Cleanup command line parsing, properly handle command line flags

main.c

@@ -10,6 +10,10 @@
 #include "linux.h"
 #include "graphics.h"
 
+#ifndef ANDROID_EFI_VERSION
+#define ANDROID_EFI_VERSION "unknown"
+#endif
+
 struct android_efi_options {
  EFI_GUID guid;
  EFI_GUID *partition_guid;
@@ -20,86 +24,120 @@ struct android_efi_options {
 };
 
 enum command_line_argument {
+ INVALID,
+ FLAG,
+ KERNEL_PARAMETERS,
+
+ // Positional
  FIRST_ARGUMENT,
  IMAGE,
- END,
- KERNEL_PARAMETERS
 };
 
-#ifndef ANDROID_EFI_VERSION
-#define ANDROID_EFI_VERSION "unknown"
-#endif
+#define is_flag(flag, len, f) ((len) == STRING_LENGTH(f) && CompareMem(flag, f, STRING_LENGTH(f)) == 0)
+
+static EFI_STATUS parse_flag(const CHAR16 *flag, UINTN len) {
+ if (is_flag(flag, len, L"--version")) {
+ Print(L"android-efi version " ANDROID_EFI_VERSION "\n");
+ return EFI_ABORTED;
+ }
 
-#define STATE_SKIP_SPACES (1 << 0)
-#define STATE_FOUND_DASH (1 << 1)
-#define STATE_IMAGE_PATH (1 << 2)
+ CHAR16 *copy = StrnDuplicate(flag, len);
+ Print(L"Unknown command line flag: %s\n", copy);
+ FreePool(copy);
+ return EFI_INVALID_PARAMETER;
+}
 
-#define RAMDISK_OPTION "initrd="
-#define RAMDISK_OPTION_SIZE (sizeof(RAMDISK_OPTION) - sizeof(RAMDISK_OPTION[0]))
-#define MAX_RAMDISK_COUNT 4
-#define MAX_PATH_LENGTH 256
+static EFI_STATUS parse_image(struct android_efi_options *options, const CHAR16 *opt, UINTN len, UINTN path) {
+ if (path) {
+ options->path = StrnDuplicate(opt, len);
+
+ // Clean path (replace forward slashes with backward slashes)
+ for (UINTN i = 0; i < len; ++i) {
+ if (options->path[i] == L'/') {
+ options->path[i] = L'\\';
+ }
+ }
+ } else if (len) {
+ options->partition_guid = &options->guid;
+ if (!guid_parse(options->partition_guid, opt, len)) {
+ CHAR16 *guid = StrnDuplicate(opt, len);
+ Print(L"Expected valid partition GUID, got '%s'\n", guid);
+ FreePool(guid);
+ return EFI_INVALID_PARAMETER;
+ }
+ }
+
+ return EFI_SUCCESS;
+}
+
+#define STATE_DASHES 3
+#define STATE_SKIP_SPACES (1 << 2)
+#define STATE_IMAGE_PATH (1 << 3)
 
 static EFI_STATUS parse_command_line(EFI_LOADED_IMAGE_PROTOCOL *loaded_image, struct android_efi_options *options) {
  const CHAR16 *opt = loaded_image->LoadOptions;
  if (!opt) {
  goto out;
  }
 
- UINTN length = loaded_image->LoadOptionsSize / sizeof(CHAR16);
-
- CHAR16 c;
- UINT8 state = STATE_SKIP_SPACES;
+ UINTN state = STATE_SKIP_SPACES;
  enum command_line_argument argument = FIRST_ARGUMENT;
-
+ enum command_line_argument last_argument = INVALID;
  UINTN start = 0;
 
- for (UINTN i = 0; i < length; ++i) {
- c = opt[i];
+ EFI_STATUS err = EFI_SUCCESS;
+ for (UINTN i = 0, length = loaded_image->LoadOptionsSize / sizeof(*opt); i < length; ++i) {
+ CHAR16 c = opt[i];
 
- // Detects two consecutive dashes ("--") that separate arguments from
- // additional kernel parameters
- if (state & STATE_FOUND_DASH) {
- if (c == L'-') {
- if (StrnCmp(&opt[start], L"--version", length - start) == 0) {
- Print(L"android-efi version " ANDROID_EFI_VERSION "\n");
- return EFI_ABORTED;
- }
-
- argument = KERNEL_PARAMETERS;
- state |= STATE_SKIP_SPACES;
+ if (state & STATE_DASHES) {
+ if (c == L'-' && (++state & STATE_DASHES) < STATE_DASHES) {
  continue;
- } else {
- state &= ~STATE_FOUND_DASH;
  }
+
+ // Detect two consecutive dashes ("--") that
+ // separate positional arguments from additional
+ // kernel parameters (or are part of command line flags)
+ if ((state & STATE_DASHES) == 2) {
+ if (c == L' ') {
+ argument = KERNEL_PARAMETERS;
+ state |= STATE_SKIP_SPACES;
+ } else if (c) {
+ last_argument = argument;
+ argument = FLAG;
+ }
+ }
+
+ state &= ~STATE_DASHES;
  }
 
- // Skips redundant spaces between arguments
  if (state & STATE_SKIP_SPACES) {
+ // Skip redundant spaces between arguments
  if (c == L' ') {
  continue;
- } else {
- state &= ~STATE_SKIP_SPACES;
- start = i;
+ }
 
- if (c == L'-') {
- state |= STATE_FOUND_DASH;
- continue;
- }
+ state &= ~STATE_SKIP_SPACES;
+ start = i;
+
+ if (c == L'-') {
+ ++state; // Count dash
+ continue;
  }
  }
 
  if (c && c != L' ') {
  switch (argument) {
+ case IMAGE:
+ if (!(state & STATE_IMAGE_PATH) && (c == L'/' || c == L'\\')) {
+ break;
+ }
+ continue;
+
  case KERNEL_PARAMETERS:
  options->kernel_parameters = &opt[i];
  options->kernel_parameters_length = length - i;
  goto out; // Break the loop
 
- case IMAGE:
- if (!(state & STATE_IMAGE_PATH) && (c == L'/' || c == L'\\')) {
- break;
- }
- // fallthrough
  default:
  continue;
  }
@@ -110,25 +148,9 @@ static EFI_STATUS parse_command_line(EFI_LOADED_IMAGE_PROTOCOL *loaded_image, st
 
  switch (argument) {
  case IMAGE:
- if (state & STATE_IMAGE_PATH) {
- // Parse file path
- options->path = StrnDuplicate(&opt[start], len);
-
- // Cleanup path (replace forward slashes with backward slashes)
- for (start = 0; start < len; ++start) {
- if (options->path[start] == L'/') {
- options->path[start] = L'\\';
- }
- }
- } else if (len) {
- // Parse command line partition GUID
- options->partition_guid = &options->guid;
- if (!guid_parse(options->partition_guid, &opt[start], len)) {
- CHAR16 *guid = StrnDuplicate(&opt[start], len);
- Print(L"Expected valid partition GUID, got '%s'\n", guid);
- FreePool(guid);
- return EFI_INVALID_PARAMETER;
- }
+ err = parse_image(options, &opt[start], len, state & STATE_IMAGE_PATH);
+ if (err) {
+ goto end;
  }
 
  state |= STATE_IMAGE_PATH; // Parse path next
@@ -137,6 +159,13 @@ static EFI_STATUS parse_command_line(EFI_LOADED_IMAGE_PROTOCOL *loaded_image, st
  case KERNEL_PARAMETERS:
  goto out; // Break the loop
 
+ case FLAG:
+ err = parse_flag(&opt[start], len);
+ if (err) {
+ goto end;
+ }
+ break;
+
  default:
  break;
  }
@@ -146,9 +175,12 @@ static EFI_STATUS parse_command_line(EFI_LOADED_IMAGE_PROTOCOL *loaded_image, st
  }
 
  if (c == L' ') {
- if (argument != END) {
+ if (argument == FLAG) {
+ argument = last_argument;
+ } else {
  ++argument;
  }
+
  state |= STATE_SKIP_SPACES;
  }
 
@@ -157,17 +189,15 @@ static EFI_STATUS parse_command_line(EFI_LOADED_IMAGE_PROTOCOL *loaded_image, st
 
 out:
  if (!options->partition_guid && !options->path) {
+ err = EFI_INVALID_PARAMETER;
  Print(L"Usage: android.efi <Boot Partition GUID/Path> [-- Additional Kernel Parameters...]\n");
- goto err;
  }
 
- return EFI_SUCCESS;
-
-err:
- if (options->path) {
+end:
+ if (err) {
  FreePool(options->path);
  }
- return EFI_INVALID_PARAMETER;
+ return err;
 }
 
 static EFI_STATUS prepare_cmdline(struct linux_setup_header *kernel_header, struct android_image *android_image,
@@ -197,11 +227,15 @@ static EFI_STATUS prepare_cmdline(struct linux_setup_header *kernel_header, stru
  return android_copy_cmdline(android_image, cmdline, cmdline_end - cmdline);
 }
 
+#define RAMDISK_OPTION "initrd="
+#define MAX_RAMDISK_COUNT 4
+#define MAX_PATH_LENGTH 256
+
 static const CHAR8 *find_initrd_option(const CHAR8 *cmdline) {
  const CHAR8 *tail = cmdline;
- for (const CHAR8 *first = cmdline + RAMDISK_OPTION_SIZE; cmdline < first && *cmdline; ++cmdline);
+ for (const CHAR8 *first = cmdline + STRING_LENGTH(RAMDISK_OPTION); cmdline < first && *cmdline; ++cmdline);
  for (; *cmdline; ++cmdline, ++tail) {
- if (CompareMem(tail, RAMDISK_OPTION, RAMDISK_OPTION_SIZE) == 0) {
+ if (CompareMem(tail, RAMDISK_OPTION, STRING_LENGTH(RAMDISK_OPTION)) == 0) {
  return cmdline;
  }
  }

string.c

@@ -48,9 +48,9 @@ CHAR8 *str_utf16_to_utf8(CHAR8 *dst, const CHAR16 *src, UINTN n) {
  }
  *dst++ = 0xf0 + (c >> 18);
  *dst++ = 0x80 + ((c >> 12) & 0x3f);
-  t2:
+ t2:
  *dst++ = 0x80 + ((c >> 6) & 0x3f);
-  t1:
+ t1:
  *dst++ = 0x80 + (c & 0x3f);
  }
 

string.h

@@ -6,6 +6,8 @@
 
 #include <efi.h>
 
+#define STRING_LENGTH(s) ((sizeof((s))/sizeof((s)[0]))-1)
+
 CHAR16 *StrnDuplicate(const CHAR16 *s, UINTN length);
 CHAR8 *str_utf16_to_utf8(CHAR8 *dst, const CHAR16 *src, UINTN n);