Re: miscellaneous patch questions...

[Geoff Keating <geoffk@ozemail.com.au>]

> Date: Sun, 16 Aug 1998 00:40:32 -0400
> From: Dan Jacobowitz <drow@false.org>

...
> Second, chown.  I understand why we do not want to propogate the ugly
> i386 fix to PPC, but without it a glibc built against recent kernel
> headers requires a recent kernel to work.  That's a problem; I would
> like for Debian to support the stable powerpc kernel also, which is
> still 2.1.24.  So is there a better solution forthcoming?

I have a better solution here, which I'm attaching; but I have never
run this code, so I don't want to put it in the distribution just yet
:-).  Feel free to help test it for me.

There are a few other patches in the pipeline.  At present, I'm trying
to find a problem with signals in linuxthreads; ex2 deadlocks for no
apparent reason (it's losing a SIGUSR1 signal, which is being sent and
received :-(. ).

> And last, is there a particular reason why the /usr/bin/ldd shell
> script prints an error message if you do not have execute permissions
> for the file in question?  Could we either (preferably) remove this
> warning, or at least add the >&2 so it gets sent to stderr?  This is
> necessary for the script 'dpkg-shlibdeps' which parses the output of
> ldd on shared libraries, which are not required to have execute
> permission set.

Generally, things that are trying to determine shared library
dependencies should use something like objdump, not ldd:

objdump -p $f | awk '/ NEEDED / { print $2 }'

prints out the libraries required.  For a proper dependency-checker,
you should also reference the program's interpreter, and maybe even
handle RPATH entries.

The problem with using ldd is that if an executable uses a shared
library 'libA' that uses another shared library 'libB', libB is noted
as a dependency of the executable.  If libA is then upgraded or
changed to require a different library libC, libB still has to be
installed, even if it conflicts with libC.


-- 
Geoffrey Keating <geoffk@ozemail.com.au>

===File ~/patches/glibc-16.diff=============================
1998-08-09  Geoff Keating  <geoffk@ozemail.com.au>

	* sysdeps/unix/sysv/linux/powerpc/chown.c: New file.
	* sysdeps/unix/sysv/linux/powerpc/lchown.S: New file.
	* sysdeps/unix/sysv/linux/powerpc/syscalls.list: Add chown, remove
	getresuid, getresgid.

diff -x *~ -urN glibc-2.0.95-old/sysdeps/unix/sysv/linux/powerpc/chown.c glibc-2.0.95/sysdeps/unix/sysv/linux/powerpc/chown.c
--- glibc-2.0.95-old/sysdeps/unix/sysv/linux/powerpc/chown.c	Thu Jan  1 10:00:00 1970
+++ glibc-2.0.95/sysdeps/unix/sysv/linux/powerpc/chown.c	Mon Aug 10 18:43:48 1998
@@ -0,0 +1,131 @@
+/* chown() compatibility.
+   Copyright (C) 1998 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+#include <limits.h>
+#include <sys/syscall.h>
+#include <stdlib.h>
+
+/*
+  In Linux 2.1.x the chown functions have been changed.  A new function lchown
+  was introduced.  The new chown now follows symlinks - the old chown and the
+  new lchown do not follow symlinks.
+  This file emulates chown() under the old kernels.
+*/
+
+extern int __syscall_chown (const char *__file,
+			    uid_t __owner, gid_t __group);
+
+int
+__chown (const char *file, uid_t owner, gid_t group)
+{
+   int err;
+   int old_errno;
+   char link[PATH_MAX+2];
+   char path[2*PATH_MAX+4];
+   int loopct;
+   int filelen;
+   static int libc_old_chown = 0 /* -1=old linux, 1=new linux, 0=unknown */;
+   
+   if (libc_old_chown == 1)
+     return __syscall_chown (file, owner, group);
+
+   old_errno = errno;
+
+#ifdef __NR_lchown
+   if (libc_old_chown == 0)
+     {
+       err = __syscall_chown (file, owner, group);
+       if (err != -1 || errno != ENOSYS)
+	 {
+	   libc_old_chown = 1;
+	   return err;
+	 }
+       libc_old_chown = -1;
+     }
+#endif
+   
+   err = __readlink (file, link, PATH_MAX+1);
+   if (err == -1)
+     {
+       errno = old_errno;
+       return __lchown(file, owner, group);
+     }
+
+   filelen = strlen (file) + 1;
+   if (filelen > sizeof(path))
+     {
+       errno = ENAMETOOLONG;
+       return -1;
+     }
+   memcpy (path, file, filelen);
+
+   /* 'The system has an arbitrary limit...'  In practise, we'll hit
+      ENAMETOOLONG before this, usually.  */
+   for (loopct = 0; loopct < 128; loopct++)
+   {
+     int linklen;
+     
+     if (err >= PATH_MAX+1)
+       {
+	 errno = ENAMETOOLONG;
+	 return -1;
+       }
+
+      link[err] = 0;  /* Null-terminate string, just-in-case.  */
+
+      linklen = strlen (link) + 1;
+      
+      if (link[0] == '/')
+	memcpy (path, link, linklen);
+      else
+	{
+	  filelen = strlen (path);
+	  
+	  while (filelen > 1 && path[filelen-1] == '/')
+	    filelen--;
+	  while (filelen > 0 && path[filelen-1] != '/')
+	    filelen--;
+	  if (filelen + linklen > sizeof(path))
+	    {
+	      errno = ENAMETOOLONG;
+	      return -1;
+	    }
+	  memcpy (path+filelen, link, linklen);
+	}
+
+      err = __readlink(path, link, PATH_MAX+1);
+      
+      if (err == -1)
+      {  
+	errno = old_errno;
+	return __lchown(path, owner, group);
+      }
+   }
+   errno = ELOOP;
+   return -1;
+}
+
+#if defined PIC && defined DO_VERSIONING
+default_symbol_version (__chown, chown, GLIBC_2.1);
+#else
+weak_alias (__chown, chown)
+#endif
diff -x *~ -urN glibc-2.0.95-old/sysdeps/unix/sysv/linux/powerpc/lchown.S glibc-2.0.95/sysdeps/unix/sysv/linux/powerpc/lchown.S
--- glibc-2.0.95-old/sysdeps/unix/sysv/linux/powerpc/lchown.S	Thu Jan  1 10:00:00 1970
+++ glibc-2.0.95/sysdeps/unix/sysv/linux/powerpc/lchown.S	Mon Aug 10 18:43:34 1998
@@ -0,0 +1,35 @@
+/* lchown system call.
+   Copyright (C) 1998 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+/* Some old kernel headers call lchown() 'chown'.  The number is
+   the same.  */
+	
+#include <sysdep.h>
+
+#ifdef __NR_lchown
+	PSEUDO (__lchown, lchown, 3)
+#else
+	PSEUDO (__lchown, chown, 3)
+#endif
+	ret
+	PSEUDO_END(__lchown)
+	weak_alias (__lchown, lchown)
+#if defined PIC && defined DO_VERSIONING
+	symbol_version (__lchown, chown, GLIBC_2.0);
+#endif
diff -x *~ -urN glibc-2.0.95-old/sysdeps/unix/sysv/linux/powerpc/syscalls.list glibc-2.0.95/sysdeps/unix/sysv/linux/powerpc/syscalls.list
--- glibc-2.0.95-old/sysdeps/unix/sysv/linux/powerpc/syscalls.list	Fri Mar 13 04:16:02 1998
+++ glibc-2.0.95/sysdeps/unix/sysv/linux/powerpc/syscalls.list	Sun Aug  9 14:24:58 1998
@@ -1,6 +1,4 @@
 # File name	Caller	Syscall name	# args	Strong name	Weak names
 
 s_llseek	llseek	_llseek		5	__sys_llseek
-
-getresuid	-	getresuid	3	getresuid
-getresgid	-	getresgid	3	getresgid
+s_chown		chown	chown		3	__syscall_chown
============================================================