debian lenny@amd64で、dlopenするコードを実行するとvalgrindで5 errorsと出る。特におかしなことしてないはずなんだけど。自分はバイナリアンではないので現象が分かってないんだけど。
$ g++ -rdynamic -g -o foo foo.c -ldl
$ valgrind ./foo
これで
[kuenishi@] $ valgrind ./foo
==19273== Memcheck, a memory error detector.
==19273== Copyright (C) 2002-2007, and GNU GPL'd, by Julian Seward et al.
==19273== Using LibVEX rev 1804, a library for dynamic binary translation.
==19273== Copyright (C) 2004-2007, and GNU GPL'd, by OpenWorks LLP.
==19273== Using valgrind-3.3.0-Debian, a dynamic binary instrumentation framework.
==19273== Copyright (C) 2000-2007, and GNU GPL'd, by Julian Seward et al.
==19273== For more details, rerun with: -v
==19273==
- 0.416147
==19273==
==19273== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 8 from 1)
==19273== malloc/free: in use at exit: 56 bytes in 1 blocks.
==19273== malloc/free: 3 allocs, 2 frees, 105 bytes allocated.
==19273== For counts of detected errors, rerun with: -v
==19273== searching for pointers to 1 not-freed blocks.
==19273== checked 190,232 bytes.
==19273==
==19273== LEAK SUMMARY:
==19273== definitely lost: 0 bytes in 0 blocks.
==19273== possibly lost: 0 bytes in 0 blocks.
==19273== still reachable: 56 bytes in 1 blocks.
==19273== suppressed: 0 bytes in 0 blocks.
==19273== Rerun with --leak-check=full to see details of leaked memory.
[kuenishi@] $
こんな風になる。ちなみにgccでコンパイルするとこんなことにはならない。コードはmanからもってきた。
#include <stdio.h> #include <stdlib.h> #include <dlfcn.h> int main(int argc, char **argv) { void *handle; double (*cosine)(double); char *error; handle = dlopen("libm.so", RTLD_LAZY); if (!handle) { fprintf(stderr, "%s\n", dlerror()); exit(EXIT_FAILURE); } dlerror(); /* Clear any existing error */ /* Writing: cosine = (double (*)(double)) dlsym(handle, "cos"); would seem more natural, but the C99 standard leaves casting from "void *" to a function pointer undefined. The assignment used below is the POSIX.1-2003 (Technical Corrigendum 1) workaround; see the Rationale for the POSIX specification of dlsym(). */ *(void **) (&cosine) = dlsym(handle, "cos"); if ((error = dlerror()) != NULL) { fprintf(stderr, "%s\n", error); exit(EXIT_FAILURE); } printf("%f\n", (*cosine)(2.0)); dlclose(handle); exit(EXIT_SUCCESS); }
valgrindに-vつけるとこんなのが出る。
