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Date: Wed, 16 Jun 2021 00:42:27 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Chris Down <chris@...isdown.name>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Petr Mladek <pmladek@...e.com>, Jessica Yu <jeyu@...nel.org>,
Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
John Ogness <john.ogness@...utronix.de>,
Steven Rostedt <rostedt@...dmis.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Johannes Weiner <hannes@...xchg.org>,
Kees Cook <keescook@...omium.org>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Rasmus Villemoes <linux@...musvillemoes.dk>, kernel-team@...com
Subject: Re: [PATCH v7 1/5] string_helpers: Escape double quotes in escape_special
On Tue, Jun 15, 2021 at 7:53 PM Chris Down <chris@...isdown.name> wrote:
In case you will need to send a new version some nit picks below WRT
commit message. Or somebody might fix them in place when applying.
> 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
(example example)
"As a more practical example, printk indexing is the case where..."
?
> this is already practically useful. Compare an example with
> `ESCAPE_SPECIAL | ESCAPE_SPACE`, with quotes not escaped:
>
> [root@...t ~]# 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@...t ~]# 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"
In both examples: '[root@...t ~]#' => '#'
> 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
checked the uses
> pretty confident that this shouldn't affect any stable interfaces.
>
> Signed-off-by: Chris Down <chris@...isdown.name>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Reviewed-by: Petr Mladek <pmladek@...e.com>
> Cc: Rasmus Villemoes <linux@...musvillemoes.dk>
> ---
> lib/string_helpers.c | 4 ++++
> lib/test-string_helpers.c | 14 +++++++-------
> 2 files changed, 11 insertions(+), 7 deletions(-)
>
> diff --git a/lib/string_helpers.c b/lib/string_helpers.c
> index 5a35c7e16e96..3806a52ce697 100644
> --- a/lib/string_helpers.c
> +++ b/lib/string_helpers.c
> @@ -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
> diff --git a/lib/test-string_helpers.c b/lib/test-string_helpers.c
> index 2185d71704f0..437d8e6b7cb1 100644
> --- a/lib/test-string_helpers.c
> +++ b/lib/test-string_helpers.c
> @@ -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]",
> --
> 2.31.1
>
--
With Best Regards,
Andy Shevchenko
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