DIAL(3C) DIAL(3C)
dial - establish an out-going terminal line connection
#include <dial.h>
int dial (CALL call);
void undial (int fd);
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; /*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 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. 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 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 need not be specified as it
will be determined from the Devices file.
Page 1
DIAL(3C) DIAL(3C)
The telno element is for a pointer to a character string representing the
telephone number to be dialed. 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.
/etc/uucp/Devices
/var/spool/locks/LCK..tty-device
alarm(2), read(2), write(2).
termio(7m).
uucp(1C).
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 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 requested baud */
NO_BD_K -11 /* no device known at requested baud */
Including the <dial.h> header file automatically includes the <termio.h>
header file.
Page 2
DIAL(3C) DIAL(3C)
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.
An alarm(2) 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(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.
PPPPaaaaggggeeee 3333 [ Back ]
|
