Added os touchfile and a workaround for vs2010 reloading

vs2010 (and above) has an issue where if the vcxproj file
isn't modified but the.vcxproj.filters is modified during
premake, then VS doesn't notify the user that the project has
changed.  This can occur if the only change to a project is
with the vpaths.  Before this fix, the user would be need to
manually unload and reload the project to pick up the change.

This VS workaround checks for the case where the vcxproj.filters
file is modified but the .vcxproj file is not. At which point
premake preforms a touch on the .vcxproj file to trigger the IDE.

src/actions/vstudio/vs2010.lua

@@ -59,7 +59,7 @@
 			end
 
 		elseif p.project.isc(prj) or p.project.iscpp(prj) then
-			p.generate(prj, ".vcxproj", vstudio.vc2010.generate)
+			local projFileModified = p.generate(prj, ".vcxproj", vstudio.vc2010.generate)
 
 			-- Skip generation of empty user files
 			local user = p.capture(function() vstudio.vc2010.generateUser(prj) end)
@@ -69,7 +69,10 @@
 
 			-- Only generate a filters file if the source tree actually has subfolders
 			if tree.hasbranches(project.getsourcetree(prj)) then
-				p.generate(prj, ".vcxproj.filters", vstudio.vc2010.generateFilters)
+				if p.generate(prj, ".vcxproj.filters", vstudio.vc2010.generateFilters) == true and projFileModified == false then
+					-- vs workaround for issue where if only the .filters file is modified, VS doesn't automaticly trigger a reload
+					p.touch(prj, ".vcxproj")
+				end
 			end
 		end
 

src/base/premake.lua

@@ -137,6 +137,7 @@
 
 
 --
+-- Returns a boolean if the file was modified
 -- Open a file for output, and call a function to actually do the writing.
 -- Used by the actions to generate workspace and project files.
 --
@@ -160,22 +161,56 @@
 
 		-- make sure output folder exists.
 		local dir = path.getdirectory(fn)
-		ok, err = os.mkdir(dir)
+		local ok, err = os.mkdir(dir)
 		if not ok then
 			error(err, 0)
 		end
 
 		local f, err = os.writefile_ifnotequal(output, fn);
 
-		if (f < 0) then
+		if (f == 0) then
+			return false -- file not modified
+		elseif (f < 0) then
 			error(err, 0)
 		elseif (f > 0) then
 			printf("Generated %s...", path.getrelative(os.getcwd(), fn))
+			return true -- file modified
 		end
 	end
 
 
 
+--
+-- Marks a file as modified without changing its contents
+--
+-- @param obj
+--    A workspace or project object; will be passed to the callback function.
+-- @param ext
+--    An optional extension for the generated file, with the leading dot.
+--
+
+	function premake.touch(obj, ext)
+		local fn = premake.filename(obj, ext)
+
+		-- make sure output folder exists.
+		local dir = path.getdirectory(fn)
+		local ok, err = os.mkdir(dir)
+		if not ok then
+			error(err, 0)
+		end
+
+		local f, err = os.touchfile(fn);
+
+		if (f == 0) then
+			return false -- file marked as modified
+		elseif (f < 0) then
+			error(err, 0)
+		elseif (f > 0) then
+			return true -- file created
+		end
+	end
+
+
 ---
 -- Returns the full path a file generated from any of the project
 -- objects (project, workspace, rule).

src/host/os_touchfile.c

@@ -0,0 +1,94 @@
+/**
+ * \file   os_touchfile.c
+ * \brief markes a file as modified without changing its contents.
+ * \author Blizzard Entertainment (contact tvandijck@blizzard.com)
+ * \author Copyright (c) 2015 Jason Perkins and the Premake project
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "premake.h"
+
+#if PLATFORM_WINDOWS
+	#include <io.h>
+#else
+	#include <unistd.h>
+	#include <sys/types.h>
+#endif
+
+#ifndef FALSE
+#define FALSE 0
+#endif
+#ifndef TRUE
+#define TRUE 1
+#endif
+
+static int truncate_file(const char* fn)
+{
+	FILE* file = fopen(fn, "rb");
+	size_t size;
+	file = fopen(fn, "ab");
+	if (file == NULL)
+	{
+		return FALSE;
+	}
+	fseek(file, 0, SEEK_END);
+	size = ftell(file);
+	// append a dummy space. There are better ways to do
+	// a touch, however this is a rather simple
+	// multiplatform method
+	if (fwrite(" ", 1, 1, file) != 1)
+	{
+		fclose(file);
+		return FALSE;
+	}
+#if PLATFORM_WINDOWS
+	if (_chsize(_fileno(file), (long)size) != 0)
+	{
+		fclose(file);
+		return FALSE;
+	}
+#endif
+	fclose(file);
+#if !PLATFORM_WINDOWS
+	if (truncate(fn, (off_t)size) != 0)
+	{
+		return FALSE;
+	}
+#endif
+	return TRUE;
+}
+
+int os_touchfile(lua_State* L)
+{
+	FILE* file;
+	const char* dst     = luaL_checkstring(L, 1);
+
+	// if destination exist, mark the file as modified
+	if (do_isfile(dst))
+	{
+		if (truncate_file(dst))
+		{
+			lua_pushinteger(L, 0);
+			return 1;
+		} else {
+			lua_pushinteger(L, -1);
+			lua_pushfstring(L, "unable to touch file '%s'", dst);
+			return 2;
+		}
+	}
+
+	file = fopen(dst, "wb");
+	if (file != NULL)
+	{
+		fclose(file);
+
+		lua_pushinteger(L, 1);
+		return 1;
+	}
+
+	lua_pushinteger(L, -1);
+	lua_pushfstring(L, "unable to create file to '%s'", dst);
+	return 2;
+}

src/host/premake.c

@@ -86,6 +86,7 @@ static const luaL_Reg os_functions[] = {
 	{ "stat",                   os_stat                 },
 	{ "uuid",                   os_uuid                 },
 	{ "writefile_ifnotequal",   os_writefile_ifnotequal },
+	{ "touchfile",              os_touchfile            },
 	{ "compile",                os_compile              },
 	{ NULL, NULL }
 };

src/host/premake.h

@@ -130,6 +130,7 @@ 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 os_touchfile(lua_State* L);
 int os_compile(lua_State* L);
 int string_endswith(lua_State* L);
 int string_hash(lua_State* L);