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Date: Wed, 22 Apr 2009 06:24:14 -0600
From: Eric Blake <ebb9 AT byu DOT net>
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To: cygwin AT cygwin DOT com
Subject: Re: [1.7] Backslash incorrectly triggers DOS style path warning
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According to Ken Brown on 4/22/2009 5:58 AM:
>>   It is maybe getting globbed on the command-line because not
>> protected by
>> quoting and it contains pattern match chars?
> 
> The text in question is in the definition of _known_hosts() in
> /etc/bash_completion, in case someone wants to try to sort this out.

Which looks like:

          COMPREPLY=($( awk 'BEGIN {FS=","}
				/^\s*[^|\#]/ {for (i=1; i<=2; ++i) { \
				       gsub(" .*$", "", $i); \
				       if ($i ~ /'$cur'/) {print $i} \
				}}' "${kh[@]}" 2>/dev/null ));

That looks properly quoted to me.  Really, the question is why does awk
call stat() on its first argument?  Here's a simpler test case:

$ echo hi > hi
$ strace -o trace.txt gawk '{ print }' hi

The strace is informative:

  110   40766 [main] gawk 2804 build_argv: argv[0] = 'gawk'
  453   41219 [main] gawk 2804 lstat64: entering
   79   41298 [main] gawk 2804 normalize_posix_path: src { print }
...
   37   42339 [main] gawk 2804 stat_worker: -1 = (\??\K:\cygwin-2\tmp\{
print }, 0x1DCB18)
   96   42435 [main] gawk 2804 globify: argv[1] = '{ print }'
   65   42500 [main] gawk 2804 build_argv: argv[2] = 'hi'
   35   42535 [main] gawk 2804 build_argv: argc 3

with no further references to '{ print }' once awk is running.

In other words, the problematic stat is occurring prior to main(), and it
is not awk's fault, but rather cygwin's, that globify() is trying to
dereference a non-file name and triggering the warning.  Even the presence
of { in a command line argument was enough to trigger globify().  But
maybe that is an artifact of strace.  Notice the difference between:

$ ls '*'
ls: cannot access *: No such file or directory
$ strace -o trace.txt ls '*'
hi  trace.txt
$

In other words, strace is mistakenly performing glob expansion on the
subsidiary arguments to the program being traced, when we really wanted to
trace ls with a literal argument of "*".

- --
Don't work too hard, make some time for fun as well!

Eric Blake             ebb9 AT byu DOT net
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