Add new function wget_free()

* examples/check_url_types.c: Use wget_xfree() instead of free()
* examples/http_get2.c: Likewise
* examples/print_css_urls2.c: Likewise
* examples/print_html_urls.c: Likewise
* include/wget/wget.h: Add wget_free() and define wget_xfree()
* libwget/xalloc.c: Implement wget_free()

* include/wget/wget.h: Add declaration for wget_free()
* libwget/xalloc.c: Implement wget_free()

examples/check_url_types.c

@@ -23,7 +23,6 @@
  */
 
 #include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
 #ifndef _WIN32
 #	include <signal.h>
@@ -74,13 +73,13 @@ static int _normalize_uri(wget_iri_t *base, wget_string_t *url, const char *enco
 
 	wget_iri_unescape_inline(urlpart);
 	rc = wget_memiconv(encoding, urlpart, strlen(urlpart), "utf-8", &urlpart_encoded, &urlpart_encoded_length);
-	free(urlpart);
+	wget_xfree(urlpart);
 
 	if (rc)
 		return -2;
 
 	rc = !wget_iri_relative_to_abs(base, urlpart_encoded, urlpart_encoded_length, buf);
-	free(urlpart_encoded);
+	wget_xfree(urlpart_encoded);
 
 	if (rc)
 		return -3;
@@ -219,7 +218,7 @@ static void html_parse(const char *html, size_t html_len, const char *encoding,
 	wget_iri_free(&allocated_base);
 	wget_html_free_urls_inline(&parsed);
 	wget_iri_free(&base);
-	free(utf8);
+	wget_xfree(utf8);
 
 	wget_info_printf("  same host: http=%d https=%d\n", stats.http_links_same_host, stats.https_links_same_host);
 	wget_info_printf("      total: http=%d https=%d\n", stats.http_links, stats.https_links);
@@ -258,7 +257,7 @@ int main(int argc G_GNUC_WGET_UNUSED, const char *const *argv G_GNUC_WGET_UNUSED
 
 	while (fscanf(stdin, "%d,%255s", &stats.id, stats.host) == 2) {
 
-		free(url);
+		wget_xfree(url);
 		if (!wget_strncasecmp_ascii(stats.host, "http://", 7))
 			url = wget_aprintf("https://%s", stats.host + 7);
 		else if (wget_strncasecmp_ascii(stats.host, "https://", 8))
@@ -308,7 +307,7 @@ int main(int argc G_GNUC_WGET_UNUSED, const char *const *argv G_GNUC_WGET_UNUSED
 						wget_info_printf("  Failed to normalize '%s', '%s'\n", url, resp->location);
 						break;
 					}
-					free(url);
+					wget_xfree(url);
 					url = newurl;
 
 					if (wget_strncasecmp(url, "https://", 8))
@@ -348,7 +347,7 @@ int main(int argc G_GNUC_WGET_UNUSED, const char *const *argv G_GNUC_WGET_UNUSED
 		write_stats();
 	}
 
-	free(url);
+	wget_xfree(url);
 
 	// free resources - needed for valgrind testing
 	wget_global_deinit();

examples/http_get2.c

@@ -27,7 +27,6 @@
  *
  */
 
-#include <stdlib.h>
 #include <wget.h>
 
 #define COOKIE_SUPPORT
@@ -104,7 +103,7 @@ int main(int argc G_GNUC_WGET_UNUSED, const char *const *argv G_GNUC_WGET_UNUSED
 	// enrich the HTTP request with the uri-related cookies we have
 	if ((cookie_string = wget_cookie_create_request_header(cookies, uri))) {
 		wget_http_add_header(req, "Cookie", cookie_string);
-		free((void *)cookie_string);
+		wget_xfree(cookie_string);
 	}
 #endif
 

examples/print_css_urls2.c

@@ -42,9 +42,6 @@
 #define error_printf       wget_error_printf
 #define error_printf_exit  wget_error_printf_exit
 
-// I try to never leave freed pointers hanging around
-#define xfree(a) do { if (a) { free((void *)(a)); a=NULL; } } while (0)
-
 struct css_context {
 	wget_iri_t
 		*base;
@@ -113,7 +110,7 @@ static void css_parse_localfile(const char *fname, wget_iri_t *base, const char
 	wget_css_parse_file(fname, css_parse_uri, css_parse_encoding, &context);
 
 	if (context.encoding_allocated)
-		xfree(context.encoding);
+		wget_xfree(context.encoding);
 
 	wget_buffer_deinit(&context.uri_buf);
 }

examples/print_html_urls.c

@@ -33,11 +33,11 @@
 
 static void html_parse_localfile(const char *fname)
 {
-	char *data;
+	char *data, *data_allocated;
 	const char *encoding = NULL;
 	size_t len;
 
-	if ((data = wget_read_file(fname, &len))) {
+	if ((data_allocated = data = wget_read_file(fname, &len))) {
 		if ((unsigned char)data[0] == 0xFE && (unsigned char)data[1] == 0xFF) {
 			// Big-endian UTF-16
 			encoding = "UTF-16BE";
@@ -72,8 +72,8 @@ static void html_parse_localfile(const char *fname)
 
 			if (wget_memiconv(encoding, data, len, "UTF-8", &utf8, &n) == 0) {
 				printf("Convert non-ASCII encoding '%s' to UTF-8\n", encoding);
-				wget_xfree(data);
-				data = utf8;
+				wget_xfree(data_allocated);
+				data_allocated = data = utf8;
 			} else {
 				printf("Failed to convert non-ASCII encoding '%s' to UTF-8, skip parsing\n", encoding);
 				return;
@@ -94,7 +94,7 @@ static void html_parse_localfile(const char *fname)
 			printf("  %s.%s '%.*s'\n", html_url->dir, html_url->attr, (int) url->len, url->p);
 		}
 
-		wget_xfree(data);
+		wget_xfree(data_allocated);
 		wget_html_free_urls_inline(&res);
 	}
 }

include/wget/wget.h

@@ -389,7 +389,7 @@ WGETAPI int
  */
 
 // I try to never leave freed pointers hanging around
-#define wget_xfree(a) do { if (a) { free((void *)(a)); a=NULL; } } while (0)
+#define wget_xfree(a) do { if (a) { wget_free((void *)(a)); a=NULL; } } while (0)
 
 typedef void (*wget_oom_callback_t)(void);
 
@@ -399,6 +399,8 @@ WGETAPI void *
 	wget_calloc(size_t nmemb, size_t size) G_GNUC_WGET_MALLOC G_GNUC_WGET_ALLOC_SIZE2(1,2);
 WGETAPI void *
 	wget_realloc(void *ptr, size_t size) G_GNUC_WGET_ALLOC_SIZE(2);
+WGETAPI void
+	wget_free(void *ptr);
 WGETAPI void
 	wget_set_oomfunc(wget_oom_callback_t);
 

libwget/xalloc.c

@@ -127,12 +127,21 @@ void *wget_realloc(void *ptr, size_t size)
 	return p;
 }
 
-/*void wget_free(const void **p)
+/**
+ * \param[in] ptr Pointer to memory-pointer to be freed
+ *
+ * This function is like free().
+ *
+ * Is is basically needed on systems where the library malloc heap is different
+ * from the caller's malloc heap, which happens on Windows when the library
+ * is a separate DLL.
+ *
+ * To prevent typical use-after-free issues, use the macro wget_xfree().
+ */
+void wget_free(void *ptr)
 {
-	if (p && *p) {
-		free(*p);
-		*p = NULL;
-	}
-}*/
+	if (ptr)
+		free(ptr);
+}
 
 /**@}*/