dladdr -- find the shared object containing a given address
Standard C Library (libc, -lc)
#include <dlfcn.h>
int
dladdr(const void *addr, Dl_info *info);
The dladdr() function queries the dynamic linker for information about
the shared object containing the address addr. The information is
returned in the structure specified by info. The structure contains at
least the following members:
const char *dli_fname The pathname of the shared object containing
the address.
void *dli_fbase The base address at which the shared object is
mapped into the address space of the calling
process.
const char *dli_sname The name of the nearest run-time symbol with a
value less than or equal to addr. When possible,
the symbol name is returned as it would
appear in C source code.
If no symbol with a suitable value is found,
both this field and dli_saddr are set to NULL.
void *dli_saddr The value of the symbol returned in dli_sname.
The dladdr() function is available only in dynamically linked programs.
If a mapped shared object containing addr cannot be found, dladdr()
returns 0. In that case, a message detailing the failure can be
retrieved by calling dlerror().
On success, a non-zero value is returned.
rtld(1), dlopen(3)
The dladdr() function first appeared in the Solaris operating system.
This implementation is bug-compatible with the Solaris implementation.
In particular, the following bugs are present:
+o If addr lies in the main executable rather than in a shared library,
the pathname returned in dli_fname may not be correct. The pathname
is taken directly from argv[0] of the calling process. When executing
a program specified by its full pathname, most shells set argv[0]
to the pathname. But this is not required of shells or guaranteed by
the operating system.
+o If addr is of the form &func, where func is a global function, its
value may be an unpleasant surprise. In dynamically linked programs,
the address of a global function is considered to point to its program
linkage table entry, rather than to the entry point of the function
itself. This causes most global functions to appear to be
defined within the main executable, rather than in the shared
libraries where the actual code resides.
+o Returning 0 as an indication of failure goes against long-standing
Unix tradition.
FreeBSD 5.2.1 February 5, 1998 FreeBSD 5.2.1 [ Back ] | 