dial(S)

dial -- establish an outgoing terminal line connection

Syntax

cc . . . -lc

#include <dial.h>

int dial (call)
CALL call;

void undial (fd)
int fd;

Description

dial returns a file-descriptor for a terminal line open for read/write. The argument to dial is a CALL structure (defined in the <dial.h> header file).

When finished with the terminal line, the calling program must invoke undial to release the semaphore that has been set during the allocation of the terminal device.

The definition of CALL in the <dial.h> header file is:

   typedef struct {
           struct termio *attr;    /* pointer to termio attribute struct */
           int    baud;            /* transmission data rate */
           int    speed;           /* 212A modem: low=300, high=1200 */
           char   *line;           /* device name for outgoing line */
           char   *telno;          /* pointer to tel-no digits string */
           int    modem;           /* specify modem control
                                      for direct lines */
           char   *device;         /* unused */
           int    dev_len;         /* unused */
   } CALL;

The CALL element speed is intended only for use with an outgoing dialed call, in which case its value should be either 300 or 1200 to identify the 113A modem, or the high- or low-speed setting on the 212A modem. Note that the 113A modem or the low-speed setting of the 212A modem transmits at any rate between 0 and 300 bits per second. However, the high-speed setting of the 212A modem transmits and receives at 1200 bits per second only. The CALL element baud is for the desired transmission baud rate. For example, one might set baud to 110 and speed to 300 (or 1200). However, if speed is set to 1200, baud must be set to high (1200).

If the desired terminal line is a direct line, a string pointer to its device-name should be placed in the line element in the CALL structure. Legal values for such terminal device names are kept in the Devices file. In this case, the value of the baud element should be set to -1. This causes dial to determine the correct value from the Devices file.

The telno element is for a pointer to a character string representing the telephone number to be dialed. Such numbers may consist only of these characters:

0-9: dial 0-9
: dial
#: dial #
=: wait for secondary dial tone
-: delay for approximately 4 seconds

The CALL element modem is used to specify modem control for direct lines. This element should be non-zero if modem control is required. The CALL element attr is a pointer to a termio structure, as defined in the <termio.h> header file. A NULL value for this pointer element may be passed to the dial function, but if such a structure is included, the elements specified in it is set for the outgoing terminal line before the connection is established. This is often important for certain attributes such as parity and baud-rate.

The CALL elements device and dev_len are no longer used. They are retained in the CALL structure for compatibility reasons.

Diagnostics

On failure, a negative value indicating the reason for the failure is returned. Mnemonics for the negative indices as listed here are defined in the <dial.h> header file.

INTRPT -1 / interrupt occurred /

D_HUNG -2 / dialer hung (no return from write) /

NO_ANS -3 / no answer within 10 seconds /

ILL_BD -4 / illegal baud-rate /

A_PROB -5 / acu problem (open() failure) /

L_PROB -6 / line problem (open() failure) /

NO_Ldv -7 / can't open Devices file /

DV_NT_A -8 / requested device not available /

DV_NT_K -9 / requested device not known /

NO_BD_A -10 / no device available at requested baud /

NO_BD_K -11 / no device known at requested baud /

DV_NT_E -12 / requested speed does not match /

BAD_SYS -13 / system not in Systems file/

Warnings

Including the <dial.h> header file automatically includes the <termio.h> header file.

The above routine uses <stdio.h>. This causes the routine to increase the size of programs that are not using standard I/O more than might be expected.

Notes

An alarm(S) system call for 3600 seconds is made (and caught) within the dial module for the purpose of ``touching'' the LCK... file and constitutes the device allocation semaphore for the terminal device. The LCK... file prevents uucp(C) from trying to transmit more than one file at a time using the particular device. If the LCK... file is not ``touched'' then uucp(C) may simply delete the file on its 90-minute clean-up rounds. The alarm may go off while the user program is in a read(S) or write(S) system call, causing an apparent error return. If the user program expects to be around for an hour or more, error returns from reads should be checked for (errno==EINTR), and the read possibly reissued.

Files

/usr/lib/uucp/Devices
/usr/lib/uucp/Systems
/usr/spool/locks/LCK..tty-device

Standards conformance

dial and undial are not part of any currently supported standard; they are an extension of AT&T System V provided by the Santa Cruz Operation.

INTRPT	-1	/ interrupt occurred /
D_HUNG	-2	/ dialer hung (no return from write) /
NO_ANS	-3	/ no answer within 10 seconds /
ILL_BD	-4	/ illegal baud-rate /
A_PROB	-5	/ acu problem (open() failure) /
L_PROB	-6	/ line problem (open() failure) /
NO_Ldv	-7	/ can't open Devices file /
DV_NT_A	-8	/ requested device not available /
DV_NT_K	-9	/ requested device not known /
NO_BD_A	-10	/ no device available at requested baud /
NO_BD_K	-11	/ no device known at requested baud /
DV_NT_E	-12	/ requested speed does not match /
BAD_SYS	-13	/ system not in Systems file/