Return to posixopen.c CVS log

Up to [Research Unix] / researchv10no / cmd / upas / libc

Annotation of researchv10no/cmd/upas/libc/posixopen.c, revision 1.1

1.1     ! root        1: #include <stdio.h>
        !             2: #include "string.h"
        !             3: #include "mail.h"
        !             4: #include <sys/stat.h>
        !             5: 
        !             6: /* imports */
        !             7: extern char *mktemp();
        !             8: extern int sleep();
        !             9: extern long lseek();
        !            10: 
        !            11: #define FILNAMSIZ 14
        !            12: #define LOCKPREFIX "/usr/spool/locks/L."
        !            13: #define TMPLNAME "/usr/spool/locks/mlXXXXXX"
        !            14: static char lockname[FILNAMSIZ+sizeof("/usr/spool/locks/")];
        !            15: static char tlockname[FILNAMSIZ+sizeof("/usr/spool/locks/")];
        !            16: static char tmplname[sizeof(TMPLNAME)];
        !            17: 
        !            18: static void lockbotch();
        !            19: 
        !            20: /*
        !            21:  *  open a file for appending.  if the file doesn't exist, create it.
        !            22:  *  return the file descriptor.
        !            23:  */
        !            24: appendopen(file)
        !            25:        char *file;
        !            26: {
        !            27:        int out;
        !            28:        long lseek();
        !            29: 
        !            30:        lock(file);
        !            31:        out = open(file, 2);
        !            32:        if (out < 0)
        !            33:                out = creat(file, 0666);
        !            34:        else
        !            35:                chmod(file, 0666);
        !            36:        lseek(out, 0L, 2);
        !            37:        return out;
        !            38: }
        !            39: 
        !            40: /*
        !            41:  *  close an append only file
        !            42:  */
        !            43: appendclose(fd)
        !            44:        int fd;
        !            45: {
        !            46:        close(fd);
        !            47:        unlock();
        !            48: }
        !            49: 
        !            50: /*
        !            51:  *  lock and open file.  If the file doesn't exist and mode!=0, create it.
        !            52:  *  return the file descriptor.
        !            53:  */
        !            54: 
        !            55: FILE *
        !            56: lockopen(file, omode, pmode, uid, gid)
        !            57:        char *file;
        !            58:        char *omode;
        !            59:        int pmode;
        !            60: {
        !            61:        FILE *fp;
        !            62:        struct stat sbuf;
        !            63:        int newfile;
        !            64: 
        !            65:        lock(file);
        !            66:        if(stat(file, &sbuf)<0)
        !            67:                newfile = 1;
        !            68:        else
        !            69:                newfile = 0;
        !            70:        fp = fopen(file, omode);
        !            71:        if(fp==NULL){
        !            72:                unlock();
        !            73:                return NULL;
        !            74:        }
        !            75:        if(newfile){
        !            76:                chown(file, uid, gid);
        !            77:                chmod(file, pmode);
        !            78:        }
        !            79:        return fp;
        !            80: }
        !            81: 
        !            82: /*
        !            83:  *  close and unlock a file.
        !            84:  */
        !            85: lockclose(fp)
        !            86:        FILE *fp;
        !            87: {
        !            88:        fclose(fp);
        !            89:        unlock();
        !            90: }
        !            91: 
        !            92: /*
        !            93:  *  reopen a file without losing the lock.
        !            94:  */
        !            95: FILE *
        !            96: lockreopen(file, omode, fp)
        !            97:        char *file;
        !            98:        char *omode;
        !            99:        FILE *fp;
        !           100: {
        !           101:        return freopen(file, omode, fp);
        !           102: }
        !           103: 
        !           104: /*
        !           105:  *  remove ALL locks
        !           106:  */
        !           107: cleanlocks()
        !           108: {
        !           109:        unlock();
        !           110: }
        !           111: 
        !           112: /* break an old lock */
        !           113: static void
        !           114: lockbotch(err, file)
        !           115:        char *err;
        !           116:        char *file;
        !           117: {
        !           118:        int fd;
        !           119:        char msg[128];
        !           120:        char log[256];
        !           121: 
        !           122:        sprintf(msg, "mail: problem with lock file\n");
        !           123:        write(2, msg, strlen(msg));
        !           124:        strcpy(log, MAILROOT);
        !           125:        strcat(log, "mail.log");
        !           126:        if ((fd=open(log, 1)) >= 0) {
        !           127:                sprintf(msg, "error %s (tmp=%s lock=%s)\n", err, file, lockname);
        !           128:                lseek(fd, (long)0, 2);
        !           129:                write(fd, msg, strlen(msg));
        !           130:                close(fd);
        !           131:        }
        !           132: }
        !           133: 
        !           134: /* Fill name with the lock name for file */
        !           135: setlname(name, file)
        !           136:        char *name, *file;
        !           137: {
        !           138:        char *slashp;
        !           139: 
        !           140:        (void)strcpy(name, LOCKPREFIX);
        !           141:        slashp = strrchr(file, '/');
        !           142:        if (slashp==NULL)
        !           143:                strncat(name, file, sizeof(lockname)-strlen(name)-1);
        !           144:        else
        !           145:                strncat(name, slashp+1, sizeof(lockname)-strlen(name)-1);
        !           146:        lockname[sizeof(lockname)-1] = '\0';
        !           147: }
        !           148: 
        !           149: /* Lock the given file */
        !           150: lock(file)
        !           151: char *file;
        !           152: {
        !           153:        int fd, i;
        !           154:        char pidbuf[20];
        !           155: 
        !           156:        /* return if we are already in the middle of a lock */
        !           157:        if (*lockname != '\0') {
        !           158:                lockbotch("double lock", tmplname);
        !           159:                return;
        !           160:        }
        !           161: 
        !           162:        /* create a temporary file */
        !           163:        (void)strcpy(tmplname, TMPLNAME);
        !           164:        (void)mktemp(tmplname);
        !           165:        if ((fd=creat(tmplname, 0444))<0) {
        !           166:                lockbotch("tmp exists", tmplname);
        !           167:                return;
        !           168:        }
        !           169:        sprintf(pidbuf, "%d upas", getpid());
        !           170:        write(fd, pidbuf, strlen(pidbuf));
        !           171:        close(fd);
        !           172: 
        !           173:        /* Make a link to it with the lock file name.  This will fail only
        !           174:         * if it already exists.
        !           175:         */
        !           176:        setlname(lockname, file);
        !           177:        i = 0;
        !           178:        while (link(tmplname, lockname) < 0) {
        !           179:                /* File is already locked */
        !           180:                sleep(2);
        !           181:                (void) islocked(file); /* might break a stale lock */
        !           182:                if (++i > 300) {
        !           183:                        lockbotch("breaking old lock", tmplname);
        !           184:                        unlink(lockname);
        !           185:                        link(tmplname, lockname);
        !           186:                        break;
        !           187:                }
        !           188:        }
        !           189:        unlink(tmplname);
        !           190:        *tmplname = '\0';
        !           191:        return;
        !           192: }
        !           193: 
        !           194: /* Return true if file has been locked by us or another program using the same
        !           195:  * lock name scheme.  Remove the lock if it too old.
        !           196:  */
        !           197: int
        !           198: islocked(file)
        !           199:        char *file;
        !           200: {
        !           201:        struct stat stbuf;
        !           202: 
        !           203:        setlname(tlockname, file);
        !           204:        if (stat(tlockname, &stbuf)<0)
        !           205:                return 0;
        !           206:        if(time(0) - stbuf.st_mtime > 15*60) {
        !           207:                lockbotch("old lock: breaking lock", tlockname);
        !           208:                unlink(tlockname);
        !           209:                return 0;
        !           210:        }
        !           211:        return 1;
        !           212: }
        !           213: 
        !           214: unlock()
        !           215: {
        !           216:        if (*tmplname != '\0') {
        !           217:                if(unlink(tmplname)<0)
        !           218:                        lockbotch("unlock of tmpfile failed", tmplname);
        !           219:                *tmplname = '\0';
        !           220:        }
        !           221:        if (*lockname != '\0') {
        !           222:                if(unlink(lockname)<0)
        !           223:                        lockbotch("unlock of lock file failed", tmplname);
        !           224:                *lockname = '\0';
        !           225:        }
        !           226: }

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.