basic/fileio: extend atomic file writing with timestamp setting

There should be no functional change.

src/basic/fileio-label.c

@@ -24,14 +24,14 @@
 #include "fileio.h"
 #include "selinux-util.h"
 
-int write_string_file_atomic_label(const char *fn, const char *line) {
+int write_string_file_atomic_label_ts(const char *fn, const char *line, struct timespec *ts) {
         int r;
 
         r = mac_selinux_create_file_prepare(fn, S_IFREG);
         if (r < 0)
                 return r;
 
-        r = write_string_file(fn, line, WRITE_STRING_FILE_CREATE|WRITE_STRING_FILE_ATOMIC);
+        r = write_string_file_ts(fn, line, WRITE_STRING_FILE_CREATE|WRITE_STRING_FILE_ATOMIC, ts);
 
         mac_selinux_create_file_clear();
 

src/basic/fileio-label.h

@@ -24,7 +24,10 @@
 
 #include "fileio.h"
 
-int write_string_file_atomic_label(const char *fn, const char *line);
+int write_string_file_atomic_label_ts(const char *fn, const char *line, struct timespec *ts);
+static inline int write_string_file_atomic_label(const char *fn, const char *line) {
+        return write_string_file_atomic_label_ts(fn, line, NULL);
+}
 int write_env_file_label(const char *fname, char **l);
 int fopen_temporary_label(const char *target,
                           const char *path, FILE **f, char **temp_path);

src/basic/fileio.c

@@ -51,7 +51,7 @@
 
 #define READ_FULL_BYTES_MAX (4U*1024U*1024U)
 
-int write_string_stream(FILE *f, const char *line, bool enforce_newline) {
+int write_string_stream_ts(FILE *f, const char *line, bool enforce_newline, struct timespec *ts) {
 
         assert(f);
         assert(line);
@@ -60,6 +60,13 @@ int write_string_stream(FILE *f, const char *line, bool enforce_newline) {
         if (enforce_newline && !endswith(line, "\n"))
                 fputc('\n', f);
 
+        if (ts) {
+                struct timespec twice[2] = {*ts, *ts};
+
+                if (futimens(fileno(f), twice) < 0)
+                        return -errno;
+        }
+
         return fflush_and_check(f);
 }
 
@@ -89,7 +96,7 @@ static int write_string_file_atomic(const char *fn, const char *line, bool enfor
         return r;
 }
 
-int write_string_file(const char *fn, const char *line, WriteStringFileFlags flags) {
+int write_string_file_ts(const char *fn, const char *line, WriteStringFileFlags flags, struct timespec *ts) {
         _cleanup_fclose_ FILE *f = NULL;
         int q, r;
 
@@ -104,7 +111,8 @@ int write_string_file(const char *fn, const char *line, WriteStringFileFlags fla
                         goto fail;
 
                 return r;
-        }
+        } else
+                assert(ts == NULL);
 
         if (flags & WRITE_STRING_FILE_CREATE) {
                 f = fopen(fn, "we");
@@ -131,7 +139,7 @@ int write_string_file(const char *fn, const char *line, WriteStringFileFlags fla
                 }
         }
 
-        r = write_string_stream(f, line, !(flags & WRITE_STRING_FILE_AVOID_NEWLINE));
+        r = write_string_stream_ts(f, line, !(flags & WRITE_STRING_FILE_AVOID_NEWLINE), ts);
         if (r < 0)
                 goto fail;
 

src/basic/fileio.h

@@ -35,8 +35,14 @@ typedef enum {
         WRITE_STRING_FILE_VERIFY_ON_FAILURE = 8,
 } WriteStringFileFlags;
 
-int write_string_stream(FILE *f, const char *line, bool enforce_newline);
-int write_string_file(const char *fn, const char *line, WriteStringFileFlags flags);
+int write_string_stream_ts(FILE *f, const char *line, bool enforce_newline, struct timespec *ts);
+static inline int write_string_stream(FILE *f, const char *line, bool enforce_newline) {
+        return write_string_stream_ts(f, line, enforce_newline, NULL);
+}
+int write_string_file_ts(const char *fn, const char *line, WriteStringFileFlags flags, struct timespec *ts);
+static inline int write_string_file(const char *fn, const char *line, WriteStringFileFlags flags) {
+        return write_string_file_ts(fn, line, flags, NULL);
+}
 
 int read_one_line_file(const char *fn, char **line);
 int read_full_file(const char *fn, char **contents, size_t *size);