source: vendor/gawk/3.1.5/vms/vms_cli.c

/*
 * vms_cli.c - command line interface routines.
 *                                                      Pat Rankin, Nov'89
 *      Routines called from vms_gawk.c for DCL parsing.
 */

#define  P(foo) ()
#include "config.h"     /* in case we want to suppress 'const' &c */
#include "vms.h"
#ifndef _STRING_H
#include <string.h>
#endif

extern U_Long CLI$PRESENT(const Dsc *);
extern U_Long CLI$GET_VALUE(const Dsc *, Dsc *, short *);
extern U_Long CLI$DCL_PARSE(const Dsc *, const void *, ...);
extern U_Long sys$cli(void *, ...);
extern U_Long sys$filescan(const Dsc *, void *, long *);
extern void  *lib$establish(U_Long (*handler)(void *, void *));
extern U_Long lib$sig_to_ret(void *, void *);   /* condition handler */

/* Cli_Present() - call CLI$PRESENT to determine whether a parameter or     */
/*                qualifier is present on the [already parsed] command line */
U_Long
Cli_Present( const char *item )
{
    Dsc item_dsc;
    (void)lib$establish(lib$sig_to_ret);

    item_dsc.len = strlen(item_dsc.adr = (char *)item);
    return CLI$PRESENT(&item_dsc);
}

/* Cli_Get_Value() - call CLI$GET_VALUE to retreive the value of a */
/*                  parameter or qualifier from the command line   */
U_Long
Cli_Get_Value( const char *item, char *result, int size )
{
    Dsc item_dsc, res_dsc;
    U_Long sts;
    short len = 0;
    (void)lib$establish(lib$sig_to_ret);

    item_dsc.len = strlen(item_dsc.adr = (char *)item);
    res_dsc.len = size,  res_dsc.adr = result;
    sts = CLI$GET_VALUE(&item_dsc, &res_dsc, &len);
    result[len] = '\0';
    return sts;
}

/* Cli_Parse_Command() - use the $CLI system service (undocumented) to   */
/*                      retreive the actual command line (which might be */
/*                      "run prog" or "mcr prog [params]") and then call */
/*                      CLI$DCL_PARSE to parse it using specified tables */
U_Long
Cli_Parse_Command( const void *cmd_tables, const char *cmd_verb )
{
    struct { short len, code; void *adr; } fscn[2];
    struct { char rqtype, rqindx, rqflags, rqstat; unsigned :32;
             Dsc rdesc; unsigned :32; unsigned :32; unsigned :32; } cmd;
    U_Long sts;
    int    ltmp;
    char   longbuf[8200];
    (void)lib$establish(lib$sig_to_ret);

    memset(&cmd, 0, sizeof cmd);
    cmd.rqtype = CLI$K_GETCMD;          /* command line minus the verb */
    sts = sys$cli(&cmd, (void *)0, (void *)0);  /* get actual command line */

    if (vmswork(sts)) {         /* ok => cli available & verb wasn't "RUN" */
        /* invoked via symbol => have command line (which might be empty) */
        /*    [might also be invoked via mcr or dcl; that's ok]           */
        if (cmd.rqstat == CLI$K_VERB_MCR) {
            /* need to strip image name from MCR invocation   */
            memset(fscn, 0, sizeof fscn);
            fscn[0].code = FSCN$_FILESPEC;      /* full file specification */
            (void)sys$filescan(&cmd.rdesc, fscn, (long *)0);
            cmd.rdesc.len -= fscn[0].len;       /* shrink size */
            cmd.rdesc.adr += fscn[0].len;       /* advance ptr */
        }
        /* prepend verb and then parse the command line */
        strcat(strcpy(longbuf, cmd_verb), " "),  ltmp = strlen(longbuf);
        if (cmd.rdesc.len + ltmp > sizeof longbuf)
            cmd.rdesc.len = sizeof longbuf - ltmp;
        strncpy(&longbuf[ltmp], cmd.rdesc.adr, cmd.rdesc.len);
        cmd.rdesc.len += ltmp,  cmd.rdesc.adr = longbuf;
        sts = CLI$DCL_PARSE( &cmd.rdesc, cmd_tables);
    }

    return sts;
}