From: Andre Noll <maan@tuebingen.mpg.de>
Date: Wed, 15 Nov 2017 18:09:06 +0000 (+0100)
Subject: Merge branch 'refs/heads/t/mountpoint'
X-Git-Tag: v1.0.0~10
X-Git-Url: http://git.tuebingen.mpg.de/dss.git/log?a=commitdiff_plain;h=c9fd9f2239319b95c46e49b1b7040e1a898cdcf7;hp=50e03ce10c3bab1c43e1e68dca3b0471d63807d9;p=dss.git

Merge branch 'refs/heads/t/mountpoint'

A new main option which aborts dss if the destination file system is
not mounted.

Cooking for two weeks.

* refs/heads/t/mountpoint:
  New option: --mountpoint.
---

diff --git a/NEWS b/NEWS
index fc80e8e..75fe3a2 100644
--- a/NEWS
+++ b/NEWS
@@ -14,6 +14,9 @@ x.y.z (to be announced)
  - New subcommand "configtest" to check the command line options and
  the configuration file for syntactic correctness.
 
+ - New option: --mountpoint. If this option is given, dss aborts if
+ no file system is mounted on the destination directory.
+
  - "make install" will install the executable and the man page.
 
  - In run mode, dss no longer exits successfully if another instance
diff --git a/dss.c b/dss.c
index 6353fbe..bd9e577 100644
--- a/dss.c
+++ b/dss.c
@@ -1060,17 +1060,36 @@ static int handle_sigchld(void)
 	return -E_BUG;
 }
 
+/* also checks if . is a mountpoint, if --mountpoint was given */
 static int change_to_dest_dir(void)
 {
 	int ret;
 	const char *dd = OPT_STRING_VAL(DSS, DEST_DIR);
+	struct stat dot, dotdot;
 
 	DSS_INFO_LOG(("changing cwd to %s\n", dd));
-	if (chdir(dd) >= 0)
-		return 1;
-	ret = -ERRNO_TO_DSS_ERROR(errno);
-	DSS_ERROR_LOG(("could not change cwd to %s\n", dd));
-	return ret;
+	if (chdir(dd) < 0) {
+		ret = -ERRNO_TO_DSS_ERROR(errno);
+		DSS_ERROR_LOG(("could not change cwd to %s\n", dd));
+		return ret;
+	}
+	if (!OPT_GIVEN(DSS, MOUNTPOINT))
+		return 0;
+	if (stat(".", &dot) < 0) {
+		ret = -ERRNO_TO_DSS_ERROR(errno);
+		DSS_ERROR_LOG(("could not stat .\n"));
+		return ret;
+	}
+	if (stat("..", &dotdot) < 0) {
+		ret = -ERRNO_TO_DSS_ERROR(errno);
+		DSS_ERROR_LOG(("could not stat ..\n"));
+		return ret;
+	}
+	if (dot.st_dev == dotdot.st_dev && dot.st_ino != dotdot.st_ino) {
+		DSS_ERROR_LOG(("mountpoint check failed for %s\n", dd));
+		return -E_MOUNTPOINT;
+	}
+	return 1;
 }
 
 static int check_config(void)
diff --git a/dss.suite b/dss.suite
index 95dd30f..1e79870 100644
--- a/dss.suite
+++ b/dss.suite
@@ -79,6 +79,18 @@ caption = Subcommands
 
 			This option is mandatory for all subcommands except kill.
 		[/help]
+	[option mountpoint]
+		summary = abort if destination directory is not a mountpoint
+		[help]
+			This option checks whether a file system is mounted on the directory
+			specified as the argument to --dest-dir. Operation proceeds only
+			if this is the case. Otherwise dss exits unsuccessfully without
+			performing any action. Use this option to prevent snapshot creation
+			if the snapshot file system is not mounted.
+
+			This option is silently ignored for subcommands which do not depend
+			on the destination directory.
+		[/help]
 	[option Rsync-options]
 		summary = Controlling how rsync is run
 		flag ignored
diff --git a/err.h b/err.h
index 3d4e136..e747bf3 100644
--- a/err.h
+++ b/err.h
@@ -48,6 +48,7 @@ static inline char *dss_strerror(int num)
 	DSS_ERROR(INVALID_NUMBER, "invalid number"), \
 	DSS_ERROR(STRFTIME, "strftime() failed"), \
 	DSS_ERROR(LOCALTIME, "localtime() failed"), \
+	DSS_ERROR(MOUNTPOINT, "destination directory is no mountpoint"), \
 	DSS_ERROR(NULL_OPEN, "can not open /dev/null"), \
 	DSS_ERROR(DUP_PIPE, "exec error: can not create pipe"), \
 	DSS_ERROR(INVOLUNTARY_EXIT, "unexpected termination cause"), \