test/nstool: Provide useful error if given a path that's too long

Normal filesystem paths can be very long (PATH_MAX is around 8k), however
Unix domain sockets can only use relatively short paths (UNIX_PATH_MAX is
108 on Linux).  Currently nstool will simply truncate paths that are too
long, leading to difficult to understand failures.

Make such failures clearer, with an explicit error message if given a path
that's too long.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 14 insertions, 8 deletions

diff --git a/test/nstool.c b/test/nstool.c
index e6d7d37..bca9569 100644
--- a/test/nstool.c
+++ b/test/nstool.c
@@ -93,14 +93,22 @@ static void usage(void)
 	    "    terminate.\n");
 }
 
+static void sockaddr_from_path(struct sockaddr_un *addr, const char *sockpath)
+{
+	if (strlen(sockpath) > UNIX_PATH_MAX)
+		die("\"%s\" is too long for Unix socket path (%zu > %d)",
+		    sockpath, strlen(sockpath), UNIX_PATH_MAX);
+
+	addr->sun_family = AF_UNIX;
+	strncpy(addr->sun_path, sockpath, UNIX_PATH_MAX);
+}
+
 static int connect_ctl(const char *sockpath, bool wait,
 		       struct holder_info *info,
 		       struct ucred *peercred)
 {
 	int fd = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, PF_UNIX);
-	struct sockaddr_un addr = {
-		.sun_family = AF_UNIX,
-	};
+	struct sockaddr_un addr;
 	struct holder_info discard;
 	ssize_t len;
 	int rc;
@@ -108,7 +116,7 @@ static int connect_ctl(const char *sockpath, bool wait,
 	if (fd < 0)
 		die("socket(): %s\n", strerror(errno));
 
-	strncpy(addr.sun_path, sockpath, UNIX_PATH_MAX);
+	sockaddr_from_path(&addr, sockpath);
 
 	do {
 		rc = connect(fd, (struct sockaddr *)&addr, sizeof(addr));
@@ -149,9 +157,7 @@ static int connect_ctl(const char *sockpath, bool wait,
 static void cmd_hold(int argc, char *argv[])
 {
 	int fd = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, PF_UNIX);
-	struct sockaddr_un addr = {
-		.sun_family = AF_UNIX,
-	};
+	struct sockaddr_un addr;
 	const char *sockpath = argv[1];
 	struct holder_info info;
 	int rc;
@@ -162,7 +168,7 @@ static void cmd_hold(int argc, char *argv[])
 	if (fd < 0)
 		die("socket(): %s\n", strerror(errno));
 
-	strncpy(addr.sun_path, sockpath, UNIX_PATH_MAX);
+	sockaddr_from_path(&addr, sockpath);
 
 	rc = bind(fd, (struct sockaddr *)&addr, sizeof(addr));
 	if (rc < 0)