refactor(fnmatch.c): removed duplicate code and added simplifications

Signed-off-by: Spago123 <harun.spago.code@gmail.com>

Author: Spago123

include/zephyr/posix/fnmatch.h

@@ -50,7 +50,26 @@
 extern "C" {
 #endif
 
-int fnmatch(const char *, const char *, int);
+/**
+ * Function used to check if the given pattern is in the string, using the given flags
+ * 
+ * @param pattern pattern that is matched against the string
+ * @param string string that is checked for the pattern
+ * @param flags used to signal special matching conditions
+ *        FNM_NOESCAPE	0x01 Disable backslash escaping.
+ *        FNM_PATHNAME	0x02 Slash must be matched by slash.
+ *        FNM_PERIOD	0x04 Period must be matched by period.
+ *        FNM_CASEFOLD	0x08 Pattern is matched case-insensitive
+ *        FNM_LEADING_DIR 0x10 Ignore /<tail> after Imatch.
+ * 
+ * 
+ * @return int
+ * @retval 0 pattern found in string
+ * @retval FNM_NOMATCH pattern not found in string
+ * @retval FNM_NORES recursion limit reached
+ * @retval FNM_NOSYS function not implemented
+ */
+int fnmatch(const char *pattern, const char *string, int flags);
 
 #ifdef __cplusplus
 }

lib/posix/options/fnmatch.c

@@ -58,10 +58,46 @@ static inline int foldcase(int ch, int flags)
 	return ch;
 }
 
+/**
+ * @brief Function to check for FNM_PERIOD condition
+ * 
+ * @param string string whose first character is checked if it is a period
+ * @param flags passed flags to check for FNM_PERIOD
+ * @return int 
+ * @retval 1 if first character is period and FNM_PERIOD flag is set
+ * @retval 0 otherwise
+ */
+static int check_fnm_period(const char* string, const int flags)
+{
+	return *string == '.' && (flags & FNM_PERIOD);
+}
+
+/**
+ * @brief Function to check for FNM_PATHNAME condition
+ * 
+ * @param letter letter to be checked if it is a '/'
+ * @param flags flags passed to check for FNM_PATHNAME
+ * @return int 
+ * @retval 1 if letter is '/' and FNM_PATHNAME flag is set
+ * @retval 0 otherwise
+ */
+static int check_for_pathname(const char letter, const int flags)
+{
+	return letter == '/' && (flags & FNM_PATHNAME);
+}
+
 #define FOLDCASE(ch, flags) foldcase((unsigned char)(ch), (flags))
 
+/**
+ * @brief Function to match POSIX character classes
+ * 
+ * @param pattern start of the pattern, should point to the character after '['
+ * @param test next character in the string to be tested against the class
+ * @return true 
+ * @return false 
+ */
 static bool match_posix_class(const char **pattern, int test) {
-    static const struct {
+    const struct {
         const char *name;
         int (*func)(int);
     } classes[] = {
@@ -118,7 +154,7 @@ static const char *rangematch(const char *pattern, int test, int flags)
 	     c = FOLDCASE(*pattern++, flags)) {
 		need = false;
 
-		if (c == '/' && (flags & FNM_PATHNAME)) {
+		if (check_for_pathname(c, flags)) {
 			return (void *)-1;
 		}
 
@@ -195,13 +231,13 @@ static int fnmatchx(const char *pattern, const char *string, int flags, size_t r
 				return FNM_NOMATCH;
 			}
 
-			if (*string == '/' && (flags & FNM_PATHNAME)) {
+			if (check_for_pathname(*string, flags)) {
 				return FNM_NOMATCH;
 			}
 
-			if (*string == '.' && (flags & FNM_PERIOD) &&
+			if (check_fnm_period(string, flags) &&
 			    (string == stringstart ||
-			     ((flags & FNM_PATHNAME) && *(string - 1) == '/'))) {
+			     check_for_pathname(*(string - 1), flags))) {
 				return FNM_NOMATCH;
 			}
 
@@ -214,23 +250,22 @@ static int fnmatchx(const char *pattern, const char *string, int flags, size_t r
 				c = FOLDCASE(*++pattern, flags);
 			}
 
-			if (*string == '.' && (flags & FNM_PERIOD) &&
+			if (check_fnm_period(string, flags) &&
 			    (string == stringstart ||
-			     ((flags & FNM_PATHNAME) && *(string - 1) == '/'))) {
+			     check_for_pathname(*(string - 1), flags))) {
 				return FNM_NOMATCH;
 			}
 
 			/* Optimize for pattern with * at end or before /. */
 			if (c == EOS) {
-				if (flags & FNM_PATHNAME) {
-					return (flags & FNM_LEADING_DIR) ||
-							       strchr(string, '/') == NULL
-						       ? 0
-						       : FNM_NOMATCH;
-				} else {
+				if(!(flags & FNM_PATHNAME)) {
 					return 0;
 				}
-			} else if (c == '/' && flags & FNM_PATHNAME) {
+				return (flags & FNM_LEADING_DIR) ||
+								strchr(string, '/') == NULL
+							? 0
+							: FNM_NOMATCH;
+			} else if (check_for_pathname(c, flags)) {
 				string = strchr(string, '/');
 				if (string == NULL) {
 					return FNM_NOMATCH;
@@ -252,7 +287,7 @@ static int fnmatchx(const char *pattern, const char *string, int flags, size_t r
 					return e;
 				}
 
-				if (test == '/' && flags & FNM_PATHNAME) {
+				if (check_for_pathname(test, flags)) {
 					break;
 				}
 
@@ -265,13 +300,13 @@ static int fnmatchx(const char *pattern, const char *string, int flags, size_t r
 				return FNM_NOMATCH;
 			}
 
-			if (*string == '/' && flags & FNM_PATHNAME) {
+			if (check_for_pathname(*string, flags)) {
 				return FNM_NOMATCH;
 			}
 
-			if (*string == '.' && (flags & FNM_PERIOD) &&
+			if (check_fnm_period(string, flags) &&
 			    (string == stringstart ||
-			     ((flags & FNM_PATHNAME) && *(string - 1) == '/'))) {
+			     check_for_pathname(*(string - 1), flags))) {
 				return FNM_NOMATCH;
 			}