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generated by cgit-pink 1.4.1 (git 2.36.1) at 2024-12-17 07:02:43 +0000


 


ble assignments on functions are no longer persistentHerbert Xu

Dirk Fieldhouse <fieldhouse@gmx.net> wrote:
>
> In POSIX.1-2017 ("simultaneously IEEE Std 1003.1™-2017 and The Open
> Group Technical Standard Base Specifications, Issue 7")
> <http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_09>,
> we read under '2.9.1 Simple Commands'
>
> "Variable assignments shall be performed as follows:
> ...
> -    If the command name is a standard utility implemented as a function
> (see XBD Utility), the effect of variable assignments shall be as if the
> utility was not implemented as a function.
> ...
> -    If the command name is a function that is not a standard utility
> implemented as a function, variable assignments shall affect the current
> execution environment during the execution of the function. It is
> unspecified:
>
>     *   Whether or not the variable assignments persist after the
> completion of the function
>
>     *   Whether or not the variables gain the export attribute during
> the execution of the function
>
>     *   Whether or not export attributes gained as a result of the
> variable assignments persist after the completion of the function (if
> variable assignments persist after the completion of the function)"

POSIX used to require the current dash behaviour.  However, you're
right that this is no longer the case.

This patch will remove the persistence of the variable assignment.

I have considered the exporting the variables during the function
execution but have decided against it because:

1) It makes the code bigger.
2) dash has never done this in the past.
3) You cannot use this portably anyway.

Reported-by: Dirk Fieldhouse <fieldhouse@gmx.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>



2018-04-19parser: Fix parameter expansion inside inner double quotesHerbert Xu

The parsing of parameter expansion inside inner double quotes
breaks because we never look for ENDVAR while innerdq is true.

	echo "${x#"${x+''}"''}

This patch fixes it by pushing the syntax stack if innerdq is
true and we enter a new parameter expansion.

This patch also fixes a corner case where a bad substitution error
occurs within arithmetic expansion.

Reported-by: Denys Vlasenko <vda.linux@googlemail.com>
Fixes: ab1cecb40478 (" parser: Add syntax stack for recursive...")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>



2018-04-19parser: Fix parsing of ${}Herbert Xu

dash -c 'echo ${}' should print "Bad subtitution" but instead
fails with "Syntax error: Missing '}'".  This is caused by us
reading an extra character beyond the right brace.  This patch
fixes it so that this construct only fails during expansion rather
than during parsing.

Fixes: 3df3edd13389 ("[PARSER] Report substition errors at...")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>



2018-04-19man: correct typos, iff -> ifMartijn Dekker

Op 27-03-18 om 20:23 schreef Larry Hynes:
> Funny, I did wonder if it might be a contraction, but I did find
> it odd that it's not mentioned or explained. I'll leave it be, if
> you all are happy enough to keep it 'as is', or can resubmit if you
> think it's warranted.

I think the simple fact that it came up here is evidence that this is
too jargony for a manual. Patch attached.

- M.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>



2018-04-19expand: Do not quote backslashes in unquoted parameter expansionHerbert Xu

On Mon, Mar 26, 2018 at 07:25:20PM +0200, Martijn Dekker wrote:
> Op 26-03-18 om 17:38 schreef Harald van Dijk:
> > And not by dash 0.5.4. Like I wrote, dash 0.5.5 had some bugs that were
> > fixed in 0.5.6, which mostly restored the behaviour to match <0.5.5.
>
> Ah, sorry. dash 0.5.4 and earlier don't compile on my system, so they
> are not included in my conveniently accessible arsenal of test shells.
>
> > As for my patches, that was by accident and doesn't work reliably. When
> > the shell sees no metacharacters, pathname expansion is bypassed, and
> > backslash isn't considered a metacharacter. Which got me to my original
> > example of /de\v: there are no metacharacters in there, so the shell
> > doesn't look to see if it matches anything. Which seems highly
> > desirable: the shell shouldn't need to hit the file system for words not
> > containing metacharacters. The only way then to get consistent behaviour
> > is if the backslash is taken as quoted, so I'm not tempted to argue for
> > the behaviour you're hoping for, sorry. :)

Here is a better example:

	a="/*/\nullx" b="/*/\null"; printf "%s\n" $a $b

dash currently prints

	/*/\nullx
	/*/\null

bash prints

	/*/\nullx
	/dev/null

You may argue the bash behaviour is inconsistent but it actually
makes sense.  What happens is that quote removal only applies to
the original token as seen by the shell.  It is never applied to
the result of parameter expansion.

Now you may ask why on earth does the second line say "/dev/null"
instead of "/dev/\null".  Well that's because it is not the quote
removal step that removed the backslash, but the pathname expansion.

The fact that the /de\v does not become /dev even though it exists
is just the result of the optimisation to avoid unnecessarily
calling stat(2).  I have checked POSIX and I don't see anything
that forbids this behaviour.

So going back to dash yes I think we should adopt the bash behaviour
for pathname expansion and keep the existing case semantics.

This patch does exactly that.  Note that this patch does not work
unless you have already applied

	https://patchwork.kernel.org/patch/10306507/

because otherwise the optimisation mentioned above does not get
detected correctly and we will end up doing quote removal twice.

This patch also updates expmeta to handle naked backslashes at
the end of the pattern which is now possible.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>



2018-04-19shell: Add subdir-objects to AM_INIT_AUTOMAKEJason Bowen

I've attached a patch which adds the subdir-objects option to AM_INIT_AUTOMAKE.

For a while now when I've compiled dash I received a warning from
automake that there are source files in a subdirectory but that the
subdir-objects automake option was not supplied. I've just been adding
it myself, but I finally got around to submitting a patch. The code
still compiles for now (i'm using automake 1.15.1), but warning text
is rarely nice to see and, if the warning text is to be believed, then
the warning will eventually become an error.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>



2018-04-19eval: Restore input files in evalcommandHerbert Xu

When evalcommand invokes a command that modifies parsefile and
then bails out without popping the file, we need to ensure the
input file is restored so that the shell can continue to execute.

Reported-by: Martijn Dekker <martijn@inlv.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>



2018-04-19eval: Reap zombies after built-in commands and functionsHerbert Xu

Currently dash does not reap dead children after built-in commands
or functions.  This means that if you construct a loop consisting
of solely built-in commands and functions, then zombies can hang
around indefinitely.

This patch fixes this by reaping when necessary after each built-in
command and function.

Reported-by: Denys Vlasenko <vda.linux@googlemail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>



2018-04-19redir: Fix typo in noclobber codeHerbert Xu

The noclobber code has a typo in it that causes it to fail.  This
patch fixes it.

Reported-by: Denys Vlasenko <vda.linux@googlemail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>



2018-04-19expand: Fix glibc glob(3) supportHerbert Xu

It's been a while since we disabled glob(3) support by default.
It appears to be working now, however, we have to change our
code to detect the no-match case correctly.

In particular, we need to test for GLOB_NOMAGIC | GLOB_NOCHECK
instead of GLOB_MAGCHAR.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>



2018-04-02expand: Fix buffer overflow in expandmetaHerbert Xu

The native version of expandmeta allocates a buffer that may be
overrun for two reasons.  First of all the size is 1 byte too small
but this is normally hidden because the minimum size is rounded
up to 2048 bytes.  Secondly, if the directory level is deep enough,
any buffer can be overrun.

This patch fixes both problems by calling realloc when necessary.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>



2018-04-02builtin: Move echo space/nl handling into print_escape_strHerbert Xu

Currently echocmd uses print_escape_str to do everything apart
from printing the spaces/newlines separating its arguments.  This
patch moves the actual printing into print_escape_str as well
using the format parameter.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>



2018-04-02builtin: Fix echo performance regressionHerbert Xu

The commit d6c0e1e2ffbf7913ab69d51cc794d48d41c8fcb1 ("[BUILTIN]
Handle embedded NULs correctly in printf") caused a performance
regression in the echo built-in because every echo call now goes
through the printf %b slow path where the string is always printed
twice to ensure the space padding is correct in the presence of
NUL characters.  In fact this regression applies to printf %b as
well.

This is easily fixed by making printf %b take the fast path when
no precision/field width modifiers are present.

This patch also changes the second strchurnul call to strspn which
generates slightly better code.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>



2018-04-02expand: Fix ghost fields with unquoted $@/$*Herbert Xu

Harald van Dijk <harald@gigawatt.nl> wrote:
> On 22/03/2018 22:38, Martijn Dekker wrote:
>> Op 22-03-18 om 20:28 schreef Harald van Dijk:
>>> On 22/03/2018 03:40, Martijn Dekker wrote:
>>>> This patch fixes the bug that, given no positional parameters, unquoted
>>>> $@ and $* incorrectly generate one empty field (they should generate no
>>>> fields). Apparently that was a side effect of the above.
>>>
>>> This seems weird though. If you want to remove the recording of empty
>>> regions because they are pointless, then how does removing them fix a
>>> bug? Doesn't this show that empty regions do have an effect? Perhaps
>>> they're not supposed to have any effect, perhaps it's a specific
>>> combination of empty regions and something else that triggers some bug,
>>> and perhaps that combination can no longer occur with your patch.
>>
>> The latter is my guess, but I haven't had time to investigate it.
>
> Looking into it again:
>
> When IFS is set to an empty string, sepc is set to '\0' in varvalue().
> This then causes *quotedp to be set to true, meaning evalvar()'s quoted
> variable is turned on. quoted is then passed to recordregion() as the
> nulonly parameter.
>
> ifsp->nulonly has a bigger effect than merely selecting whether to use
> $IFS or whether to only split on null bytes: in ifsbreakup(), nulonly
> also causes string termination to be suppressed. That's correct: that
> special treatment is required to preserve empty fields in "$@"
> expansion. But it should *only* be used when $@ is quoted: ifsbreakup()
> takes nulonly from the last IFS region, even if it's empty, so having an
> additional zero-length region with nulonly enabled causes confusion.
>
> Passing quoted by value to varvalue() and not attempting to modify it
> should therefore, and in my quick testing does, also work to fix the
> original $@ bug.

You're right.  The proper fix to this is to ensure that nulonly
is not set in varvalue for $*.  It should only be set for $@ when
it's inside double quotes.

In fact there is another bug while we're playing with $@/$*.
When IFS is set to a non-whitespace character such as :, $*
outside quotes won't remove empty fields as it should.

This patch fixes both problems.

Reported-by: Martijn Dekker <martijn@inlv.org>
Suggested-by: Harald van Dijk <harald@gigawatt.nl>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>



2018-04-02parser: Allow newlines within parameter substitutionHerbert Xu

On Fri, Mar 16, 2018 at 11:27:22AM +0800, Herbert Xu wrote:
> On Thu, Mar 15, 2018 at 10:49:15PM +0100, Harald van Dijk wrote:
> >
> > Okay, it can be trivially modified to something that does work in other
> > shells (even if it were actually executed), but gets rejected at parse time
> > by dash:
> >
> >   if false; then
> >     : ${$+
> >   }
> >   fi
>
> That's just a bug in dash's parser with ${} in general, because
> it bombs out without the if clause too:
>
> 	: ${$+
> 	}

This patch fixes the parsing of newlines with parameter substitution.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>



2018-04-02expand: Fix bugs with words connected to the right of $@Herbert Xu

On Sun, Mar 04, 2018 at 12:44:59PM +0100, Harald van Dijk wrote:
>
> command:      set -- a ""; space=" "; printf "<%s>" "$@"$space
> bash:         <a><>
> dash 0.5.8:   <a>< >
> dash 0.5.9.1: <a>< >
> dash patched: <a><>

This is actually composed of two bugs.  First of all our tracking
of quotemark is wrong so anything after "$@" becomes quoted.  Once
we fix that then the problem is that the first space character
after "$@" is not recognised as an IFS.

This patch fixes both.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>



2018-03-25Revert "[BUILTIN] Remove unnecessary restoration of format string in printf"Herbert Xu

This reverts commit 7bb413255368e94395237d789f522891093c5774.

The commit breaks printf with more than argument.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>



2018-03-22parser: Fix backquote support in here-document EOF markHerbert Xu