path.c: added dirname_s function.

docs/technical/path.txt

@@ -38,3 +38,11 @@ The function performs this type of checks/manipulation:
 +
 Returns `NULL` if 'base' is not an absolute path or 'name' contains a delimiter.
 
+`dirname_s`::
+
+    Safe dirname implementation. works like POSIX dirname with some modifications: +
++
+--
+    * 'slash' may be used to terminate the string with a \'/' character. +
+    * The function will never modify 'path' instead the function will *always* return a static buffer that will be overwritten by subsequent calls.
+--

src/path.c

@@ -1,6 +1,6 @@
 /* path.c - path handling routines
  * 
- *   Copyright (C) 2010  Henrik Hautakoski <henrik.hautakoski@gmail.com>
+ *   Copyright (C) 2010-2011  Henrik Hautakoski <henrik.hautakoski@gmail.com>
  *
  *   This program is free software: you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -12,6 +12,7 @@
  *   so we use funky heap memory based algorithms instead :)
  */
 
+#include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
 #include <sys/types.h>
@@ -67,6 +68,29 @@ int is_dir(const char *path) {
     return 0;
 }
 
+const char* dirname_s(const char *path, int slash) {
+
+    static strbuf_t sb = STRBUF_INIT;
+    
+    strbuf_reduce(&sb, sb.len);
+    strbuf_append_str(&sb, path);
+    strbuf_squeeze(&sb, '/');
+
+    if (sb.len > 1) {
+        if (sb.buf[sb.len-1] == '/')
+            strbuf_reduce(&sb, 1);
+
+        if (!strbuf_rchop(&sb, '/'))
+            strbuf_reduce(&sb, sb.len-1);
+    }
+
+    if (sb.buf[0] != '/')
+        sb.buf[0] = '.';
+    if (slash)
+        strbuf_term(&sb, '/');
+    return sb.buf;
+}
+
 const char *mkpath(const char *fmt, ...) {
 
     static strbuf_t sb = STRBUF_INIT;

src/path.h

@@ -1,6 +1,6 @@
 /* path.h - path handling routines
  * 
- *   Copyright (C) 2010  Henrik Hautakoski <henrik@fiktivkod.org>
+ *   Copyright (C) 2010-2011  Henrik Hautakoski <henrik@fiktivkod.org>
  *
  *   This program is free software: you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -20,6 +20,8 @@ int is_file(const char *path);
 
 int is_dir(const char *path);
 
+const char* dirname_s(const char *path, int slash);
+
 const char* mkpath(const char *fmt, ...);
 
 char* path_normalize(const char *base, const char *name, unsigned dir);

test/t_path.c

@@ -97,22 +97,24 @@ void test_dirname() {
 
     int i;
 
-    char data[11][2][64] = {
+    char data[13][2][64] = {
         { "", "." },
         { "/", "/" },
         { "///", "/" },
         { ".", "."},
         { "..", "." },
+        { "../", "." },
         { "../../rel", "../.." },
         { "./rel", "." },
+        { "x", "." },
         { "justsomestring", "." },
         { "/usr/src/", "/usr" },
         { "/usr/src///", "/usr" },
         { "/usr/src/linux-2.6.30-r5/drivers", "/usr/src/linux-2.6.30-r5" }
     };
 
-    for(i=0; i < 11; i++)
-        assert_string(dirname(data[i][0]), data[i][1]);
+    for(i=0; i < 12; i++)
+        assert_string(dirname_s(data[i][0], 0), data[i][1]);
 }
 
 int main(int argc, char *argv[]) {