[PATCH] fsync applet

virtuoso at slind.org virtuoso at slind.org
Thu Jun 11 09:09:46 UTC 2009


From: Pekka Pessi <Pekka.Pessi at nokia.com>

Issue fsync() system call on a file to ensure its buffers are synchronized
with the backing storage.

Signed-off-by: Alexander Shishkin <virtuoso at slind.org>
---
 coreutils/Config.in |    6 ++++++
 coreutils/Kbuild    |    1 +
 coreutils/fsync.c   |   46 ++++++++++++++++++++++++++++++++++++++++++++++
 include/applets.h   |    1 +
 include/usage.h     |    7 +++++++
 5 files changed, 61 insertions(+), 0 deletions(-)
 create mode 100644 coreutils/fsync.c

diff --git a/coreutils/Config.in b/coreutils/Config.in
index b047ce5..88642d7 100644
--- a/coreutils/Config.in
+++ b/coreutils/Config.in
@@ -249,6 +249,12 @@ config FOLD
 	help
 	  Wrap text to fit a specific width.
 
+config FSYNC
+	bool "fsync"
+	default n
+	help
+	  fsync is used to flush file-related cached blocks to disk.
+
 config HEAD
 	bool "head"
 	default n
diff --git a/coreutils/Kbuild b/coreutils/Kbuild
index 57100a9..4d6bde7 100644
--- a/coreutils/Kbuild
+++ b/coreutils/Kbuild
@@ -36,6 +36,7 @@ lib-$(CONFIG_EXPR)      += expr.o
 lib-$(CONFIG_EXPAND)    += expand.o
 lib-$(CONFIG_FALSE)     += false.o
 lib-$(CONFIG_FOLD)      += fold.o
+lib-$(CONFIG_FSYNC)     += fsync.o
 lib-$(CONFIG_HEAD)      += head.o
 lib-$(CONFIG_HOSTID)    += hostid.o
 lib-$(CONFIG_ID)        += id.o
diff --git a/coreutils/fsync.c b/coreutils/fsync.c
new file mode 100644
index 0000000..4ef6921
--- /dev/null
+++ b/coreutils/fsync.c
@@ -0,0 +1,46 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Mini fsync implementation for busybox
+ *
+ * Copyright (C) 2008 Nokia Corporation. All rights reserved.
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ */
+
+#include "libbb.h"
+
+/* This is a NOFORK applet. Be very careful! */
+
+int fsync_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int fsync_main(int argc, char **argv)
+{
+	int status = EXIT_SUCCESS;
+	int flags;
+	int fd;
+	char *path;
+
+	flags = getopt32(argv, "d"); /* fdatasync */
+	argv += optind;
+
+	if (!*argv) {
+		bb_show_usage();
+	}
+
+	for (path = *argv++; path; path = *argv++) {
+		fd = open(path, O_NOATIME | O_NOCTTY | O_RDONLY);
+
+		if (fd == -1) {
+			bb_simple_perror_msg(path);
+			status = EXIT_FAILURE;
+			continue;
+		}
+
+		if ((flags ? fdatasync(fd) : fsync(fd)) == -1) {
+			bb_simple_perror_msg(path);
+		}
+
+		close(fd);
+	}
+
+	return status;
+}
diff --git a/include/applets.h b/include/applets.h
index 5fbb346..9296160 100644
--- a/include/applets.h
+++ b/include/applets.h
@@ -165,6 +165,7 @@ IF_FSCK(APPLET(fsck, _BB_DIR_SBIN, _BB_SUID_NEVER))
 //IF_E2FSCK(APPLET_ODDNAME(fsck.ext2, e2fsck, _BB_DIR_SBIN, _BB_SUID_NEVER, fsck_ext2))
 //IF_E2FSCK(APPLET_ODDNAME(fsck.ext3, e2fsck, _BB_DIR_SBIN, _BB_SUID_NEVER, fsck_ext3))
 IF_FSCK_MINIX(APPLET_ODDNAME(fsck.minix, fsck_minix, _BB_DIR_SBIN, _BB_SUID_NEVER, fsck_minix))
+IF_FSYNC(APPLET_NOFORK(fsync, fsync, _BB_DIR_BIN, _BB_SUID_NEVER, fsync))
 IF_FTPD(APPLET(ftpd, _BB_DIR_USR_SBIN, _BB_SUID_NEVER))
 IF_FTPGET(APPLET_ODDNAME(ftpget, ftpgetput, _BB_DIR_USR_BIN, _BB_SUID_NEVER, ftpget))
 IF_FTPPUT(APPLET_ODDNAME(ftpput, ftpgetput, _BB_DIR_USR_BIN, _BB_SUID_NEVER, ftpput))
diff --git a/include/usage.h b/include/usage.h
index e606925..3ea9a3d 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -4208,6 +4208,13 @@
 #define sync_full_usage "\n\n" \
        "Write all buffered filesystem blocks to disk"
 
+#define fsync_trivial_usage \
+       "[OPTION]... FILE..."
+#define fsync_full_usage \
+       "Write files' buffered blocks to disk\n" \
+     "\nOptions:" \
+     "\n        -d     Avoid syncing metadata (like access time)"
+
 #define sysctl_trivial_usage \
        "[OPTIONS]... [VALUE]..."
 #define sysctl_full_usage "\n\n" \
-- 
1.6.3.1



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