config-parser: Improve error checks for strtol/strtoul calls

Check errno, which is set of over/underflow, out of range, etc.  Also
check for empty strings (the usages covered in this patch already also
cover the case where there are non-digits present).  Set errno to 0
before making the strto*l call in case of pre-existing errors
(i.e. ENOTTY when running under the testsuite).

This follows the error checking style used in Wayland
(c.f. wayland-client.c and scanner.c).

In tests, also check errno, and add testcases for parsing '0'.

Signed-off-by: Bryce Harrington <bryce@osg.samsung.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>

shared/config-parser.c

@@ -169,8 +169,9 @@ weston_config_section_get_int(struct weston_config_section *section,
 		return -1;
 	}
 
+	errno = 0;
 	*value = strtol(entry->value, &end, 0);
-	if (*end != '\0') {
+	if (errno != 0 || end == entry->value || *end != '\0') {
 		*value = default_value;
 		errno = EINVAL;
 		return -1;
@@ -195,8 +196,9 @@ weston_config_section_get_uint(struct weston_config_section *section,
 		return -1;
 	}
 
+	errno = 0;
 	*value = strtoul(entry->value, &end, 0);
-	if (*end != '\0') {
+	if (errno != 0 || end == entry->value || *end != '\0') {
 		*value = default_value;
 		errno = EINVAL;
 		return -1;

tests/config-parser-test.c

@@ -116,6 +116,7 @@ static struct zuc_fixture config_test_t1 = {
 	"[bar]\n"
 	"# more comments\n"
 	"number=5252\n"
+	"zero=0\n"
 	"flag=false\n"
 	"\n"
 	"[stuff]\n"
@@ -263,6 +264,7 @@ ZUC_TEST_F(config_test_t1, test006, data)
 
 	ZUC_ASSERT_EQ(0, r);
 	ZUC_ASSERT_EQ(5252, n);
+	ZUC_ASSERT_EQ(0, errno);
 }
 
 ZUC_TEST_F(config_test_t1, test007, data)
@@ -289,8 +291,10 @@ ZUC_TEST_F(config_test_t1, test008, data)
 
 	section = weston_config_get_section(config, "bar", NULL, NULL);
 	r = weston_config_section_get_uint(section, "number", &u, 600);
+
 	ZUC_ASSERT_EQ(0, r);
 	ZUC_ASSERT_EQ(5252, u);
+	ZUC_ASSERT_EQ(0, errno);
 }
 
 ZUC_TEST_F(config_test_t1, test009, data)
@@ -427,6 +431,36 @@ ZUC_TEST_F(config_test_t1, test017, data)
 	ZUC_ASSERT_EQ(5, i);
 }
 
+ZUC_TEST_F(config_test_t1, test018, data)
+{
+	int r;
+	int32_t n;
+	struct weston_config_section *section;
+	struct weston_config *config = data;
+
+	section = weston_config_get_section(config, "bar", NULL, NULL);
+	r = weston_config_section_get_int(section, "zero", &n, 600);
+
+	ZUC_ASSERT_EQ(0, r);
+	ZUC_ASSERT_EQ(0, n);
+	ZUC_ASSERT_EQ(0, errno);
+}
+
+ZUC_TEST_F(config_test_t1, test019, data)
+{
+	int r;
+	uint32_t n;
+	struct weston_config_section *section;
+	struct weston_config *config = data;
+
+	section = weston_config_get_section(config, "bar", NULL, NULL);
+	r = weston_config_section_get_uint(section, "zero", &n, 600);
+
+	ZUC_ASSERT_EQ(0, r);
+	ZUC_ASSERT_EQ(0, n);
+	ZUC_ASSERT_EQ(0, errno);
+}
+
 ZUC_TEST_F(config_test_t2, doesnt_parse, data)
 {
 	struct weston_config *config = data;