include/cctype: fix string comparison

Reimplement c_strcasecmp() and c_strncasecmp() to be libc compatible
and fix c_strncasecmp() to avoid \0 misinterpretation. The original
implementation was pretty stupid (sorry).

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

diff --git a/include/cctype.h b/include/cctype.h
index b673b6cff134676415b8e7297d1d3748c4b6565b..e55c008b80ee2e08ae9d88da2341cd82ed1eb717 100644 (file)
--- a/include/cctype.h
+++ b/include/cctype.h
@@ -23,6 +23,9 @@
 #ifndef UTIL_LINUX_CCTYPE_H
 #define UTIL_LINUX_CCTYPE_H
 
+#include <stddef.h>
+#include <limits.h>
+
 /**
  * The functions defined in this file assume the "C" locale and a character
  * set without diacritics (ASCII-US or EBCDIC-US or something like that).
@@ -317,38 +320,54 @@ static inline int c_toupper (int c)
        }
 }
 
+#define C_CTYPE_CMP(c1, c2)    (((c1) > (c2)) - ((c1) < (c2)))
+
 static inline int c_strncasecmp(const char *a, const char *b, size_t n)
 {
-       int res = 0;
+       const unsigned char *p1 = (const unsigned char *) a;
+       const unsigned char *p2 = (const unsigned char *) b;
+       unsigned char x, y;
 
-        for (; n > 0; a++, b++, n--) {
-               unsigned int x = (unsigned int) *a;
-               unsigned int y = (unsigned int) *b;
+       if (n == 0 || p1 == p2)
+               return 0;
 
-               res = c_tolower(x) - c_tolower(y);
-                if (res)
-                        break;
-        }
-        return res;
+       do {
+               x = c_tolower(*p1);
+               y = c_tolower(*p2);
+
+               if (--n == 0 || x == '\0')
+                       break;
+               ++p1, ++p2;
+       } while (x == y);
+
+       if (UCHAR_MAX <= INT_MAX)
+               return x - y;
+
+       return C_CTYPE_CMP(x, y);
 }
 
 static inline int c_strcasecmp(const char *a, const char *b)
 {
-       int res = 0;
+       const unsigned char *p1 = (const unsigned char *) a;
+       const unsigned char *p2 = (const unsigned char *) b;
+       unsigned char x, y;
 
-       if (a == b)
+       if (p1 == p2)
                return 0;
 
-       for (; *a != '\0'; a++, b++) {
-               unsigned int x = (unsigned int) *a;
-               unsigned int y = (unsigned int) *b;
+       do {
+               x = c_tolower(*p1);
+               y = c_tolower(*p2);
 
-               res = c_tolower(x) - c_tolower(y);
-               if (res)
+               if (x == '\0')
                        break;
-       }
+               ++p1, ++p2;
+       } while (x == y);
+
+       if (UCHAR_MAX <= INT_MAX)
+               return x - y;
 
-       return res;
+       return C_CTYPE_CMP(x, y);
 }
 
 #endif /* UTIL_LINUX_CCTYPE_H */