git.zerfleddert.de Git - micropolis/blob - src/tcl/compat/opendir.c

   1 /*
   2  * opendir.c --
   3  *
   4  *      This file provides dirent-style directory-reading procedures
   5  *      for V7 Unix systems that don't have such procedures.  The
   6  *      origin of this code is unclear, but it seems to have come
   7  *      originally from Larry Wall.
   8  *
   9  */
  10
  11 #include <tclint.h>
  12 #include <tclunix.h>
  13
  14 #undef DIRSIZ
  15 #define DIRSIZ(dp) \
  16     ((sizeof (struct dirent) - (MAXNAMLEN+1)) + (((dp)->d_namlen+1 + 3) &~ 3))
  17
  18 /*
  19  * open a directory.
  20  */
  21 DIR *
  22 opendir(name)
  23 char *name;
  24 {
  25         register DIR *dirp;
  26         register int fd;
  27         char *myname;
  28
  29         myname = ((*name == '\0') ? "." : name);
  30         if ((fd = open(myname, 0, 0)) == -1)
  31                 return NULL;
  32         if ((dirp = (DIR *)ckalloc(sizeof(DIR))) == NULL) {
  33                 close (fd);
  34                 return NULL;
  35         }
  36         dirp->dd_fd = fd;
  37         dirp->dd_loc = 0;
  38         return dirp;
  39 }
  40
  41 /*
  42  * read an old style directory entry and present it as a new one
  43  */
  44 #ifndef pyr
  45 #define ODIRSIZ 14
  46
  47 struct  olddirect {
  48         ino_t   od_ino;
  49         char    od_name[ODIRSIZ];
  50 };
  51 #else   /* a Pyramid in the ATT universe */
  52 #define ODIRSIZ 248
  53
  54 struct  olddirect {
  55         long    od_ino;
  56         short   od_fill1, od_fill2;
  57         char    od_name[ODIRSIZ];
  58 };
  59 #endif
  60
  61 /*
  62  * get next entry in a directory.
  63  */
  64 struct dirent *
  65 readdir(dirp)
  66 register DIR *dirp;
  67 {
  68         register struct olddirect *dp;
  69         static struct dirent dir;
  70
  71         for (;;) {
  72                 if (dirp->dd_loc == 0) {
  73                         dirp->dd_size = read(dirp->dd_fd, dirp->dd_buf,
  74                             DIRBLKSIZ);
  75                         if (dirp->dd_size <= 0)
  76                                 return NULL;
  77                 }
  78                 if (dirp->dd_loc >= dirp->dd_size) {
  79                         dirp->dd_loc = 0;
  80                         continue;
  81                 }
  82                 dp = (struct olddirect *)(dirp->dd_buf + dirp->dd_loc);
  83                 dirp->dd_loc += sizeof(struct olddirect);
  84                 if (dp->od_ino == 0)
  85                         continue;
  86                 dir.d_ino = dp->od_ino;
  87                 strncpy(dir.d_name, dp->od_name, ODIRSIZ);
  88                 dir.d_name[ODIRSIZ] = '\0'; /* insure null termination */
  89                 dir.d_namlen = strlen(dir.d_name);
  90                 dir.d_reclen = DIRSIZ(&dir);
  91                 return (&dir);
  92         }
  93 }
  94
  95 /*
  96  * close a directory.
  97  */
  98 void
  99 closedir(dirp)
 100 register DIR *dirp;
 101 {
 102         close(dirp->dd_fd);
 103         dirp->dd_fd = -1;
 104         dirp->dd_loc = 0;
 105         ckfree((char *) dirp);
 106 }