Subject: Re: bin/8681: grep may bomb out with "memory exhausted"
To: None <>
From: Simon Burge <simonb@NetBSD.ORG>
List: netbsd-bugs
Date: 10/26/1999 11:21:03 wrote:

> > With both this and bin/8461, seems like a very strong case to turn off
> > HAVE_MMAP.  Any objections?
> Gah, even doing that appears not to be sufficient to cure the
> problem:

It seems that under some circumstances that grep wants to save a very
large chunk of the current file in a buffer, and that five times that
buffer is allocated when the buffers are expanded.  So when it tries to
look in:

	 532947  72608 -rwxr-xr-x    1 root     wheel     37136160 Oct 25 11:05 ./compile/SERVER_1/netbsd.gdb

it'll _could_ try to allocate up to 175MB...  A simple reproduction is:

	% dd if=/dev/zero of=/tmp/foo bs=1m count=8
	% limit data 8192
	% grep foo /tmp/foo
	grep: memory exhausted

The following patch limits the size of the save buffer to 2MB, which
means up to 10MB will be allocated.  I'm really not sure what the
implications of this are though - simple tests still seem to work ok.

I'll send something to the BUG bugs list and see what they say about

Index: grep.c
RCS file: /cvsroot/gnusrc/gnu/dist/grep/src/grep.c,v
retrieving revision 1.4
diff -p -u -r1.4 grep.c
--- grep.c	1999/04/06 16:54:55	1.4
+++ grep.c	1999/10/26 00:55:55
@@ -334,6 +334,9 @@ fillbuf (save, stats)
   caddr_t maddr;
+  /* limit save area to 2MB so that memory doesn't overflow on large files */
+  if (save > 2 * 1024 * 1024)
+    save = 2 * 1024 * 1024;
   if (save > bufsalloc)
       char *nubuffer;