dial(3C) AT&T SYSTEM V dial(3C)
NAME
dial, undial - establish an out-going terminal line connec-
tion
SYNOPSIS
#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>
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 out-going line */
char *telno; /* pointer to tel-no digits string */
int modem; /* specify modem control for direct lines */
char *device; /* unused */
int devlen; /* unused */
} CALL;
The CALL element speed is intended only for use with an out-
going 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 will
transmit at any rate between 0 and 300 bits per second. How-
ever, 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 exam-
ple, 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 ele-
ment in the CALL structure. Legal values for such terminal
device names are kept in the Devices file. In this case,
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dial(3C) AT&T SYSTEM V dial(3C)
the value of the baud element should be set to -1. This
will cause dial to determine the correct value from the Dev-
ices 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 con-
trol 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 ele-
ments specified in it will be 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.
FILES
/etc/uucp/Devices
/etc/uucp/Systems
/var/spool/uucp/LCK..tty-device
SEE ALSO
alarm(2), read(2), write(2).
termio(7) in the CX/UX Administrator's Reference Manual.
uucp(1C) in the CX/UX User's Reference Manual.
DIAGNOSTICS
On failure, a negative value indicating the reason for the
failure will be returned. Mnemonics for these 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 */
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dial(3C) AT&T SYSTEM V dial(3C)
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>, which causes it to
increase the size of programs, not otherwise using standard
I/O, more than might be expected.
BUGS
An alarm(2) system call for 3600 seconds is made (and
caught) within the dial module for the purpose of ``touch-
ing'' the LCK.. file and constitutes the device allocation
semaphore for the terminal device. Otherwise, uucp(1C) may
simply delete the LCK.. entry on its 90-minute clean-up
rounds. The alarm may go off while the user program is in a
read(2) or write(2) 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.
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