Technical Reference: Base Operating System and Extensions, Volume 1

getpass Subroutine

Purpose

Reads a password.

Library

Standard C Library (libc.a)

Syntax

#include <stdlib.h>

char *getpass ( Prompt) char *Prompt;

Description

Attention: The characters are returned in a static data area. Subsequent calls to this subroutine overwrite the static data area.

The getpass subroutine does the following:

Opens the controlling terminal of the current process.
Writes the characters specified by the Prompt parameter to that device.
Reads from that device the number of characters up to the value of the PASS_MAX constant until a new-line or end-of-file (EOF) character is detected.
Restores the terminal state and closes the controlling terminal.

During the read operation, character echoing is disabled.

The getpass subroutine is not safe in a multithreaded environment. To use the getpass subroutine in a threaded application, the application must keep the integrity of each thread.

Parameters

Prompt

Specifies a prompt to display on the terminal.

Return Values

If this subroutine is successful, it returns a pointer to the string. If an error occurs, the subroutine returns a null pointer and sets the errno global variable to indicate the error.

Error Codes

If the getpass subroutine is unsuccessful, it returns one or more of the following error codes:

EINTR	Indicates that an interrupt occurred while the getpass subroutine was reading the terminal device. If a SIGINT or SIGQUIT signal is received, the getpass subroutine terminates input and sends the signal to the calling process.
ENXIO	Indicates that the process does not have a controlling terminal.

Note: Any subroutines called by the getpass subroutine may set other error codes.

Implementation Specifics

This subroutine is part of Base Operating System (BOS) Runtime.

Related Information

The getuserpw (getuserpw, putuserpw, or putuserpwhist Subroutine) subroutine, newpass (newpass Subroutine) subroutine.

List of Security and Auditing Subroutines, Subroutines Overview in AIX 5L Version 5.1 General Programming Concepts: Writing and Debugging Programs.