HP UX Software Transition Kit (STK) manual Example 1 Unsatisfied Symbols

(3E) These functions constitute the ELF access library (libelf) which lets a program manipulate ELF (Executable and Linking Format) object files, archive files, and archive members. The linker searches this library if the -lelfoption is specified. The header file <libelf.h> provides type and function declarations for all library services (described in elf(3E).

(3S) These functions comprise the Standard input/output routines (see stdio(3S)). They are located in libc.

(3M) These functions comprise the Math library. The linker searches this library under the -lmoption (for the SVID math library) or the -lM option (for the POSIX math library).

(3G) These functions comprise the Graphics library.

(3I) These functions comprise the Instrument support library.

(3X) Various specialized libraries. The names of the libraries in which these routines reside are documented on the manpage.

The routines marked by (2), (3C), and (3S) comprise the standard C library libc. The C, C++, and FORTRAN compilers automatically link with this library when creating an executable program.

For more information on these libraries, see C, A Reference Manual by Samual P. Harbison and Guy L. Steele Jr., published in 1991 by Prentice-Hall, or UNIX System V Libraries by Baird Peterson, published in 1992 by Van Nostrand Reinhold, or C Programming for UNIX by John Valley, published in 1992 by Sams Publishing. For more information on system calls, see Advanced UNIX Programming by Marc J. Rochkind, published in 1985 by Prentice-Hall or Advanced Programming in the UNIX Environment by W. Richard Stevens, published in 1992 by Addison-Wesley.

Caution When Mixing Shared and Archive Libraries

Mixing shared and archive libraries in an application is not recommended and must be avoided. That is, an application must use only shared libraries or only archive libraries.

Mixing shared and archive libraries can lead to: unsatisfied symbols, hidden definitions, duplicate definitions, and cause an application to abort or exhibit incorrect behavior at run time. The following examples illustrate some of these problems.

NOTE: The examples in this section apply only to PA-32 compatibility mode.

Example 1: Unsatisfied Symbols

This example (in PA-32 and PA-64/IPF(+compat mode) shows how mixing shared and archive libraries can cause a program to abort. Suppose you have a main program, main(), and three functions, f1(), f2(), and f3() each in a separate source file. The program main() calls f1() and f3() but not f2():

$ cc	-c	main.c f1.c f2.c	//Compile	to	relocatable object code.
$ cc	-c	+z f3.c	//Compile	to	position-independent code

Figure 12 Example 1: Unsatisfied Symbols: Compiling

Next, suppose you put f3.o into the shared library lib3.so and f1.o and f2.o into the archive library lib12.a:

$ ld	-b -o lib3.so f3.o	Create	a shared library.
$ ar	qvc lib12.a f1.o f2.o	Create	an archive library.

118 Creating and Using Libraries