158 lines
3.7 KiB
C
158 lines
3.7 KiB
C
/* VTreeFS - read.c - by Alen Stojanov and David van Moolenbroek */
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#include "inc.h"
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#include <dirent.h>
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#define GETDENTS_BUFSIZ 4096
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/*===========================================================================*
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* fs_read *
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*===========================================================================*/
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ssize_t fs_read(ino_t ino_nr, struct fsdriver_data *data, size_t bytes,
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off_t pos, int __unused call)
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{
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/* Read from a file.
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*/
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struct inode *node;
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size_t len;
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char *ptr;
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int r;
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/* Try to get inode by its inode number. */
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if ((node = find_inode(ino_nr)) == NULL)
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return EINVAL;
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/* Check whether the node is a regular file. */
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if (!S_ISREG(node->i_stat.mode))
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return EINVAL;
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/* Call the read hook, if any. */
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if (!is_inode_deleted(node) && vtreefs_hooks->read_hook != NULL) {
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len = bytes;
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/* On success, the read hook provides us with a pointer to the
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* resulting data. This avoids copying overhead.
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*/
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r = vtreefs_hooks->read_hook(node, pos, &ptr, &len,
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get_inode_cbdata(node));
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assert(len <= bytes);
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/* Copy the resulting data to user space. */
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if (r == OK && len > 0)
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r = fsdriver_copyout(data, 0, ptr, len);
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} else {
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/* Feign an empty file. */
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r = OK;
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len = 0;
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}
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return (r != OK) ? r : len;
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}
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/*===========================================================================*
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* fs_getdents *
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*===========================================================================*/
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ssize_t fs_getdents(ino_t ino_nr, struct fsdriver_data *data, size_t bytes,
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off_t *posp)
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{
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/* Retrieve directory entries.
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*/
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struct fsdriver_dentry fsdentry;
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struct inode *node, *child;
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const char *name;
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off_t pos;
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int r, skip, get_next, indexed;
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static char buf[GETDENTS_BUFSIZ];
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if (*posp >= ULONG_MAX)
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return EIO;
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if ((node = find_inode(ino_nr)) == NULL)
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return EINVAL;
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indexed = node->i_indexed;
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get_next = FALSE;
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child = NULL;
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/* Call the getdents hook, if any, to "refresh" the directory. */
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if (!is_inode_deleted(node) && vtreefs_hooks->getdents_hook != NULL) {
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r = vtreefs_hooks->getdents_hook(node, get_inode_cbdata(node));
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if (r != OK) return r;
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}
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fsdriver_dentry_init(&fsdentry, data, bytes, buf, sizeof(buf));
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do {
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/* Determine which inode and name to use for this entry. */
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pos = (*posp)++;
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if (pos == 0) {
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/* The "." entry. */
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child = node;
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name = ".";
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}
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else if (pos == 1) {
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/* The ".." entry. */
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child = get_parent_inode(node);
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if (child == NULL)
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child = node;
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name = "..";
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}
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else if (pos - 2 < indexed) {
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/* All indexed entries. */
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child = get_inode_by_index(node, pos - 2);
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/* If there is no inode with this particular index,
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* continue with the next index number.
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*/
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if (child == NULL) continue;
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name = child->i_name;
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}
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else {
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/* All non-indexed entries. */
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/* If this is the first loop iteration, first get to
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* the non-indexed child identified by the current
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* position.
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*/
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if (get_next == FALSE) {
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skip = pos - indexed - 2;
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child = get_first_inode(node);
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/* Skip indexed children. */
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while (child != NULL &&
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child->i_index != NO_INDEX)
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child = get_next_inode(child);
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/* Skip to the right position. */
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while (child != NULL && skip-- > 0)
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child = get_next_inode(child);
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get_next = TRUE;
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}
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else {
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child = get_next_inode(child);
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}
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/* No more children? Then stop. */
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if (child == NULL)
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break;
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assert(!is_inode_deleted(child));
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name = child->i_name;
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}
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/* Add the directory entry to the output. */
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r = fsdriver_dentry_add(&fsdentry,
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(ino_t) get_inode_number(child), name, strlen(name),
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IFTODT(child->i_stat.mode));
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if (r < 0)
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return r;
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} while (r > 0);
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return fsdriver_dentry_finish(&fsdentry);
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}
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