Re: [PATCH 10/18] Do proper conversion from UTF-16 to UTF-8

["H. Peter Anvin" <hpa@zytor.com>]

Sorry this version is broken and doesn't even compile due to remaining options_size references.

Roy Franz <roy.franz@linaro.org> wrote:
>From: "H. Peter Anvin" <hpa@zytor.com>
>
>Improve the conversion of the UTF-16 EFI command line
>to UTF-8 for passing to the kernel.
>
>Signed-off-by: Roy Franz <roy.franz@linaro.org>
>---
> arch/x86/boot/compressed/eboot.c       |    3 +-
>drivers/firmware/efi/efi-stub-helper.c |   92
>++++++++++++++++++++++++--------
> 2 files changed, 72 insertions(+), 23 deletions(-)
>
>diff --git a/arch/x86/boot/compressed/eboot.c
>b/arch/x86/boot/compressed/eboot.c
>index 5e708c0..4723dc89 100644
>--- a/arch/x86/boot/compressed/eboot.c
>+++ b/arch/x86/boot/compressed/eboot.c
>@@ -486,8 +486,7 @@ struct boot_params *make_boot_params(void *handle,
>efi_system_table_t *_table)
> 	hdr->type_of_loader = 0x21;
> 
> 	/* Convert unicode cmdline to ascii */
>-	cmdline_ptr = efi_convert_cmdline_to_ascii(sys_table, image,
>-						   &options_size);
>+	cmdline_ptr = efi_convert_cmdline(sys_table, image, &options_size);
> 	if (!cmdline_ptr)
> 		goto fail;
> 	hdr->cmd_line_ptr = (unsigned long)cmdline_ptr;
>diff --git a/drivers/firmware/efi/efi-stub-helper.c
>b/drivers/firmware/efi/efi-stub-helper.c
>index 335d17d..8331892 100644
>--- a/drivers/firmware/efi/efi-stub-helper.c
>+++ b/drivers/firmware/efi/efi-stub-helper.c
>@@ -548,61 +548,111 @@ static efi_status_t
>efi_relocate_kernel(efi_system_table_t *sys_table_arg,
> 
> 	return status;
> }
>-/* Convert the unicode UEFI command line to ASCII to pass to kernel.
>+
>+/*
>+ * Get the number of UTF-8 bytes corresponding to an UTF-16 character.
>+ * This overestimates for surrogates, but that is okay.
>+ */
>+static int efi_utf8_bytes(u16 c)
>+{
>+	return 1 + (c >= 0x80) + (c >= 0x800);
>+}
>+
>+/*
>+ * Convert an UTF-16 string, not necessarily null terminated, to
>UTF-8.
>+ */
>+static u8 *efi_utf16_to_utf8(u8 *dst, const u16 *src, int n)
>+{
>+	unsigned int c;
>+
>+	while (n--) {
>+		c = *src++;
>+		if (n && c >= 0xd800 && c <= 0xdbff &&
>+		    *src >= 0xdc00 && *src <= 0xdfff) {
>+			c = 0x10000 + ((c & 0x3ff) << 10) + (*src & 0x3ff);
>+			src++;
>+			n--;
>+		}
>+		if (c >= 0xd800 && c <= 0xdfff)
>+			c = 0xfffd; /* Unmatched surrogate */
>+		if (c < 0x80) {
>+			*dst++ = c;
>+			continue;
>+		}
>+		if (c < 0x800) {
>+			*dst++ = 0xc0 + (c >> 6);
>+			goto t1;
>+		}
>+		if (c < 0x10000) {
>+			*dst++ = 0xe0 + (c >> 12);
>+			goto t2;
>+		}
>+		*dst++ = 0xf0 + (c >> 18);
>+		*dst++ = 0x80 + ((c >> 12) & 0x3f);
>+t2:
>+		*dst++ = 0x80 + ((c >> 6) & 0x3f);
>+t1:
>+		*dst++ = 0x80 + (c & 0x3f);
>+	}
>+
>+	return dst;
>+}
>+
>+/*
>+ * Convert the unicode UEFI command line to ASCII to pass to kernel.
>  * Size of memory allocated return in *cmd_line_len.
>  * Returns NULL on error.
>  */
>-static char *efi_convert_cmdline_to_ascii(efi_system_table_t
>*sys_table_arg,
>-				      efi_loaded_image_t *image,
>-				      int *cmd_line_len)
>+static char *efi_convert_cmdline(efi_system_table_t *sys_table_arg,
>+				 efi_loaded_image_t *image,
>+				 int *cmd_line_len)
> {
>-	u16 *s2;
>+	const u16 *s2;
> 	u8 *s1 = NULL;
> 	unsigned long cmdline_addr = 0;
> 	int load_options_size = image->load_options_size / 2; /* ASCII */
>-	void *options = image->load_options;
>-	int options_size = 0;
>+	const u16 *options = image->load_options;
>+	int options_bytes = 0;	/* UTF-8 bytes */
>+	int options_chars = 0;	/* UTF-16 chars */
> 	efi_status_t status;
>-	int i;
> 	u16 zero = 0;
> 
> 	if (options) {
> 		s2 = options;
>-		while (*s2 && *s2 != '\n' && options_size < load_options_size) {
>+		while (*s2 && *s2 != '\n' && options_bytes < load_options_size) {
>+			options_bytes += efi_utf8_bytes(*s2);
> 			s2++;
>-			options_size++;
> 		}
>+		options_chars = s2 - options;
> 	}
> 
>-	if (options_size == 0) {
>-		/* No command line options, so return empty string*/
>-		options_size = 1;
>+	if (!options_chars) {
>+		/* No command line options, so return empty string */
> 		options = &zero;
> 	}
> 
>-	options_size++;  /* NUL termination */
>+	options_bytes++;	/* NUL termination */
>+
> #ifdef CONFIG_ARM
> 	/* For ARM, allocate at a high address to avoid reserved
> 	 * regions at low addresses that we don't know the specfics of
> 	 * at the time we are processing the command line.
> 	 */
>-	status = efi_high_alloc(sys_table_arg, options_size, 0,
>+	status = efi_high_alloc(sys_table_arg, options_bytes, 0,
> 			    &cmdline_addr, 0xfffff000);
> #else
>-	status = efi_low_alloc(sys_table_arg, options_size, 0,
>+	status = efi_low_alloc(sys_table_arg, options_bytes, 0,
> 			    &cmdline_addr);
> #endif
> 	if (status != EFI_SUCCESS)
> 		return NULL;
> 
> 	s1 = (u8 *)cmdline_addr;
>-	s2 = (u16 *)options;
>-
>-	for (i = 0; i < options_size - 1; i++)
>-		*s1++ = *s2++;
>+	s2 = (const u16 *)options;
> 
>+	s1 = efi_utf16_to_utf8(s1, s2, options_chars);
> 	*s1 = '\0';
> 
>-	*cmd_line_len = options_size;
>+	*cmd_line_len = options_bytes;
> 	return (char *)cmdline_addr;
> }

-- 
Sent from my mobile phone.  Please pardon brevity and lack of formatting.