Hi,
I'm having some trouble with a C project in a Linux system.
I already know which is the problem but I don't know how to fix it.
I have a program that links to a third party static library.
The problem is that the library declares a internal global variable
named 'accept' not visible by the user.
In my program I use the system Internet Sockets which API have a
function named 'accept'.
When I compile it does not complies but when I run the program it
segfaults because a call to Internet Sockets 'accept' function tries
to execute a function which address is the address of the 'accept'
global variable from the third party library.
I made a little source code that reproduce the problem with the
'printf' function. In this case the compiler gives me a warning, but
the beavior is equal.
Is this my problem? Is it a bug? I don't think a programer have to
know all possible system functions names...
I have three files:
mylib.c and mylib.h represents the third party library;
main.c is my program.
I also made a simple Makefile.
Here are the files:
---------------------------------------
$ cat mylib.h
int myfunc();
---------------------------------------
$ cat mylib.c
#include "mylib.h"
int printf[2];
int myfunc(){ // Just for example
printf[0] = 0;
return printf[1];
}
---------------------------------------
$ cat main.c
#include <stdio.h>
#include "mylib.h"
int main(){
printf("Helo World!");
return 0;
}
---------------------------------------
$ cat Makefile
exec: main mylib
gcc main.o mylib.o -o exec
main: main.c
gcc main.c -c -o main.o
mylib: mylib.c
gcc mylib.c -c -o mylib.o
---------------------------------------------------
And here are the results:
$ make
gcc main.c -c -o main.o
gcc mylib.c -c -o mylib.o
mylib.c:3: warning: built-in function 'printf' declared as non-
function
gcc main.o mylib.o -o exec
$ ./exec
Segmentation fault (core dumped)
$ gdb ./exec core
Core was generated by `./exec'.
Program terminated with signal 11, Segmentation fault.
#0 0x0000000000600 884 in printf ()
Thanks in advance,
Cristóvão Sousa
ISR - FCT - University of Coimbra
I'm having some trouble with a C project in a Linux system.
I already know which is the problem but I don't know how to fix it.
I have a program that links to a third party static library.
The problem is that the library declares a internal global variable
named 'accept' not visible by the user.
In my program I use the system Internet Sockets which API have a
function named 'accept'.
When I compile it does not complies but when I run the program it
segfaults because a call to Internet Sockets 'accept' function tries
to execute a function which address is the address of the 'accept'
global variable from the third party library.
I made a little source code that reproduce the problem with the
'printf' function. In this case the compiler gives me a warning, but
the beavior is equal.
Is this my problem? Is it a bug? I don't think a programer have to
know all possible system functions names...
I have three files:
mylib.c and mylib.h represents the third party library;
main.c is my program.
I also made a simple Makefile.
Here are the files:
---------------------------------------
$ cat mylib.h
int myfunc();
---------------------------------------
$ cat mylib.c
#include "mylib.h"
int printf[2];
int myfunc(){ // Just for example
printf[0] = 0;
return printf[1];
}
---------------------------------------
$ cat main.c
#include <stdio.h>
#include "mylib.h"
int main(){
printf("Helo World!");
return 0;
}
---------------------------------------
$ cat Makefile
exec: main mylib
gcc main.o mylib.o -o exec
main: main.c
gcc main.c -c -o main.o
mylib: mylib.c
gcc mylib.c -c -o mylib.o
---------------------------------------------------
And here are the results:
$ make
gcc main.c -c -o main.o
gcc mylib.c -c -o mylib.o
mylib.c:3: warning: built-in function 'printf' declared as non-
function
gcc main.o mylib.o -o exec
$ ./exec
Segmentation fault (core dumped)
$ gdb ./exec core
Core was generated by `./exec'.
Program terminated with signal 11, Segmentation fault.
#0 0x0000000000600 884 in printf ()
Thanks in advance,
Cristóvão Sousa
ISR - FCT - University of Coimbra