X-Recipient:	archive-cygwin AT delorie DOT com
DomainKey-Signature:	a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:to:from:subject:date:message-id; q=dns; s=
	default; b=ucTwvUUuBe84dgrTKexJBfW8wXdSCKG2YE+PhEdzqWY5WGlHhbI4o
	oDXbPB0o6/IRSn4kFFpLniZsUNxr19WEgDBosrSSkpXOSmg4+bhgUY7bwK6byTnV
	+3ncqySD1Fb2mGnC6D4ZK5hVDzKcCS1jtfxT7hT79PPlfRzbYZon1s=
DKIM-Signature:	v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:to:from:subject:date:message-id; s=default;
	bh=qm+RdSod5xofTeaRO5Ohs4czx2o=; b=rTwzzZXde4i8fbo61sC5i/BTGlrl
	aHL82MYvtCFvKhqCPSbrcwgtuuuvbk2v0DSWGxrHp+9R/+szqOJO6mZIzGNrgRUW
	1UpQAySIkd/GFpW9SJf2rkPINXu9qUudtzzput4xE0oTnp7b2T4gpZDCJ0t59gKP
	DHnQtlubTv1VmlI=
Mailing-List:	contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Id:	<cygwin.cygwin.com>
List-Subscribe:	<mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive:	<http://sourceware.org/ml/cygwin/>
List-Post:	<mailto:cygwin AT cygwin DOT com>
List-Help:	<mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender:	cygwin-owner AT cygwin DOT com
Mail-Followup-To:	cygwin AT cygwin DOT com
Delivered-To:	mailing list cygwin AT cygwin DOT com
Authentication-Results:	sourceware.org; auth=none
X-Virus-Found:	No
X-Spam-SWARE-Status:	No, score=-1.2 required=5.0 tests=AWL,BAYES_00,SPF_PASS autolearn=ham version=3.3.2
X-HELO:	na3sys009aog107.obsmtp.com
To:	cygwin AT cygwin DOT com
From:	David Levine <levinedl AT acm DOT org>
Subject:	nested popen()'s lead to fgets() failure on 64-bit only
Date:	Sun, 12 Jan 2014 21:15:59 -0500
Message-ID:	<18833-1389579359.738859@Poig.bVYt.cj35>

Hi,

The program below works just fine on 32-bit Cygwin:
  buf1 = /usr/bin/file.exe
  buf2 = /usr/bin/file.exe: application/x-dosexec

But on 64-bit Cygwin (2.831), the second fgets() fails:
  buf1 = /usr/bin/file.exe
fgets2: No error

It only seems to happen with nested popen()'s.  Is it due to a
problem in the Cygwin lib?

Thanks,
David


#include <stdio.h>

int
main() {
  FILE *f1, *f2;

  if ((f1 = popen("ls /usr/bin/file.exe", "r"))) {
    char buf1[BUFSIZ];

    while (fgets(buf1, sizeof buf1, f1)) {
      printf("  buf1 = %s", buf1);

      if ((f2 = popen("file --mime-type /usr/bin/file.exe", "r"))) {
        char buf2[BUFSIZ];

        /* This fgets call fails on 64-bit Cygwin, with "No error". */
        if (fgets(buf2, sizeof buf2, f2)) {
          printf("  buf2 = %s", buf2);
        } else {
          perror("fgets2");
        }

        pclose(f2);
      } else {
        perror("popen2");
      }
    }

    pclose(f1);
  } else {
    perror("popen1");
  }

  return 0;
}

--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple

- Raw text -