gdb symbolic link bug

gdb symbolic link bug

[Carter, Mark Andrew (Andy)]

Gdb will not run an executable when it is a symbolic link in the post Cygwin release 3.1.5 form.  As seen below I am currently running Cygwin 3.1.7.  I have confirmed this is due to the change of the "ln -s" implementation.  Links created by Cygwin 2.8 and 3.1.0 work with this gdb version, and links created with Cygwin 3.1.7 do not work with gdb from Cygwin release 2.8.  The following capture demonstrates the issue.  Note the workaround using readlink!

$ uname -a
CYGWIN_NT-10.0 P1163-8573-10 3.1.7(0.340/5/3) 2020-08-22 17:48 x86_64 Cygwin

$ ls -l vital.exe
lrwxrwxrwx 1 p00002737 Domain Users 18 Oct 19 06:59 vital.exe -> ../vital/vital.exe

$ gdb vital.exe
GNU gdb (GDB) (Cygwin 8.2.1-1) 8.2.1
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-pc-cygwin".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from vital.exe...done.
(gdb) r
Starting program: /home/p00002737/vital/tap/vital.exe
Error creating process /home/p00002737/vital/tap/vital.exe, (error 1920).
(gdb) quit

$ gdb `readlink vital.exe`
GNU gdb (GDB) (Cygwin 8.2.1-1) 8.2.1
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-pc-cygwin".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from ../vital/vital.exe...done.
(gdb) r
Starting program: /home/p00002737/vital/vital/vital.exe
[New Thread 54032.0xc1e8]
[New Thread 54032.0x10e4]
[New Thread 54032.0xdee8]
[New Thread 54032.0xcd20]
[New Thread 54032.0x8e60]
[New Thread 54032.0xc378]

Thread 6 received signal SIGINT, Interrupt.
[Switching to Thread 54032.0xc378]
0x00007fff3b4b5a03 in TlsGetValue () from /cygdrive/c/WINDOWS/System32/KERNELBASE.dll
(gdb)

Re: gdb symbolic link bug

[Brian Inglis]

On 2021-11-19 08:08, Carter, Mark Andrew (Andy) via Cygwin wrote:
> Gdb will not run an executable when it is a symbolic link in the post
> Cygwin release 3.1.5 form. As seen below I am currently running 
> Cygwin 3.1.7. I have confirmed this is due to the change of the "ln 
> -s" implementation. Links created by Cygwin 2.8 and 3.1.0 work with 
> this gdb version, and links created with Cygwin 3.1.7 do not work 
> with gdb from Cygwin release 2.8. The following capture demonstrates
> the issue.  Note the workaround using readlink!
> $ uname -a
> CYGWIN_NT-10.0 P1163-8573-10 3.1.7(0.340/5/3) 2020-08-22 17:48 x86_64 Cygwin
> $ ls -l vital.exe
> lrwxrwxrwx 1 p00002737 Domain Users 18 Oct 19 06:59 vital.exe -> ../vital/vital.exe
> $ gdb vital.exe
> Reading symbols from vital.exe...done.
> (gdb) r
> Starting program: /home/p00002737/vital/tap/vital.exe
> Error creating process /home/p00002737/vital/tap/vital.exe, (error 1920).
> (gdb) quit
> $ gdb `readlink vital.exe`
> Reading symbols from ../vital/vital.exe...done.
> (gdb) r
> Starting program: /home/p00002737/vital/vital/vital.exe
> [New Thread 54032.0xc1e8]
> [New Thread 54032.0x10e4]
> [New Thread 54032.0xdee8]
> [New Thread 54032.0xcd20]
> [New Thread 54032.0x8e60]
> [New Thread 54032.0xc378]
> Thread 6 received signal SIGINT, Interrupt.
> [Switching to Thread 54032.0xc378]
> 0x00007fff3b4b5a03 in TlsGetValue () from /cygdrive/c/WINDOWS/System32/KERNELBASE.dll
> (gdb)

Cygwin is a rolling release system where only current releases are 
supported: Cygwin 3.3.2 and gdb 10.2.
Please update Cygwin and gdb to currently supported releases (and if 
possible rebuild the exe with current compilers and libraries) to see if 
the bug has been fixed or can still be reproduced.

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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