On 9/6/2020 4:28 PM, Ken Brown via Cygwin wrote:
On 9/6/2020 3:47 PM, Ken Brown via Cygwin wrote:
On 9/6/2020 2:43 PM, David Dyck via Cygwin wrote:
This command triggers an assertion failure
"ag" is from the_silver_searcher
$ ag 2 <(echo 2)
assertion "p >= path" failed: file
"/home/corinna/src/cygwin/cygwin-3.1.7/cygwin-3.1.7-1.x86_64/src/newlib-cygwin/winsup/cygwin/path.cc",
line 3065, function: int symlink_info::check(char*, const
suffix_info*, fs_info&, path_conv_handle&)
Aborted (core dumped)
3473k 2020/08/22 C:\cygwin64\bin\cygwin1.dll
Cygwin DLL version info:
DLL version: 3.1.7
bash 4.4.12-3 OK
the_silver_searcher 2.2.0-1 OK
[...]
assertion "p >= path" failed: file
"/home/corinna/src/cygwin/cygwin-3.1.7/cygwin-3.1.7-1.x86_64/src/newlib-cygwin/winsup/cygwin/path.cc",
line 3065, function: int symlink_info::check(char*, const
suffix_info*, fs_info&, path_conv_handle&)
Aborted (core dumped)
[...]
I've reported this on github as an "ag" bug, but I think it is a bug in cygwin
An assertion failure in Cygwin code is a Cygwin bug. I'll take a look.
Running
bash -c '/usr/bin/ag 2 <(echo 2)'
under strace yields the following:
242 191767 [main] ag 33659 open: open(/dev/fd/63/.ignore, 0x0)
[...]
30 192584 [main] ag 33659 mount_info::conv_to_win32_path: src_path
/proc/self/fd/63/.ignore, dst /proc/self/fd/63/.ignore, flags 0x0, rc 0
[...]
31 193366 [main] ag 33659 mount_info::conv_to_win32_path:
conv_to_win32_path (pipe:[4295036184]/.ignore)
[...]
31 193550 [main] ag 33659 mount_info::conv_to_win32_path:
conv_to_win32_path (pipe:[4295036184])
[...]
34 193615 [main] ag 33659 symlink_info::check: 0xC0000034 = NtCreateFile
(\??\C:pipe:[4295036184])
The assertion fails because the path 'C:pipe:[4295036184]' doesn't contain a
backslash. But probably we should never have allowed ourselves to get to the
point of considering that path.
I've made some progress but haven't figured out the fix yet. First, for easier
debugging, here's a simpler way to reproduce the problem:
$ cat proc_bug.c
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
int
main ()
{
int fd[2];
char fname[100];
if (pipe (fd) < 0)
{
perror ("pipe");
exit (1);
}
sprintf (fname, "/dev/fd/%d/foo", fd[0]);
if (open (fname, O_RDONLY) < 0)
{
perror ("open");
exit (1);
}
}
$ gcc -o proc_bug proc_bug.c
$ ./proc_bug.exe
assertion "p >= path" failed: file
"../../../../newlib-cygwin/winsup/cygwin/path.cc", line 3065, function: int
symlink_info::check(char*, const suffix_info*, fs_info&, path_conv_handle&)
Aborted (core dumped)
Here's what happens. The program is trying to open /dev/fd/3/foo, where file
descriptor 3 is the read end of a pipe. path_conv check resolves this to
/proc/<pid>/fd/3/foo, creates an fhandler_process for this path, and calls (at
path.cc:782) fhandler_process::exists. The latter fills the filebuf with
"pipe:[xxxxxxxxxx]/foo" and returns virt_fsdir. We're now at path.cc:808, and
everything is set up for the assertion failure.
I think fhandler_process::exists is not doing the right thing here, but I'm not
familiar with this part of the code, so I'll have to stare at it for a while to
see what's going wrong.
Corinna, if you are able to see it more quickly and want to go ahead and fix it,
you won't hurt my feelings.
Ken
--
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
