linux write system call and libc

Question

in linux, 'write' is a small system call wapper function.

in GDB. if I search for symbol 'write' (info addr write) GDB tells me an address which is in range of libc. but, when I check the export function list of libc there is no 'write' symbol.

what is happening here?

Maxim Egorushkin · Accepted Answer · 2012-12-06T18:28:40.927

3

when I check the export function list of libc there is no 'write' symbol.

Let's have a look:

[max@xxx:~/tmp] $ nm --dynamic --defined-only /lib64/libc-2.15.so | grep write
0000003c7a4f1990 T eventfd_write
0000003c7a46c540 W fwrite
0000003c7a475570 T fwrite_unlocked
0000003c7a476d50 T _IO_do_write
0000003c7a475fa0 T _IO_file_write
0000003c7a46c540 T _IO_fwrite
0000003c7a471d10 T _IO_wdo_write
0000003c7a4e3060 T __libc_pwrite
0000003c7a4f2310 T process_vm_writev
0000003c7a4e3060 W pwrite
0000003c7a4e3060 W pwrite64
0000003c7a4e3060 W __pwrite64
0000003c7a4ea520 T pwritev
0000003c7a4ea520 T pwritev64
0000003c7a4e4940 W write
0000003c7a4e4940 W __write
0000003c7a4ea3d0 W writev

edited Dec 06 '12 at 18:28

answered Dec 06 '12 at 17:12

Maxim Egorushkin

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thank you! but when I open the binary with IDA, the write function is not listed in export section... – daehee Dec 12 '12 at 05:45
@daehee I am not familiar with IDA. – Maxim Egorushkin Dec 12 '12 at 08:44

linux write system call and libc

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