rewrite to look like times()

[unix-history] / usr / src / lib / libc / gen / devname.c

/*
* Copyright (c) 1989 The Regents of the University of California.
* All rights reserved.
*
* %sccs.include.redist.c%
*/

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)devname.c   5.6 (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <dirent.h>
#include <paths.h>

static struct devs {
       struct  devs *next;
       dev_t   dev;
       char    name[MAXNAMLEN+1];
       mode_t  type;
};

#define hash(x) ((x)&0xff)
static struct devs *devhash[0xff + 1];

static int devinit;

char *
devname(dev, type)
       dev_t dev;
       mode_t type;
{
       struct devs *devp;

       if (devinit == 0) {
               register struct devs *devpp;
               register struct dirent *entry;
               struct stat sb;
               DIR *dp = opendir(_PATH_DEV);
               int savewd = open(".", O_RDONLY, 0);
               mode_t specialtype;

               if (savewd == -1 || dp == NULL || chdir(_PATH_DEV) == -1)
                       return (NULL);
               while ((entry = readdir(dp)) != NULL) {
                       if (stat(entry->d_name, &sb) == -1)
                               continue;
                       switch(sb.st_mode&S_IFMT) {
                       case S_IFCHR:
                               specialtype = S_IFCHR;
                               break;
                       case S_IFBLK:
                               specialtype = S_IFBLK;
                               break;
                       default:
                               continue;
                       }
                       devp = (struct devs *)malloc(sizeof (struct devs));
                       if (devp == NULL)
                               return (NULL);
                       devp->type = specialtype;
                       devp->dev = sb.st_rdev;
                       strcpy(devp->name, entry->d_name);
                       devp->next = NULL;
                       if ((devpp = devhash[hash(sb.st_rdev)]) == NULL)
                               devhash[hash(sb.st_rdev)] = devp;
                       else {
                               for (;devpp->next != NULL; devpp = devpp->next)
                                       ;
                               devpp->next = devp;
                       }
               }
               fchdir(savewd);
               close(savewd);
               closedir(dp);
               devinit = 1;
       }
       for (devp = devhash[hash(dev)]; devp != NULL; devp = devp->next)
               if (dev == devp->dev && type == devp->type)
                       return(devp->name);

       return (NULL);
}

#ifdef TEST
main() {
       printf(" %s \n", devname(0));
}
#endif