DIAL(3C)                             SysV                             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;   /* ptr to termio attribute struct */
             int    baud;           /* transmission baud-rate */
             int    speed;          /* 212A modem: low=300, high=1200 */
             char   *line;          /* device name for out-going line */
             char   *telno;         /* ptr to tel-no digits string */
             int    modem;          /* allow modem control on 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
                                    /* a 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 secound 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 L-devices
     file.  In this case, the value of the baud element need not be specified
     as it will be determined from the L-devices file.

     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 nonzero 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(2), read(2), write(2), termio(7).  in the Managing SysV System
     Software.
     uucp(1C) in the SysV Command Reference.

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 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 */

WARNINGS
     The dial (3C) library function is not compatible with Basic Networking
     Utilities on UNIX System V Release 2.0.

     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 "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.