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Subject: |
Re: guile-1.5.6: some build comments: regcomp() behavior |
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Date: |
Mon, 1 Apr 2002 09:06:50 -0700 (MST) |
>> ...
>> Nelson> Sun Solaris 2.7 and 2.8:
>> Nelson> Testing
>> /export/staff/computing/beebe/i386/build/guile-1.5.6/pre-inst-guile ...
>> Nelson> with
>> GUILE_LOAD_PATH=/export/staff/computing/beebe/i386/build/guile-1.5.6/test-suite
>> Nelson> ERROR: regexp.test: regexp-substitute/global: ("" "" ""):
>> port is string port - arguments: ((regular-expression-syntax "make-regexp"
>> "empty (sub)expression" #f #f))
>> Nelson> ERROR: regexp.test: regexp-substitute/global: ("" "" ""):
>> port is #f - arguments: ((regular-expression-syntax "make-regexp" "empty
>> (sub)expression" #f #f))
>>
>> These errors are being passed through from the Solaris libc's
>> implementation of regcomp and regerror - apparently, its regcomp
>> doesn't handle empty expressions. Perhaps best just documented and
>> lived with, although we could probably code a workaround on the Scheme
>> level if we wanted to.
>> ...
I made a small test program, with one illegal pattern to regcomp(),
and one empty one, and then ran it on 16 or so platforms:
% cat regcomp.c
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <regex.h>
#include <errno.h>
#ifndef EXIT_SUCCESS
#define EXIT_SUCCESS 0
#endif
int
main(int argc, char* argv[])
{
int ret;
regex_t preg;
ret = regcomp(&preg, "[", 0);
if (ret != 0)
{
(void)printf("regcomp(&preg, \"[\", 0) returns %ld\n", ret);
perror("perror() says: ");
}
ret = regcomp(&preg, "", 0);
if (ret != 0)
{
(void)printf("regcomp(&preg, \"\", 0) returns %ld\n", ret);
perror("perror() says: ");
}
return (EXIT_SUCCESS);
}
Most platforms produced output like this:
cc regcomp.c && ./a.out
regcomp(&preg, "[", 0) returns 7
perror() says: : Error 0
Both Solaris 2.7 and 2.8 behaved this way.
However, two platforms, Apple Darwin (== MacOS X) and FreeBSD 4.4.0,
gave an error for the empty string:
% cc regcomp.c && ./a.out
regcomp(&preg, "[", 0) returns 7
perror() says: : Undefined error: 0
regcomp(&preg, "", 0) returns 14
perror() says: : Undefined error: 0
On HP-UX 10.01, a.out appeared to go into an infinite loop, and I had
to kill the xterm window to it, since it did not respond to Ctl-C.
That could be a different problem: that particular local system has a
history of suddenly becoming inaccessible, and at the moment, I cannot
get a fresh connection to it.
Based on these experiments, I recommend that guile should take special
care never to pass an empty pattern to regcomp().
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