Make most love.filesystem functions return nil, err instead of erroring (when used correctly)

Note that argument exceptions, for instance, are still thrown as errors.
Also fixes a potential uncaught exception with getSize being called for the optional
size arg in read, now it just uses the ALL constant instead.
File:read no longer opens and closes a file automagically (this was undocumented, and weird)

NOTE: the love.filesystem.lines iterator can still error, but this should only happen in
case there's something really, really wrong (otherwise love.filesystem.lines would've failed
already)
NOTE: love.filesystem.lines still errors, because otherwise you'd get weird errors from the for
loop (namely 'attempt to call nil value') instead of seeing anything useful

src/modules/filesystem/physfs/File.cpp

@@ -155,10 +155,8 @@ FileData *File::read(int64 size)
 
 int64 File::read(void *dst, int64 size)
 {
-	bool isOpen = (file != 0);
+	if (!file || mode != READ)
-
+		throw love::Exception("File is not opened for reading.");
-	if (!isOpen)
-		open(READ);
 
 	int64 max = (int64)PHYSFS_fileLength(file);
 	size = (size == ALL) ? max : size;
@@ -168,16 +166,13 @@ int64 File::read(void *dst, int64 size)
 
 	int64 read = (int64)PHYSFS_read(file, dst, 1, (int) size);
 
-	if (!isOpen)
-		close();
-
 	return read;
 }
 
 bool File::write(const void *data, int64 size)
 {
-	if (file == 0)
+	if (!file || (mode != WRITE && mode != APPEND))
-		throw love::Exception("Could not write to file. File not open.");
+		throw love::Exception("File is not opened for writing.");
 
 	// Another clamp, for the time being.
 	size = (size > LOVE_UINT32_MAX) ? LOVE_UINT32_MAX : size;

src/modules/filesystem/physfs/wrap_File.cpp

@@ -24,6 +24,18 @@
 #include "common/Exception.h"
 #include "common/int.h"
 
+static int ioError(lua_State *L, const char *fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+
+	lua_pushnil(L);
+	lua_pushvfstring(L, fmt, args);
+
+	va_end(args);
+	return 2;
+}
+
 namespace love
 {
 namespace filesystem
@@ -65,7 +77,7 @@ int w_File_open(lua_State *L)
 	}
 	catch (love::Exception &e)
 	{
-		return luaL_error(L, "%s", e.what());
+		return ioError(L, "%s", e.what());
 	}
 
 	return 1;
@@ -83,7 +95,7 @@ int w_File_read(lua_State *L)
 	File *file = luax_checkfile(L, 1);
 	Data *d = 0;
 
-	int64 size = (int64)luaL_optnumber(L, 2, (lua_Number) file->getSize());
+	int64 size = (int64)luaL_optnumber(L, 2, File::ALL);
 
 	try
 	{
@@ -91,7 +103,7 @@ int w_File_read(lua_State *L)
 	}
 	catch (love::Exception &e)
 	{
-		return luaL_error(L, "%s", e.what());
+		return ioError(L, "%s", e.what());
 	}
 
 	lua_pushlstring(L, (const char *) d->getData(), d->getSize());
@@ -104,8 +116,6 @@ int w_File_write(lua_State *L)
 {
 	File *file = luax_checkfile(L, 1);
 	bool result;
-	if (file->getMode() == File::CLOSED)
-		return luaL_error(L, "File is not open.");
 
 	if (lua_isstring(L, 2))
 	{
@@ -115,7 +125,7 @@ int w_File_write(lua_State *L)
 		}
 		catch (love::Exception &e)
 		{
-			return luaL_error(L, "%s", e.what());
+			return ioError(L, "%s", e.what());
 		}
 
 	}
@@ -128,7 +138,7 @@ int w_File_write(lua_State *L)
 		}
 		catch (love::Exception &e)
 		{
-			return luaL_error(L, "%s", e.what());
+			return ioError(L, "%s", e.what());
 		}
 	}
 	else

src/modules/filesystem/physfs/wrap_Filesystem.cpp

@@ -21,6 +21,18 @@
 // LOVE
 #include "wrap_Filesystem.h"
 
+static int ioError(lua_State *L, const char *fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+
+	lua_pushnil(L);
+	lua_pushvfstring(L, fmt, args);
+
+	va_end(args);
+	return 2;
+}
+
 namespace love
 {
 namespace filesystem
@@ -113,7 +125,7 @@ int w_newFile(lua_State *L)
 		catch (love::Exception &e)
 		{
 			t->release();
-			return luaL_error(L, "%s", e.what());
+			return ioError(L, "%s", e.what());
 		}
 	}
 
@@ -141,7 +153,7 @@ int w_newFileData(lua_State *L)
 			}
 			catch (love::Exception &e)
 			{
-				return luaL_error(L, "%s", e.what());
+				return ioError(L, "%s", e.what());
 			}
 			luax_newtype(L, "FileData", FILESYSTEM_FILE_DATA_T, (void *) data);
 			return 1;
@@ -249,11 +261,11 @@ int w_read(lua_State *L)
 	}
 	catch (love::Exception &e)
 	{
-		return luaL_error(L, "%s", e.what());
+		return ioError(L, "%s", e.what());
 	}
 
 	if (data == 0)
-		return luaL_error(L, "File could not be read.");
+		return ioError(L, "File could not be read.");
 
 	// Push the string.
 	lua_pushlstring(L, (const char *) data->getData(), data->getSize());
@@ -297,7 +309,7 @@ static int w_write_or_append(lua_State *L, File::Mode mode)
 	}
 	catch (love::Exception &e)
 	{
-		return luaL_error(L, "%s", e.what());
+		return ioError(L, "%s", e.what());
 	}
 
 	luax_pushboolean(L, true);
@@ -356,7 +368,7 @@ int w_load(lua_State *L)
 	}
 	catch (love::Exception &e)
 	{
-		return luaL_error(L, "%s", e.what());
+		return ioError(L, "%s", e.what());
 	}
 
 	int status = luaL_loadbuffer(L, (const char *)data->getData(), data->getSize(), ("@" + filename).c_str());
@@ -407,12 +419,12 @@ int w_getSize(lua_State *L)
 	}
 	catch (love::Exception &e)
 	{
-		return luaL_error(L, "%s", e.what());
+		return ioError(L, "%s", e.what());
 	}
 
 	// Error on failure or if size does not fit into a double precision floating-point number.
 	if (size == -1)
-		return luaL_error(L, "Could not determine file size.");
+		return ioError(L, "Could not determine file size.");
 	else if (size >= 0x20000000000000LL)
 		return luaL_error(L, "Size too large to fit into a Lua number!");