main: SDL_RunApp now explicitly handles NULL argv in all implementations.

It'll usually replace it with `{ "SDL_app", NULL }`, but things like Win32
can query the OS for the original command line arguments.

This allows apps/scripting languages that provide their own entry points to
use SDL_RunApp and not have to worry about how to compose an argv array on
things like Windows, when SDL was going to do it for them anyhow.

Most things won't experience any change with this commit, including apps that
that want extra control but originate in a standard main()-style entry point
and can just pass the existing argc/argv through to SDL_RunApp.

Windows isn't addressed here, since a previous commit already updated it.
GDK has a different fix here, but we'll unify that in a later commit.

Closes #12676.

include/SDL3/SDL_main.h

@@ -555,6 +555,9 @@ extern SDL_DECLSPEC void SDLCALL SDL_SetMainReady(void);
  * using SDL_main (like when using SDL_MAIN_HANDLED). When using this, you do
  * *not* need SDL_SetMainReady().
  *
+ * If `argv` is NULL, SDL will provide command line arguments, either by
+ * querying the OS for them if possible, or supplying a filler array if not.
+ *
  * \param argc the argc parameter from the application's main() function, or 0
  *             if the platform's main-equivalent has no argc.
  * \param argv the argv parameter from the application's main() function, or

src/main/SDL_main_callbacks.c

@@ -147,3 +147,13 @@ void SDL_QuitMainCallbacks(SDL_AppResult result)
     SDL_Quit();
 }
 
+void SDL_CheckDefaultArgcArgv(int *argc, char ***argv)
+{
+    if (!argv)
+    {
+        static char dummyargv0[] = { 'S', 'D', 'L', '_', 'a', 'p', 'p', '\0' };
+        static char *argvdummy[2] = { dummyargv0, NULL };
+        *argc = 1;
+        *argv = argvdummy;
+    }
+}

src/main/SDL_main_callbacks.h

@@ -27,6 +27,10 @@ SDL_AppResult SDL_InitMainCallbacks(int argc, char *argv[], SDL_AppInit_func app
 SDL_AppResult SDL_IterateMainCallbacks(bool pump_events);
 void SDL_QuitMainCallbacks(SDL_AppResult result);
 
+// (not a callback thing, but convenient to stick this in here.)
+// If *_argv is NULL, update *_argc and *_argv to point at a static array of { "SDL_app", NULL }.
+void SDL_CheckDefaultArgcArgv(int *_argc, char ***_argv);
+
 #endif // SDL_main_callbacks_h_
 
 

src/main/SDL_runapp.c

@@ -19,6 +19,7 @@
   3. This notice may not be removed or altered from any source distribution.
 */
 #include "SDL_internal.h"
+#include "SDL_main_callbacks.h"
 
 /* Most platforms that use/need SDL_main have their own SDL_RunApp() implementation.
  * If not, you can special case it here by appending || defined(__YOUR_PLATFORM__) */
@@ -27,16 +28,7 @@
 int SDL_RunApp(int argc, char *argv[], SDL_main_func mainFunction, void * reserved)
 {
     (void)reserved;
-
-    if(!argv)
-    {
-        // make sure argv isn't NULL, in case some user code doesn't like that
-        static char dummyargv0[] = { 'S', 'D', 'L', '_', 'a', 'p', 'p', '\0' };
-        static char *argvdummy[2] = { dummyargv0, NULL };
-        argc = 1;
-        argv = argvdummy;
-    }
-
+    SDL_CheckDefaultArgcArgv(&argc, &argv);
     return mainFunction(argc, argv);
 }
 

src/main/emscripten/SDL_sysmain_runapp.c

@@ -22,6 +22,8 @@
 
 #ifdef SDL_PLATFORM_EMSCRIPTEN
 
+#include "../SDL_main_callbacks.h"
+
 #include <emscripten/emscripten.h>
 
 EM_JS_DEPS(sdlrunapp, "$dynCall,$stringToNewUTF8");
@@ -35,6 +37,8 @@ int SDL_RunApp(int argc, char *argv[], SDL_main_func mainFunction, void * reserv
 {
     (void)reserved;
 
+    SDL_CheckDefaultArgcArgv(&argc, &argv);
+
     // Move any URL params that start with "SDL_" over to environment
     //  variables, so the hint system can pick them up, etc, much like a user
     //  can set them from a shell prompt on a desktop machine. Ignore all

src/main/gdk/SDL_sysmain_runapp.cpp

@@ -37,53 +37,52 @@ static BOOL OutOfMemory(void)
     return FALSE;
 }
 
-/* Gets the arguments with GetCommandLine, converts them to argc and argv
-   and calls SDL_main */
 extern "C"
-int SDL_RunApp(int, char **, SDL_main_func mainFunction, void *reserved)
+int SDL_RunApp(int _argc, char **_argv, SDL_main_func mainFunction, void *reserved)
 {
-    LPWSTR *argvw;
-    char **argv;
-    int i, argc, result;
-    HRESULT hr;
-    XTaskQueueHandle taskQueue;
+    char **allocated_argv = NULL;
+    char **argv = _argv;
+    int argc = _argc;
 
-    argvw = CommandLineToArgvW(GetCommandLineW(), &argc);
-    if (argvw == NULL) {
-        return OutOfMemory();
-    }
-
-    /* Note that we need to be careful about how we allocate/free memory here.
-     * If the application calls SDL_SetMemoryFunctions(), we can't rely on
-     * SDL_free() to use the same allocator after SDL_main() returns.
-     */
-
-    // Parse it into argv and argc
-    argv = (char **)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, (argc + 1) * sizeof(*argv));
-    if (argv == NULL) {
-        return OutOfMemory();
-    }
-    for (i = 0; i < argc; ++i) {
-        const int utf8size = WideCharToMultiByte(CP_UTF8, 0, argvw[i], -1, NULL, 0, NULL, NULL);
-        if (!utf8size) {  // uhoh?
-            SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Fatal Error", "Error processing command line arguments", NULL);
-            return -1;
-        }
-
-        argv[i] = (char *)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, utf8size);  // this size includes the null-terminator character.
-        if (!argv[i]) {
+    if (!argv) {
+        // Get the arguments with GetCommandLine, convert them to argc and argv
+        LPWSTR *argvw = CommandLineToArgvW(GetCommandLineW(), &argc);
+        if (argvw == NULL) {
             return OutOfMemory();
         }
 
-        if (WideCharToMultiByte(CP_UTF8, 0, argvw[i], -1, argv[i], utf8size, NULL, NULL) == 0) {  // failed? uhoh!
-            SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Fatal Error", "Error processing command line arguments", NULL);
-            return -1;
-        }
-    }
-    argv[i] = NULL;
-    LocalFree(argvw);
+        // Note that we need to be careful about how we allocate/free memory here.
+        // If the application calls SDL_SetMemoryFunctions(), we can't rely on
+        // SDL_free() to use the same allocator after SDL_main() returns.
 
-    hr = XGameRuntimeInitialize();
+        argv = allocated_argv = (char **)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, (argc + 1) * sizeof(*argv));
+        if (argv == NULL) {
+            return OutOfMemory();
+        }
+        for (int i = 0; i < argc; ++i) {
+            const int utf8size = WideCharToMultiByte(CP_UTF8, 0, argvw[i], -1, NULL, 0, NULL, NULL);
+            if (!utf8size) {  // uhoh?
+                SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Fatal Error", "Error processing command line arguments", NULL);
+                return -1;
+            }
+
+            argv[i] = (char *)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, utf8size);  // this size includes the null-terminator character.
+            if (!argv[i]) {
+                return OutOfMemory();
+            }
+
+            if (WideCharToMultiByte(CP_UTF8, 0, argvw[i], -1, argv[i], utf8size, NULL, NULL) == 0) {  // failed? uhoh!
+                SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Fatal Error", "Error processing command line arguments", NULL);
+                return -1;
+            }
+        }
+        argv[argc] = NULL;
+        LocalFree(argvw);
+    }
+
+    int result = -1;
+    XTaskQueueHandle taskQueue;
+    HRESULT hr = XGameRuntimeInitialize();
 
     if (SUCCEEDED(hr) && SDL_GetGDKTaskQueue(&taskQueue)) {
         Uint32 titleid = 0;
@@ -134,14 +133,15 @@ int SDL_RunApp(int, char **, SDL_main_func mainFunction, void *reserved)
 #else
         SDL_assert_always(0 && "[GDK] Could not initialize - aborting");
 #endif
-        result = -1;
     }
 
     // Free argv, to avoid memory leak
-    for (i = 0; i < argc; ++i) {
-        HeapFree(GetProcessHeap(), 0, argv[i]);
+    if (allocated_argv) {
+        for (int i = 0; i < argc; ++i) {
+            HeapFree(GetProcessHeap(), 0, allocated_argv[i]);
+        }
+        HeapFree(GetProcessHeap(), 0, allocated_argv);
     }
-    HeapFree(GetProcessHeap(), 0, argv);
 
     return result;
 }

src/main/n3ds/SDL_sysmain_runapp.c

@@ -23,11 +23,16 @@
 
 #ifdef SDL_PLATFORM_3DS
 
+#include "../SDL_main_callbacks.h"
+
 #include <3ds.h>
 
 int SDL_RunApp(int argc, char *argv[], SDL_main_func mainFunction, void * reserved)
 {
     int result;
+
+    SDL_CheckDefaultArgcArgv(&argc, &argv);
+
     // init
     osSetSpeedupEnable(true);
     romfsInit();

src/main/ps2/SDL_sysmain_runapp.c

@@ -25,6 +25,8 @@
 
 // SDL_RunApp() code for PS2 based on SDL_ps2_main.c, fjtrujy@gmail.com
 
+#include "../SDL_main_callbacks.h"
+
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
@@ -69,6 +71,8 @@ int SDL_RunApp(int argc, char *argv[], SDL_main_func mainFunction, void * reserv
     int res;
     (void)reserved;
 
+    SDL_CheckDefaultArgcArgv(&argc, &argv);
+
     prepare_IOP();
     init_drivers();
 

src/main/psp/SDL_sysmain_runapp.c

@@ -28,6 +28,7 @@
 #include <pspkernel.h>
 #include <pspthreadman.h>
 #include "../../events/SDL_events_c.h"
+#include "../SDL_main_callbacks.h"
 
 /* If application's main() is redefined as SDL_main, and libSDL_main is
    linked, then this file will create the standard exit callback,
@@ -72,6 +73,9 @@ int sdl_psp_setup_callbacks(void)
 int SDL_RunApp(int argc, char *argv[], SDL_main_func mainFunction, void * reserved)
 {
     (void)reserved;
+
+    SDL_CheckDefaultArgcArgv(&argc, &argv);
+
     sdl_psp_setup_callbacks();
 
     SDL_SetMainReady();

src/video/uikit/SDL_uikitappdelegate.m

@@ -29,6 +29,7 @@
 #import "SDL_uikitwindow.h"
 
 #include "../../events/SDL_events_c.h"
+#include "../../main/SDL_main_callbacks.h"
 
 #ifdef main
 #undef main
@@ -41,7 +42,7 @@ static int exit_status;
 
 int SDL_RunApp(int argc, char *argv[], SDL_main_func mainFunction, void *reserved)
 {
-    int i;
+    SDL_CheckDefaultArgcArgv(&argc, &argv);
 
     // store arguments
     /* Note that we need to be careful about how we allocate/free memory here.
@@ -51,11 +52,11 @@ int SDL_RunApp(int argc, char *argv[], SDL_main_func mainFunction, void *reserve
     forward_main = mainFunction;
     forward_argc = argc;
     forward_argv = (char **)malloc((argc + 1) * sizeof(char *)); // This should NOT be SDL_malloc()
-    for (i = 0; i < argc; i++) {
+    for (int i = 0; i < argc; i++) {
         forward_argv[i] = malloc((strlen(argv[i]) + 1) * sizeof(char)); // This should NOT be SDL_malloc()
         strcpy(forward_argv[i], argv[i]);
     }
-    forward_argv[i] = NULL;
+    forward_argv[argc] = NULL;
 
     // Give over control to run loop, SDLUIKitDelegate will handle most things from here
     @autoreleasepool {
@@ -71,7 +72,7 @@ int SDL_RunApp(int argc, char *argv[], SDL_main_func mainFunction, void *reserve
     }
 
     // free the memory we used to hold copies of argc and argv
-    for (i = 0; i < forward_argc; i++) {
+    for (int i = 0; i < forward_argc; i++) {
         free(forward_argv[i]); // This should NOT be SDL_free()
     }
     free(forward_argv); // This should NOT be SDL_free()