usr/src/usr.bin/uucp/libuu/gename.c

#ifndef lint
static char sccsid[] = "@(#)gename.c    5.3 (Berkeley) %G%";
#endif

#include "uucp.h"
#include <sys/types.h>

#define SEQLEN 4

/*******
 *      gename(pre, sys, grade, file)   generate file name
 *      char grade, *sys, pre, *file;
 *
 *      return codes:  none
 */

gename(pre, sys, grade, file)
char pre, *sys, grade, *file;
{
        static char sqnum[SEQLEN+1];

        getseq(sqnum);
        sprintf(file, "%c.%.7s%c%.*s", pre, sys, grade, SEQLEN, sqnum);
        DEBUG(4, "file - %s\n", file);
        return;
}


#define SLOCKTIME 10L
#define SLOCKTRIES 5

/*******
 *      getseq(snum)    get next sequence number
 *      char *snum;
 *
 *      return codes:  none
 */

static
getseq(snum)
register char *snum;
{
        /*
         * the alphabet can be anything, but if it's not in ascii order,
         * sequence ordering is not preserved
         */
        char    *alphabet =
            "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
        register int i, fd;
        static char *lastchar;

        if (lastchar == NULL || (snum[SEQLEN-1] = *(lastchar++)) == '\0') {
                for (i = 0; i < SLOCKTRIES; i++) {
                        if (!ulockf(SEQLOCK, (time_t)SLOCKTIME))
                                break;
                        sleep(5);
                }

                ASSERT(i < SLOCKTRIES, "CAN NOT GET", "SEQLOCK", 0);

                if ((fd = open(SEQFILE, 2)) >= 0) {
                        int alphalen;
                        register char   *p;
                        char *index();

                        alphalen = strlen(alphabet);
                        read(fd, snum, SEQLEN);
                        /* increment the penultimate character */
                        for (i = SEQLEN - 2; i >= 0; --i) {
                                if ((p = index(alphabet, snum[i])) == NULL) {
                                        /* drastic but effective */
                                        snum[i] = alphabet[alphalen - 1];
                                        DEBUG(6, "bad seqf: %s\n", snum);
                                }
                                if (++p < &alphabet[alphalen]) {
                                        snum[i] = *p;
                                        break;
                                } else          /* carry */
                                        snum[i] = alphabet[0];  /* continue */
                        }
                        snum[SEQLEN-1] = alphabet[0];
                } else {
                        if ((fd = creat(SEQFILE, 0666)) < 0)
                                return(FAIL);
                        for (i = 0; i < SEQLEN; i++)
                                snum[i] = alphabet[0];
                }

                lseek(fd, 0L, 0);
                write(fd, snum, SEQLEN);
                close(fd);
                rmlock(SEQLOCK);
                lastchar = alphabet + 1;
        }
        return(0);
}