Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help 
DLADDR(3)		     Library Functions Manual		       DLADDR(3)

NAME
     dladdr -- find the shared object containing a given address

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <dlfcn.h>

     int
     dladdr(const void *addr, Dl_info *info);

DESCRIPTION
     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 fol-
     lowing 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.

ERRORS
     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 call-
     ing dlerror().

     On success, a non-zero value is returned.

SEE ALSO
     rtld(1), dlopen(3)

HISTORY
     The dladdr() function first appeared in the Solaris operating system.

BUGS
     This implementation is bug-compatible with the Solaris implementation.   In
     particular, the following bugs are present:

     *	 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  op-
	 erating system.

     *	 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 it-
	 self.	This causes most global functions to appear to be defined within
	 the main executable, rather than in the shared libraries where the  ac-
	 tual code resides.

     *	 Returning 0 as an indication of failure goes against long-standing Unix
	 tradition.

FreeBSD ports 15.quarterly	February 5, 1998		       DLADDR(3)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=dladdr&sektion=3&manpath=FreeBSD+15.1-RELEASE+and+Ports.quarterly>

home | help