Thread: fgets and gets

well, the function gets(), reads char until the user press <enter>, right?
the function fgets(), reads char from a file until apear '\n' or '\0'?
plz explain me this

Some of you know what buffer expliots are...
well....gets is the buggy one that is unsafe....even the compiler tells you i think...
and fgets...or something like that is a revised version...

In gets, you specified the buffer length.....
So lets say you said you got a size of 12....
AND
ANSI is encoded in basically, a character per a byte....
So you have a 12 byte buffer, + 4 bytes for prog stack ops, and then return address from call.
SO, using gets, you can convert assembly code instructions, and a return address to execute, in fact, the string in gets as assembly code.....
You can compile your assembly into object code and then dump it to get hex instructions, and then just tag on the return address(the address of gets in the buffer which can be found using GDB) and the program will execute you exploit code...
Basically, thats how a hack is made....
If your really good, you'll patch the stack during your exploit so the prog doesnt even know it did something wrong and wont segfault.....
fgets fixes that....or some other gets function....i dont remember.....c was a while back...

Fgets() and gets() are two different functions. Gets() is never a macro like printf() can be.

Originally Posted by iRMX® C Library Reference, on gets

The line consists of all characters up to and including the first newline character \n.
The gets( ) function replaces the newline character with a null character \0 before
returning the line.
The fgets( ) function retains the newline character.

fgets() also takes an aditional length paramitter. Prototypes:
char *fgets (char *string, int n, FILE *stream);
char *gets (char *buffer);