Merge branch 'master' of git+ssh://openadk.org/git/openadk

1 files changed, 216 insertions, 0 deletions

diff --git a/package/aufs2-util/src/mtab.c b/package/aufs2-util/src/mtab.c
new file mode 100644
index 000000000..713e9e267
--- /dev/null
+++ b/package/aufs2-util/src/mtab.c
@@ -0,0 +1,216 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+/* cf. fstab.c or the locking for /etc/mtab in util-linux */
+/*
+ * we need to extract a part of util-linux and create a simple and generic
+ * library for locking /etc/mtab.
+ */
+
+/* #include <linux/proc_fs.h> */
+#define PROC_SUPER_MAGIC 0x9fa0
+#include <sys/stat.h>
+#include <sys/statfs.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <fcntl.h>
+#include <mntent.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "au_util.h"
+
+void au_print_ent(struct mntent *ent)
+{
+	printf("%s on %s type %s (%s)\n",
+	       ent->mnt_fsname, ent->mnt_dir, ent->mnt_type, ent->mnt_opts);
+}
+
+/* ---------------------------------------------------------------------- */
+
+static void lock_mtab(char *pid_file)
+{
+	int err, i;
+
+	for (i = 0; i < 5; i++) {
+		err = link(pid_file, MTab "~");
+		if (!err)
+			break;
+		sleep(1);
+	}
+	if (err)
+		AuFin(MTab "~");
+}
+
+static void unlock_mtab(void)
+{
+	int err;
+
+	err = rename(MTab "~", MTab);
+	if (err)
+		AuFin(MTab);
+}
+
+static void append_mtab(FILE *fp, FILE *ofp, struct mntent *ent)
+{
+	int err;
+	struct mntent *p;
+
+	while ((p = getmntent(ofp))) {
+		err = addmntent(fp, p);
+		if (err)
+			AuFin("addmntent");
+	}
+
+	err = addmntent(fp, ent);
+	if (err)
+		AuFin("addmntent");
+}
+
+/* todo: there are some cases which options are not changed */
+static void update_mtab(FILE *fp, char *mntpnt, int do_remount, int do_verbose)
+{
+	int err;
+	long pos;
+	FILE *ofp;
+	struct mntent ent, *p;
+
+	/* prohibit updating mount options for this mntpnt */
+	au_plink_maint(mntpnt);
+	err = au_proc_getmntent(mntpnt, &ent);
+	if (err)
+		AuFin("no such mount point");
+
+	ofp = setmntent(MTab, "r");
+	if (!ofp)
+		AuFin(MTab);
+
+	if (do_remount) {
+		/* find the last one */
+		pos = -1;
+		while ((p = getmntent(ofp))) {
+			if (!strcmp(p->mnt_dir, mntpnt))
+				pos = ftell(ofp);
+		}
+		rewind(ofp);
+
+		if (pos > 0) {
+			while ((p = getmntent(ofp))) {
+				if (ftell(ofp) == pos) {
+					/* replace the line */
+					p = &ent;
+					pos = -1;
+				}
+				err = addmntent(fp, p);
+				if (err)
+					AuFin("addmntent");
+			}
+			if (pos > 0)
+				AuFin("internal error");
+		} else
+			append_mtab(fp, ofp, &ent);
+	} else
+		append_mtab(fp, ofp, &ent);
+
+	endmntent(ofp); /* ignore */
+	au_plink_maint(NULL);
+	if (do_verbose)
+		au_print_ent(&ent);
+}
+
+/* ---------------------------------------------------------------------- */
+
+int au_update_mtab(char *mntpnt, int do_remount, int do_verbose)
+{
+	int err, fd, status, e2;
+	pid_t pid;
+	ino_t ino;
+	struct stat st;
+	struct statfs stfs;
+	struct flock flock = {
+		.l_type		= F_WRLCK,
+		.l_whence	= SEEK_SET,
+		.l_start	= 0,
+		.l_len		= 0
+	};
+	char pid_file[sizeof(MTab "~.") + 20];
+	FILE *fp;
+
+	err = statfs(MTab, &stfs);
+	if (stfs.f_type == PROC_SUPER_MAGIC)
+		return 0;
+
+	snprintf(pid_file, sizeof(pid_file), MTab "~.%d", getpid());
+	fd = open(pid_file, O_RDWR | O_CREAT | O_EXCL,
+		  S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+	if (fd < 0)
+		AuFin("%s", pid_file);
+	err = fcntl(fd, F_SETLK, &flock);
+	if (err)
+		AuFin("%s", pid_file);
+	fp = fdopen(fd, "r+");
+	if (!fp)
+		AuFin("%s", pid_file);
+
+	pid = fork();
+	if (!pid) {
+		lock_mtab(pid_file);
+		update_mtab(fp, mntpnt, do_remount, do_verbose);
+		unlock_mtab();
+		return 0;
+	} else if (pid < 0)
+		AuFin("fork");
+
+	err = fstat(fd, &st);
+	if (err)
+		perror(pid_file);
+	ino = st.st_ino;
+
+	err = waitpid(pid, &status, 0);
+	if (err < 0) {
+		perror(pid_file);
+		goto out;
+	}
+	err = !WIFEXITED(status);
+	if (!err)
+		err = WEXITSTATUS(status);
+
+	e2 = unlink(pid_file);
+	if (e2 && errno != ENOENT)
+		perror(pid_file);
+	e2 = stat(MTab "~", &st);
+	if (!e2) {
+		if (st.st_ino == ino) {
+			/*
+			 * The inode number is same,
+			 * it means it is we who made the file.
+			 * If someone else removed our file between stat(2) and
+			 * unlink(2), it is a breakage of the rule.
+			 */
+			e2 = unlink(MTab "~");
+			if (e2)
+				perror(MTab);
+		}
+	} else if (errno != ENOENT)
+		perror(MTab "~");
+	fclose(fp);
+
+ out:
+	return err;
+}