Changed fusermount to avoid calling getpwuid(3) if '-o user=<username>'
is provided in the command line. This prevents glibc's implementation of
getpwuid from invoking socket/connect syscalls, which allows ChromiumOS
daemons to put more restrictive seccomp filters on fusermount.

diff --git a/util/fusermount.c b/util/fusermount.c
index 245aeea..e30f950 100644
--- a/util/fusermount.c
+++ b/util/fusermount.c
@@ -656,6 +656,21 @@ static int add_option(char **optsp, const char *opt, unsigned expand)
 	return 0;
 }
 
+static int add_user_option(char **mnt_optsp, const char *user)
+{
+	if (getuid() != 0) {
+		if (user == NULL)
+			user = get_user_name();
+		if (user == NULL)
+			return -1;
+
+		if (add_option(mnt_optsp, "user=", strlen(user)) == -1)
+			return -1;
+		strcat(*mnt_optsp, user);
+	}
+	return 0;
+}
+
 static int get_mnt_opts(int flags, char *opts, char **mnt_optsp)
 {
 	int i;
@@ -676,15 +691,6 @@ static int get_mnt_opts(int flags, char *opts, char **mnt_optsp)
 	l = strlen(*mnt_optsp);
 	if ((*mnt_optsp)[l-1] == ',')
 		(*mnt_optsp)[l-1] = '\0';
-	if (getuid() != 0) {
-		const char *user = get_user_name();
-		if (user == NULL)
-			return -1;
-
-		if (add_option(mnt_optsp, "user=", strlen(user)) == -1)
-			return -1;
-		strcat(*mnt_optsp, user);
-	}
 	return 0;
 }
 
@@ -737,6 +743,7 @@ static int do_mount(const char *mnt, char **typep, mode_t rootmode,
 	char *subtype = NULL;
 	char *source = NULL;
 	char *type = NULL;
+	char *user = NULL;
 	int check_empty = 1;
 	int blkdev = 0;
 
@@ -750,6 +757,7 @@ static int do_mount(const char *mnt, char **typep, mode_t rootmode,
 		unsigned len;
 		const char *fsname_str = "fsname=";
 		const char *subtype_str = "subtype=";
+		const char *user_str = "user=";
 		bool escape_ok = begins_with(s, fsname_str) ||
 				 begins_with(s, subtype_str);
 		for (len = 0; s[len]; len++) {
@@ -764,6 +772,9 @@ static int do_mount(const char *mnt, char **typep, mode_t rootmode,
 		} else if (begins_with(s, subtype_str)) {
 			if (!get_string_opt(s, len, subtype_str, &subtype))
 				goto err;
+		} else if (begins_with(s, user_str)) {
+			if (!get_string_opt(s, len, user_str, &user))
+				goto err;
 		} else if (opt_eq(s, len, "blkdev")) {
 			if (getuid() != 0) {
 				fprintf(stderr,
@@ -826,6 +837,9 @@ static int do_mount(const char *mnt, char **typep, mode_t rootmode,
 	}
 	*d = '\0';
 	res = get_mnt_opts(flags, optbuf, &mnt_opts);
+	if (res == -1)
+		goto err;
+	res = add_user_option(&mnt_opts, user);
 	if (res == -1)
 		goto err;