Commit 91027d0a authored by Chris Down's avatar Chris Down Committed by Petr Mladek
Browse files

string_helpers: Escape double quotes in escape_special 



From an abstract point of view, escape_special's counterpart,
unescape_special, already handles the unescaping of blackslashed double
quote sequences.

As a more practical example, printk indexing is an example case where
this is already practically useful. Compare an example with
`ESCAPE_SPECIAL | ESCAPE_SPACE`, with quotes not escaped:

    [root@ktst ~]# grep drivers/pci/pci-stub.c:69 /sys/kernel/debug/printk/index/vmlinux
    <4> drivers/pci/pci-stub.c:69 pci_stub_init "pci-stub: invalid ID string "%s"\n"

...and the same after this patch:

    [root@ktst ~]# grep drivers/pci/pci-stub.c:69 /sys/kernel/debug/printk/index/vmlinux
    <4> drivers/pci/pci-stub.c:69 pci_stub_init "pci-stub: invalid ID string \"%s\"\n"

One can of course, alternatively, use ESCAPE_APPEND with a quote in
@only, but without this patch quotes are coerced into hex or octal which
can hurt readability quite significantly.

I've checked uses of ESCAPE_SPECIAL and %pE across the codebase, and I'm
pretty confident that this shouldn't affect any stable interfaces.

Signed-off-by: default avatarChris Down <chris@chrisdown.name>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: default avatarPetr Mladek <pmladek@suse.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/af144c5b75e41ce417386253ba2694456bc04118.1623775748.git.chris@chrisdown.name
parent e73f0f0e

lib/string_helpers.c

+4 −0
Original line number Diff line number Diff line
@@ -361,6 +361,9 @@ static bool escape_special(unsigned char c, char **dst, char *end) 
	case '\e':

		to = 'e';

		break;

	case '"':

		to = '"';

		break;

	default:

		return false;

	}
@@ -474,6 +477,7 @@ static bool escape_hex(unsigned char c, char **dst, char *end) 
 *		'\t' - horizontal tab

 *		'\v' - vertical tab

 *	%ESCAPE_SPECIAL:

 *		'\"' - double quote

 *		'\\' - backslash

 *		'\a' - alert (BEL)

 *		'\e' - escape

lib/test-string_helpers.c

+7 −7
Original line number Diff line number Diff line
@@ -140,13 +140,13 @@ static const struct test_string_2 escape0[] __initconst = {{ 
},{

	.in = "\\h\\\"\a\e\\",

	.s1 = {{

		.out = "\\\\h\\\\\"\\a\\e\\\\",

		.out = "\\\\h\\\\\\\"\\a\\e\\\\",

		.flags = ESCAPE_SPECIAL,

	},{

		.out = "\\\\\\150\\\\\\042\\a\\e\\\\",

		.out = "\\\\\\150\\\\\\\"\\a\\e\\\\",

		.flags = ESCAPE_SPECIAL | ESCAPE_OCTAL,

	},{

		.out = "\\\\\\x68\\\\\\x22\\a\\e\\\\",

		.out = "\\\\\\x68\\\\\\\"\\a\\e\\\\",

		.flags = ESCAPE_SPECIAL | ESCAPE_HEX,

	},{

		/* terminator */
@@ -157,10 +157,10 @@ static const struct test_string_2 escape0[] __initconst = {{ 
		.out = "\eb \\C\007\"\x90\\r]",

		.flags = ESCAPE_SPACE,

	},{

		.out = "\\eb \\\\C\\a\"\x90\r]",

		.out = "\\eb \\\\C\\a\\\"\x90\r]",

		.flags = ESCAPE_SPECIAL,

	},{

		.out = "\\eb \\\\C\\a\"\x90\\r]",

		.out = "\\eb \\\\C\\a\\\"\x90\\r]",

		.flags = ESCAPE_SPACE | ESCAPE_SPECIAL,

	},{

		.out = "\\033\\142\\040\\134\\103\\007\\042\\220\\015\\135",
@@ -169,10 +169,10 @@ static const struct test_string_2 escape0[] __initconst = {{ 
		.out = "\\033\\142\\040\\134\\103\\007\\042\\220\\r\\135",

		.flags = ESCAPE_SPACE | ESCAPE_OCTAL,

	},{

		.out = "\\e\\142\\040\\\\\\103\\a\\042\\220\\015\\135",

		.out = "\\e\\142\\040\\\\\\103\\a\\\"\\220\\015\\135",

		.flags = ESCAPE_SPECIAL | ESCAPE_OCTAL,

	},{

		.out = "\\e\\142\\040\\\\\\103\\a\\042\\220\\r\\135",

		.out = "\\e\\142\\040\\\\\\103\\a\\\"\\220\\r\\135",

		.flags = ESCAPE_SPACE | ESCAPE_SPECIAL | ESCAPE_OCTAL,

	},{

		.out = "\eb \\C\007\"\x90\r]",