site_archiver@lists.apple.com Delivered-To: darwin-dev@lists.apple.com /usr/lib/libSystem.B.dylib(malloc.So): 901200d0 T __malloc_fork_child 90032bc4 T __malloc_fork_parent 90032a58 T __malloc_fork_prepare 90008574 T _calloc 90005ccc T _free 90003424 T _malloc a000425c D _malloc_check_counter a0004258 D _malloc_check_each a0004260 D _malloc_check_start 90043b4c T _malloc_create_zone 901201b8 T _malloc_debug a0004264 D _malloc_debug_flags 90014f38 T _malloc_default_zone 901207f0 T _malloc_destroy_zone 9012009c T _malloc_error 9011fc7c T _malloc_get_all_zones 9011fa74 T _malloc_get_zone_name 90032f88 T _malloc_good_size a0004268 D _malloc_logger a0004270 D _malloc_num_zones 9011fa7c T _malloc_printf 900442c0 T _malloc_set_zone_name 90120168 T _malloc_singlethreaded 90048318 T _malloc_size 90120430 T _malloc_zone_batch_free 9012054c T _malloc_zone_batch_malloc 90014e7c T _malloc_zone_calloc 9011f860 T _malloc_zone_check 900137e4 T _malloc_zone_free 90052ef4 T _malloc_zone_from_ptr 9011ffcc T _malloc_zone_log 900039f8 T _malloc_zone_malloc 9011fe50 T _malloc_zone_print 9011fd90 T _malloc_zone_print_ptr_info 90033c4c T _malloc_zone_realloc 9011f910 T _malloc_zone_register 9011fef4 T _malloc_zone_statistics 9011fb5c T _malloc_zone_unregister 90120648 T _malloc_zone_valloc a000426c D _malloc_zones 90120708 T _mstats 90017360 T _realloc 9002c0bc T _set_malloc_singlethreaded 9004a3a4 T _valloc 901206fc T _vfree /usr/lib/libSystem.B.dylib(devname.So): 900be638 T _devname 90062320 T _devname_r int main(int argc, char *argv[]) { char dev[100], *dev2; devname_r(234881027, S_IFBLK, dev, sizeof(dev)); printf("%s\n", dev); dev2 = devname(234881027, S_IFBLK); printf("%s\n", dev2); return 0; } [shantonu@repl]$ cat devname.c #include <sys/types.h> #include <string.h> #ifdef DO_DEVNAME char *devname(dev_t dev, mode_t type) { return "something"; } #endif #ifdef DO_DEVNAME_R char *devname_r(dev_t dev, mode_t type, char *buf, int len) { if(len < 10) return NULL; strcpy(buf, "something"); return buf; } #endif Shantonu On Jun 4, 2005, at 4:55 PM, Damien Cooke wrote: Thanks for the hint: I am now linking like this But I now get: Damien On 05/06/2005, at 8:51 AM, Shantonu Sen wrote: Shantonu On Jun 4, 2005, at 4:06 PM, Damien Cooke wrote: I build the two object files as such gcc -g -fPIC -c source/lpmalloc.c -o output/lpmalloc.o gcc -g -fPIC -c source/global.c -o output/global.o This is what I get: ld: for architecture ppc ld: Undefined symbols: _printf libtool: internal link edit command failed Damien This email sent to ssen@opendarwin.org _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.appl... On order to correctly override a function, the 32-bit linker requires that all global symbols in the function's containing module be overridden. For your case, this means you need to implement at most: [shantonu@repl]$ nm -g "/usr/lib/libSystem.B.dylib(malloc.So)" | grep -v " U " As a demonstration, here's an example using the devname(3) API, which has devname() and devname_r() implemented in a single module in libSystem: [shantonu@repl]$ nm -g "/usr/lib/libSystem.B.dylib(devname.So)" | grep -v " U " In order to provide a dylib that replaces the implementation of one of these functions (correctly), I need to implement both functions. [shantonu@repl]$ cat test.c #include <stdlib.h> #include <stdio.h> #include <sys/stat.h> If my dylib just implements devname(), I get this warning: [shantonu@repl]$ cc -c devname.c -DDO_DEVNAME [shantonu@repl]$ cc -dynamiclib -o libdevname.dylib devname.o - install_name $PWD/libdevname.dylib [shantonu@repl]$ cc -o test test.c -L. -ldevname /usr/bin/ld: warning multiple definitions of symbol _devname ./libdevname.dylib(devname.o) definition of _devname /usr/lib/gcc/powerpc-apple-darwin8/4.0.0/../../../libSystem.dylib (devname.So) definition of _devname [shantonu@repl]$ nm -mg test| grep devname (undefined [lazy bound]) external _devname (from libdevname) (undefined [lazy bound]) external _devname_r (from libSystem) [shantonu@repl]$ ./test disk0s5 something Note here that devname() came from my dylib but devname_r() came from libSystem. This is exactly the kind of behavior the linker is trying to prevent. An analagous situation would be to using the system's calloc() with your custom free(), with no guarantee that they are compatible. If you just implement devname_r(), you get a similar but different warning (and behavior) [shantonu@repl]$ cc -c devname.c -DDO_DEVNAME_R [shantonu@repl]$ cc -dynamiclib -o libdevname.dylib devname.o - install_name $PWD/libdevname.dylib [shantonu@repl]$ cc -o test test.c -L. -ldevname /usr/bin/ld: warning suggest use of -bind_at_load, as lazy binding may result in errors or different symbols being used symbol _devname_r used from dynamic library /usr/lib/gcc/powerpc- apple-darwin8/4.0.0/../../../libSystem.dylib(devname.So) not from earlier dynamic library /tmp/libdevname.dylib(devname.o) [shantonu@repl]$ nm -mg test| grep devname (undefined [lazy bound]) external _devname (from libSystem) (undefined [lazy bound]) external _devname_r (from libSystem) [shantonu@repl]$ ./test disk0s5 disk0s5 In this case, because of the order in which the linker searched libraries, the system version was used. Only if you override both functions does the entire module get overridden: [shantonu@repl]$ cc -c devname.c -DDO_DEVNAME -DDO_DEVNAME_R [shantonu@repl]$ cc -dynamiclib -o libdevname.dylib devname.o - install_name $PWD/libdevname.dylib [shantonu@repl]$ cc -o test test.c -L. -ldevname [shantonu@repl]$ nm -mg test| grep devname (undefined [lazy bound]) external _devname (from libdevname) (undefined [lazy bound]) external _devname_r (from libdevname) [shantonu@repl]$ ./test something something For your case, you might get away with just implementing on the order of 20 functions and constants, based on what symbols are used internally to libSystem and by clients. In the worst case, you'll need to implement all 45 symbols so that nothing can cause libSystem.B.dylib(malloc.So) to be accessed (and cause duplicate symbol warnings with your dylib) cc -dynamiclib -fPIC -o bin/liblpmalloc.so output/lpmalloc.o output/ global.o ld: warning multiple definitions of symbol _malloc output/lpmalloc.o definition of _malloc in section (__TEXT,__text) /usr/lib/gcc/powerpc-apple-darwin8/4.0.0/../../../libSystem.dylib (malloc.So) definition of _malloc So how do I tell it I am building a replacement for malloc other than re-implementing the System.dylib ? Is there a way of dropping duplicate entries? Why are you using libtool(1) instead of the compiler driver cc(1) to create your shared library? Your problem is that you are not linking against libSystem.dylib (via -lSystem). You're also missing a host of other libraries automatically included when you link a dylib with cc(1). for example: /usr/bin/libtool -dynamic -arch_only ppc -noall_load - weak_reference_mismatches non-weak -v -o libfoo.dylib -L/usr/lib/ gcc/powerpc-apple-darwin8/4.0.0 -L/usr/lib/gcc/powerpc-apple- darwin8/4.0.0 -L/usr/lib/gcc/powerpc-apple-darwin8/4.0.0/../../.. foo.o -lgcc -lgcc_eh -lSystemStubs -lmx -lSystem You should use cc/gcc and the -dynamiclib option to build your library. You probably also want to read the various man pages and use the -install_name flag as well. Sorry for the dumb question. I am porting my malloc to Darwin. I have built it as a shared dynamic library on Solaris. However I am having a large amount of problems with this on OS X 10.4.1 using XCode 2.0 and gcc 4.0 Then I use Libtool as such libtool -dynamic -o bin/ liblpmalloc.so output/lpmalloc.o output/global.o I am probably doing something really dumb but any help would be greatly appreciated. _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/ssen% 40opendarwin.org This email sent to site_archiver@lists.apple.com