libmount: add a generic append_string() function

Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 38 insertions, 0 deletions

diff --git a/libmount/src/utils.c b/libmount/src/utils.c
index 6c5171eca..165576464 100644
--- a/libmount/src/utils.c
+++ b/libmount/src/utils.c
@@ -54,6 +54,31 @@ int startswith(const char *s, const char *sx)
         return !strncmp(s, sx, off);
 }
 
+int append_string(char **a, const char *b)
+{
+	size_t al, bl;
+	char *tmp;
+
+	assert(a);
+
+	if (!b || !*b)
+		return 0;
+	if (!*a) {
+		*a = strdup(b);
+		return !*a ? -ENOMEM : 0;
+	}
+
+	al = strlen(*a);
+	bl = b ? strlen(b) : 0;
+
+	tmp = realloc(*a, al + bl + 1);
+	if (!tmp)
+		return -ENOMEM;
+	*a = tmp;
+	memcpy((*a) + al, b, bl + 1);
+	return 0;
+}
+
 /*
  * Return 1 if the file does not accessible of empty
  */
@@ -1082,6 +1107,18 @@ int test_endswith(struct libmnt_test *ts, int argc, char *argv[])
 	return 0;
 }
 
+int test_appendstr(struct libmnt_test *ts, int argc, char *argv[])
+{
+	char *str = strdup(argv[1]);
+	const char *ap = argv[2];
+
+	append_string(&str, ap);
+	printf("new string: '%s'\n", str);
+
+	free(str);
+	return 0;
+}
+
 int test_mountpoint(struct libmnt_test *ts, int argc, char *argv[])
 {
 	char *path = canonicalize_path(argv[1]),
@@ -1177,6 +1214,7 @@ int main(int argc, char *argv[])
 	{ "--filesystems",   test_filesystems,	   "[<pattern>] list /{etc,proc}/filesystems" },
 	{ "--starts-with",   test_startswith,      "<string> <prefix>" },
 	{ "--ends-with",     test_endswith,        "<string> <prefix>" },
+	{ "--append-string", test_appendstr,       "<string> <appendix>" },
 	{ "--mountpoint",    test_mountpoint,      "<path>" },
 	{ "--fs-root",       test_fsroot,          "<path>" },
 	{ "--cd-parent",     test_chdir,           "<path>" },