Can gdb print the contents of the buffer written to by the C write() function?

Question

I have the following code:

write(fd[1], user_id, sizeof(user_id));

Is it possible to use gdb to see the contents of the buffer written to by this command? Using x or print just gives the memory address, not the contents of the buffer in that address.

(gdb) x write
0x7ffff7af4140 <__GI___libc_write>: 0xb1058d48

Since the fd[1] refers to stdout, this request should be equivalent to checking the status of the stdout buffer.

Additional info: user_id is a char array. fd[1] means write is writing to stdout (fd[0] refers to stdin). This is line 44 of a program, and I am accessing it with a breakpoint.

Answer 1

Let suppose you are interested in a variable user_id which is present at line 44 of file myfile.c of a program myprogram

write(fd[1], user_id, sizeof(user_id)); //line 44 of myfile.c

You must execute this :

gdb myprogram

Set breakpoint in gdb:

b myfile.c:44 

Run program (After this command the breakpoint will be reached):

run

Print your variable value:

p user_id

Answer 2

似乎没有这样的 GDB 功能。