dial(3C) dial(3C)NAME dial - establishes 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- speed 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). January 1992 1
dial(3C) dial(3C)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, which causes 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. Telephone numbers may consist of only these characters: 0-9 * # = - All the characters in the telno element are written to the terminal line (that is, ``dialed''). Some modems interpret the equal sign (=) as a command a wait for a secondary dial tone and the hyphen (-) as a command to delay for approximately 4 seconds before writing the next character. If the modem uses other characters for these commands, you can cause the dial function to translate the equal sign and the hyphen to the appropriate characters by using the substitutions field in the Dialers file. See ``Configuring and Managing UUCP'' in A/UX Network System Administration for details. 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 important for attributes such as parity and baud rate. The CALL element device and dev_len are no longer used. They are retained in the CALL structure for compatibility reasons. ERRORS On failure, a negative value indicating the reason for the failure is 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 */ 2 January 1992
dial(3C) dial(3C)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. LIMITATIONS An alarm(2) system call for 3600 seconds is made (and caught) within the dial module for the purpose of ``touching'' the lock file and constitutes the device allocation semaphore for the terminal device. Otherwise, uucp may simply delete the lock file 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 is to run for an hour or more, error returns from reads should be checked for (errno==EINTR), and the read possibly reissued. FILES /usr/lib/uucp/Devices File containing device information /usr/lib/uucp/Dialers File containing dialer information /usr/lib/uucp/Systems File containing the phone number to be dialed /usr/spool/locks/* Directory in which lock files are made SEE ALSO alarm(2), read(2), write(2), termio(7) uucp(1C) in A/UX Command Reference January 1992 3