From: Timo Sirainen <timo.sirainen@dovecot.fi>
Date: Thu, 26 Apr 2018 16:38:55 +0000 (+0300)
Subject: lib-fs: fs-posix - Add accurate-mtime parameter
X-Git-Tag: 2.3.9~1908
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d0d7b0a1de722f181605a98b003005f91077f5a5;p=thirdparty%2Fdovecot%2Fcore.git

lib-fs: fs-posix - Add accurate-mtime parameter

This is mainly useful for testing to find out whether one file was created
after another.
---

diff --git a/src/lib-fs/fs-posix.c b/src/lib-fs/fs-posix.c
index 5c7952c60f..b999f7d8f7 100644
--- a/src/lib-fs/fs-posix.c
+++ b/src/lib-fs/fs-posix.c
@@ -37,6 +37,7 @@ struct posix_fs {
 	bool mode_auto;
 	bool have_dirs;
 	bool disable_fsync;
+	bool accurate_mtime;
 };
 
 struct posix_fs_file {
@@ -106,6 +107,8 @@ fs_posix_init(struct fs *_fs, const char *args, const struct fs_settings *set)
 			fs->have_dirs = TRUE;
 		} else if (strcmp(arg, "no-fsync") == 0) {
 			fs->disable_fsync = TRUE;
+		} else if (strcmp(arg, "accurate-mtime") == 0) {
+			fs->accurate_mtime = TRUE;
 		} else if (str_begins(arg, "mode=")) {
 			unsigned int mode;
 			if (str_to_uint_oct(arg+5, &mode) < 0) {
@@ -475,6 +478,21 @@ static int fs_posix_write_finish(struct posix_fs_file *file)
 			return -1;
 		}
 	}
+	if (fs->accurate_mtime) {
+		/* Linux updates the mtime timestamp only on timer interrupts.
+		   This isn't anywhere close to being microsecond precision.
+		   If requested, use utimes() to explicitly set a more accurate
+		   mtime. */
+		struct timeval tv[2];
+		if (gettimeofday(&tv[0], NULL) < 0)
+			i_fatal("gettimeofday() failed: %m");
+		tv[1] = tv[0];
+		if ((utimes(file->temp_path, tv)) < 0) {
+			fs_set_error(file->file.fs, "utimes(%s) failed: %m",
+				     file->temp_path);
+			return -1;
+		}
+	}
 
 	fs_posix_write_rename_if_needed(file);
 	switch (file->open_mode) {