源码下载地址如下：
http://web.mit.edu/freebsd/csup/fnmatch.h
http://web.mit.edu/freebsd/csup/fnmatch.c
代码整体不错，但是中有一些地方稍有不足。我没有去改（添加了一些{}，以便结构清晰）。
/*
* Copyright (c) 1989, 1993, 1994
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Guido van Rossum.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* From FreeBSD fnmatch.c 1.11
* $Id: fnmatch.c,v 1.3 1997/08/19 02:34:30 jdp Exp $
*/
#ifndef _FNMATCH_H_
#define _FNMATCH_H_
#define FNM_NOMATCH 1 /* Match failed. */
#define FNM_NOESCAPE 0x01 /* 禁用反斜杠进行转义 */
#define FNM_PATHNAME 0x02 /* 斜杠只能被斜杠匹配(即不能被*或者?匹配) */
#define FNM_PERIOD 0x04 /* Period must be matched by period. */
/*如果这个标志设置了，string 里的起始点号必须匹配 pattern 里的点号。
一个点号被认为是起始点号，如果它是string 第一个字符，或者如果同时设
置了 FNM_PATHNAME，紧跟在斜杠后面的点号。
*/
#define FNM_LEADING_DIR 0x08 /* Ignore /<tail> after Imatch. */
/*如果这个标志(GNU 扩展)设置了，模式必须匹配跟随在斜杠之后的 string
的初始片断。这个标志主要是给 glibc 内部使用并且只在一定条件下实现。
即只匹配目录路径部分，不匹配到具体文件名
*/
#define FNM_CASEFOLD 0x10 /* 模式匹配忽略大小写. */
#define FNM_PREFIX_DIRS 0x20 /* Directory prefixes of pattern match too. */
/* Make this compile successfully with "gcc -traditional" */
#ifndef __STDC__
#define const /* empty */
#endif
int fnmatch(const char *, const char *, int);
#endif /* !_FNMATCH_H_ */
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)fnmatch.c 8.2 (Berkeley) 4/16/94";
#endif /* LIBC_SCCS and not lint */
/*
* 函数fnmatch()，如POSIX 1003.2-1992 B.6节所述。
* 将文件名或者目录名与pattern进行比较
*/
#include <ctype.h>
#include <string.h>
#include <stdio.h>
// 定义字符串结尾标志
#define EOS '\0'
static const char *rangematch(const char *, char, int);
int
fnmatch(const char *pattern, const char *string, int flags)
{
const char *stringstart;
char c, test;
for (stringstart = string;;){
// 逐个取匹配字符串中的成分(分为*?和range三种)
switch (c = *pattern++) {
case EOS: // 没有匹配串的情况
// 如果忽略'/'后面的部分，则匹配成功
if ((flags & FNM_LEADING_DIR) && *string == '/'){
return (0);
}
// 如果string也是空串，则匹配成功
return (*string == EOS ? 0 : FNM_NOMATCH);
case '?': // 匹配单个任意字符
// string为空则不能匹配
if (*string == EOS){
return (FNM_NOMATCH);
}
// 判断'/'是否只能由'/'进行匹配
if (*string == '/' && (flags & FNM_PATHNAME)){
return (FNM_NOMATCH);
}
// 判断是否string中的起始'.'必须匹配pattern中的'.'（即'?'不能匹配'.'）
if (*string == '.' && (flags & FNM_PERIOD) &&
(string == stringstart ||
((flags & FNM_PATHNAME) && *(string - 1) == '/'))){
return (FNM_NOMATCH);
}
// 匹配成功则匹配string的下一个字符
++string;
break;
case '*': // 匹配单个或多个任意字符
c = *pattern;
/* 多个'*'当做一个 */
while (c == '*'){
c = *++pattern;
}
// 判断是否需要对'.'进行处理
if (*string == '.' && (flags & FNM_PERIOD) &&
(string == stringstart ||
((flags & FNM_PATHNAME) && *(string - 1) == '/'))){
return (FNM_NOMATCH);
}
/* 优化 * 在匹配串结尾或者在 /. 之前的匹配*/
if (c == EOS){ // 在结尾
// 判断 * 是否不匹配斜杠
if (flags & FNM_PATHNAME){
// 不匹配斜杠，则判断是否忽略'/'之后部分
return ((flags & FNM_LEADING_DIR) ||
((strchr(string, '/') == NULL) ? 0 : FNM_NOMATCH));
}else{
return (0);
}
}
else if (c == '/' && flags & FNM_PATHNAME) { // 在 /. 之前
// 如果string后没有 '/'则匹配失败
if ((string = strchr(string, '/')) == NULL){
return (FNM_NOMATCH);
}
break;
}
/* 非特殊情况下，递归匹配 */
while ((test = *string) != EOS) {
// 不对'.'进行特殊处理，进行匹配（则只需判断'/'匹配情况）
if (!fnmatch(pattern, string, flags & ~FNM_PERIOD)){
return (0); // 匹配成功
}
// 对 '/'进行处理（斜杠只匹配斜杠，则匹配失败）
if (test == '/' && flags & FNM_PATHNAME){
break;
}
++string;
}
// 返回匹配失败（即*没有匹配成功,'.'和'/'上的匹配没有成功）
return (FNM_NOMATCH);
case '[': // range 范围匹配
if (*string == EOS){
return (FNM_NOMATCH); // 空串匹配失败
}
if (*string == '/' && flags & FNM_PATHNAME){
return (FNM_NOMATCH); // '/'匹配失败
}
if ((pattern =
rangematch(pattern, *string, flags)) == NULL){
return (FNM_NOMATCH); // 范围匹配失败
}
++string;
break;
case '\\': // 斜杠匹配（判断是否需要转义）
if (!(flags & FNM_NOESCAPE)) {
if ((c = *pattern++) == EOS) {
c = '\\';
--pattern;
}
}
/* 非上述部分，则直接匹配单个字符 */
default:
if (c == *string){
; // 直接匹配上了
}else if ((flags & FNM_CASEFOLD) &&
(tolower((unsigned char)c) ==
tolower((unsigned char)*string))){
; // 忽略大小写匹配成功
}
else if ((flags & FNM_PREFIX_DIRS) && *string == EOS &&
((c == '/' && string != stringstart) ||
(string == stringstart + 1 && *stringstart == '/'))){
return (0); // 匹配成功
}
else{
return (FNM_NOMATCH); // 匹配失败
}
string++;
break;
}
}
/* NOTREACHED */
}
// 字符范围匹配
// pattern传入如 [a-x]*** 形式的字符串
// 匹配失败或匹配到EOS结束(也是失败)，返回NULL
// 成功返回匹配串的下一个匹配成分首地址
static const char *
rangematch(const char *pattern, char test, int flags)
{
// 此处没有对c进行初始化，可能出问题（栈上变量默认值未定）
int negate, ok;
char c, c2;
/*
* A bracket expression starting with an unquoted circumflex
* character produces unspecified results
* 以无引号 ^ 字符开始的方括号表达式，将产生未指定的结果
* (IEEE 1003.2-1992,3.13.2). 此实现将其视为 '!',以与正则表达式语法保持一致.
* J.T. Conklin (conklin@ngai.kaleida.com)
*/
// 检测方括号表达式中第一个字符
// 如果为!或者^，则对后面匹配的结果取反
if ((negate = (*pattern == '!' || *pattern == '^'))){
++pattern;
}
// 忽略大小写，则转为小写处理
if (flags & FNM_CASEFOLD){
test = tolower((unsigned char)test);
}
// 循环到方括号表达式结束
for (ok = 0; (c = *pattern++) != ']';) {
// 如果没有禁用转义，获取字符
if (c == '\\' && !(flags & FNM_NOESCAPE)){
c = *pattern++;
}
// 匹配结束
if (c == EOS){
return (NULL);
}
// 忽略大小写，则转为小写
if (flags & FNM_CASEFOLD){
c = tolower((unsigned char)c);
}
// 如果当前匹配项c 的下一个是'-'，则获取'-'后面的一个字符
// 例如，匹配串为 [a-x] 当前c为a,则c2为x，表示匹配a-x之间字符
if (*pattern == '-'
&& (c2 = *(pattern + 1)) != EOS && c2 != ']') {
pattern += 2;
// 判断是否需要转义
if (c2 == '\\' && !(flags & FNM_NOESCAPE)){
c2 = *pattern++;
}
if (c2 == EOS){
return (NULL);
}
// 判断是否区分大小写
if (flags & FNM_CASEFOLD){
c2 = tolower((unsigned char)c2);
}
// 判断test是否位于 [c,c2]区间
if ((unsigned char)c <= (unsigned char)test &&
(unsigned char)test <= (unsigned char)c2){
ok = 1;
}
}
else if (c == test){
ok = 1;
}
}
// 返回匹配结果
return (ok == negate ? NULL : pattern);
}