I've been messing around with libspotify for a while now but I get a segmentation fault every once in a while when I call the sp_session_logout() API.
I did a test that does the following loop:
Create a session
Login
Logout
Release the session
It usually crashes after 3-4 iterations.
The code and the stdout can be found here:
https://gist.github.com/jonas-lundqvist/4bb759a1f1ed09de46a1
Compiled with:
gcc -std=gnu99 -g -Wall `pkg-config --cflags libspotify` -o test_login_logout login_logout.c appkey.c cred.c -lpthread `pkg-config --libs libspotify`
I noticed however that two threads was created in the start of each iteration, but only one exited.
This is the output from gdb
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7ffff7fbf700 (LWP 31308)]
[New Thread 0x7ffff7f3e700 (LWP 31309)]
[Thread 0x7ffff7f3e700 (LWP 31309) exited]
[New Thread 0x7ffff7f3e700 (LWP 31310)]
[New Thread 0x7ffff7ebd700 (LWP 31311)]
[Thread 0x7ffff7ebd700 (LWP 31311) exited]
[New Thread 0x7ffff7ebd700 (LWP 31313)]
[New Thread 0x7ffff6638700 (LWP 31314)]
[Thread 0x7ffff6638700 (LWP 31314) exited]
[New Thread 0x7ffff6638700 (LWP 31315)]
[New Thread 0x7ffff65b7700 (LWP 31316)]
Program received signal SIGSEGV, Segmentation fault.
Inspecting the threads I can see:
Id Target Id Frame
9 Thread 0x7ffff65b7700 (LWP 31316) "Network Thread" 0x00007ffff744b50d in poll () at ../sysdeps/unix/syscall-template.S:81
8 Thread 0x7ffff6638700 (LWP 31315) "Dns Thread" 0x00007ffff744b50d in poll () at ../sysdeps/unix/syscall-template.S:81
6 Thread 0x7ffff7ebd700 (LWP 31313) "Dns Thread" sem_wait ()
at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:85
4 Thread 0x7ffff7f3e700 (LWP 31310) "Dns Thread" sem_wait ()
at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:85
2 Thread 0x7ffff7fbf700 (LWP 31308) "Dns Thread" sem_wait ()
at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:85
* 1 Thread 0x7ffff7fc1700 (LWP 31304) "test_login_logo" 0x00007ffff77eb5ac in ?? () from /home/jonas/lib/libspotify/lib/libspotify.so.12
And if I pick on of the threds created in one of the iterations I can see this:
[Switching to thread 4 (Thread 0x7ffff7f3e700 (LWP 31310))]
#0 sem_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:85
85 ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S: No such file or directory.
#0 sem_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:85
#1 0x00007ffff780c1f8 in ?? () from /home/jonas/lib/libspotify/lib/libspotify.so.12
#2 0x00007ffff77c608d in ?? () from /home/jonas/lib/libspotify/lib/libspotify.so.12
#3 0x00007ffff7bc70a4 in start_thread (arg=0x7ffff7f3e700) at pthread_create.c:309
#4 0x00007ffff745404d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
Unfortunatley the libspotify development seems quite dead, but does anybody know if there is a work around?
I need to be able to do multiple sp_session_create()/sp_session_release() in my application...
Edit: bt of the crashing thread (from another, yet similar, run)
#0 0x00007ffff77eb5ac in ?? () from /home/jonas/lib/libspotify/lib/libspotify.so.12
#1 0x00007ffff7860b5a in ?? () from /home/jonas/lib/libspotify/lib/libspotify.so.12
#2 0x00007ffff781683f in ?? () from /home/jonas/lib/libspotify/lib/libspotify.so.12
#3 0x00007ffff7817141 in ?? () from /home/jonas/lib/libspotify/lib/libspotify.so.12
#4 0x00007ffff78add7d in sp_session_logout () from /home/jonas/lib/libspotify/lib/libspotify.so.12
#5 0x0000000000400d51 in main (argc=1, argv=0x7fffffffe3a8) at login_logout.c:99
Related
I simply try to open a file through a dialog using Gtk3. This is the code I am using, no modifications at all:
https://docs.gtk.org/gtk3/class.FileChooserNative.html#typical-usage-gtkfilechoosernative-typical-usage
The window opens fine but when I try to open the file, it segfaults. According to gdb:
Thread 1 "a.out" received signal SIGSEGV, Segmentation fault.
__strlen_avx2 () at ../sysdeps/x86_64/multiarch/strlen-avx2.S:76
76 VPCMPEQ (%rdi), %ymm0, %ymm1
Using debuginfod of course. What am I doing wrong?
EDIT: Some backtrace from gdb:
(gdb) bt
#0 __strlen_avx2 () at ../sysdeps/x86_64/multiarch/strlen-avx2.S:76
#1 0x00007ffff7e1b948 in __GI__IO_puts (str=0x0) at ioputs.c:35
#2 0x00005555555551d6 in main (argc=1, argv=0x7fffffffdb28) at main.c:6
I have a project in C which I am compiling with gcc. It sometimes shows a segmentation fault when run and sometimes it doesn't. When run with gcc $ gdb -q ./build/program, it does not show any errors. After doing a bit of research, I found this question on stack overflow. Setting (gdb) set disable-randomization off does allow me to see the segmentation fault in gdb. However, I have no clue what address space randomization does and where should I look to find the problem. Is there a particular tool or a particular type of construct that I should look into?
I am also including the backtrace here for more context:
(gdb) set disable-randomization off
(gdb) run -n 10 -s 10
Starting program: /path/to/code/build/exact_diag_simulation -n 10 -s 10
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".
Exact Diagonalization
---------------------
len: 10 nospin: 0 coupling: 0.00e+00
disorder: 1.00e+01 hopping: 1.00e+00
Starting Simulation for Exact Diagonalization...
Run 1 started...[New Thread 0x7f4e34bff6c0 (LWP 12972)]
[New Thread 0x7f4e343fe6c0 (LWP 12973)]
[New Thread 0x7f4e33bfd6c0 (LWP 12974)]
[New Thread 0x7f4e333fc6c0 (LWP 12975)]
[New Thread 0x7f4e32bfb6c0 (LWP 12976)]
[New Thread 0x7f4e323fa6c0 (LWP 12977)]
[New Thread 0x7f4e31bf96c0 (LWP 12978)]
Thread 1 "exact_diag_simu" received signal SIGSEGV, Segmentation fault.
0x00007f4e75934a02 in zgemv_n_SKYLAKEX () from /usr/lib/libblas.so.3
(gdb) bt
#0 0x00007f4e75934a02 in zgemv_n_SKYLAKEX () from /usr/lib/libblas.so.3
#1 0x00007f4e74ff550c in zgemv_ () from /usr/lib/libblas.so.3
#2 0x00007f4e76772142 in zlatrd_ () from /usr/lib/liblapack.so.3
#3 0x00007f4e766f3ba0 in zhetrd_ () from /usr/lib/liblapack.so.3
#4 0x00007f4e766ea105 in zheev_ () from /usr/lib/liblapack.so.3
#5 0x00007f4e77195e07 in LAPACKE_zheev_work () from /usr/lib/liblapacke.so.3
#6 0x00007f4e77195fba in LAPACKE_zheev () from /usr/lib/liblapacke.so.3
#7 0x00005612184a3287 in utils_get_eigh (matrix=0x7f4e3135c010, size=200, eigvals=0x561218f1a0c0)
at src/utils/utils.c:273
#8 0x00005612184a27c4 in run (params=0x7fffa9f5ffd0, create_neighbours=1, gfunc=0x7f4e74ee1010)
at src/exact_diag_simulation.c:155
#9 0x00005612184a2577 in main (argc=5, argv=0x7fffa9f60348) at src/exact_diag_simulation.c:103
I have compiled with the following flags in my makefile:
CFLAGS=-Wall -Wextra -g -fdiagnostics-color=always -fopenmp -ffast-math -fsanitize=address,undefined
LFLAGS=-llapacke -lm -lgsl -lcblas
On MinGW's GDB (7.6.1) I sometimes run into the problem that a SegFault does not leave much useful information on the stacks (see transcript below).
For the error in the transcript I know why it occured: I called fseeki64 with a bad value as file-pointer. The fseeki64 does appear in the stack-trace but I cant see which part of my program indirectly called it.
I dont want to see the Microsoft symbols, I want to see the part of the stack that belongs to my program (which was compiled with -g).
Since I dont run into SegFaults often, my current workaround is some manual labor: 'next' through main (spamming enter) to find out which top-level function was responsible, restart, 'step' (spamming enter) through that function until the segfault.
GNU gdb (GDB) 7.6.1
Copyright (C) 2013 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 "mingw32".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from A:\prj\lib\fileBuffer\test.exe...done.
(gdb) r
Starting program: A:\prj\lib\fileBuffer/test.exe
[New Thread 3408.0x4094]
[New Thread 3408.0x3e40]
[New Thread 3408.0x4c14]
[New Thread 3408.0x5754]
Program received signal SIGSEGV, Segmentation fault.
0x77e2b2e3 in ?? ()
(gdb) info thr
Id Target Id Frame
4 Thread 3408.0x5754 0x77e5396c in ?? ()
3 Thread 3408.0x4c14 0x77e5396c in ?? ()
2 Thread 3408.0x3e40 0x77e5396c in ?? ()
* 1 Thread 3408.0x4094 0x77e2b2e3 in ?? ()
(gdb) where
#0 0x77e2b2e3 in ?? ()
#1 0x74d38384 in msvcrt!__p__iob () from C:\WINDOWS\SysWOW64\msvcrt.dll
#2 0x000000f4 in ?? ()
#3 0x000000d4 in ?? ()
#4 0x0063fd88 in ?? ()
#5 0x74d43175 in msvcrt!_fseeki64 () from C:\WINDOWS\SysWOW64\msvcrt.dll
#6 0x000000d4 in ?? ()
#7 0x0ab2d946 in ?? ()
#8 0x00000000 in ?? ()
(gdb) thr 2
[Switching to thread 2 (Thread 3408.0x3e40)]
#0 0x77e5396c in ?? ()
(gdb) where
#0 0x77e5396c in ?? ()
#1 0x75588744 in KERNEL32!BaseThreadInitThunk () from C:\WINDOWS\SysWOW64\kernel32.dll
#2 0x77e4582d in ?? ()
#3 0x77e457fd in ?? ()
#4 0x00000000 in ?? ()
(gdb) thr 3
[Switching to thread 3 (Thread 3408.0x4c14)]
#0 0x77e5396c in ?? ()
(gdb) where
#0 0x77e5396c in ?? ()
#1 0x75588744 in KERNEL32!BaseThreadInitThunk () from C:\WINDOWS\SysWOW64\kernel32.dll
#2 0x77e4582d in ?? ()
#3 0x77e457fd in ?? ()
#4 0x00000000 in ?? ()
(gdb) thr 4
[Switching to thread 4 (Thread 3408.0x5754)]
#0 0x77e5396c in ?? ()
(gdb) where
#0 0x77e5396c in ?? ()
#1 0x75588744 in KERNEL32!BaseThreadInitThunk () from C:\WINDOWS\SysWOW64\kernel32.dll
#2 0x77e4582d in ?? ()
#3 0x77e457fd in ?? ()
#4 0x00000000 in ?? ()
(gdb)
I'm using gdb-7.11.1 and I get this message on my embedded powerpc system. Some more background, the libpthread I use has been stripped off all the non-dynamic symbols, including nptl_version, which libthread_db uses to make sure it is compatible with libpthread.
Coming to my problem, gdb says it won't be able to debug threads, but it seemingly can as evidenced below. Am I simply misunderstanding what 'thread debugging' means? (The ?? you see are naturally due to the missing symbol table in libpthread)
(gdb) break fn2
Breakpoint 1 at 0x1000052c: file test.c, line 7.
(gdb) run
Starting program: /tmp/test
warning: Unable to find libthread_db matching inferior's thread library, thread debugging will not be available.
[New LWP 21312]
[New LWP 21313]
[New LWP 21314]
[New LWP 21315]
[New LWP 21316]
[New LWP 21317]
[Switching to LWP 21315]
Thread 5 hit Breakpoint 1, fn2 () at test.c:7
7 test.c: No such file or directory.
(gdb) thread apply all bt
Thread 7 (LWP 21317):
#0 0x0fdcf030 in ?? () from /lib/libpthread.so.0
#1 0x0fdc892c in pthread_mutex_lock () from /lib/libpthread.so.0
#2 0x00000000 in ?? ()
Thread 6 (LWP 21316):
#0 0x0fdcf030 in ?? () from /lib/libpthread.so.0
#1 0x0fdc892c in pthread_mutex_lock () from /lib/libpthread.so.0
#2 0x00000000 in ?? ()
Thread 5 (LWP 21315):
#0 fn2 () at test.c:7
#1 0x0fdc6d8c in ?? () from /lib/libpthread.so.0
#2 0x0fd26074 in clone () from /lib/libc.so.6
Thread 4 (LWP 21314):
#0 0x0fdcf030 in ?? () from /lib/libpthread.so.0
#1 0x0fdc892c in pthread_mutex_lock () from /lib/libpthread.so.0
#2 0x00000000 in ?? ()
Thread 3 (LWP 21313):
#0 0x0fdcf030 in ?? () from /lib/libpthread.so.0
#1 0x0fdc892c in pthread_mutex_lock () from /lib/libpthread.so.0
#2 0x00000000 in ?? ()
Thread 2 (LWP 21312):
#0 0x0fdcefdc in ?? () from /lib/libpthread.so.0
#1 0x0fdc892c in pthread_mutex_lock () from /lib/libpthread.so.0
#2 0x00000000 in ?? ()
Thread 1 (LWP 21309):
#0 0x0fd26038 in clone () from /lib/libc.so.6
#1 0x0fdc5f2c in ?? () from /lib/libpthread.so.0
#2 0x0fde6150 in ?? () from /lib/libpthread.so.0
#3 0x0fdc6424 in pthread_create () from /lib/libpthread.so.0
#4 0x100006a4 in main () at test.c:23
(gdb)
On Linux (at least, and others), an important part of the threading library is implemented in the kernel: that the "kernel-thread", called LWPs (for light-weight process).
GDB doesn't need libthread_db help to track them, as the OS itself can give the information the key information about them: their CPU registers (mainly IP, SP, FP).
I'm not sure what libthread_db provides in that context. The only thing I can think of is the LWP <-> Thread id mapping:
* 3 Thread 0x7ffff6d19700 (LWP 21571) "erato" primes_computer_runner2 (param=0x7fffffffca50) at erato.c:46
1 Thread 0x7ffff7fad700 (LWP 21565) "erato" 0x00007ffff7bc568d in pthread_join () from /usr/lib/libpthread.so.0
(gdb) print/x thread_handle
$1 = 0x7ffff6d19700
See, Thread 0x7ffff7fad700 maps to LWP 21565.
In comparison, without libthread_db it just gives the LWP id (in another run):
* 3 LWP 22060 "erato" primes_computer_runner2 (param=0x7fffffffca50) at erato.c:46
1 LWP 22058 "erato" 0x00007ffff76037b1 in clone () from /usr/lib/libc.so.6
If you want further details about pthread_db purpose, and why it's mandatory (or something equivalent) for user and hybrid threading libraries, you can take a look at this article I wrote several years ago:
User Level DB: a Debugging API for User-Level Thread Libraries
The common cause for this error message:
Unable to find libthread_db matching inferior's thread library, ...
is having libpthread.so.0 that is fully stripped. Don't do that.
In particular, libthread_db.so needs nptl_version (local) symbol. You can verify whether your libpthread.so.0 has it with:
nm /path/to/libpthread.so.0 | grep version
which should produce something like:
0000000000012cc6 r nptl_version
Does anyone know a way to go from a pthread_t to what GDB displays with info threads?
So I have:
(gdb) info threads
37 Thread 22887 0xb7704422 in __kernel_vsyscall ()
36 Thread 22926 0xb7704422 in __kernel_vsyscall ()
35 Thread 22925 0xb7704422 in __kernel_vsyscall ()
34 Thread 22924 0xb7704422 in __kernel_vsyscall ()
33 Thread 22922 0xb7704422 in __kernel_vsyscall ()
32 Thread 22921 0xb7704422 in __kernel_vsyscall ()
(gdb) p m_messageQueue->m_creationThread
$3 = 2694822768
(gdb) p/x m_messageQueue->m_creationThread
$4 = 0xa09fbb70
Does anyone know how I figure out which thread this is? It would appear to be 22768, but none of my threads go that low.
New versions of GDB actually output the value of pthread_t in the info thread, making association of pthread_t with thread number trivial.
For example, using GDB 7.0:
cat t.c
#include <pthread.h>
void *fn(void *p)
{
sleep(180);
}
int main()
{
pthread_t pth1, pth2;
pthread_create(&pth1, 0, fn, 0);
pthread_create(&pth2, 0, fn, 0);
pthread_join(pth1, 0);
return 0;
}
gcc -g -m32 -pthread t.c && gdb -q ../a.out
(gdb) r
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
[New Thread 0xf7e56b90 (LWP 25343)]
[New Thread 0xf7655b90 (LWP 25344)]
Program received signal SIGINT, Interrupt.
0xffffe405 in __kernel_vsyscall ()
(gdb) info thread
3 Thread 0xf7655b90 (LWP 25344) 0xffffe405 in __kernel_vsyscall ()
2 Thread 0xf7e56b90 (LWP 25343) 0xffffe405 in __kernel_vsyscall ()
* 1 Thread 0xf7e576b0 (LWP 25338) 0xffffe405 in __kernel_vsyscall ()
(gdb) up 2
#2 0x080484e2 in main () at t.c:13
13 pthread_join(pth1, 0);
(gdb) p/x pth1
$1 = 0xf7e56b90 ## this is thread #2 above
(gdb) p/x pth2
$2 = 0xf7655b90 ## this is thread #3 above
The value of pthread_t is not the same as that thread's system dependent thread id (in Linux gettid(2)) which you see in GDB.
AFAIK, there isn't any function to convert between the two. You need to keep track of that yourself.