Parse EFI command line arguments (#12)

libc/runtime/efimain.greg.c

@@ -0,0 +1,94 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2021 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/calls/efi.h"
+#include "libc/dce.h"
+#include "libc/macros.h"
+#include "libc/nt/efi.h"
+#include "libc/nt/thunk/msabi.h"
+#include "libc/runtime/internal.h"
+#include "libc/runtime/runtime.h"
+
+struct EfiArgs {
+  char *args[4096];
+  char argblock[ARG_MAX];
+};
+
+static const EFI_GUID kEfiLoadedImageProtocol = LOADED_IMAGE_PROTOCOL;
+
+/**
+ * EFI Application Entrypoint.
+ *
+ * This entrypoint is mutually exclusive from WinMain since
+ * Windows apps and EFI apps use the same PE binary format.
+ * By default, we build binaries to support Windows. If you
+ * want to your APE executable to boot on UEFI instead then
+ * you need to run the following build command:
+ *
+ *     make -j8 CPPFLAGS=-DSUPPORT_VECTOR=251
+ *
+ * That'll remove all the Windows code and turn EFI on. You
+ * can also remove by BIOS code too, by changing 251 to 249
+ * but it shouldn't matter. Here's how to emulate EFI apps:
+ *
+ *     qemu-system-x86_64 \
+ *       -bios OVMF.fd    \
+ *       -nographic       \
+ *       -net none        \
+ *       -drive format=raw,file=fat:rw:o/tool/viz
+ *     FS0:
+ *     deathstar.com
+ *
+ * If you're using the amalgamated release binaries then it
+ * should be possible to enable UEFI mode by having this at
+ * the top of your main source file to hint the APE linker:
+ *
+ *     STATIC_YOINK("EfiMain");
+ *     int main() { ... }
+ *
+ * @see libc/dce.h
+ */
+__msabi noasan EFI_STATUS EfiMain(EFI_HANDLE ImageHandle,
+                                  EFI_SYSTEM_TABLE *SystemTable) {
+  intptr_t argc;
+  struct EfiArgs *ea;
+  EFI_LOADED_IMAGE *img;
+  extern char os asm("__hostos");
+  os = UEFI;
+  __efi_image_handle = ImageHandle;
+  __efi_system_table = SystemTable;
+  SystemTable->BootServices->AllocatePool(EfiConventionalMemory, sizeof(*ea),
+                                          &ea);
+  SystemTable->BootServices->HandleProtocol(ImageHandle,
+                                            &kEfiLoadedImageProtocol, &img);
+  argc = GetDosArgv(img->LoadOptions, ea->argblock, ARG_MAX, ea->args,
+                    ARRAYLEN(ea->args));
+  asm("push\t$0\n\t" /* auxv[0][1] */
+      "push\t$0\n\t" /* auxv[0][0] */
+      "push\t$0\n\t" /* envp[0] */
+      "sub\t%2,%%rsp\n\t"
+      "mov\t%%rsp,%%rdi\n\t"
+      "rep movsb\n\t" /* argv */
+      "push\t%0\n\t"  /* argc */
+      "xor\t%%edi,%%edi\n\t"
+      ".weak\t_start\n\t"
+      "jmp\t_start"
+      : /* no outputs */
+      : "a"(argc), "S"(ea->args), "c"((argc + 1) * 8));
+  unreachable;
+}