DIAL(3C) (C Programming Language Utilities) DIAL(3C)
NAME
dial - establish an out-going terminal line connection
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> 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 out-going 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 will
transmit at any rate between 0 and 300 bits per second.
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DIAL(3C) (C Programming Language Utilities) DIAL(3C)
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 will cause 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 dail 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 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
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DIAL(3C) (C Programming Language Utilities) DIAL(3C)
/usr/lib/uucp/Devices
/usr/lib/uucp/Systems
/usr/spool/uucp/LCK..tty-device
SEE ALSO
alarm(2), read(2), write(2).
acu(7), termio(7) in the System Administrator's Reference
Manual.
uucp(1C) in the 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 */
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
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DIAL(3C) (C Programming Language Utilities) DIAL(3C)
caught) within the dial module for the purpose of
``touching'' 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.
Page 4 May 1989