336 lines
8.2 KiB
C
336 lines
8.2 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#include <stdio.h>
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#include <sys/mman.h>
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#include "alloc-util.h"
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#include "fd-util.h"
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#include "fileio.h"
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#include "fs-util.h"
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#include "hexdecoct.h"
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#include "macro.h"
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#include "memfd-util.h"
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#include "missing_fcntl.h"
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#include "missing_syscall.h"
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#include "path-util.h"
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#include "process-util.h"
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#include "random-util.h"
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#include "stdio-util.h"
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#include "string-util.h"
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#include "tmpfile-util.h"
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#include "umask-util.h"
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int fopen_temporary(const char *path, FILE **_f, char **_temp_path) {
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FILE *f;
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char *t;
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int r, fd;
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assert(path);
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assert(_f);
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assert(_temp_path);
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r = tempfn_xxxxxx(path, NULL, &t);
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if (r < 0)
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return r;
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fd = mkostemp_safe(t);
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if (fd < 0) {
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free(t);
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return -errno;
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}
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/* This assumes that returned FILE object is short-lived and used within the same single-threaded
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* context and never shared externally, hence locking is not necessary. */
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r = fdopen_unlocked(fd, "w", &f);
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if (r < 0) {
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unlink(t);
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free(t);
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safe_close(fd);
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return r;
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}
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*_f = f;
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*_temp_path = t;
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return 0;
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}
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/* This is much like mkostemp() but is subject to umask(). */
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int mkostemp_safe(char *pattern) {
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_cleanup_umask_ mode_t u = 0;
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int fd;
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assert(pattern);
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u = umask(077);
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fd = mkostemp(pattern, O_CLOEXEC);
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if (fd < 0)
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return -errno;
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return fd;
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}
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int fmkostemp_safe(char *pattern, const char *mode, FILE **ret_f) {
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int fd;
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FILE *f;
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fd = mkostemp_safe(pattern);
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if (fd < 0)
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return fd;
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f = fdopen(fd, mode);
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if (!f) {
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safe_close(fd);
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return -errno;
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}
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*ret_f = f;
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return 0;
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}
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int tempfn_xxxxxx(const char *p, const char *extra, char **ret) {
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const char *fn;
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char *t;
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assert(ret);
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if (isempty(p))
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return -EINVAL;
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if (path_equal(p, "/"))
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return -EINVAL;
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/*
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* Turns this:
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* /foo/bar/waldo
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*
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* Into this:
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* /foo/bar/.#<extra>waldoXXXXXX
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*/
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fn = basename(p);
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if (!filename_is_valid(fn))
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return -EINVAL;
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extra = strempty(extra);
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t = new(char, strlen(p) + 2 + strlen(extra) + 6 + 1);
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if (!t)
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return -ENOMEM;
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strcpy(stpcpy(stpcpy(stpcpy(mempcpy(t, p, fn - p), ".#"), extra), fn), "XXXXXX");
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*ret = path_simplify(t, false);
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return 0;
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}
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int tempfn_random(const char *p, const char *extra, char **ret) {
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const char *fn;
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char *t, *x;
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uint64_t u;
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unsigned i;
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assert(ret);
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if (isempty(p))
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return -EINVAL;
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if (path_equal(p, "/"))
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return -EINVAL;
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/*
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* Turns this:
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* /foo/bar/waldo
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*
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* Into this:
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* /foo/bar/.#<extra>waldobaa2a261115984a9
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*/
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fn = basename(p);
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if (!filename_is_valid(fn))
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return -EINVAL;
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extra = strempty(extra);
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t = new(char, strlen(p) + 2 + strlen(extra) + 16 + 1);
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if (!t)
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return -ENOMEM;
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x = stpcpy(stpcpy(stpcpy(mempcpy(t, p, fn - p), ".#"), extra), fn);
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u = random_u64();
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for (i = 0; i < 16; i++) {
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*(x++) = hexchar(u & 0xF);
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u >>= 4;
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}
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*x = 0;
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*ret = path_simplify(t, false);
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return 0;
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}
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int tempfn_random_child(const char *p, const char *extra, char **ret) {
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char *t, *x;
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uint64_t u;
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unsigned i;
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int r;
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assert(ret);
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/* Turns this:
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* /foo/bar/waldo
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* Into this:
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* /foo/bar/waldo/.#<extra>3c2b6219aa75d7d0
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*/
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if (!p) {
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r = tmp_dir(&p);
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if (r < 0)
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return r;
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}
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extra = strempty(extra);
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t = new(char, strlen(p) + 3 + strlen(extra) + 16 + 1);
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if (!t)
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return -ENOMEM;
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if (isempty(p))
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x = stpcpy(stpcpy(t, ".#"), extra);
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else
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x = stpcpy(stpcpy(stpcpy(t, p), "/.#"), extra);
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u = random_u64();
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for (i = 0; i < 16; i++) {
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*(x++) = hexchar(u & 0xF);
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u >>= 4;
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}
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*x = 0;
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*ret = path_simplify(t, false);
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return 0;
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}
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int open_tmpfile_unlinkable(const char *directory, int flags) {
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char *p;
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int fd, r;
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if (!directory) {
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r = tmp_dir(&directory);
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if (r < 0)
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return r;
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} else if (isempty(directory))
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return -EINVAL;
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/* Returns an unlinked temporary file that cannot be linked into the file system anymore */
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/* Try O_TMPFILE first, if it is supported */
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fd = open(directory, flags|O_TMPFILE|O_EXCL, S_IRUSR|S_IWUSR);
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if (fd >= 0)
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return fd;
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/* Fall back to unguessable name + unlinking */
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p = strjoina(directory, "/systemd-tmp-XXXXXX");
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fd = mkostemp_safe(p);
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if (fd < 0)
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return fd;
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(void) unlink(p);
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return fd;
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}
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int open_tmpfile_linkable(const char *target, int flags, char **ret_path) {
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_cleanup_free_ char *tmp = NULL;
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int r, fd;
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assert(target);
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assert(ret_path);
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/* Don't allow O_EXCL, as that has a special meaning for O_TMPFILE */
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assert((flags & O_EXCL) == 0);
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/* Creates a temporary file, that shall be renamed to "target" later. If possible, this uses O_TMPFILE – in
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* which case "ret_path" will be returned as NULL. If not possible a the tempoary path name used is returned in
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* "ret_path". Use link_tmpfile() below to rename the result after writing the file in full. */
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fd = open_parent(target, O_TMPFILE|flags, 0640);
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if (fd >= 0) {
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*ret_path = NULL;
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return fd;
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}
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log_debug_errno(fd, "Failed to use O_TMPFILE for %s: %m", target);
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r = tempfn_random(target, NULL, &tmp);
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if (r < 0)
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return r;
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fd = open(tmp, O_CREAT|O_EXCL|O_NOFOLLOW|O_NOCTTY|flags, 0640);
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if (fd < 0)
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return -errno;
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*ret_path = TAKE_PTR(tmp);
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return fd;
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}
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int link_tmpfile(int fd, const char *path, const char *target) {
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int r;
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assert(fd >= 0);
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assert(target);
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/* Moves a temporary file created with open_tmpfile() above into its final place. if "path" is NULL an fd
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* created with O_TMPFILE is assumed, and linkat() is used. Otherwise it is assumed O_TMPFILE is not supported
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* on the directory, and renameat2() is used instead.
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*
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* Note that in both cases we will not replace existing files. This is because linkat() does not support this
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* operation currently (renameat2() does), and there is no nice way to emulate this. */
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if (path) {
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r = rename_noreplace(AT_FDCWD, path, AT_FDCWD, target);
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if (r < 0)
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return r;
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} else {
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char proc_fd_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(fd) + 1];
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xsprintf(proc_fd_path, "/proc/self/fd/%i", fd);
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if (linkat(AT_FDCWD, proc_fd_path, AT_FDCWD, target, AT_SYMLINK_FOLLOW) < 0)
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return -errno;
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}
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return 0;
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}
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int mkdtemp_malloc(const char *template, char **ret) {
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_cleanup_free_ char *p = NULL;
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int r;
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assert(ret);
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if (template)
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p = strdup(template);
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else {
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const char *tmp;
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r = tmp_dir(&tmp);
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if (r < 0)
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return r;
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p = strjoin(tmp, "/XXXXXX");
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}
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if (!p)
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return -ENOMEM;
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if (!mkdtemp(p))
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return -errno;
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*ret = TAKE_PTR(p);
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return 0;
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}
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