.Dd September 24, 2004
.Os
.Dt DLADDR 3
.Sh NAME
.Nm dladdr
.Nd find the image containing a given address
.Sh SYNOPSIS
.In dlfcn.h
.Ft int
.Fn dladdr "const void* addr" "Dl_info* info"
.Sh DESCRIPTION
The
.Fn dladdr
function
queries dyld (the dynamic linker) for information about the image
containing the address
.Fa addr .
The information is returned in the structure specified by
.Fa info .
The structure contains at least the following members:
.Bl -tag -width "XXXconst char *dli_fname"
.It Li "const char* dli_fname"
The pathname of the shared object containing the address.
.It Li "void* dli_fbase"
The base address (mach_header) at which the image is mapped into the
address space of the calling process.
.It Li "const char* dli_sname"
The name of the nearest run-time symbol with a value less than or
equal to
.Fa addr .
.It Li "void* dli_saddr"
The value of the symbol returned in
.Li dli_sname .
.El
.Pp
The
.Fn dladdr
function
is available only in dynamically linked programs.
.Sh ERRORS
If an image containing
.Fa addr
cannot be found,
.Fn dladdr
returns 0.
On success, a non-zero value is returned.
.Pp
If the image containing 
.Fa addr
is found, but no nearest symbol was found,
the dli_sname and dli_saddr fields are set to NULL.
.Sh SEE ALSO
.Xr dyld 3 ,
.Xr dlopen 3
.Sh HISTORY
The
.Fn dladdr
function first appeared in the Solaris operating system.
.Sh AUTHORS
Mac OS X 10.3 incorporated the dlcompat package written by Jorge Acereda <jacereda@users.sourceforge.net>
and Peter O'Gorman <ogorman@users.sourceforge.net>.
.Pp
In Mac OS X 10.4, dlopen was rewritten to be a native part of dyld.
.Pp
This man page was borrowed from FreeBSD and modified.
.Sh BUGS
This implementation is almost bug-compatible with the Solaris
implementation.  The following bugs are present:
.Bl -bullet
.It
Returning 0 as an indication of failure goes against long-standing
Unix tradition.
.El