DIAL(S) XENIX System V DIAL(S)
Name
dial - Establishes an out-going terminal line connection.
Syntax
#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 it is 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; /*Will hold the name of the device used
to make a connection */
int dev_len; /* The length of the device used to
make connection */
} CALL;
The CALL element speed is intended for use only 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.
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
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DIAL(S) XENIX System V DIAL(S)
element in the CALL structure. Legal values for such
terminal device names are kept in the L-devices file. In
this case, the value of the baud element does not have to be
specified as it will be determined from the L-devices file.
The telno element is a pointer to a character string
representing the telephone number to be dialed. Such
numbers may consist of symbols only described on the acu(7).
The termination symbol will be supplied by the dial
function, and should not be included in the telno string
passed to dial in the CALL structure.
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 element device is used to hold the device name
(cul..) that establishes the connection.
The CALL element dev_len is the length of the device name
that is copied into the array device.
Files
/usr/lib/uucp/L-devices
/usr/spool/uucp/LCK..tty-device
See Also
alarm(S), dial(M), read(S), termcap(M), uucp(C), write(S)
Diagnostics
On failure, a negative value indicating the reason for the
failure will be returned. Mnemonics for these negative
indices listed below 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 LDEVS 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
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DIAL(S) XENIX System V DIAL(S)
requested baud */
NO_BD_K -11 /* no device known at
requested baud */
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. Otherwise,
uucp(C) 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(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.
Warnings
When you include the <dial.h> header file, the <termio.h>
header file is automatically included.
Note that the above routine uses <stdio.h>, which causes it
to increase its program size, otherwise not using standard
I/O, more than might be expected.
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