chore(fnmatch): added Doxygen

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

@@ -58,18 +58,44 @@ 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) {
     const struct {
         const char *name;