dial(3C) (C Programming Language Utilities) dial(3C)
NAME
dial - establish an outgoing terminal line connection
SYNOPSIS
#include <dial.h>
int dial(CALL call);
void undial(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; /* ptr to termio attribute struct */
int baud; /* unused */
int speed; /* 212A modem: low=300, high=1200 */
char *line; /* device name for out-going line */
char *telno; /* pointer to tel-no/system name string */
int modem; /* unused */
char *device; /* unused */
int devlen; /* 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. 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 value will cause dial to determine the correct
value from the Devices file.
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dial(3C) (C Programming Language Utilities) dial(3C)
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 will be set for the outgoing
terminal line before the connection is established. This setting is
often important for certain attributes such as parity and baud-rate.
The CALL elements device and devlen 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 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 */
DHUNG -2 /* dialer hung (no return from write) */
NOANS -3 /* no answer within 10 seconds */
ILLBD -4 /* illegal baud-rate */
APROB -5 /* acu problem (open() failure) */
LPROB -6 /* line problem (open() failure) */
NOLdv -7 /* can't open Devices file */
DVNTA -8 /* requested device not available */
DVNTK -9 /* requested device not known */
NOBDA -10 /* no device available at requested baud */
NOBDK -11 /* no device known at requested baud */
DVNTE -12 /* requested speed does not match */
BADSYS -13 /* system not in Systems file*/
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dial(3C) (C Programming Language Utilities) dial(3C)
NOTES
Including the dial.h header file automatically includes the termio.h
header file.
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.
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