[BusyBox 0001380]: /usr/bin/[ gives "[: ]: unknown operand" message

[bugs at busybox.net]

The following issue has been CLOSED 
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http://busybox.net/bugs/view.php?id=1380 
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Reported By:                dmaizer
Assigned To:                BusyBox
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Project:                    BusyBox
Issue ID:                   1380
Category:                   Other
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     closed
Resolution:                 open
Fixed in Version:           
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Date Submitted:             06-05-2007 08:44 PDT
Last Modified:              06-08-2007 00:34 PDT
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Summary:                    /usr/bin/[ gives "[: ]: unknown operand" message
Description: 
We are working in an Apache (httpd 2.2.3) suexec CGI scripts environment
and our CGI scripts need to provide full paths to all applets/programs
used, so we have something like the following in the CGI script:

if /usr/bin/[ $# -lt 1 ]; then
   /bin/echo "sitediag: too few arguments"
   /bin/echo "Try sitediag --help for more information"
   exit 1
fi

However - this gives the error:
[: ]: unknown operand

Meaning that the "]" closing bracket is being recognized as an unknown
operand. But of course this bracket is needed to close the test...

If we remove the /usr/bin prefix from [ - then it works and gives the
expected echo messages above.

I tried looking at busybox code (being no expert of that code) and found
the following in coreutils/test.c:

	if (*t_wp != NULL && *++t_wp != NULL) {
		bb_error_msg("%s: unknown operand", *t_wp);
		return 2;
	}

My guess is that somehow using the pathname causes that condition above to
be true, but I haven't been able to find out why yet (I started looking
from ash.c and "lower" to see why this happens, but haven't been able to
find anything meaningful so far - hopefully someone who knows the code
better can provide a clue or a fix.
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---------------------------------------------------------------------- 
 dmaizer - 06-05-07 08:45  
---------------------------------------------------------------------- 
We use version 1.4.2 of busybox... 

---------------------------------------------------------------------- 
 bernhardf - 06-05-07 09:26  
---------------------------------------------------------------------- 
confirmed.

As a quick workaround, just use "test" instead of "[" or "[[".

I will also note, that the check for surplus args is borked (as you note)
since some closing brackets are a legit character to see -- IFF we were
called as "[" one and two otherwise.

For the sake of code-size, there is currently no checking for the correct
number of closing brackets, so just omitting any closing bracket bypasses
the reported behaviour. 

---------------------------------------------------------------------- 
 vda - 06-08-07 00:34  
---------------------------------------------------------------------- 
Fixed in rev 18775, thanks 

Issue History 
Date Modified   Username       Field                    Change               
====================================================================== 
06-05-07 08:44  dmaizer        New Issue                                    
06-05-07 08:44  dmaizer        Status                   new => assigned     
06-05-07 08:44  dmaizer        Assigned To               => BusyBox         
06-05-07 08:45  dmaizer        Note Added: 0002442                          
06-05-07 09:26  bernhardf      Note Added: 0002443                          
06-08-07 00:34  vda            Status                   assigned => closed  
06-08-07 00:34  vda            Note Added: 0002464                          
======================================================================