sfm

commit 98a1481d100468b02f4f422a597e40dd1a1a94f0
parent e8a78ffb8ec0e64f376c94022a934a7b02630800
Author: afify <hassan@afify.dev>
Date:   Fri,  9 Apr 2021 17:41:45 +0300

[fix] get_ext() max extension

problem 0: strlen() not check filename max length
solution 0: use strnlen with MAX_N

problem 1: allocating memory depends on counter
solution 1: always allocate MAX_EXT + 1 for '\0'

problem 2: ext string could be not null terminated
solution 2: make ext[MAX_EXT] = '\0'

Diffstat:
M
sfm.c
 | 
7
++++---

1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/sfm.c b/sfm.c
@@ -422,7 +422,7 @@ get_ext(char *str)
 
 	dot = '.';
 	counter = 0;
-	len = strlen(str);
+	len = strnlen(str, MAX_N);
 
 	for (i = len - 1; i > 0; i--) {
 		if (str[i] == dot) {
@@ -432,8 +432,9 @@ get_ext(char *str)
 		}
 	}
 
-	ext = ecalloc(counter + 1, sizeof(char));
-	strncpy(ext, &str[len - counter], counter);
+	ext = ecalloc(MAX_EXT + 1, sizeof(char));
+	strncpy(ext, &str[len - counter], MAX_EXT);
+	ext[MAX_EXT] = '\0';
 	return ext;
 }