nlist_pa(3C)

NAME

nlist_pa: nlist(), nlist64() — get entries from name list on PA-RISC systems

SYNOPSIS

nlist()

Command: cc [flag]... cfile...

#include <nlist.h>

int nlist(
const char *file_name,
struct nlist *nl
);

nlist64()

Command: cc [flag]... cfile... -lelf [library]...

#include <nlist.h>

int nlist64(
const char *file_name,
struct nlist64 *nl
);

Remarks

The use of symbol table type and value information is inherently nonportable. The use of nlist() or nlist64() should reduce the effort required to port a program that uses such information, but complete portability across all HP-UX implementations cannot be expected.

This manpage describes nlist() and nlist64() for PA-RISC systems. For nlist() and nlist64() on Integrity systems, see nlist_ia(3C).

DESCRIPTION

nlist() and nlist64() have basically the same functionality except that nlist64() uses the nlist64 structure and can process SOM or ELF files. nlist() uses the nlist structure and can only process SOM files.

The nlist() or nlist64() function examines the name list in the executable file whose name is pointed to by file_name, and selectively extracts a list of values and puts them in the array of nlist/nlist64 structures pointed to by nl. The array of nlist/nlist64 structures initially contains only the names of variables. Once the nlist() or nlist64() function has been called, the variable names are augmented with symbol information. The list is terminated by a null name, which consists of a null string in the variable-name position of the structure. The name list of the file is searched for each variable name. If the name is found, the symbol's type, scope, and value in the file is inserted into the name list structure. For nlist64(), if the file searched is an ELF file, the section index is also inserted. For nlist() and SOM files, the subspace index is inserted. On wide-mode systems, the symbol value is 64-bit. If the file searched is a SOM file, then the value field is zero padded. If the name is not found, the fields in the name list structure are set to 0. The structures nlist and nlist64 are defined in the include file <nlist.h>. See a.out(4) and nlist(4) for further description of the symbol table structure.

The file must have the organization and symbol table described for an a.out file in a.out(4). The information is extracted from the symbol table used by the linker, ld(1).

On machines that have such a file, this subroutine is useful for examining the system name list kept in file /stand/vmunix. In this way programs can obtain system addresses that are up to date.

RETURN VALUE

All nlist/nlist64 structure fields are set to 0 if the file cannot be found or if it is not a valid object file containing a linker symbol table.

nlist() and nlist64() return:

-1: An error occurred.
0: Success.

WARNINGS

The <nlist.h> header file is automatically included by <a.out.h> for compatibility. However, including <a.out.h> is discouraged if the only information needed from <a.out.h> is for use by nlist() or nlist64(). If <a.out.h> is included, the line #undef n_name may need to follow it.

STANDARDS CONFORMANCE

nlist(): SVID2, SVID3