minix/fs/isofs/read.c

   1 #include "inc.h"
   2
   3 static char getdents_buf[GETDENTS_BUFSIZ];
   4
   5 ssize_t fs_read(ino_t ino_nr, struct fsdriver_data *data, size_t bytes,
   6         off_t pos, int __unused call)
   7 {
   8         size_t off, chunk, block_size, cum_io;
   9         off_t f_size;
  10         struct inode *i_node;
  11         struct buf *bp;
  12         int r;
  13
  14         /* Try to get inode according to its index. */
  15         if ((i_node = get_inode(ino_nr)) == NULL)
  16                 return EINVAL; /* No inode found. */
  17
  18         f_size = i_node->i_stat.st_size;
  19         if (pos >= f_size)
  20                 return 0; /* EOF */
  21
  22         /* Limit the request to the remainder of the file size. */
  23         if ((off_t)bytes > f_size - pos)
  24                 bytes = (size_t)(f_size - pos);
  25
  26         block_size = v_pri.logical_block_size_l;
  27         cum_io = 0;
  28
  29         r = OK;
  30
  31         /* Split the transfer into chunks that don't span two blocks. */
  32         while (bytes > 0) {
  33                 off = pos % block_size;
  34
  35                 chunk = block_size - off;
  36                 if (chunk > bytes)
  37                         chunk = bytes;
  38
  39                 /* Read 'chunk' bytes. */
  40                 bp = read_extent_block(&i_node->extent, pos);
  41                 if (bp == NULL)
  42                         panic("bp not valid in rw_chunk; this can't happen");
  43
  44                 r = fsdriver_copyout(data, cum_io, b_data(bp)+off, chunk);
  45
  46                 lmfs_put_block(bp);
  47
  48                 if (r != OK)
  49                         break;
  50
  51                 /* Update counters and pointers. */
  52                 bytes -= chunk;         /* Bytes yet to be read. */
  53                 cum_io += chunk;        /* Bytes read so far. */
  54                 pos += chunk;           /* Position within the file. */
  55         }
  56
  57         return (r == OK) ? cum_io : r;
  58 }
  59
  60 ssize_t fs_getdents(ino_t ino_nr, struct fsdriver_data *data, size_t bytes,
  61         off_t *pos)
  62 {
  63         struct fsdriver_dentry fsdentry;
  64         struct inode *i_node;
  65         off_t cur_pos;
  66         int r, len;
  67         char *cp;
  68
  69         if ((i_node = get_inode(ino_nr)) == NULL)
  70                 return EINVAL;
  71
  72         if (*pos < 0 || *pos > SSIZE_MAX)
  73                 return EINVAL;
  74
  75         r = read_directory(i_node);
  76         if (r != OK)
  77                 return r;
  78
  79         fsdriver_dentry_init(&fsdentry, data, bytes, getdents_buf,
  80             sizeof(getdents_buf));
  81
  82         r = OK;
  83
  84         for (cur_pos = *pos; cur_pos < i_node->dir_size; cur_pos++) {
  85                 /* Compute the length of the name */
  86                 cp = memchr(i_node->dir_contents[cur_pos].name, '\0', NAME_MAX);
  87                 if (cp == NULL)
  88                         len = NAME_MAX;
  89                 else
  90                         len = cp - i_node->dir_contents[cur_pos].name;
  91
  92                 r = fsdriver_dentry_add(&fsdentry,
  93                     i_node->dir_contents[cur_pos].i_node->i_stat.st_ino,
  94                     i_node->dir_contents[cur_pos].name, len,
  95                     IFTODT(i_node->dir_contents[cur_pos].i_node->i_stat.st_mode));
  96
  97                 if (r <= 0)
  98                         break;
  99         }
 100
 101         if (r >= 0 && (r = fsdriver_dentry_finish(&fsdentry)) >= 0)
 102                 *pos = cur_pos;
 103
 104         return r;
 105 }