As a preparatory step towards adding support for extra kernel command
line arguments passed via a UEFI variable, do a slight refactor of the
existing code so we can extend it more cleanly in a subsequent patch.
No change is functionality is intended.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
drivers/firmware/efi/libstub/efi-stub-helper.c | 43 ++++++++++++--------
1 file changed, 25 insertions(+), 18 deletions(-)
diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
index 50a9cab5a834..97a2423782af 100644
--- a/drivers/firmware/efi/libstub/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
@@ -726,6 +726,22 @@ static int efi_utf8_bytes(u16 c)
return 1 + (c >= 0x80) + (c >= 0x800);
}
+/*
+ * Get an upper bound for the number of UTF-8 bytes corresponding
+ * to a \n or \0 terminated UTF-16 string.
+ */
+static int count_utf8_bytes(const u16 *s, int max_chars, int *num_chars)
+{
+ int ret = 0;
+
+ while (*s != '\0' && *s != '\n' && --max_chars >= 0) {
+ ret += efi_utf8_bytes(*s++);
+ ++*num_chars;
+ }
+
+ return ret;
+}
+
/*
* Convert an UTF-16 string, not necessarily null terminated, to UTF-8.
*/
@@ -779,44 +795,35 @@ char *efi_convert_cmdline(efi_system_table_t *sys_table_arg,
efi_loaded_image_t *image,
int *cmd_line_len)
{
- const u16 *s2;
- u8 *s1 = NULL;
+ u8 *s1;
unsigned long cmdline_addr = 0;
int load_options_chars = image->load_options_size / 2; /* UTF-16 */
const u16 *options = image->load_options;
- int options_bytes = 0; /* UTF-8 bytes */
+ int cmd_line_bytes = 0; /* UTF-8 bytes */
int options_chars = 0; /* UTF-16 chars */
efi_status_t status;
u16 zero = 0;
- if (options) {
- s2 = options;
- while (*s2 && *s2 != '\n'
- && options_chars < load_options_chars) {
- options_bytes += efi_utf8_bytes(*s2++);
- options_chars++;
- }
- }
+ if (options)
+ cmd_line_bytes = count_utf8_bytes(options, load_options_chars,
+ &options_chars);
if (!options_chars) {
/* No command line options, so return empty string*/
options = &zero;
}
- options_bytes++; /* NUL termination */
+ cmd_line_bytes++; /* NUL termination */
- status = efi_high_alloc(sys_table_arg, options_bytes, 0,
+ status = efi_high_alloc(sys_table_arg, cmd_line_bytes, 0,
&cmdline_addr, MAX_CMDLINE_ADDRESS);
if (status != EFI_SUCCESS)
return NULL;
- s1 = (u8 *)cmdline_addr;
- s2 = (const u16 *)options;
-
- s1 = efi_utf16_to_utf8(s1, s2, options_chars);
+ s1 = efi_utf16_to_utf8((u8 *)cmdline_addr, options, options_chars);
*s1 = '\0';
- *cmd_line_len = options_bytes;
+ *cmd_line_len = cmd_line_bytes;
return (char *)cmdline_addr;
}
--
2.17.1
--
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