Merge pull request #16 from Blizzard/pr10

add os.writefile_ifnotequal

src/host/os_writefile_ifnotequal.c

@@ -0,0 +1,91 @@
+/**
+ * \file   os_copyfile.c
+ * \brief  Copy a file from one location to another.
+ * \author Copyright (c) 2002-2008 Jason Perkins and the Premake project
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "premake.h"
+
+#ifndef FALSE
+#define FALSE 0
+#endif
+#ifndef TRUE
+#define TRUE 1
+#endif
+
+static int compare_file(const char* content, size_t length, const char* dst)
+{
+	FILE* file = fopen(dst, "rb");
+	long size;
+	char buffer[4096];
+	int num;
+
+	if (file == NULL)
+	{
+		return FALSE;
+	}
+
+	// check sizes.
+	fseek(file, 0, SEEK_END);
+	size = ftell(file);
+	fseek(file, 0, SEEK_SET);
+
+	if (length != size)
+	{
+		fclose(file);
+		return FALSE;
+	}
+
+	while (size > 0)
+	{
+		num = size > 4096 ? 4096 : size;
+
+		fread(buffer, 1, num, file);
+
+		if (memcmp(content, buffer, num) != 0)
+		{
+			fclose(file);
+			return FALSE;
+		}
+
+		size    -= num;
+		content += num;
+	}
+
+	fclose(file);
+	return TRUE;
+}
+
+
+int os_writefile_ifnotequal(lua_State* L)
+{
+	FILE* file;
+	size_t length;
+	const char* content = luaL_checklstring(L, 1, &length);
+	const char* dst     = luaL_checkstring(L, 2);
+
+	// if destination exist, and they are the same, no need to copy.
+	if (do_isfile(dst) && compare_file(content, length, dst))
+	{
+		lua_pushinteger(L, 0);
+		return 1;
+	}
+
+
+	file = fopen(dst, "wb");
+	if (file != NULL)
+	{
+		fwrite(content, 1, length, file);
+		fclose(file);
+
+		lua_pushinteger(L, 1);
+		return 1;
+	}
+
+	lua_pushinteger(L, -1);
+	lua_pushfstring(L, "unable to write file to '%s'", dst);
+	return 2;
+}

src/host/premake.c

@@ -74,6 +74,7 @@ static const luaL_Reg os_functions[] = {
 	{ "rmdir",                  os_rmdir                },
 	{ "stat",                   os_stat                 },
 	{ "uuid",                   os_uuid                 },
+	{ "writefile_ifnotequal",   os_writefile_ifnotequal },
 	{ NULL, NULL }
 };
 

src/host/premake.h

@@ -116,6 +116,7 @@ int os_realpath(lua_State* L);
 int os_rmdir(lua_State* L);
 int os_stat(lua_State* L);
 int os_uuid(lua_State* L);
+int os_writefile_ifnotequal(lua_State* L);
 int string_endswith(lua_State* L);
 int string_hash(lua_State* L);
 int string_sha1(lua_State* L);