minix/lib/libfsdriver/dentry.c

   1
   2 #include "fsdriver.h"
   3 #include <sys/dirent.h>
   4
   5 /*
   6  * Initialize a directory entry listing.
   7  */
   8 void
   9 fsdriver_dentry_init(struct fsdriver_dentry * __restrict dentry,
  10         const struct fsdriver_data * __restrict data, size_t bytes,
  11         char * __restrict buf, size_t bufsize)
  12 {
  13
  14         dentry->data = data;
  15         dentry->data_size = bytes;
  16         dentry->data_off = 0;
  17         dentry->buf = buf;
  18         dentry->buf_size = bufsize;
  19         dentry->buf_off = 0;
  20 }
  21
  22 /*
  23  * Add an entry to a directory entry listing.  Return the entry size if it was
  24  * added, zero if no more entries could be added and the listing should stop,
  25  * or an error code in case of an error.
  26  */
  27 ssize_t
  28 fsdriver_dentry_add(struct fsdriver_dentry * __restrict dentry, ino_t ino_nr,
  29         const char * __restrict name, size_t namelen, unsigned int type)
  30 {
  31         struct dirent *dirent;
  32         size_t len, used;
  33         int r;
  34
  35         /* We could do several things here, but it should never happen.. */
  36         if (namelen > MAXNAMLEN)
  37                 panic("fsdriver: directory entry name excessively long");
  38
  39         len = _DIRENT_RECLEN(dirent, namelen);
  40
  41         if (dentry->data_off + dentry->buf_off + len > dentry->data_size) {
  42                 if (dentry->data_off == 0 && dentry->buf_off == 0)
  43                         return EINVAL;
  44
  45                 return 0;
  46         }
  47
  48         if (dentry->buf_off + len > dentry->buf_size) {
  49                 if (dentry->buf_off == 0)
  50                         panic("fsdriver: getdents buffer too small");
  51
  52                 if ((r = fsdriver_copyout(dentry->data, dentry->data_off,
  53                     dentry->buf, dentry->buf_off)) != OK)
  54                         return r;
  55
  56                 dentry->data_off += dentry->buf_off;
  57                 dentry->buf_off = 0;
  58         }
  59
  60         dirent = (struct dirent *)&dentry->buf[dentry->buf_off];
  61         dirent->d_fileno = ino_nr;
  62         dirent->d_reclen = len;
  63         dirent->d_namlen = namelen;
  64         dirent->d_type = type;
  65         memcpy(dirent->d_name, name, namelen);
  66
  67         /*
  68          * Null-terminate the name, and zero out any alignment bytes after it,
  69          * so as not to leak any data.
  70          */
  71         used = _DIRENT_NAMEOFF(dirent) + namelen;
  72         if (used >= len)
  73                 panic("fsdriver: inconsistency in dirent record");
  74         memset(&dirent->d_name[namelen], 0, len - used);
  75
  76         dentry->buf_off += len;
  77
  78         return len;
  79 }
  80
  81 /*
  82  * Finish a directory entry listing operation.  Return the total number of
  83  * bytes copied to the caller, or an error code in case of an error.
  84  */
  85 ssize_t
  86 fsdriver_dentry_finish(struct fsdriver_dentry *dentry)
  87 {
  88         int r;
  89
  90         if (dentry->buf_off > 0) {
  91                 if ((r = fsdriver_copyout(dentry->data, dentry->data_off,
  92                     dentry->buf, dentry->buf_off)) != OK)
  93                         return r;
  94
  95                 dentry->data_off += dentry->buf_off;
  96         }
  97
  98         return dentry->data_off;
  99 }