🚀 go-pugleaf

>
>I have been looking at the documentation for ld 2.0 and it would appear
>that a fairly powerful command language comes with this linker. This has me
>to wondering whether the question of remapping (not an accurate term, but
>it will do for now) of library/system calls in a fairly portable manner is
>possible using gld.
>
>Basically what I want to do is create and link in a routine called, say,
>my_read() which would be called in place of *any and all* calls (including
>libc calls!)  to the real read().  The tricky part is that my_read() will
>at some point be calling the real read().
>
>Any info/tips/advice greatly appreciated.


Ok, no problem:

Just link thus:

ld  -defsym _real_read=_read -defsym _read=_my_read  ...

Here's an example on the sparc:

sac@thepub$ cat e.c


read()
{
printf("read called\n");
}
sac@thepub$ cat r.c


my_read ()
{
  printf("my read called\n");
  real_read ();
  printf("my read done\n");
}
sac@thepub$ cat t.c


main ()
{
  printf("calling read\n");
  read ();
  printf("done\n");
  return 0;
}

sac@thepub$ cc -c t.c r.c e.c
t.c:
r.c:
e.c:
sac@thepub$ ld -o foo  -defsym _real_read=_read -defsym _read=_my_read  /lib/crt0.o e.o r.o t.o -lc
ld -o foo  -defsym _real_read=_read -defsym _read=_my_read  /lib/crt0.o e.o r.o t.o -lc
sac@thepub$ ./foo
calling read
my read called
read called
my read done
done



Steve