[libvirt] [PATCH] tests: Lower stack usage below 4096 bytes

[Matthias Bolte]

2011/4/25 Eric Blake <eblake at redhat.com>:
> On 04/24/2011 04:26 PM, Matthias Bolte wrote:
>> Make virtTestLoadFile allocate the buffer to read the file into.
>>
>> Fix logic error in virtTestLoadFile, stop reading on the an empty line.
>>
>> Use virFileReadLimFD in virtTestCaptureProgramOutput.
>> ---
>> +++ b/tests/commandhelper.c
>> @@ -99,8 +99,8 @@ int main(int argc, char **argv) {
>>      }
>>
>>      fprintf(log, "DAEMON:%s\n", getpgrp() == getsid(0) ? "yes" : "no");
>> -    char cwd[1024];
>> -    if (!getcwd(cwd, sizeof(cwd)))
>> +    char *cwd = NULL;
>> +    if (!(cwd = getcwd(NULL, 0)))
>
> Ouch.  This is not portable to POSIX, and while gnulib can guarantee
> that it works, the current gnulib getcwd module is GPL (and relies on
> openat, which is a rather heavy-weight replacement!).
>
> I'm going to work on a gnulib module getcwd-lgpl which doesn't fix all
> the known bugs in getcwd, but at least guarantees that getcwd(NULL,0)
> will malloc insofar as the underlying getcwd is not buggy; we'll need to
> import that into libvirt before applying the rest of this patch.
>
> I haven't closely reviewed the rest of this patch yet, but like the
> general idea once we have getcwd sorted out.
>

Oops. At first I used getcwd(NULL, 0) to replace the getcwd(cwd,
sizeof(cwd)) calls in the main functions, but then decided to just
move the cwd buffer to global scope instead. I just missed this one in
the second rewrite round.

Matthias