[U-Boot] [PATCH v2 03/11] cmd: efidebug: rework "boot dump" sub-command using GetNextVariableName()

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

On Wed, Apr 24, 2019 at 10:13:37PM +0200, Heinrich Schuchardt wrote:
> On 4/24/19 8:30 AM, AKASHI Takahiro wrote:
> >Efidebug command should be implemented using well-defined EFI interfaces,
> >rather than using internal functions/data. This change will be needed in
> >a later patch where UEFI variables are re-implemented.
> 
> I had trouble to get the point. In the next version I suggest to write:
> 
> Currently in do_efi_boot_dump() we directly read EFI variables from the
> related environment variables. To accomodate alternative storage
> backends we should switch to using the UEFI API instead.

Okay.

> >
> >Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> >---
> >  cmd/efidebug.c | 92 ++++++++++++++++++++++++++++++++++++--------------
> >  1 file changed, 66 insertions(+), 26 deletions(-)
> >
> >diff --git a/cmd/efidebug.c b/cmd/efidebug.c
> >index a40c4f4be286..8890dd7268f1 100644
> >--- a/cmd/efidebug.c
> >+++ b/cmd/efidebug.c
> >@@ -509,7 +509,7 @@ static int do_efi_boot_add(cmd_tbl_t *cmdtp, int flag,
> >  	if (argc < 6 || argc > 7)
> >  		return CMD_RET_USAGE;
> >
> >-	id = (int)simple_strtoul(argv[1], &endp, 16);
> >+	id = simple_strtoul(argv[1], &endp, 16);
> 
> This change is correct but unrelated. Please, put it into a separate
> patch. Or at least mention it in the commit message.

Sure.

> >  	if (*endp != '\0' || id > 0xffff)
> >  		return CMD_RET_USAGE;
> >
> >@@ -595,7 +595,7 @@ static int do_efi_boot_rm(cmd_tbl_t *cmdtp, int flag,
> >
> >  	guid = efi_global_variable_guid;
> >  	for (i = 1; i < argc; i++, argv++) {
> >-		id = (int)simple_strtoul(argv[1], &endp, 16);
> >+		id = simple_strtoul(argv[1], &endp, 16);
> 
> Same here.
> 
> >  		if (*endp != '\0' || id > 0xffff)
> >  			return CMD_RET_FAILURE;
> >
> >@@ -693,6 +693,27 @@ static void show_efi_boot_opt(int id)
> >  	free(data);
> >  }
> >
> >+static bool u16_isxdigit(u16 c)
> >+{
> >+	if (c & 0xff00)
> >+		return false;
> >+
> >+	return isxdigit((u8)c);
> >+}
> >+
> >+static int u16_tohex(u16 c)
> >+{
> >+	if (c >= '0' && c < '9')
> >+		return c - '0';
> >+	if (c >= 'A' && c < 'F')
> >+		return c - 'A' + 10;
> >+	if (c >= 'a' && c < 'f')
> >+		return c - 'a' + 10;
> 
> Does the UEFI spec really allow lower case hexadecimal numbers here?
> I only found an example with capital numbers. Would this imply that I
> could have variables Boot00a0 and Boot00A0 side by side? Which one would
> be selected by boot option 00a0?
> 
> Or should SetVariable() make a case insensitive search for variable names?

Good point. I found the description below in UEFI section 3.1.1:
        Each load option entry resides in a Boot####, Driver####,
        SysPrep####, OsRecovery####
        or PlatformRecovery#### variable where #### is replaced by
        a unique option number in
        printable hexadecimal representation using the digits 0-9,
        and the upper case versions of the
        characters A-F (0000-FFFF).

> In EDK2 function FindVariableEx() in
> MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
> uses CompareMem() to compare variable names.
> 
> Function BmCharToUint() is used to check the digits of boot options and
> has this comment:
> 
> "It assumes the input Char is in the scope of L'0' ~ L'9'
> and L'A' ~ L'F'"
> 
> So let's us assume that variable names are case sensitive and Boot
> entries can only have capital hexadecimal digits.
> 
> So u16_isxdigit() is incorrect.
> 
> >+
> >+	/* dummy */
> >+	return -1;
> 
> As we do not check bounds here the function could be reduced to:
> 
> return c > '9' ? c - ('A' - 0xa) : c - '9';
> 
> But I would prefer one library function instead of the two static
> functions which returns -1 for a non-digit and 0 - 15 for a digit.
> And a unit test in test/unicoode_ut.c

Okay.

> >+}
> >+
> >  /**
> >   * show_efi_boot_dump() - dump all UEFI load options
> >   *
> >@@ -709,38 +730,57 @@ static void show_efi_boot_opt(int id)
> >  static int do_efi_boot_dump(cmd_tbl_t *cmdtp, int flag,
> >  			    int argc, char * const argv[])
> >  {
> >-	char regex[256];
> >-	char * const regexlist[] = {regex};
> >-	char *variables = NULL, *boot, *value;
> >-	int len;
> >-	int id;
> >+	u16 *var_name16, *p;
> >+	efi_uintn_t buf_size, size;
> >+	efi_guid_t guid;
> >+	int id, i;
> >+	efi_status_t ret;
> >
> >  	if (argc > 1)
> >  		return CMD_RET_USAGE;
> >
> >-	snprintf(regex, 256, "efi_.*-.*-.*-.*-.*_Boot[0-9A-F]+");
> >-
> >-	/* TODO: use GetNextVariableName? */
> >-	len = hexport_r(&env_htab, '\n', H_MATCH_REGEX | H_MATCH_KEY,
> >-			&variables, 0, 1, regexlist);
> >+	buf_size = 128;
> >+	var_name16 = malloc(buf_size);
> >+	if (!var_name16)
> >+		return CMD_RET_FAILURE;
> >
> >-	if (!len)
> >-		return CMD_RET_SUCCESS;
> >+	var_name16[0] = 0;
> >+	for (;;) {
> >+		size = buf_size;
> >+		ret = EFI_CALL(efi_get_next_variable_name(&size, var_name16,
> >+							  &guid));
> >+		if (ret == EFI_NOT_FOUND)
> >+			break;
> >+		if (ret == EFI_BUFFER_TOO_SMALL) {
> >+			buf_size = size;
> >+			p = realloc(var_name16, buf_size);
> >+			if (!p) {
> >+				free(var_name16);
> >+				return CMD_RET_FAILURE;
> >+			}
> >+			var_name16 = p;
> >+			ret = EFI_CALL(efi_get_next_variable_name(&size,
> >+								  var_name16,
> >+								  &guid));
> >+		}
> >+		if (ret != EFI_SUCCESS) {
> >+			free(var_name16);
> >+			return CMD_RET_FAILURE;
> >+		}
> >
> >-	if (len < 0)
> >-		return CMD_RET_FAILURE;
> >+		if (u16_strncmp(var_name16, L"Boot", 4) || var_name16[8] ||
> 
> We can use memcmp() here. This avoids introducing u16_strncmp().

Okay.

> >+		    !u16_isxdigit(var_name16[4]) ||
> >+		    !u16_isxdigit(var_name16[5]) ||
> >+		    !u16_isxdigit(var_name16[6]) ||
> >+		    !u16_isxdigit(var_name16[7]))
> >+			continue;
> >
> >-	boot = variables;
> >-	while (*boot) {
> >-		value = strstr(boot, "Boot") + 4;
> >-		id = (int)simple_strtoul(value, NULL, 16);
> >+		for (id = 0, i = 0; i < 4; i++)
> >+			id = (id << 4) + u16_tohex(var_name16[4 + i]);
> 
> This all can be simplified if we unify u16_isxdigit() and u16_tohex().
> Just one function returning -1 if not a hexadecimal and 0 - 15 otherwise.

Will manage that.

> >  		show_efi_boot_opt(id);
> >-		boot = strchr(boot, '\n');
> >-		if (!*boot)
> >-			break;
> >-		boot++;
> >  	}
> >-	free(variables);
> >+
> >+	free(var_name16);
> >
> >  	return CMD_RET_SUCCESS;
> >  }
> >@@ -914,7 +954,7 @@ static int do_efi_boot_order(cmd_tbl_t *cmdtp, int flag,
> >  		return CMD_RET_FAILURE;
> >
> >  	for (i = 0; i < argc; i++) {
> >-		id = (int)simple_strtoul(argv[i], &endp, 16);
> >+		id = simple_strtoul(argv[i], &endp, 16);
> 
> This change is correct but unrelated. Please, put it into a separate
> patch. Or at least mention it in the commit message.

Okay

Thanks,
-Takahiro Akashi

> Best regards
> 
> Heinrich
> 
> >  		if (*endp != '\0' || id > 0xffff) {
> >  			printf("invalid value: %s\n", argv[i]);
> >  			ret = CMD_RET_FAILURE;
> >
>