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eucioctl - Interface to EUC-handling modules and drivers  


#include <sys/ioctl.h> #include <sys/eucioctl.h> #include <sys/stropts.h>

ioctl(        int fd,
       const I_STR,
       struct strioctl *argp);


Specifies a valid file descriptor. Points to a strioctl structure.  


The eucioctl interface is used with STREAMS modules and drivers for tty and pty devices that handle Extended UNIX Code (EUC) code sets. This interface consists of ioctl commands, which control character classification and conversion related to EUC character processing.

Users issue the EUC ioctl commands to modules and drivers by calling the STREAMS I_STR ioctl() function. (Refer to the streamio reference page for details on the use of the STREAMS I_STR ioctl() function.)

The I_STR ioctl() function takes an argument argp that is a pointer to a strioctl structure. The members of this structure, as defined in the /sys/stropts.h header file, are as follows:

struct strioctl {
        int ic_cmd;
        int ic_timout;
        int ic_len;
        char *ic_dp; };

The EUC ioctl commands are specified by placing one of the following values into the ic_cmd field of the strioctl structure. The use of the pointer field, ic_dp, depends on the command.

The following commands are used to specify or retrieve the character width information associated with the different classes of EUC code sets handled in the local environment: Sets the values for the byte widths and display widths of the classes of EUC code set in the ldterm line discipline module's local definition. The line discipline will use these values for its subsequent operations. Gets the current settings of the byte widths and display widths of the classes of EUC code sets in the ldterm module's local definition.

For the EUC_SET and EUC_GET commands, the ic_dp pointer is a pointer to an eucioc data structure, as defined in the eucioctl.h header file:

struct eucioc {
        unsigned char eucw[4];    /* byte width of character sets */
        unsigned char scrw[4];    /* display width of character sets */ };

The ic_len field contains the size of the eucioc structure.

When using the EUC_WSET command, the user process stores character width values in the eucioc structure, then calls the I_STR ioctl() function to set the values for the specified file descriptor, which must be a tty or pty device.

When issued by the user process, the EUC_WGET command gets the values currently in use for the specified file descriptor and stores them in the eucioc structure.

The remaining EUC ioctl commands control character code conversion as performed by the STREAMS modules and drivers comprising a tty or pty device stream: If the module or driver previously saved its state and turned off input conversion, this command reenables input conversion. If the module or driver is performing input conversion, then the conversion is disabled and the mode is saved. When the EUC_IXLOFF command is used with ICANON off, it creates a behavior roughly equivalent to raw mode. Turns output conversion back on if previously disabled by EUC_OXLOFF. Disables output conversion and saves the current mode status. This command is only recognized by modules and drivers that are not operating in ASCII mode. Saves the current mode status and disables input and output conversion. Restores the mode previously saved by EUC_MSAVE, restoring the saved mode and clearing the saved state flag.

None of the preceding commands use the ic_dp pointer.

The ldterm line discipline module provided by Tru64 UNIX uses EUC encoding as its internal character representation. This means that the module will only recognize data encoded in EUC. If an application or the terminal hardware sends character codes in other than the EUC format, these codes must be translated into EUC before reaching the ldterm module. Once the module finishes processing the codes, the codes must be translated back into the format that the application or terminal hardware handles.

If an application or the terminal hardware uses a code other than EUC and does not perform code translation, a code conversion module must be used to convert incoming data from its external representation into EUC and to convert outgoing data from EUC into the appropriate external representation. This kind of module is known as an upper converter when it is positioned between the stream head and ldterm module in the device stream, and a lower converter when it is positioned between the ldterm module and device driver in the device stream.  


In the following coding example, the application gets the current settings of the EUC character widths, then changes the settings for code set class 2 to 2 and 4 bytes for the encoding and display widths, respectively: #include <sys/ioctl.h> #include <sys/stropts.h> #include <sys/eucioctl.h>

main() {         struct eucioc   euc, *eucp = &euc;
        struct strioctl i_str;

       bzero((caddr_t) eucp, sizeof(struct eucioc));
        i_str.ic_cmd = EUC_WGET;
        i_str.ic_timout = 0;
        i_str.ic_len = sizeof(struct eucioc);
        i_str.ic_dp = (char *)eucp;
        if (ioctl(0, I_STR, &i_str) < 0) {

        i_str.ic_cmd = EUC_WSET;         eucp->eucw[2] = 2;
        eucp->scrw[2] = 4;

        if (ioctl(0, I_STR, &i_str) < 0) {
                perror("ioctl");                 exit(1);


If an error occurs, a value of -1 is returned, and errno is set to indicate the error.  


If any of the following conditions occurs, the EUC ioctl commands set errno to the corresponding value: The fd parameter is not a valid file descriptor. The fd parameter is not a terminal device. The command or argp parameter is not valid, or the terminal is not a STREAMS-based device. The argp parameter or ic_dp field points to memory that is not part of the process's address space. The struct eucioc argument is invalid. Processing of the command timed out.  


Contains definitions for EUC-related ioctl calls. Contains the ioctl() call prototype. Contains the definitions for STREAMS ioctl functions.  


Commands: eucset(1)

Interfaces: ldterm(7), streamio(7) delim off




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Time: 02:40:26 GMT, October 02, 2010