Questions tagged [ltrace]
The ltrace tag has no usage guidance.
17
questions
1
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1
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Timing system call with ltrace: Adding `syscall` + `clock_gettime`?
I'm looking for some clarity in terms of the system calls. I tried avoiding the vDSO by calling a system call clock_gettime directly. Here is a snippet of a program named sys_clock_gettime.
int clock =...
- 177
4
votes
0
answers
252
views
Is there any solution to ltrace calls made by libs opened using dlopen()?
I wrote different two different types of queues. Bundled them in different .sos. I have a driver main.c which tests functions offered by those queues. main.c makes use dlfcn.h to load, unload required ...
- 45
0
votes
1
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1k
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Why ltrace doesn't show a call to glibc __nss_configure_lookup()
I'm trying to understand how ltrace command works.
So I've been poking around in /etc/nsswitch.conf. I have a "hosts: resolve" line in there - it tells glibc to dynamically load nss-resolve ...
- 11
2
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1
answer
1k
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Are there any alternatives to ltrace that does the same job?
ltrace doesn't work on binaries linked with the -z now option—Check this question—which is the default on my Ubuntu 19.10 system. It only works on binaries linked with -z lazy.
Is there any ...
- 181
3
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1
answer
1k
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Why do strace and ltrace cause EINTR to happen?
Consider this program:
#include <stdio.h>
#include <sys/epoll.h>
int main(void) {
int epfd = epoll_create1(0);
struct epoll_event event;
event.events = EPOLLIN;
...
1
vote
0
answers
350
views
Systemtap causes a segfault, why?
I'm trying to monitor library calls system-wide. I've written this script to trace library calls for libguestfs:
probe begin {
printf("ok\n")
}
probe process("/usr/lib64/libguestfs.so.0....
- 31
0
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1
answer
558
views
How to continuously check ltrace command output in C program [closed]
I'm trying to capture output of ltrace command using C program.
I have tried using popen() but that's not working, I need to capture continuously output not only once.
Below is my code:
#include &...
1
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2
answers
1k
views
vfork() calls SYS_vfork but fork() calls SYS_clone?
After running ltrace -S on two programs that were compiled by gcc (version 5.4.0), one that calls vfork() and one that calls fork(), I find that vfork() calls SYS_vfork whilst fork() calls SYS_clone. ...
- 113
3
votes
1
answer
1k
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System-wide monitoring of calls to a library function
I have a modern Linux desktop with lots of processes running concurrently. One of those processes, and I don't know which one, calls a function some_func from a popular dynamic library some_lib (think ...
- 1,857
3
votes
1
answer
445
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Can getauxval be used to determine whether or not you're being traced?
Coming off of this question, I patched my kernel in a quest to get SQL Server 2017 on Linux to start up. Now I'm getting further but I'm being shut down,
strstr("TracerPid:\t0\n", "TracerPid:") ...
- 32.3k
5
votes
2
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3k
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How do I hide TracerPID from a process?
I'm conjecturing SQL Server on Linux is checking /proc/self/status for TracerPID and then dying if it's not 0. I want to test that. Playing around, here is the strace,
... lots of stuff
openat(...
- 32.3k
2
votes
1
answer
2k
views
why does ltrace produce no output
For several days I have left this command running in a terminal emulator
ltrace -p `pgrep xfwm4`
while using the system normally, and I'm yet to see any output from ltrace. Note: xfwm4 is Xfce's ...
- 1,883
2
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0
answers
1k
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How to trace at runtime the symbols of loaded shared library?
I want to be able to know what are the symbols that are used from a certain shared library at runtime.
I use gdb and I set the solib-search-path to the user defined shared library. I am not sure if ...
- 307
6
votes
1
answer
1k
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ltracing shared libraries, how?
I would like to trace the function calls to a particular library, call it libfoo. Unfortunately the documentation I have found on it is sparse, so I have a lot of questions.
In the documentation of ...
- 2,047
9
votes
2
answers
4k
views
How to determine what instructions a process is executing?
I know about strace and ltrace, but that only tells me what system calls and library calls a process is executing, respectively. I would like to know exactly what instructions a process is executing. ...
- 195
2
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0
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2k
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How to trace calls to library from library?
I have an program that calls libcurl, and libcurl calls libgssapi_krb5.
If I want to debug calls to libcurl, then ltrace works.
But now I want to debug calls to libgssapi_krb5, then ltrace ...
- 763
10
votes
2
answers
9k
views
Which file in kernel specifies fork(), vfork()... to use sys_clone() system call
When ltrace is used for tracing the system calls, I could see that fork() uses sys_clone() rather than sys_fork(). But I couldn't find the linux source where it is defined.
My program is:
#include<...
- 4,408