Why my asm code can not link with clock_gettime and attr_copy_fd?

问题

I am trying to compile a asm code disassembled from GNU coreutils.

In the asm code, I see this:

            extrn memchr@@GLIBC_2_0:near
            extrn clock_gettime@@GLIBC_2_0:near
            extrn attr_copy_fd@@ATTR_1_1:near

and I declare externs like this:

            extern attr_copy_fd 
        extern clock_gettime
          extern memchr

then asm like this:

   nasm -f elf final.s -o final.o
   gcc -W -o final final.o

And I got errors :

   final.o: In function `loc_804BD8D':
   final.s:(.text+0x2111): undefined reference to `attr_copy_fd'
   final.o: In function `gettime':
   final.s:(.text+0xdf06): undefined reference to `clock_gettime'

I think clock_gettime is defined in GLIBC and I don't know why linker can not find it(Other functions like memchr can be found by the linker)

What is worse, I don't know where is attr_copy_fd?

When building coreuitls from source code, you should link a static library libcoreutils.a

I tried to static link it as:

gcc -L/home/computereasy/work/lib/coreutils/coreutils-8.15/lib -lcoreutils -W -o final final.o

But nothing changed. and I don't think I should link libcoreutils.a because basically all the functions required in this binary from libcoreutils.a has been put into the disassemble code...

Could anyone give me some help on how to link the clock_gettime and attr_copy_fd ？

Thank you!

来源：https://stackoverflow.com/questions/21770827/why-my-asm-code-can-not-link-with-clock-gettime-and-attr-copy-fd

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