workaround: mingw: make passing native path to magiskboot work when c…

…ompiled using MSYS2 (#27)

- closes #27

Signed-off-by: Ookiineko <[email protected]>

CMakeLists.stub.txt

@@ -64,6 +64,7 @@ if (WIN32)
         src/libc-compat/winsup/file.c
         src/libc-compat/winsup/io.c
         src/libc-compat/winsup/link.c
+        src/libc-compat/winsup/main_hack.c
         src/libc-compat/winsup/mkdir.c
         src/libc-compat/winsup/mknod_stub.c
         src/libc-compat/winsup/open.c
@@ -90,6 +91,9 @@ if (WIN32)
 
     target_include_directories(android_libbase PRIVATE src/libc-compat/include)
 
+    # HACK: fix passing native path in argv when using MSYS2's MinGW runtime
+    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,--wrap=main")
+
     # libc-compat overrides
     set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,--wrap=mkdir -Wl,--wrap=creat -Wl,--wrap=open -Wl,--wrap=fopen")
     set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,--wrap=fdopen -Wl,--wrap=fstat -Wl,--wrap=CreateFileW")

src/libc-compat/winsup/main_hack.c

@@ -0,0 +1,73 @@
+// HACK:
+//   native paths like \\?\C:\windows doesn't get passed correctly
+//   to main() when compiled with MSYS2's compiler and MinGW-runtime.
+//
+//   so until the root cause is discovered, this hack will be used.
+
+#include <assert.h>
+#include <stdlib.h>
+#include <wchar.h>
+
+#include <windows.h>
+
+#include "internal/assert.h"
+
+#define LOG_TAG             "main_hack"
+
+// defined in:
+//   src/Magisk/native/src/boot/main.cpp
+
+int __real_main(int argc, char **argv);
+
+int __wrap_main(int argc, char **argv) {
+    int argc_new, i, len, res;
+    wchar_t **argv_w;
+    char **argv_new;
+
+    // get wide argv
+
+    argv_w = CommandLineToArgvW(GetCommandLineW(), &argc_new);
+    if (!argv_w) {
+        LOG_ERR("CommandLineToArgvW failed: %s", win_strerror(GetLastError()));
+
+        abort();
+    }
+
+    // convert it to system code page
+
+    argv_new = calloc(argc_new + 1, sizeof(char *));
+    assert(argv_new);
+
+    for (i = 0; i < argc_new; i++) {
+        len = WideCharToMultiByte(CP_ACP, WC_NO_BEST_FIT_CHARS,
+                                  argv_w[i], -1, NULL, 0, NULL, NULL);
+        if (!len) {
+wcstombs_failed:
+            LOG_ERR("WideCharToMultiByte failed: %s", win_strerror(GetLastError()));
+
+            abort();
+        }
+
+        argv_new[i] = malloc(len);
+        assert(argv_new[i]);
+
+        if (!WideCharToMultiByte(CP_ACP, WC_NO_BEST_FIT_CHARS, argv_w[i],
+                                 -1, argv_new[i], len, NULL, NULL))
+            goto wcstombs_failed;
+    }
+
+    // the last arg is always a NULL entry,
+    // which indicates the end of our argv
+    argv_new[argc_new] = NULL;
+
+    LocalFree(argv_w);
+
+    res = __real_main(argc_new, argv_new);
+
+    for (i = 0; i < argc_new; i++)
+        free(argv_new[i]);
+
+    free(argv_new);
+
+    return res;
+}