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@MARS ~
$ g++ blah.cc
user@MARS ~
$ ./a.exe # this does not work
Unable to open /proc/cpuinfo
user@MARS ~
$ ./a.exe foobar # this works
user@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@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
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