fileio: simplify mkostemp_safe() (#4090)

According to its manual page, flags given to mkostemp(3) shouldn't include
O_RDWR, O_CREAT or O_EXCL flags as these are always included. Beyond
those, the only flag that all callers (except a few tests where it
probably doesn't matter) use is O_CLOEXEC, so set that unconditionally.

src/basic/fileio.c

@@ -1043,7 +1043,7 @@ int fopen_temporary(const char *path, FILE **_f, char **_temp_path) {
         if (r < 0)
                 return r;
 
-        fd = mkostemp_safe(t, O_WRONLY|O_CLOEXEC);
+        fd = mkostemp_safe(t);
         if (fd < 0) {
                 free(t);
                 return -errno;
@@ -1076,7 +1076,7 @@ int fflush_and_check(FILE *f) {
 }
 
 /* This is much like mkostemp() but is subject to umask(). */
-int mkostemp_safe(char *pattern, int flags) {
+int mkostemp_safe(char *pattern) {
         _cleanup_umask_ mode_t u = 0;
         int fd;
 
@@ -1084,7 +1084,7 @@ int mkostemp_safe(char *pattern, int flags) {
 
         u = umask(077);
 
-        fd = mkostemp(pattern, flags);
+        fd = mkostemp(pattern, O_CLOEXEC);
         if (fd < 0)
                 return -errno;
 
@@ -1289,7 +1289,7 @@ int open_tmpfile_unlinkable(const char *directory, int flags) {
         /* Fall back to unguessable name + unlinking */
         p = strjoina(directory, "/systemd-tmp-XXXXXX");
 
-        fd = mkostemp_safe(p, flags);
+        fd = mkostemp_safe(p);
         if (fd < 0)
                 return fd;
 

src/basic/fileio.h

@@ -71,7 +71,7 @@ int search_and_fopen_nulstr(const char *path, const char *mode, const char *root
 int fflush_and_check(FILE *f);
 
 int fopen_temporary(const char *path, FILE **_f, char **_temp_path);
-int mkostemp_safe(char *pattern, int flags);
+int mkostemp_safe(char *pattern);
 
 int tempfn_xxxxxx(const char *p, const char *extra, char **ret);
 int tempfn_random(const char *p, const char *extra, char **ret);