X-Recipient: archive-cygwin AT delorie DOT com
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E1BC1397EC2C
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com;
	s=default; t=1625722980;
	bh=4r9nP75HQ0wzxMd+W+DeZl8nlZiAlbXeluv9Gy/XDw4=;
	h=Date:To:Subject:List-Id:List-Unsubscribe:List-Archive:List-Post:
	 List-Help:List-Subscribe:From:Reply-To:From;
	b=Ccy45s6oWyvAvW8L8p02j+y5Zd87OO5CBQ7AhQ06r8QUYk1J7LXJC7HteScoqB/MN
	 PM2CEWgKyMWXA2yYV2OKFqbY/ZZhPnhjJKx+/Uz2hhU/MPObyp7hwrYvvtemi/o3h0
	 hgw3AHueSjjoCR2+ZHOsKcTBpkgk3bTmFUCTE+oE=
X-Original-To: cygwin AT cygwin DOT com
Delivered-To: cygwin AT cygwin DOT com
DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 311BA383B825
Date: Thu, 08 Jul 2021 05:41:40 +0000
To: "cygwin AT cygwin DOT com" <cygwin AT cygwin DOT com>
Subject: fstream::open crashes if first file it ever opening is in /proc
Message-ID: <_022Gh93RaZBX0JIf3f3UuZ7mekqKNi9g4ap-KHKpAa_ppq6O8Y3WXBDUUCw6yK6KJCdfhrFhwGfbB-UZD5R0wmWa2Lo6ZE6glWt4JzyDns=@protonmail.com>
MIME-Version: 1.0
X-Spam-Status: No, score=-2.5 required=5.0 tests=BAYES_00, DKIM_SIGNED,
 DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, RCVD_IN_MSPIKE_H3,
 RCVD_IN_MSPIKE_WL, SPF_HELO_PASS, SPF_PASS,
 TXREP autolearn=ham autolearn_force=no version=3.4.4
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on
 server2.sourceware.org
X-BeenThere: cygwin AT cygwin DOT com
X-Mailman-Version: 2.1.29
List-Id: General Cygwin discussions and problem reports <cygwin.cygwin.com>
List-Archive: <https://cygwin.com/pipermail/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-request AT cygwin DOT com?subject=help>
List-Subscribe: <https://cygwin.com/mailman/listinfo/cygwin>,
 <mailto:cygwin-request AT cygwin DOT com?subject=subscribe>
From: Max Mikhanosha via Cygwin <cygwin AT cygwin DOT com>
Reply-To: Max Mikhanosha <max DOT mikhanosha AT protonmail DOT com>
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Sender: "Cygwin" <cygwin-bounces+archive-cygwin=delorie DOT com AT cygwin DOT com>

Fully updated Windows 10, with freshly downloaded Cygwin.

trying to compile google/benchmark does not work coz it can't read /proc/cpuinfo

Reduced test test program

#include <iostream>
#include <fstream>

int main (int argc, char **argv)
{
  if (argc > 1)
  {
    std::fstream booya ("whatever");
  }
  std::fstream f("/proc/cpuinfo");
  if (!f.is_open ()){
    std::cout << "Unable to open /proc/cpuinfo" << std::endl;
  }
  return 0;
}

Repro log


user AT MARS ~
$ g++ blah.cc

user AT MARS ~
$ ./a.exe    # this does not work
Unable to open /proc/cpuinfo

user AT MARS ~
$ ./a.exe foobar   # this works

user AT MARS ~
$ ldd a.exe
        ntdll.dll => /cygdrive/c/WINDOWS/SYSTEM32/ntdll.dll (0x7ffa5c790000)
        KERNEL32.DLL => /cygdrive/c/WINDOWS/System32/KERNEL32.DLL (0x7ffa5ab20000)
        KERNELBASE.dll => /cygdrive/c/WINDOWS/System32/KERNELBASE.dll (0x7ffa5a000000)
        cygwin1.dll => /usr/bin/cygwin1.dll (0x180040000)
        cyggcc_s-seh-1.dll => /usr/bin/cyggcc_s-seh-1.dll (0x3e6ea0000)
        cygstdc++-6.dll => /usr/bin/cygstdc++-6.dll (0x3be3a0000)
user AT MARS ~
$ cygcheck -f /usr/bin/cyggcc_s-seh-1.dll /usr/bin/cygstdc++-6.dll /usr/bin/cygwin1.dll
cygwin-3.2.0-1
libgcc1-10.2.0-1
libstdc++6-10.2.0-1



gdb shows that it crashes inside _newlib_flockfile_start(fp) as shown below


Thread 1 "a" hit Breakpoint 1, _fopen_r (ptr=0xffffd680,
    file=0x10040300a <std::piecewise_construct+10> "/proc/cpuinfo", mode=0x3be4a17bb "r+")
    at /usr/src/debug/cygwin-3.2.0-1/newlib/libc/stdio/fopen.c:119
119     {
(gdb) n
124       if ((flags = __sflags (ptr, mode, &oflags)) == 0)
(gdb) n
126       if ((fp = __sfp (ptr)) == NULL)
(gdb) n
129       if ((f = _open_r (ptr, file, oflags, 0666)) < 0)
(gdb) n
140       _newlib_flockfile_start (fp);
(gdb) n
      0 [main] a 4876 cygwin_exception::open_stackdumpfile: Dumping stack trace to a.exe.stackdump
[Thread 8800.0x4220 exited with code 35584]
[Thread 8800.0x1100 exited with code 35584]
[Thread 8800.0x1230 exited with code 35584]
[Thread 8800.0x3cc4 exited with code 35584]

Googling around found this https://sourceware.org/pipermail/newlib/2015/012649.html  which gave me idea to try opening normal file first to see if this fixes it, and it does, so likely this patch will fix this problem




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