HP UX Software Transition Kit (STK) manual Return Value, Example

handle The shared library's handle (type shl_t).

filename A character array containing the library's path name as specified at link time or at explicit load time.

initializer A pointer to the shared library's initializer routine (see Initializers for Shared Libraries. It is NULL if there is no initializer. This field is useful for calling the initializer if it was disabled by the BIND_NOSTART flag to shl_load.

If the shared library has multiple initializers, this field is also set to NULL. Multiple initializers can be found with shl_getsymbols, described later in this chapter.

This buffer is statically allocated. Therefore, if a program intends to use any of the members of the structure, the program must make a copy of the structure before the next call to shl_get. Otherwise, shl_get overwrites the static buffer when called again.

Return Value

If successful, shl_get returns an integer value 0. If the index value exceeds the number of currently loaded libraries, shl_get returns -1 and sets errno to EINVAL.

Description

To obtain information on currently loaded libraries, use the shl_get function. If you are programming in a threaded environment, use the thread-safe version shl_get_r which is the same as shl_get in all other respects. (See Programming with Threads on HP-UXfor more information about threads.)

Other than obtaining interesting information, this routine is of little use to most programmers. A typical use may be to display the names and starting/ending address of all shared libraries in a process's virtual memory address space.

Example

The function show_loaded_libs shown below displays the name and start and end address of the text and data/bss segments the library occupies in a process's virtual address space.

show_loaded_libs - Display Library Information

#include	<stdio.h>	/* contains standard I/O defs	*/
#include	<dl.h>	/* contains shared library type defs		*/
void	show_loaded_libs(void)
{
int	idx;
struct	shl_descriptor	*desc;

printf("SUMMARY of currently loaded libraries:\n"); printf("%-25s %10s %10s %10s %10s\n",

"___library___", "_tstart_", "__tend__", "_dstart_", "__dend__");

idx = 0;

for (idx = 0; shl_get(idx, &desc) != -1; idx++) printf("%-25s %#10lx %#10lx %#10lx %#10lx\n",

desc->filename, desc->tstart, desc->tend, desc->dstart, desc->dend);

}

Calling this function from a C program compiled with shared libc and libdld produced the following output:

SUMMARY of currently loaded libraries:
___library___	_tstart_	__tend__	_dstart_	__dend__
./a.out	0x1000	0x1918	0x40000000	0x40000200
/usr/lib/libdld.so	0x800ac800	0x800ad000	0x6df62800	0x6df63000
/usr/lib/libc.so	0x80003800	0x80091000	0x6df63000	0x6df85000

176 Shared Library Management Routines