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diff --git a/crypto/heimdal/lib/kafs/README.dlfcn b/crypto/heimdal/lib/kafs/README.dlfcn deleted file mode 100644 index cee1b75..0000000 --- a/crypto/heimdal/lib/kafs/README.dlfcn +++ /dev/null @@ -1,246 +0,0 @@ -Copyright (c) 1992,1993,1995,1996, Jens-Uwe Mager, Helios Software GmbH -Not derived from licensed software. - -Permission is granted to freely use, copy, modify, and redistribute -this software, provided that the author is not construed to be liable -for any results of using the software, alterations are clearly marked -as such, and this notice is not modified. - -libdl.a -------- - -This is an emulation library to emulate the SunOS/System V.4 functions -to access the runtime linker. The functions are emulated by using the -AIX load() function and by reading the .loader section of the loaded -module to find the exports. The to be loaded module should be linked as -follows (if using AIX 3): - - cc -o module.so -bM:SRE -bE:module.exp -e _nostart $(OBJS) - -For AIX 4: - - cc -o module.so -bM:SRE -bE:module.exp -bnoentry $(OBJS) - -If you want to reference symbols from the main part of the program in a -loaded module, you will have to link against the export file of the -main part: - - cc -o main -bE:main.exp $(MAIN_OBJS) - cc -o module.so -bM:SRE -bI:main.exp -bE:module.exp -bnoentry $(OBJS) - -Note that you explicitely have to specify what functions are supposed -to be accessible from your loaded modules, this is different from -SunOS/System V.4 where any global is automatically exported. If you -want to export all globals, the following script might be of help: - -#!/bin/sh -/usr/ucb/nm -g $* | awk '$2 == "B" || $2 == "D" { print $3 }' - -The module export file contains the symbols to be exported. Because -this library uses the loader section, the final module.so file can be -stripped. C++ users should build their shared objects using the script -makeC++SharedLib (part of the IBM C++ compiler), this will make sure -that constructors and destructors for static and global objects will be -called upon loading and unloading the module. GNU C++ users should use -the -shared option to g++ to link the shared object: - - g++ -o module.so -shared $(OBJS) - -If the shared object does have permissions for anybody, the shared -object will be loaded into the shared library segment and it will stay -there even if the main application terminates. If you rebuild your -shared object after a bugfix and you want to make sure that you really -get the newest version you will have to use the "slibclean" command -before starting the application again to garbage collect the shared -library segment. If the performance utilities (bosperf) are installed -you can use the following command to see what shared objects are -loaded: - -/usr/lpp/bosperf/genkld | sort | uniq - -For easier debugging you can avoid loading the shared object into the -shared library segment alltogether by removing permissions for others -from the module.so file: - -chmod o-rwx module.so - -This will ensure you get a fresh copy of the shared object for every -dlopen() call which is loaded into the application's data segment. - -Usage ------ - -void *dlopen(const char *path, int mode); - -This routine loads the module pointed to by path and reads its export -table. If the path does not contain a '/' character, dlopen will search -for the module using the LIBPATH environment variable. It returns an -opaque handle to the module or NULL on error. The mode parameter can be -either RTLD_LAZY (for lazy function binding) or RTLD_NOW for immediate -function binding. The AIX implementation currently does treat RTLD_NOW -the same as RTLD_LAZY. The flag RTLD_GLOBAL might be or'ed into the -mode parameter to allow loaded modules to bind to global variables or -functions in other loaded modules loaded by dlopen(). If RTLD_GLOBAL is -not specified, only globals from the main part of the executable or -shared libraries are used to look for undefined symbols in loaded -modules. - - -void *dlsym(void *handle, const char *symbol); - -This routine searches for the symbol in the module referred to by -handle and returns its address. If the symbol could not be found, the -function returns NULL. The return value must be casted to a proper -function pointer before it can be used. SunOS/System V.4 allows handle -to be a NULL pointer to refer to the module the call is made from, this -is not implemented. - -int dlclose(void *handle); - -This routine unloads the module referred to by the handle and disposes -of any local storage. this function returns -1 on failure. Any function -pointers obtained through dlsym() should be considered invalid after -closing a module. - -As AIX caches shared objects in the shared library segment, function -pointers obtained through dlsym() might still work even though the -module has been unloaded. This can introduce subtle bugs that will -segment fault later if AIX garbage collects or immediatly on -SunOS/System V.4 as the text segment is unmapped. - -char *dlerror(void); - -This routine can be used to retrieve a text message describing the most -recent error that occured on on of the above routines. This function -returns NULL if there is no error information. - -Initialization and termination handlers ---------------------------------------- - -The emulation provides for an initialization and a termination -handler. The dlfcn.h file contains a structure declaration named -dl_info with following members: - - void (*init)(void); - void (*fini)(void); - -The init function is called upon first referencing the library. The -fini function is called at dlclose() time or when the process exits. -The module should declare a variable named dl_info that contains this -structure which must be exported. These functions correspond to the -documented _init() and _fini() functions of SunOS 4.x, but these are -appearently not implemented in SunOS. When using SunOS 5.0, these -correspond to #pragma init and #pragma fini respectively. At the same -time any static or global C++ object's constructors or destructors will -be called. - -BUGS ----- - -Please note that there is currently a problem with implicitely loaded -shared C++ libaries: if you refer to a shared C++ library from a loaded -module that is not yet used by the main program, the dlopen() emulator -does not notice this and does not call the static constructors for the -implicitely loaded library. This can be easily demonstrated by -referencing the C++ standard streams from a loaded module if the main -program is a plain C program. - -Jens-Uwe Mager - -HELIOS Software GmbH -Lavesstr. 80 -30159 Hannover -Germany - -Phone: +49 511 36482-0 -FAX: +49 511 36482-69 -AppleLink: helios.de/jum -Internet: jum@helios.de - -Revison History ---------------- - -SCCS/s.dlfcn.h: - -D 1.4 95/04/25 09:36:52 jum 4 3 00018/00004/00028 -MRs: -COMMENTS: -added RTLD_GLOBAL, include and C++ guards - -D 1.3 92/12/27 20:58:32 jum 3 2 00001/00001/00031 -MRs: -COMMENTS: -we always have prototypes on RS/6000 - -D 1.2 92/08/16 17:45:11 jum 2 1 00009/00000/00023 -MRs: -COMMENTS: -added dl_info structure to implement initialize and terminate functions - -D 1.1 92/08/02 18:08:45 jum 1 0 00023/00000/00000 -MRs: -COMMENTS: -Erstellungsdatum und -uhrzeit 92/08/02 18:08:45 von jum - -SCCS/s.dlfcn.c: - -D 1.11 96/04/10 20:12:51 jum 13 12 00037/00000/00533 -MRs: -COMMENTS: -Integrated the changes from John W. Eaton <jwe@bevo.che.wisc.edu> to initialize -g++ generated shared objects. - -D 1.10 96/02/15 17:42:44 jum 12 10 00012/00007/00521 -MRs: -COMMENTS: -the C++ constructor and destructor chains are now called properly for either -xlC 2 or xlC 3 (CSet++). - -D 1.9 95/09/22 11:09:38 markus 10 9 00001/00008/00527 -MRs: -COMMENTS: -Fix version number - -D 1.8 95/09/22 10:14:34 markus 9 8 00008/00001/00527 -MRs: -COMMENTS: -Added version number for dl lib - -D 1.7 95/08/14 19:08:38 jum 8 6 00026/00004/00502 -MRs: -COMMENTS: -Integrated the fixes from Kirk Benell (kirk@rsinc.com) to allow loading of -shared objects generated under AIX 4. Fixed bug that symbols with exactly -8 characters would use garbage characters from the following symbol value. - -D 1.6 95/04/25 09:38:03 jum 6 5 00046/00006/00460 -MRs: -COMMENTS: -added handling of C++ static constructors and destructors, added RTLD_GLOBAL to bind against other loaded modules - -D 1.5 93/02/14 20:14:17 jum 5 4 00002/00000/00464 -MRs: -COMMENTS: -added path to dlopen error message to make clear where there error occured. - -D 1.4 93/01/03 19:13:56 jum 4 3 00061/00005/00403 -MRs: -COMMENTS: -to allow calling symbols in the main module call load with L_NOAUTODEFER and -do a loadbind later with the main module. - -D 1.3 92/12/27 20:59:55 jum 3 2 00066/00008/00342 -MRs: -COMMENTS: -added search by L_GETINFO if module got loaded by LIBPATH - -D 1.2 92/08/16 17:45:43 jum 2 1 00074/00006/00276 -MRs: -COMMENTS: -implemented initialize and terminate functions, added reference counting to avoid multiple loads of the same library - -D 1.1 92/08/02 18:08:45 jum 1 0 00282/00000/00000 -MRs: -COMMENTS: -Erstellungsdatum und -uhrzeit 92/08/02 18:08:45 von jum - |