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Windows GetBasePath should use GetModuleFileNameExW() and check for o…

…verflows.

Apparently you might get strange paths from GetModuleFileName(), such as
short path names or UNC filenames, so this avoids that problem. Since you have
to tapdance with linking different libraries and defining macros depending on
what Windows you plan to target, we dynamically load the API we need, which
works on all versions of Windows (on Win7, it'll load a compatibility wrapper
for the newer API location).

What a mess.

This also now does the right thing if there isn't enough space to store the
path, looping with a larger allocated buffer each try.

Fixes Bugzilla #2435.
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icculus committed May 28, 2015
1 parent 75702ff commit 6d1ad3847ab8af71195feb640a9583930cef2e1d
Showing with 42 additions and 5 deletions.
  1. +42 −5 src/filesystem/windows/SDL_sysfilesystem.c
@@ -36,11 +36,44 @@
char *
SDL_GetBasePath(void)
{
TCHAR path[MAX_PATH];
const DWORD len = GetModuleFileName(NULL, path, SDL_arraysize(path));
size_t i;
DWORD (WINAPI * pGetModuleFileNameExW)(HANDLE, HMODULE, LPWSTR, DWORD) = NULL;
DWORD buflen = 128;
WCHAR *path = NULL;
HANDLE psapi = LoadLibrary(L"psapi.dll");
char *retval = NULL;
DWORD len = 0;

if (!psapi) {
WIN_SetError("Couldn't load psapi.dll");
return NULL;
}

pGetModuleFileNameExW = GetProcAddress(psapi, "GetModuleFileNameExW");
if (!pGetModuleFileNameExW) {
WIN_SetError("Couldn't find GetModuleFileNameExW");
FreeLibrary(psapi);
return NULL;
}

SDL_assert(len < SDL_arraysize(path));
while (SDL_TRUE) {
path = (WCHAR *) SDL_malloc(path, buflen * sizeof (WCHAR));
if (!path) {
FreeLibrary(psapi);
SDL_OutOfMemory();
return NULL;
}

len = pGetModuleFileNameEx(GetCurrentProcess(), NULL, path, buflen);
if (len != buflen) {
break;
}

/* buffer too small? Try again. */
SDL_free(path);
len *= 2;
}

FreeLibrary(psapi);

if (len == 0) {
WIN_SetError("Couldn't locate our .exe");
@@ -55,7 +88,11 @@ SDL_GetBasePath(void)

SDL_assert(i > 0); /* Should have been an absolute path. */
path[i+1] = '\0'; /* chop off filename. */
return WIN_StringToUTF8(path);

retval = WIN_StringToUTF8(path);
SDL_free(path);

return retval;
}

char *

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