Research V7 development

[unix-history] / usr / src / cmd / uucp / ulockf.c

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


/*******
*      ulockf(file, atime)
*      char *file;
*      time_t atime;
*
*      ulockf  -  this routine will create a lock file (file).
*      If one already exists, the create time is checked for
*      older than the age time (atime).
*      If it is older, an attempt will be made to unlink it
*      and create a new one.
*
*      return codes:  0  |  FAIL
*/

ulockf(file, atime)
char *file;
time_t atime;
{
       struct stat stbuf;
       time_t ptime;
       int ret;
       static int pid = -1;
       static char tempfile[NAMESIZE];

       if (pid < 0) {
               pid = getpid();
               sprintf(tempfile, "LTMP.%d", pid);
       }
       if (onelock(pid, tempfile, file) == -1) {
               /* lock file exists */
               /* get status to check age of the lock file */
               ret = stat(file, &stbuf);
               ASSERT(ret != -1, "LOCK PROBLEM - %s", file);

               time(&ptime);
               if ((ptime - stbuf.st_ctime) < atime) {
                       /* file not old enough to delete */
                       return(FAIL);
               }
       
               ret = unlink(file);
               ASSERT(ret != -1, "LOCK PROBLEM - %s", file);
       
               ret = onelock(pid, tempfile, file);
               ASSERT(ret == 0, "LOCK PROBLEM - %s", file);
       }
       stlock(file);
       return(0);
}


#define MAXLOCKS 10     /* maximum number of lock files */
char *Lockfile[MAXLOCKS];
int Nlocks = 0;

/***
*      stlock(name)    put name in list of lock files
*      char *name;
*
*      return codes:  none
*/

stlock(name)
char *name;
{
       char *p;
       extern char *calloc();
       int i;

       for (i = 0; i < Nlocks; i++) {
               if (Lockfile[i] == NULL)
                       break;
       }
       ASSERT(i < MAXLOCKS, "TOO MANY LOCKS %d", i);
       if (i >= Nlocks)
               i = Nlocks++;
       p = calloc(strlen(name) + 1, sizeof (char));
       ASSERT(p != NULL, "CAN NOT ALLOCATE FOR %s", name);
       strcpy(p, name);
       Lockfile[i] = p;
       return;
}


/***
*      rmlock(name)    remove all lock files in list
*      char *name;     or name
*
*      return codes: none
*/

rmlock(name)
char *name;
{
       int i;

       for (i = 0; i < Nlocks; i++) {
               if (Lockfile[i] == NULL)
                       continue;
               if (name == NULL
               || strcmp(name, Lockfile[i]) == SAME) {
                       unlink(Lockfile[i]);
                       free(Lockfile[i]);
                       Lockfile[i] = NULL;
               }
       }
       return;
}


/*  this stuff from pjw  */
/*  /usr/pjw/bin/recover - check pids to remove unnecessary locks */
/*      isalock(name) returns 0 if the name is a lock */
/*      unlock(name)  unlocks name if it is a lock*/
/*      onelock(pid,tempfile,name) makes lock a name
       on behalf of pid.  Tempfile must be in the same
       file system as name. */
/*      lock(pid,tempfile,names) either locks all the
       names or none of them */
isalock(name) char *name;
{
       struct stat xstat;
       if(stat(name,&xstat)<0) return(0);
       if(xstat.st_size!=sizeof(int)) return(0);
       return(1);
}
unlock(name) char *name;
{
       if(isalock(name)) return(unlink(name));
       else return(-1);
}
onelock(pid,tempfile,name) char *tempfile,*name;
{       int fd;
       fd=creat(tempfile,0444);
       if(fd<0) return(-1);
       write(fd,&pid,sizeof(int));
       close(fd);
       if(link(tempfile,name)<0)
       {       unlink(tempfile);
               return(-1);
       }
       unlink(tempfile);
       return(0);
}
lock(pid,tempfile,names) char *tempfile,**names;
{       int i,j;
       for(i=0;names[i]!=0;i++)
       {       if(onelock(pid,tempfile,names[i])==0) continue;
               for(j=0;j<i;j++) unlink(names[j]);
               return(-1);
       }
       return(0);
}

#define LOCKPRE "LCK."

/***
*      delock(s)       remove a lock file
*      char *s;
*
*      return codes:  0  |  FAIL
*/

delock(s)
char *s;
{
       char ln[30];

       sprintf(ln, "%s.%s", LOCKPRE, s);
       rmlock(ln);
}


/***
*      mlock(sys)      create system lock
*      char *sys;
*
*      return codes:  0  |  FAIL
*/

mlock(sys)
char *sys;
{
       char lname[30];
       sprintf(lname, "%s.%s", LOCKPRE, sys);
       return(ulockf(lname, (time_t) 24*3600 ) < 0 ? FAIL : 0);
}