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List: dash
Subject: Re: [PATCH] [BUILTIN] describe_command: fix incorrect path
From: Youfu Zhang <zhangyoufu () gmail ! com>
Date: 2017-05-26 14:47:50
Message-ID: CAEKhA2xgjEsag=RTmMxCCy9usyc_W6u0ZoZ9YXpAP9D9yL0DBA () mail ! gmail ! com
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Your patch looks better than mine :)
Please consider post this patch to busybox as well.
Their ash has same code and same issue.
See http://lists.busybox.net/pipermail/busybox/2017-May/085459.html
On Fri, May 26, 2017 at 3:59 PM, Harald van Dijk <harald@gigawatt.nl> wrote:
> Hi,
>
> On 26/05/17 09:04, Youfu Zhang wrote:
>>
>> $ PATH=/extra/path:/usr/sbin:/usr/bin:/sbin:/bin \
>>>
>>> sh -xc 'command -V ls; command -V ls; command -Vp ls; command -vp ls'
>>
>> + command -V ls
>> ls is /bin/ls
>> + command -V ls
>> ls is a tracked alias for /bin/ls
>> + command -Vp ls
>> ls is a tracked alias for (null)
>> + command -vp ls
>> Segmentation fault (core dumped)
>>
>> describe_command should respect `path' argument. Looking up in the hash
>> table
>> may gives incorrect index in entry.u.index and finally causes incorrect
>> output
>> or SIGSEGV.
>
>
> True, but only when a path is passed in. If the default path is used,
> looking up in the hash table is correct, and printing tracked aliases is
> intentional.
>
> If it's desirable to drop that feature, then it should be dropped
> completely, code shouldn't be left in that can no longer be used. But it's
> possible to keep it working: how about this instead?
>
> Signed-off-by: Harald van Dijk <harald@gigawatt.nl>
> ---
> src/exec.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/src/exec.c b/src/exec.c
> index ec0eadd..1350da3 100644
> --- a/src/exec.c
> +++ b/src/exec.c
> @@ -743,8 +743,6 @@ describe_command(out, command, path, verbose)
> struct tblentry *cmdp;
> const struct alias *ap;
>
> - path = path ?: pathval();
> -
> if (verbose) {
> outstr(command, out);
> }
> @@ -767,8 +765,15 @@ describe_command(out, command, path, verbose)
> goto out;
> }
>
> - /* Then check if it is a tracked alias */
> - if ((cmdp = cmdlookup(command, 0)) != NULL) {
> + /* Then if the standard search path is used, check if it is a
> tracked alias. */
> + if (path == NULL) {
> + path = pathval();
> + cmdp = cmdlookup(command, 0);
> + } else {
> + cmdp = NULL;
> + }
> +
> + if (cmdp != NULL) {
> entry.cmdtype = cmdp->cmdtype;
> entry.u = cmdp->param;
> } else {
--
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