(p);
+ if (!filename_is_valid(fn))
+ return -EINVAL;
+
+ extra = strempty(extra);
+
+ t = new(char, strlen(p) + 2 + strlen(extra) + 16 + 1);
+ if (!t)
+ return -ENOMEM;
+
+ x = stpcpy(stpcpy(stpcpy(mempcpy(t, p, fn - p), ".#"), extra), fn);
+
+ u = random_u64();
+ for (i = 0; i < 16; i++) {
+ *(x++) = hexchar(u & 0xF);
+ u >>= 4;
+ }
+
+ *x = 0;
+
+ *ret = path_simplify(t, false);
+ return 0;
+}
+
+int tempfn_random_child(const char *p, const char *extra, char **ret) {
+ char *t, *x;
+ uint64_t u;
+ unsigned i;
+ int r;
+
+ assert(ret);
+
+ /* Turns this:
+ * /foo/bar/waldo
+ * Into this:
+ * /foo/bar/waldo/.#<extra>3c2b6219aa75d7d0
+ */
+
+ if (!p) {
+ r = tmp_dir(&p);
+ if (r < 0)
+ return r;
+ }
+
+ extra = strempty(extra);
+
+ t = new(char, strlen(p) + 3 + strlen(extra) + 16 + 1);
+ if (!t)
+ return -ENOMEM;
+
+ if (isempty(p))
+ x = stpcpy(stpcpy(t, ".#"), extra);
+ else
+ x = stpcpy(stpcpy(stpcpy(t, p), "/.#"), extra);
+
+ u = random_u64();
+ for (i = 0; i < 16; i++) {
+ *(x++) = hexchar(u & 0xF);
+ u >>= 4;
+ }
+
+ *x = 0;
+
+ *ret = path_simplify(t, false);
+ return 0;
+}
+
+int open_tmpfile_unlinkable(const char *directory, int flags) {
+ char *p;
+ int fd, r;
+
+ if (!directory) {
+ r = tmp_dir(&directory);
+ if (r < 0)
+ return r;
+ } else if (isempty(directory))
+ return -EINVAL;
+
+ /* Returns an unlinked temporary file that cannot be linked into the file system anymore */
+
+ /* Try O_TMPFILE first, if it is supported */
+ fd = open(directory, flags|O_TMPFILE|O_EXCL, S_IRUSR|S_IWUSR);
+ if (fd >= 0)
+ return fd;
+
+ /* Fall back to unguessable name + unlinking */
+ p = strjoina(directory, "/systemd-tmp-XXXXXX");
+
+ fd = mkostemp_safe(p);
+ if (fd < 0)
+ return fd;
+
+ (void) unlink(p);
+
+ return fd;
+}
+
+int open_tmpfile_linkable(const char *target, int flags, char **ret_path) {
+ _cleanup_free_ char *tmp = NULL;
+ int r, fd;
+
+ assert(target);
+ assert(ret_path);
+
+ /* Don't allow O_EXCL, as that has a special meaning for O_TMPFILE */
+ assert((flags & O_EXCL) == 0);
+
+ /* Creates a temporary file, that shall be renamed to "target" later. If possible, this uses O_TMPFILE – in
+ * which case "ret_path" will be returned as NULL. If not possible the temporary path name used is returned in
+ * "ret_path". Use link_tmpfile() below to rename the result after writing the file in full. */
+
+ fd = open_parent(target, O_TMPFILE|flags, 0640);
+ if (fd >= 0) {
+ *ret_path = NULL;
+ return fd;
+ }
+
+ log_debug_errno(fd, "Failed to use O_TMPFILE for %s: %m", target);
+
+ r = tempfn_random(target, NULL, &tmp);
+ if (r < 0)
+ return r;
+
+ fd = open(tmp, O_CREAT|O_EXCL|O_NOFOLLOW|O_NOCTTY|flags, 0640);
+ if (fd < 0)
+ return -errno;
+
+ *ret_path = TAKE_PTR(tmp);
+
+ return fd;
+}
+
+int link_tmpfile(int fd, const char *path, const char *target) {
+ int r;
+
+ assert(fd >= 0);
+ assert(target);
+
+ /* Moves a temporary file created with open_tmpfile() above into its final place. if "path" is NULL an fd
+ * created with O_TMPFILE is assumed, and linkat() is used. Otherwise it is assumed O_TMPFILE is not supported
+ * on the directory, and renameat2() is used instead.
+ *
+ * Note that in both cases we will not replace existing files. This is because linkat() does not support this
+ * operation currently (renameat2() does), and there is no nice way to emulate this. */
+
+ if (path) {
+ r = rename_noreplace(AT_FDCWD, path, AT_FDCWD, target);
+ if (r < 0)
+ return r;
+ } else {
+ char proc_fd_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(fd) + 1];
+
+ xsprintf(proc_fd_path, "/proc/self/fd/%i", fd);
+
+ if (linkat(AT_FDCWD, proc_fd_path, AT_FDCWD, target, AT_SYMLINK_FOLLOW) < 0)
+ return -errno;
+ }
+
+ return 0;
+}
+
+int mkdtemp_malloc(const char *template, char **ret) {
+ _cleanup_free_ char *p = NULL;
+ int r;
+
+ assert(ret);
+
+ if (template)
+ p = strdup(template);
+ else {
+ const char *tmp;
+
+ r = tmp_dir(&tmp);
+ if (r < 0)
+ return r;
+
+ p = path_join(tmp, "XXXXXX");
+ }
+ if (!p)
+ return -ENOMEM;
+
+ if (!mkdtemp(p))
+ return -errno;
+
+ *ret = TAKE_PTR(p);
+ return 0;
+}
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