Microsoft Programmer's Library 1.3/Microsoft-Programers-Library-v1.3.iso/sampcode/alde_c/ci_c86/bisicc/execf.c

C/C++ Source or Header | 1985-06-26 | 4.4 KB | 170 lines

/*        execf.c        execute another program and return status */

#include <stdio.h>

struct {unsigned int ax,bx,cx,dx,si,di,ds,es;} r;
unsigned char cline[128],*ep,*envfind();
int status=-1;

#define NUMINTS 30
static char *internals[] = {"copy","ren","rename","del","erase","chdir","cd",\
"md","mkdir","dir","rd","rmdir","type","cls","ctty","date","time",\
"path","prompt","set","ver","verify","vol","echo","rem","goto","if",\
"shift","pause","for"};

fork(cmdl)                /* parses off name and cmdl for execf */
char *cmdl;
{
    char *sp;
    char *name;
    char comlin[128];
    int er;

    sp = strcpy(name,cmdl);
    strcat(name," ");                    /* pad for find */
    while(*++sp != ' ');                /* find 1st space */
    *sp++ = '\0';                        /* term name str */
    strcpy(comlin,sp);                /* get command line */
    er= execf(name,comlin);
    return(er);
}

execf(name,cmdl)        /* executes name with command line cmdl */
char *name;
char *cmdl;
{
    int i,er;
    char tp[255];
    char *ts;
    char *path;
    char *findexecf();
    char lcmdl[255];        /* local command line */

    lcmdl[0] = ' ';            /* tack on a space at the beginning */
    strcpy(lcmdl+1,cmdl);    /* to keep DOS happy */
    name = lower(name);        /* convert to lowercase for search */
    for (i=0;i<NUMINTS;i++) {
        if (!strcmp(name,internals[i]))    /* check for an internal command */
            return (system(strcat(name,lcmdl)));    /* use c86 system() if internal */
    }
    /* it's not an internal command, process it */

    path = alloc(255);
    curdrv(path);            /* get current drive */
    getpath(path);        /* and path */
    ep = envfind("PATH");
    if (*ep != ';') strcat(path,";");    /* if none at beginning already */
    strcat(path,ep);                            /* all one path string */
    free(ep);
    while (*path) {                            /* until we hit EOS */
        strcpy(tp,path);
        i = 0;
        while (*path++ != ';') i++;        /* find end of path */
        tp[i] = '\0';                            /* term path string */
        if (tp[i-2] != '\\' || tp[i-2] != '/') strcat(tp,"/");
        if ((ts=findexecf(tp,name))) {
            er = _execf(ts,lcmdl);
            if (!er) {
                r.ax = 0x4d00;
                sysint21(&r,&r);
                er = r.ax&0xff;
            }
            return(er);
        }
    }
    return(-1);                                /* command not found, ret err */
}

char *findexecf(path,name)                /* tries to find an execable name along path */
char *path,*name;
{
    char tn[255];
    char *first,*next;
    static char *exet[] = {".COM",".EXE",".BAT"};
    int i;

    name = upper(name);
    strcpy(tn,path);
    strcat(tn,name);
    strcat(tn,".*");            /* add wildcard to find all */
    first = filedir(tn,0);    /* look for all normal files */
    strcpy(tn,name);
    for (next=first;*next != '\0';) {
        for (i=0;i<3;i++) {
            if (!(strcmp(strcat(tn,exet[i]),next))) return(strcat(path,tn));
            strcpy(tn,name);        /* nope, try again */
        }
        next += strlen(next)+1;        /* look at next name in list */
    }
    return(NULL);                        /* didn't find one */
}

_execf(path,cmdl)                /* execs path(incl. name.ext) with cmdl */
char *path,*cmdl;
{
    int er;
    struct {
        int env_seg;
        char *line_off,*line_seg;
        char *fcb1_off,*fcb1_seg;
        char *fcb2_off,*fcb2_seg;
    } ctrl;

    cline[0] = strlen(cmdl);        /* put in length */
    strcpy(cline+1,cmdl);            /* copy in command line */
    strcat(cline,"\r");                /* add a CR */
    segread(&r.si);                    /* get current cs */
    ctrl.env_seg=0;                    /* no environment to pass */
    ctrl.line_off=cline;                /* offset of command line */
    ctrl.line_seg=r.ds;                /* segment of command line */
    er = loadexec(path,r.ds,&ctrl,r.ds,0);    /* launch! */
    return(er);
}

/* curdrv - get current default drive */

curdrv(sp)
char *sp;
{
    struct { int ax, bx, cx;
             char *dx, *si, *di, *ds, *es;
           } r;

    r.ax = 0x1900;                            /* DOS interrupt 19 */
    sysint(0x21, &r, &r);                /* gets current drive number */
    *sp++ = r.ax + 'a';                    /* convert to symbolic drive name */
    *sp++ = ':';
    *sp++ = '\0';
    sp--;
    return;
}

/* getpath - get path to directory on indicated drive */

getpath(sp)
char *sp;
{
    struct { int ax, bx, cx, dx;
             char *si;
             int di, ds, es;
           } r;
    extern int _showds();

    strcat(sp, "/");                /* append root file symbol to drive name */

    r.ax = 0x4700;                    /* DOS interrupt 47 gets path string */
    r.dx = *sp - '`';                /* convert drive name to index */
    r.ds = _showds();
    r.si = sp + 3;                    /* paste string after root symbol */
    sysint(0x21, &r, &r);
    return;
}

_showds()
{
    struct{int cs, ss, ds, es;} r;

    segread(&r);
    return(r.ds);
}