sysfile.c

unix环境高级编程的源代码

#include    "calld.h"

static FILE    *fpsys = NULL;
static int     syslineno;            /* for error messages */
static char     sysline[MAXLINE];
        /* can't be automatic; sys_next() returns pointers into here */

/* Read and break apart a line in the Systems file. */

long                        /* return >0 if OK, -1 on EOF */
sys_next(Systems *sysptr)    /* structure is filled in with pointers */
{
    if (fpsys == NULL) {
        if ( (fpsys = fopen(SYSTEMS, "r")) == NULL)
            log_sys("can't open %s", SYSTEMS);
        syslineno = 0;
    }

again:
    if (fgets(sysline, MAXLINE, fpsys) == NULL)
        return(-1);        /* EOF */
    syslineno++;

    if ( (sysptr->name = strtok(sysline, WHITE)) == NULL) {
        if (sysline[0] == '\n')
            goto again;        /* ignore empty line */
        log_quit("missing `name' in Systems file, line %d", syslineno);
    }
    if (sysptr->name[0] == '#')
        goto again;            /* ignore comment line */

    if ( (sysptr->time = strtok(NULL, WHITE)) == NULL)
        log_quit("missing `time' in Systems file, line %d", syslineno);

    if ( (sysptr->type = strtok(NULL, WHITE)) == NULL)
        log_quit("missing `type' in Systems file, line %d", syslineno);

    if ( (sysptr->class = strtok(NULL, WHITE)) == NULL)
        log_quit("missing `class' in Systems file, line %d", syslineno);

    if ( (sysptr->phone = strtok(NULL, WHITE)) == NULL)
        log_quit("missing `phone' in Systems file, line %d", syslineno);

    if ( (sysptr->login = strtok(NULL, "\n")) == NULL)
        log_quit("missing `login' in Systems file, line %d", syslineno);

    return(ftell(fpsys));    /* return the position in Systems file */
}

void
sys_rew(void)
{
    if (fpsys != NULL)
        rewind(fpsys);
    syslineno = 0;
}

void
sys_posn(long posn)        /* position Systems file */
{
    if (posn == 0)
        sys_rew();
    else if (fseek(fpsys, posn, SEEK_SET) != 0)
        log_sys("fseek error");
}