mandag 16 august 2004, 17:42, skrev Segher Boessenkool: > See http://gcc.gnu.org/ml/gcc-help/2003-07/msg00232.html . Thanks, but I'm still having problems. The shared library can now be run and call functions without a problem, but argc and argv are garbage. This is a problem, because the main function needs to know its invocation name, and it also takes arguments. I suppose I can use readlink with /proc/self/exe to get the executable name at least, and possibly /proc/self/cmdline for the arguments (gotta try that), but is there another (better) way ? (Also, returning from main segfaults, is that normal ? Not that *that*'s a problem, setting return type to void and just using exit works fine). Also, I had to change "/lib/ld.so.1" to "/lib/ld-linux.so.2" since the first one doesn't exist on my box ("ld-linux.so.2" is a symlink to "ld-2.3.2.so"). Is there a way to have this work with both (or any ld.so's) without a recompile ? The lib is open source, so compile-time config isn't a problem, but it'd be nice if pre-compiled binaries could support both. (Tried using multiple .interp strings, but that didn't seem to work.) Here's a test program, compiled with (seem to remember that -DPIC from somewhere, don't know if it's necessary ?) gcc -W -Wall -fPIC -DPIC -shared test.c -o test -Wl,-e,my_main -- 8< -- #include <stdio.h> #include <stdlib.h> const char interp[] __attribute__((section(".interp"))) = "/lib/ld-linux.so.2"; void my_main (int argc, char *argv[]) { printf("argc = %i (%u)\nargv = %p\n", argc, argc, argv); printf("*argv = %s\n", *argv); exit(0); } -- 8< -- Output (the numbers at argc/argv are constant for same arguments, but change for different args -- the difference in values seems to hint that the args are stored, but the address isn't readable): -- 8< -- $ ./test argc = -1073744275 (3221223021) argv = (nil) Segmentation fault $ ./test 1 argc = -1073744277 (3221223019) argv = 0xbffff672 Segmentation fault $ ./test 1 2 argc = -1073744279 (3221223017) argv = 0xbffff670 Segmentation fault $ ./test 1 23 argc = -1073744280 (3221223016) argv = 0xbffff66f Segmentation fault -- 8< -- Any ideas ? (Thought about using mprotect, but that seems a bit, eh, hackish and insecure..) - Gerry
