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/* This file contains file and directory reading file system call handlers.
*
* The entry points into this file are:
* do_read perform the READ file system call
* do_getdents perform the GETDENTS file system call
*
* Created:
* April 2009 (D.C. van Moolenbroek)
*/
#include "inc.h"
#include <dirent.h>
/*===========================================================================*
* do_read *
*===========================================================================*/
ssize_t do_read(ino_t ino_nr, struct fsdriver_data *data, size_t count,
off_t pos, int call)
{
/* Read data from a file.
*/
struct inode *ino;
size_t size, off;
char *ptr;
int r, chunk;
if ((ino = find_inode(ino_nr)) == NULL)
return EINVAL;
if (IS_DIR(ino)) return EISDIR;
if ((r = get_handle(ino)) != OK)
return r;
assert(count > 0);
/* Use the buffer from below to eliminate extra copying. */
size = sffs_table->t_readbuf(&ptr);
off = 0;
while (count > 0) {
chunk = MIN(count, size);
if ((r = sffs_table->t_read(ino->i_file, ptr, chunk, pos)) <= 0)
break;
chunk = r;
if ((r = fsdriver_copyout(data, off, ptr, chunk)) != OK)
break;
count -= chunk;
off += chunk;
pos += chunk;
}
if (r < 0)
return r;
return off;
}
/*===========================================================================*
* do_getdents *
*===========================================================================*/
ssize_t do_getdents(ino_t ino_nr, struct fsdriver_data *data, size_t bytes,
off_t *posp)
{
/* Retrieve directory entries.
*/
struct fsdriver_dentry fsdentry;
char name[NAME_MAX+1];
struct inode *ino, *child;
struct sffs_attr attr;
off_t pos;
int r;
/* must be at least sizeof(struct dirent) + NAME_MAX */
static char buf[BLOCK_SIZE];
if ((ino = find_inode(ino_nr)) == NULL)
return EINVAL;
if (!IS_DIR(ino)) return ENOTDIR;
if (*posp < 0 || *posp >= ULONG_MAX) return EINVAL;
/* We are going to need at least one free inode to store children in. */
if (!have_free_inode()) return ENFILE;
/* If we don't have a directory handle yet, get one now. */
if ((r = get_handle(ino)) != OK)
return r;
fsdriver_dentry_init(&fsdentry, data, bytes, buf, sizeof(buf));
/* We use the seek position as file index number. The first position is for
* the "." entry, the second position is for the ".." entry, and the next
* position numbers each represent a file in the directory.
*/
for (;;) {
/* Determine which inode and name to use for this entry.
* We have no idea whether the host will give us "." and/or "..",
* so generate our own and skip those from the host.
*/
pos = (*posp)++;
if (pos == 0) {
/* Entry for ".". */
child = ino;
strcpy(name, ".");
get_inode(child);
}
else if (pos == 1) {
/* Entry for "..", but only when there is a parent. */
if (ino->i_parent == NULL)
continue;
child = ino->i_parent;
strcpy(name, "..");
get_inode(child);
}
else {
/* Any other entry, not being "." or "..". */
attr.a_mask = SFFS_ATTR_MODE;
r = sffs_table->t_readdir(ino->i_dir, pos - 2, name,
sizeof(name), &attr);
if (r != OK) {
/* No more entries? Then close the handle and stop. */
if (r == ENOENT) {
put_handle(ino);
break;
}
/* FIXME: what if the error is ENAMETOOLONG? */
return r;
}
if (!strcmp(name, ".") || !strcmp(name, ".."))
continue;
if ((child = lookup_dentry(ino, name)) == NULL) {
child = get_free_inode();
/* We were promised a free inode! */
assert(child != NULL);
child->i_flags = MODE_TO_DIRFLAG(attr.a_mode);
add_dentry(ino, name, child);
}
}
r = fsdriver_dentry_add(&fsdentry, INODE_NR(child), name, strlen(name),
IS_DIR(child) ? DT_DIR : DT_REG);
put_inode(child);
if (r < 0)
return r;
if (r == 0)
break;
}
return fsdriver_dentry_finish(&fsdentry);
}
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