Commit Graph

84 Commits

Author SHA1 Message Date
John Polstra
926ea445fe Revamp the symbol lookup algorithm to cope better with objects
loaded separately by dlopen that have global symbols with identical
names.  Viewing each dlopened object as a DAG which is linked by its
DT_NEEDED entries in the dynamic table, the search order is as
follows:

  * If the referencing object was linked with -Bsymbolic, search it
    internally.
  * Search all dlopened DAGs containing the referencing object.
  * Search all objects loaded at program start up.
  * Search all objects which were dlopened() using the RTLD_GLOBAL
    flag (which is now supported too).

The search terminates as soon as a strong definition is found.
Lacking that, the first weak definition is used.

These rules match those of Solaris, as best I could determine them
from its vague manual pages and the results of experiments I performed.

PR:		misc/12438
1999-08-30 01:48:19 +00:00
John Polstra
7326e0b620 When honoring -Bsymbolic, still keep searching if only a weak
definition was found in the referencing object.
1999-08-30 01:25:38 +00:00
John Polstra
6bd9374580 Simplify the logic in find_symdef(). 1999-08-30 01:24:08 +00:00
Peter Wemm
7f3dea244c $Id$ -> $FreeBSD$ 1999-08-28 00:22:10 +00:00
John Polstra
41f83b07a8 Add a NULL pointer check whose absence could cause segmentation
violations in certain obscure cases involving failed dlopens.  Many
thanks to Archie Cobbs for providing me with a good test case.

Eliminate a block that existed only to localize a declaration.
1999-08-20 22:33:44 +00:00
John Polstra
bfb1ef6058 Change many asserts into normal errors. They were all for conditions
caused by invalid shared objects rather than by internal errors.

Enable format string mismatch checking for _rtld_error().
1999-07-18 00:02:19 +00:00
John Polstra
cb435fa919 Change the symbol used to find the end of an object's address space
from "end" to "_end".  The former does not exist in most shared
libraries.  This fixes problems in dladdr() and dlsym(RTLD_NEXT, ...).
1999-07-14 04:09:11 +00:00
John Polstra
8d05e8c453 Fix bug: if a dlopen() failed (e.g., because of undefined symbols),
the dynamic linker didn't clean up properly.  A subsequent dlopen()
of the same object would appear to succeed.

Another excellent fix from Max Khon.

PR:		bin/12471
Submitted by:	Max Khon <fjoe@iclub.nsu.ru>
1999-07-09 16:22:55 +00:00
John Polstra
5bf3700dae Shake hands with GDB a little bit earlier so that it is possible to
debug the init functions.

Submitted by:	dfr
1999-07-03 23:54:02 +00:00
John Polstra
d16ad2d055 Fix a reference counting problem when using dlopen(NULL, ...).
PR:		bin/12129
1999-06-25 04:50:06 +00:00
John Polstra
962fdc466a Fix a serious performance bug for large programs on the Alpha,
discovered by Hidetoshi Shimokawa.  Large programs need multiple
GOTs.  The lazy binding stub in the PLT can be reached from any of
these GOTs, but the dynamic linker only has enough information to
fix up the first GOT entry.  Thus calls through the other GOTs went
through the time-consuming lazy binding process on every call.

This fix rewrites the PLT entries themselves to bypass the lazy
binding.

Tested by Hidetoshi Shimokawa and Steve Price.

Reviewed by:	Doug Rabson <dfr@freebsd.org>
1999-06-25 02:53:59 +00:00
John Polstra
6d30b16752 Back out my change from 6 April PDT that added a new dlversion()
function.  It was an ill-considered feature.  It didn't solve the
problem I wanted it to solve.   And it added Yet Another Version
Number that would have to be maintained at every release point.
I'm nuking it now before anybody grows too fond of it.
1999-04-22 01:54:38 +00:00
John Polstra
5353bfc3b4 After relocating the main program, but before calling any of the
_init() functions, initialize the global variables "__progname" and
"environ".  This makes it possible for the _init() functions to call
things like getenv() and err().
1999-04-21 04:06:57 +00:00
John Polstra
a18cde535d The ELF specification says that the RPATH in the executable or
shared object takes precedence over LD_LIBRARY_PATH.  Make the
dynamic linker do it that way.
1999-04-09 06:42:00 +00:00
John Polstra
d5b537d01a Eliminate all machine-dependent code from the main source body and
the Makefile, and move it down into the architecture-specific
subdirectories.

Eliminate an asm() statement for the i386.

Make the dynamic linker work if it is built as an executable instead
of as a shared library.  See i386/Makefile.inc to find out how to
do it.  Note, this change is not enabled and it might never be
enabled.  But it might be useful in the future.  Building the
dynamic linker as an executable should make it start up faster,
because it won't have any relocations.  But in practice I suspect
the difference is negligible.
1999-04-09 00:28:43 +00:00
John Polstra
a16ed197f2 Fix a couple of typos in comments. 1999-04-07 02:48:43 +00:00
John Polstra
14f5fa0596 Add a new function dlversion() which returns the version number of
the dynamic linker in the same form as __FreeBSD_version.  This is
mainly intended for checking the dynamic linker version during a make
world.
1999-04-07 02:43:11 +00:00
John Polstra
5e4636f2b0 Resolve undefined weak references to a value of 0. This solves the
"__deregister_frame_info" problem that was seen when combining a
program linked using the old gcc with shared libraries that were
built using egcs.
1999-04-05 02:36:40 +00:00
Peter Wemm
faba5e7488 If somebody does an execv("foo", NULL) (which theoretically is an error),
avoid crashing inside rtld (since it's easy) since everything else handles
it.  Of course, if the target program checks argv[], it'll fall over.

Reviewed by:	jdp
1999-04-04 06:01:09 +00:00
Nate Williams
38ccb4c214 - Commit the correct dladdr() implementation.
Reviewed by:	jdp@FreeBSD.org <This is the version he reviewed!>
1999-03-24 23:47:29 +00:00
Nate Williams
e818e307ee - Added dladdr(3) support.
Reviewed by:	jdp@FreeBSD.org
1999-03-24 23:37:35 +00:00
Doug Rabson
eace1a8ad9 Use the runpath of the main program for locating libraries loaded by
dlopen().

Reviewed by: jdp
1998-11-27 21:19:52 +00:00
John Polstra
1280c211e2 Fix a bug in dlclose that broke the apache13 port. The list of
loaded objects wasn't being maintained properly.
1998-10-13 03:31:59 +00:00
John Polstra
b19042b569 Make LD_PRELOAD work for ELF. 1998-09-22 02:09:56 +00:00
John Polstra
29218d94d3 Fix a bug that showed up when debugging dynamically linked programs.
References from GDB to "printf" and various other functions would
find the versions in the dynamic linker itself, rather than the
versions in the program's libc.  This fix moves the GDB link map
entry for the dynamic linker to the end of the search list, where
its symbols will be found only if they are not found anywhere else.
It was suggested by Doug Rabson, though I implemented it a little
differently.

I personally would prefer to leave the dynamic linker's entry out
of the GDB search list altogether.  But Doug argues that it is
handy there for such things as setting breakpoints on dlopen().
So it stays for now, at least.

Note, if we ever integrate the dynamic linker with libc (which has
several important benefits to recommend it), this whole problem
goes away.
1998-09-16 02:54:08 +00:00
John Polstra
4e25d42aee Make the pathname pointed to by the Obj_Entry structure for the
dynamic linker itself dynamically allocated.  All of them are
supposed to be dynamically allocated, but we cheated before.  It
made gdb unhappy under some circumstances.
1998-09-15 21:07:52 +00:00
John Polstra
a565ca5920 Implement ldconfig functionality for ELF. The hints are stored in
a different file than the a.out hints, namely, "/var/run/ld-elf.so.hints".
These hints consist only of the directory search path.  There is
no hash table as in the a.out hints, because ELF doesn't have to
search for the file with the highest minor version number.  (It
doesn't have minor version numbers at all.)

A single run of ldconfig updates either the a.out hints or the ELF
hints, but not both.  The set of hints to process is selected in
the usual way, via /etc/objformat, or ${OBJFORMAT}, or the "-aout"
or "-elf" command line option.  The rationale is that you probably
want to search different directories for ELF than for a.out.

"ldconfig -r" is faked up to produce output like we are used to,
except that for ELF there are no minor version numbers.  This should
enable "ldconfig -r" to be used for checking LIB_DEPENDS in ports
even for ELF.

I implemented the ELF functionality in a new source file, with an
eye toward eliminating the a.out code entirely at some point in
the future.
1998-09-05 03:31:00 +00:00
Doug Rabson
13575fc46f Add alpha support.
Submitted by: John Birrell <jb@cimlogic.com.au> (with extra hacks by me)
Obtained from: Probably NetBSD
1998-09-04 19:03:57 +00:00
John Polstra
63fac2b9ef Suppress duplicate entries in ldd output. 1998-09-02 02:51:12 +00:00
John Polstra
93df8d681b Style fixes. If it seems like a lot of lines of changes, it's
because I moved some functions.  Mr. Tidy likes them to be in
alphabetical order.
1998-09-02 02:00:20 +00:00
John Polstra
cefbc49679 Handle dlsym(NULL, ...) properly, by searching in the caller's
shared object.  Note, this searches _only_ that object, and not its
needed objects, in accordance with the documentation.

Also fix dlopen(NULL, ...) so that the executable's needed objects
are searched as well as the executable itself.
1998-09-02 01:09:34 +00:00
Doug Rabson
46066cf144 Add support for ldd. 1998-05-01 08:39:27 +00:00
Doug Rabson
2001f720ce Add GDB support. The method and some of the code came from NetBSD's elf
runtime linker.
1998-04-30 07:48:02 +00:00
John Polstra
3124c3e093 Import the ELF dynamic linker. This is the ElfKit version with
quite a few enhancements and bug fixes.  There are still some known
deficiencies, but it should be adequate to get us started with ELF.

Submitted by:	John Polstra <jdp@polstra.com>
1998-03-07 19:24:35 +00:00