This package contains my shared, dynamic linker (ld.so) and utilities (ldconfig and ldd) for Linux. For those that were not involved in the development of ld.so, its main feature is that the user-level, shared library and dynamic linking support has been moved to its own, special shared library. This has two significant advantages. First, the startup code for all binaries, which must be linked statically, is reduced by about 2.5k. Second, and probably more important, the shared library and dynamic linking support can be upgraded for all binaries without having to relink by simply installing a new ld.so. In addition to ld.so, this package also includes two, related utilities, ldconfig and ldd. Ldconfig is used to automatically update symbolic links to shared libraries and build the library cache used by ld.so. This should hopefully put an end to the common problem of accidentally deleting a critical library link (eg. /lib/libc.so.4). Ldd is used to list the shared libraries dependencies for a binary. In order to use the debugging, library version of ld.so, the program must be explcitly linked with the static libc.a. Please see the included manual pages for further details. To install, simply run "sh instldso.sh" as root. Ready-to-go versions of all end-products are provided so nothing should need to be compiled or linked. Both a.out and ELF versions of gcc, binutils and libc are currently needed to recompile everything. If the ELF version is installed as the default, set the value of GCC_DEFAULT to 'elf' in Config.mk, otherwise, either leave it undefined or set it to a.out. Furthermore, optimization level O2 or higher must be used to recompile ld-linux.so due the use of inline functions. Notable contributors to this package include Eric Youngdale, Peter MacDonald, Hongjiu Lu, Linus Torvalds, Lars Wirzenius, Mitch D'Souza, Rik Faith, Andreas Schwab and Adam Richter (not necessarily in that order). Changes in version 1.7.3: Changed ld-linux.so to only print a library name the first time it is loaded when run from ldd. Fixed a bug in ldconfig where an invalid cache could be generated if a directory was specified multiple times in ld.so.conf. Changed ld-linux.so so it will return the address of a weak symbol when called from dlsym in libdl. Changes in version 1.7.2: Changed libdl.so again to fix the undefined foobar problem. Changes in version 1.7.1: Changed libdl so it will compile at optimization level O3 or higher. Changed ldconfig to always create the cache file with mode 644. Changed ldconfig to not ingore valid symlinks. Changed ldconfig to use the library name as the soname for ELF libraries that do not have an soname entry. Changed ld-linux.so to print the actual, requested library name at the time it is loaded instead of trying to figure it out after the fact. Changes in version 1.7.0: Changed ldconfig to read the actual soname from the image for ELF libraries and make it available to ld-linux.so. The soname for DLL libraries is still determined by truncating the minor numbers from the image file name. Changed ldconfig to no longer support the undocumented sort options. Changed ld.so to require a valid cache to find libraries in directories specified in ld.so.conf. /usr/lib and /lib are still searched as a last resort. Ld-linux.so already operated this way. Fixed a bug in libldso.a where the arguments to shared_loader were not parsed correctly (Wolfram Gloger). Added support for RELA-style relocations under Linux/68k (Andreas Schwab). Changed ld-linux.so to only map the cache once for all libraries instead of individually for each library. Changed ld-linux.so continue searching the cache instead of giving up when failing to load the first entry found. Changed ld-linux.so to produce output similar to ld.so when run from ldd or when errors occur. Changes in version 1.6.7: Changed the install scripts to make sure that ld.so and ld-linux.so are always usable. Added support for Linux/Sparc (Eric Youngdale). Added support for Linux/68k (Andreas Schwab). Fixed various bugs in ld-linux.so dealing with closing files, unmapping memory, dereferencing NULL pointers and printing library names (David Engel, Eric Youngdale and Andreas Schwab). Replaced the manual page for libdl with a freely distributable one (Adam Richter). Fixed a bug in ld-linux.so where LD_LIBRARY_PATH and LD_PRELOAD were not cleared for setuid/setgid programs. Fixed a bug in libdl where dlsym would not return the correct address of a symbol if it was redefined in another library (Oleg Kibirev). Changed ld-linux.so to use the following order to search for libraries: LD_{ELF_}LIBRARY_PATH, ld.so.cache, rpath, /usr/lib and /lib. Changed ld-linux.so to not needlessly allocate memory when using ld.so.cache. Changes in version 1.6.6: Changed ldconfig to not warn about removing stale links unless the -v option is specified. Added manual pages for libdl (from FreeBSD/Sun) Fixed a bug in ld.so dealing with preloading of objects generated by recent versions of ld (Mitch D'Souza). Fixed bugs in ldd where some errors were either not detected or not printed. Fixed a bug in ld-linux.so where the trailing nul in a library name was not being copied (Owen Taylor). Changes in version 1.6.5: Changed ldconfig to remove stale symbolic links. Added debug hooks in ld-linux.so and libdl.so to be used by a future version of gdb (Eric Youngdale). Changes in version 1.6.4: Change ld-linux.so to print on stdout instead of stderr when run from ldd. Added support for Debian GNU/Linux packaging. Changes in version 1.6.3: Fixed a bug in libdl when closing a library (H.J. Lu). Changes in version 1.6.2: Changed the error message printed by ldd when a file is not a.out or ELF. It used to only list a.out formats. Changed ldconfig to no longer cache and set up links for ld-linux.so. Changed ld-linux.so and libdl to not conflict with upcoming changes in kernel header files. Changed ld-linux.so to not print preloaded libraries. Changes in version 1.6.1: Updated the installation script. Changed ld.so and ld-linux.so to look for LD_AOUT_PRELOAD and LD_ELF_PRELOAD, respectively, before LD_PRELOAD. Changed ld.so and ld-linux.so to use LD_AOUT_LIBRARY_PATH and LD_ELF_LIBRARY_PATH, respectively, instead of AOUT_LD_LIBRARY_PATH and ELF_LD_LIBRARY_PATH. Changes in version 1.6.0: Changed ldconfig to process libraries which do not have a minor version or patch level number. Incorporated ld-linux.so and libdl.so. Changed ld.so and ld-linux.so to not miss entries in the cache when the fully qualified library is requested. Changed ldconfig to use stdout instead of stderr when printing the cache. Changes in version 1.5.3: LD_PRELOAD enhancements (Tristan Gigold). LD_PRELOAD patch for linux-68k (Andreas Schwab). Changes in version 1.5.2: More ELF changes (Mitch D'Souza). Changed ldconfig to also update the link for ld-linux.so. Changes in version 1.5.1: More ELF and LD_PRELOAD changes (Mitch D'Souza). Changes in version 1.5.0: Chnaged all executables to QMAGIC (Mitch D'Souza and Rick Sladkey). Added preliminary support for ELF to ldd and ldconfig (Eric Youndale and H.J. Lu). Added support for LD_PRELOAD to ld.so (Mitch D'Souza). Removed the "advertising" clause from the copyright notices in all source files. Changes in version 1.4.4: Changed ldconfig to support QMAGIC libraries. Fixed a bug in ld.so where some of the error messages had transposed arguments. Changes in version 1.4.3: Fixed an obscure bug in ld.so where an index was not being incremented when a library was not found using the cache. Changes in version 1.4.2: Changed ldconfig to issue a warning and continue instead of an error and exiting when a link can't be updated. This is useful when some libraries are imported on read- only file systems, such as an NFS mounted /usr. Changed ld.so to be more robust in searching for libraries. A library is not considered found unless it can actually be loaded. If a library is not found using the cache, the standard directories are searched as in pre-cache versions. Changes in version 1.4.1: Fixed minor Makefile problems. Added support for linux-68k. Fixed a bug in ld.so where libraries with absolute paths were not handled correctly. Changed ld.so to ignore the directory in the names of shared libraries by default. This allows older libraries with absolute paths, such as the XView libraries, to take advantage of the cache support. Added a minimal usage message to ldconfig. Changes in version 1.4: Fixed bug in ld.so where minor version numbers were not reported correctly when a minor version incompatibility was found. Fixed bug in ldconfig where libraries with subversion numbers greater than 9 were not compared correctly. Added Mitch D'Souza's support for suppressing warning messages from ld.so about minor version incompatibilities. Added Mitch D'Souza's support for using a cache to speed up searching for libraries in the standard directories. Added Mitch D'Souza's support for a debugging version of ld.so. Link with -lldso if you think you are experiencing dynamic linker problems. Changes in version 1.3: Added support for libraries using absolute pathnames. If I had known that the XView libraries used them, I would have added this earlier. Fixed a bug handling old libraries using a pathname beginning with '/' or '/lib/'. Changes in version 1.2a: Fixed a minor bug in ldd which caused all files, specifically scripts, to be recognized as binaries. Thanks to Olaf Flebbe for reporting it. David Engel david@ods.com