logo
Tags down

shadow

How can I debug functions in shared object libraries with GDB?


By : Ray Diansyah
Date : September 13 2020, 01:00 PM
it fixes the issue I'm trying to verify the functionality of functions in a shared object library. In programs with a main function, I would simply start the program and gdb would automatically breakpoint on main, but that's obviously not available here. , You can do so with starti, as shown below:
code :
(gdb) file libadd.so
Reading symbols from libadd.so...(no debugging symbols found)...done.
(gdb) starti
Starting program /tmp/minimal/libadd.so

Program stopped.
0x00007ffff7dfd4a0 in deregister_tm_clones ()
(gdb) call (long)add(5,6)
$1 = 11


Share : facebook icon twitter icon

How to runtime debug shared libraries?


By : Renaud H.
Date : March 29 2020, 07:55 AM
this one helps. You just need to call gdb with the executable (it does not matter if it is yours or a 3rd party one). Here is an example where I debug the ls command and set a breakpoint in the (shared) c library. This example uses gdb 6.8 which supports deferred (pending) breakpoints which makes this easy:
code :
gdb /bin/ls
GNU gdb 6.8-debian
Copyright (C) 2008 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-linux-gnu"...
(no debugging symbols found)
(gdb) b write
Function "write" not defined.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 1 (write) pending.
(gdb) r
Starting program: /bin/ls
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
[Thread debugging using libthread_db enabled]
(no debugging symbols found)
(no debugging symbols found)
[New Thread 0x7f98d2d23780 (LWP 7029)]
[Switching to Thread 0x7f98d2d23780 (LWP 7029)]

Breakpoint 1, 0x00007f98d2264bb0 in write () from /lib/libc.so.6
(gdb)
ps ux | grep tail
lothar    8496  0.0  0.0   9352   804 pts/3    S+   12:38   0:00 tail -f /tmp/ttt
lothar    8510  0.0  0.0   5164   840 pts/4    S+   12:39   0:00 grep tail

gdb
GNU gdb 6.8-debian
Copyright (C) 2008 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-linux-gnu"...
(no debugging symbols found)
(gdb) attach 8496
Attaching to program: /usr/bin/tail, process 8496
Reading symbols from /lib/librt.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/librt.so.1
Reading symbols from /lib/libc.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib/libc.so.6
Reading symbols from /lib/libpthread.so.0...(no debugging symbols found)...done.
[Thread debugging using libthread_db enabled]
[New Thread 0x7f24853f56e0 (LWP 8496)]
Loaded symbols for /lib/libpthread.so.0
Reading symbols from /lib/ld-linux-x86-64.so.2...
(no debugging symbols found)...done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
(no debugging symbols found)
0x00007f2484d2bb50 in nanosleep () from /lib/libc.so.6
(gdb) b write
Breakpoint 1 at 0x7f2484d57bb0
(gdb) c
Continuing.
[Switching to Thread 0x7f24853f56e0 (LWP 8496)]

Breakpoint 1, 0x00007f2484d57bb0 in write () from /lib/libc.so.6
(gdb)

error while loading shared libraries: libevent-1.4.so.2: cannot open shared object file:


By : coenroest
Date : March 29 2020, 07:55 AM
I wish this help you Your "A" system has a symlink from /usr/lib/libevent-1.4.so.2 to /usr/local/lib/libevent-1.4.so.2 but system "B" does not. Chances are, if you create it then everything will start working.
The command should be as follows.
code :
sudo ln -s /usr/local/lib/libevent-1.4.so.2 /usr/lib/libevent-1.4.so.2

Linux, Shared library uses functions from main program instead of other shared libraries


By : Brett Gese
Date : March 29 2020, 07:55 AM
should help you out I'm building a shared library that is loaded from an application (which I have no control of). My library uses other shared libraries which in turn uses other shared libraries, complex but not unusual. , The solution was to use RTLD_DEEPBIND in dlopen(3):

How to debug shared libraries compiled with debug information


By : Nilanko Halder
Date : March 29 2020, 07:55 AM
I wish this helpful for you al_load_bitmap@plt is the PLT stub (located in the main program, not the shared object), which does not have debugging information. You need to step over several instructions, then you'll reach the actual function, which hopefully has debugging information. You may also encounter the dynamic linker if lazy binding is active (it can be disabled with the LD_BIND_NOW=1 environment variable setting).
For these reasons, it is much easier to use the s (step) command to enter the function (if the called function has debugging information).

C, C++: Shared libraries: Are single functions or complete libraries loaded into memory?


By : Dave Spring
Date : March 29 2020, 07:55 AM
it should still fix some issue With static compilation, only the functions of a library which are actually needed by a program are linked to the program. How is that with shared libraries ?
Shared libraries are referenced by the program symbolically, that is, the program will identify, by name, the shared library it was linked with.
Related Posts Related Posts :
  • Importance of '0' character and << operator in this program
  • How to debug a quadratic probing implementation for hash tables in C without using pointers?
  • Pointer to Pointer in c, getting unexpected value
  • "Permission denied" in open() function in C
  • How to assign an array of structs
  • Sort an Array of struct by a value of a field inside the struct
  • Implement stack with pointers in c
  • C program that goes through a string and flags for non-letters
  • C while statement in switch clause
  • Can we allocate memory for char * but return it as const char *?
  • How do Comma-separated expressions as condition in a for-loop work?
  • Sort Structs by the value of an attribute in it
  • How should I make users to put in the info that I want?
  • Are bitmask checks more efficient than comparing numbers?
  • Are the fast integer types faster when stored in the CPU registers?
  • Does realloc deallocate before trying to allocate new memory?
  • Failing to compile a 15+ year old MUD codebase written in C
  • opendir dont get content of buffer char * on C language?
  • Can we have '+' operator inside printf()?
  • Why scanf function do not accept escape sequences as an input?
  • Print strings of length of k from a and b
  • C problem with passing pointer to struct to function
  • Shall I use register class variables in modern C programs?
  • Can I specify conditions for the rand() function?
  • C fprintf and fscanf saving game state
  • Fast formula to get the range a number is in, given a perfect binary subdivision?
  • Why can't I use more than two registers in inline asm?
  • A question of strstr() and fgets() in a demo from the book《Head First C》
  • the problem is from a algorithm problem I do recently,but I can't gain the right answer
  • Problem to access members in pointer struct located in another pointer struct
  • Check that all symbols defined in static library
  • Function will only properly work if I've printed the values of the attributes
  • Why my code is showing time limit exceeded
  • #define statement for address of memory
  • How to call a function from another .c file
  • Memory layout of C struct
  • Why should we use return statement when using a recursive call?
  • error: expected identifier or '(' before '=' token
  • Why is it not possible to exchange the position of array name and index in swift like C (a[i] == i[a])?
  • How can I allocate enough memory to store an entire text file in C?
  • Segmentation fault when I use afl fuzzer
  • What happens in the assembly output when we add "cc" to clobber list
  • What is the equivalent of Keil _at_ in gcc
  • Simple question about declaring an empty string in C
  • Heap-Overflow or Buffer-Overflow?
  • C: Why is &= better that =?
  • Create exactly 5 process with fork()
  • gcc compile function in ifdef
  • where is the memory leak in the code below?
  • Most efficient formula for unpacking 16-bit BCD? (e.g. 0x1234 to 0x01020304)
  • how to find which integer no is maximim out of given numbers
  • Difference between a VOID function with a string argument VS a function with a string argument that returns a char array
  • why the output of the following program different (random value) every time?
  • Why does this macro expression in C behave unexpectedly?
  • When is memory allocated and de-allocated static and dynamic memory in C?
  • In C, what happens if we left shift the bits out of range and again right shift the values in the same operation
  • why the following c program is giving segmentation error?
  • How can I run through all the characters of a string and check if they're all numbers in C?
  • adc frequency vs accuracy
  • why the output of following c program is 16 16 16?
  • shadow
    Privacy Policy - Terms - Contact Us © 35dp-dentalpractice.co.uk