Ping: Re: [PATCH] libiberty/buildargv: POSIX behaviour for backslash handling

[Andrew Burgess <aburgess@redhat.com>]

Ping!

Thanks,
Andrew

Andrew Burgess <aburgess@redhat.com> writes:

> GDB makes use of the libiberty function buildargv for splitting the
> inferior (program being debugged) argument string in the case where
> the inferior is not being started under a shell.
>
> I have recently been working to improve this area of GDB, and have
> tracked done some of the unexpected behaviour to the libiberty
> function buildargv, and how it handles backslash escapes.
>
> For reference, I've been mostly reading:
>
>   https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html
>
> The issues that I would like to fix are:
>
>   1. Backslashes within single quotes should not be treated as an
>   escape, thus: '\a' should split to \a, retaining the backslash.
>
>   2. Backslashes within double quotes should only act as an escape if
>   they are immediately before one of the characters $ (dollar),
>   ` (backtick), " (double quote), ` (backslash), or \n (newline).  In
>   all other cases a backslash should not be treated as an escape
>   character.  Thus: "\a" should split to \a, but "\$" should split to
>   $.
>
>   3. A backslash-newline sequence should be treated as a line
>   continuation, both the backslash and the newline should be removed.
>
> I've updated libiberty and also added some tests.  All the existing
> libiberty tests continue to pass, but I'm not sure if there is more
> testing that should be done, buildargv is used within lto-wraper.cc,
> so maybe there's some testing folk can suggest that I run?
> ---
>  libiberty/argv.c                      |  8 +++++--
>  libiberty/testsuite/test-expandargv.c | 34 +++++++++++++++++++++++++++
>  2 files changed, 40 insertions(+), 2 deletions(-)
>
> diff --git a/libiberty/argv.c b/libiberty/argv.c
> index c2823d3e4ba..6bae4ca2ee9 100644
> --- a/libiberty/argv.c
> +++ b/libiberty/argv.c
> @@ -224,9 +224,13 @@ char **buildargv (const char *input)
>  		  if (bsquote)
>  		    {
>  		      bsquote = 0;
> -		      *arg++ = *input;
> +		      if (*input != '\n')
> +			*arg++ = *input;
>  		    }
> -		  else if (*input == '\\')
> +		  else if (*input == '\\'
> +			   && !squote
> +			   && (!dquote
> +			       || strchr ("$`\"\\\n", *(input + 1)) != NULL))
>  		    {
>  		      bsquote = 1;
>  		    }
> diff --git a/libiberty/testsuite/test-expandargv.c b/libiberty/testsuite/test-expandargv.c
> index 30f2337ef77..b8dcc6a269a 100644
> --- a/libiberty/testsuite/test-expandargv.c
> +++ b/libiberty/testsuite/test-expandargv.c
> @@ -142,6 +142,40 @@ const char *test_data[] = {
>    "b",
>    0,
>  
> +  /* Test 7 - No backslash removal within single quotes.  */
> +  "'a\\$VAR' '\\\"'",    /* Test 7 data */
> +  ARGV0,
> +  "@test-expandargv-7.lst",
> +  0,
> +  ARGV0,
> +  "a\\$VAR",
> +  "\\\"",
> +  0,
> +
> +  /* Test 8 - Remove backslash / newline pairs.  */
> +  "\"ab\\\ncd\" ef\\\ngh",    /* Test 8 data */
> +  ARGV0,
> +  "@test-expandargv-8.lst",
> +  0,
> +  ARGV0,
> +  "abcd",
> +  "efgh",
> +  0,
> +
> +  /* Test 9 - Backslash within double quotes.  */
> +  "\"\\$VAR\" \"\\`\" \"\\\"\" \"\\\\\" \"\\n\" \"\\t\"",    /* Test 9 data */
> +  ARGV0,
> +  "@test-expandargv-9.lst",
> +  0,
> +  ARGV0,
> +  "$VAR",
> +  "`",
> +  "\"",
> +  "\\",
> +  "\\n",
> +  "\\t",
> +  0,
> +
>    0 /* Test done marker, don't remove. */
>  };
>  
>
> base-commit: 458e7c937924bbcef80eb006af0b61420dbfc1c1
> -- 
> 2.25.4