dlmodinfo.3c (2010 09)

d
dlmodinfo(3C) dlmodinfo(3C)
(ELF Applications Only)
NAME
dlmodinfo() - retrieve information about a loaded module (program or shared library)
SYNOPSIS
cc [flag]... file...
-ldl [library ]...
#include <dlfcn.h>
uint64_t dlmodinfo(uint64_t ip_value,
struct load_module_desc *desc,
size_t desc_size,
void *(*read_tgt_mem)(void* buffer,
uint64_t ptr,
size_t bufsiz,
int ident),
int ident_parm,
uint64_t load_map_parm);
Multithread Usage
Thread safe in
libdl.sl but not in libxpdl.sl
.
DESCRIPTION
dlmodinfo() is one of a family of routines that give the user direct access to the dynamic linking facili-
ties. dlmodinfo() retrieves information about a loaded module from a given address value. dlmo-
dinfo() searches all currently loaded load modules looking for a load module whose address range
(address range of all loaded segments) holds the given address value. The dlmodinfo() routine fills
the load_module_desc with information from the matching load module.
ip_value is the instruction pointer value of the requested library. If the value is NULL, then desc con-
tains the module info of
dld itself. desc is a buffer of memory allocated by the user program. The
dynamic loader fills this in with module information. desc_size is the size in bytes of the desc buffer.
read_tgt_mem is a pointer to a function used by
dlmodinfo() to retrieve needed information. If the
value is NULL, the dynamic loader uses its own internal data structures to find the correct load module
and the following two parameters are ignored.
ident_parm Is only used to pass the fourth parameter to read_tgt_mem .
load_map_parm Is only used when calling through read_tgt_mem . It contains the starting
address of the load map.
Otherwise, the function pointer is used to read memory during its search, using these parameters:
buffer a buffer supplied by
dlmodinfo() to read into
ptr the virtual memory address to read from
bufsiz the size of buffer in bytes
ident the value of the ident_parm parameter to dlmodinfo().
On success, read_tgt_mem returns the value of its buffer parameter, otherwise, it returns NULL.
read_tgt_mem allows
dlmodinfo to find a load module in one process on behalf of another. The calling
process passes a callback via read_tgt_mem in order to read memory in a different process address space
from the one in which dlmodinfo() resides. ip_value , load_map_parm, and ptr from read_tgt_mem
can be pointers to objects in another process. For example, when a 32-bit program wants to enquire about
a 64-bit program, the ip_value and load_map_parm should be 64-bit values. Any 32-bit pointers should
be typecasted to 64 bits by the user program when passed in the ip_value or load_map_parm parameters.
If the calling process calls
dlmodinfo() with a callback registered via read_tgt_mem , it must supply
the starting address of the target process’ load map in the load_map_parm parameter to dlmodinfo().
This can be retrieved by using the DT_HP_LOAD_MAP dynamic table entry in the target program file.
A cross-process load module operation can be done via
dlmodinfo(), for example, by issuing a call to
ttrace().
RETURN VALUE
If successful,
dlmodinfo() returns a handle for the shared library as defined by the return value from
dlopen(). NULL is returned otherwise. The return values are type-converted to uint64_t.
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1