[PATCH] Tools: lib: string: Fix isspace() parameter to avoid undefined behavior

[hyunji-Hong]

isspace() could be vulnerable in terms of unpredictable results. So, the parameter of the isspace() should be cast with 'unsigned int'. We found out that information through these sites. (Microsoft, Stack Overflow)
url: [https://docs.microsoft.com/en-us/cpp/code-quality/c6328?view=msvc-160]
url: [https://stackoverflow.com/questions/122721]

Signed-off-by: SeungHoon Woo, Hyunji Hong, Kyeongseok Yang <hyunji_hong@xxxxxxxxxxx>
---
 tools/lib/string.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/lib/string.c b/tools/lib/string.c
index 8b6892f959ab..7d01be5cdcf8 100644
--- a/tools/lib/string.c
+++ b/tools/lib/string.c
@@ -123,7 +123,7 @@ size_t __weak strlcpy(char *dest, const char *src, size_t size)
  */
 char *skip_spaces(const char *str)
 {
-	while (isspace(*str))
+	while (isspace((unsigned char)*str))
 		++str;
 	return (char *)str;
 }
@@ -146,7 +146,7 @@ char *strim(char *s)
 		return s;
 
 	end = s + size - 1;
-	while (end >= s && isspace(*end))
+	while (end >= s && isspace((unsigned char)*end))
 		end--;
 	*(end + 1) = '\0';
 
-- 
2.17.1