linux/fs/readdir.c
Al Viro bb6f619b3a [readdir] introduce ->iterate(), ctx->pos, dir_emit()
New method - ->iterate(file, ctx).  That's the replacement for ->readdir();
it takes callback from ctx->actor, uses ctx->pos instead of file->f_pos and
calls dir_emit(ctx, ...) instead of filldir(data, ...).  It does *not*
update file->f_pos (or look at it, for that matter); iterate_dir() does the
update.

Note that dir_emit() takes the offset from ctx->pos (and eventually
filldir_t will lose that argument).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29 12:46:47 +04:00

315 lines
7.1 KiB
C

/*
* linux/fs/readdir.c
*
* Copyright (C) 1995 Linus Torvalds
*/
#include <linux/stddef.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/time.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/stat.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/dirent.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/unistd.h>
#include <asm/uaccess.h>
int iterate_dir(struct file *file, struct dir_context *ctx)
{
struct inode *inode = file_inode(file);
int res = -ENOTDIR;
if (!file->f_op || (!file->f_op->readdir && !file->f_op->iterate))
goto out;
res = security_file_permission(file, MAY_READ);
if (res)
goto out;
res = mutex_lock_killable(&inode->i_mutex);
if (res)
goto out;
res = -ENOENT;
if (!IS_DEADDIR(inode)) {
if (file->f_op->iterate) {
ctx->pos = file->f_pos;
res = file->f_op->iterate(file, ctx);
file->f_pos = ctx->pos;
} else {
res = file->f_op->readdir(file, ctx, ctx->actor);
ctx->pos = file->f_pos;
}
file_accessed(file);
}
mutex_unlock(&inode->i_mutex);
out:
return res;
}
EXPORT_SYMBOL(iterate_dir);
/*
* Traditional linux readdir() handling..
*
* "count=1" is a special case, meaning that the buffer is one
* dirent-structure in size and that the code can't handle more
* anyway. Thus the special "fillonedir()" function for that
* case (the low-level handlers don't need to care about this).
*/
#ifdef __ARCH_WANT_OLD_READDIR
struct old_linux_dirent {
unsigned long d_ino;
unsigned long d_offset;
unsigned short d_namlen;
char d_name[1];
};
struct readdir_callback {
struct dir_context ctx;
struct old_linux_dirent __user * dirent;
int result;
};
static int fillonedir(void * __buf, const char * name, int namlen, loff_t offset,
u64 ino, unsigned int d_type)
{
struct readdir_callback *buf = (struct readdir_callback *) __buf;
struct old_linux_dirent __user * dirent;
unsigned long d_ino;
if (buf->result)
return -EINVAL;
d_ino = ino;
if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
buf->result = -EOVERFLOW;
return -EOVERFLOW;
}
buf->result++;
dirent = buf->dirent;
if (!access_ok(VERIFY_WRITE, dirent,
(unsigned long)(dirent->d_name + namlen + 1) -
(unsigned long)dirent))
goto efault;
if ( __put_user(d_ino, &dirent->d_ino) ||
__put_user(offset, &dirent->d_offset) ||
__put_user(namlen, &dirent->d_namlen) ||
__copy_to_user(dirent->d_name, name, namlen) ||
__put_user(0, dirent->d_name + namlen))
goto efault;
return 0;
efault:
buf->result = -EFAULT;
return -EFAULT;
}
SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
struct old_linux_dirent __user *, dirent, unsigned int, count)
{
int error;
struct fd f = fdget(fd);
struct readdir_callback buf;
if (!f.file)
return -EBADF;
buf.ctx.actor = fillonedir;
buf.result = 0;
buf.dirent = dirent;
error = iterate_dir(f.file, &buf.ctx);
if (buf.result)
error = buf.result;
fdput(f);
return error;
}
#endif /* __ARCH_WANT_OLD_READDIR */
/*
* New, all-improved, singing, dancing, iBCS2-compliant getdents()
* interface.
*/
struct linux_dirent {
unsigned long d_ino;
unsigned long d_off;
unsigned short d_reclen;
char d_name[1];
};
struct getdents_callback {
struct dir_context ctx;
struct linux_dirent __user * current_dir;
struct linux_dirent __user * previous;
int count;
int error;
};
static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
u64 ino, unsigned int d_type)
{
struct linux_dirent __user * dirent;
struct getdents_callback * buf = (struct getdents_callback *) __buf;
unsigned long d_ino;
int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
sizeof(long));
buf->error = -EINVAL; /* only used if we fail.. */
if (reclen > buf->count)
return -EINVAL;
d_ino = ino;
if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
buf->error = -EOVERFLOW;
return -EOVERFLOW;
}
dirent = buf->previous;
if (dirent) {
if (__put_user(offset, &dirent->d_off))
goto efault;
}
dirent = buf->current_dir;
if (__put_user(d_ino, &dirent->d_ino))
goto efault;
if (__put_user(reclen, &dirent->d_reclen))
goto efault;
if (copy_to_user(dirent->d_name, name, namlen))
goto efault;
if (__put_user(0, dirent->d_name + namlen))
goto efault;
if (__put_user(d_type, (char __user *) dirent + reclen - 1))
goto efault;
buf->previous = dirent;
dirent = (void __user *)dirent + reclen;
buf->current_dir = dirent;
buf->count -= reclen;
return 0;
efault:
buf->error = -EFAULT;
return -EFAULT;
}
SYSCALL_DEFINE3(getdents, unsigned int, fd,
struct linux_dirent __user *, dirent, unsigned int, count)
{
struct fd f;
struct linux_dirent __user * lastdirent;
struct getdents_callback buf;
int error;
if (!access_ok(VERIFY_WRITE, dirent, count))
return -EFAULT;
f = fdget(fd);
if (!f.file)
return -EBADF;
buf.current_dir = dirent;
buf.previous = NULL;
buf.count = count;
buf.error = 0;
buf.ctx.actor = filldir;
error = iterate_dir(f.file, &buf.ctx);
if (error >= 0)
error = buf.error;
lastdirent = buf.previous;
if (lastdirent) {
if (put_user(buf.ctx.pos, &lastdirent->d_off))
error = -EFAULT;
else
error = count - buf.count;
}
fdput(f);
return error;
}
struct getdents_callback64 {
struct dir_context ctx;
struct linux_dirent64 __user * current_dir;
struct linux_dirent64 __user * previous;
int count;
int error;
};
static int filldir64(void * __buf, const char * name, int namlen, loff_t offset,
u64 ino, unsigned int d_type)
{
struct linux_dirent64 __user *dirent;
struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;
int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1,
sizeof(u64));
buf->error = -EINVAL; /* only used if we fail.. */
if (reclen > buf->count)
return -EINVAL;
dirent = buf->previous;
if (dirent) {
if (__put_user(offset, &dirent->d_off))
goto efault;
}
dirent = buf->current_dir;
if (__put_user(ino, &dirent->d_ino))
goto efault;
if (__put_user(0, &dirent->d_off))
goto efault;
if (__put_user(reclen, &dirent->d_reclen))
goto efault;
if (__put_user(d_type, &dirent->d_type))
goto efault;
if (copy_to_user(dirent->d_name, name, namlen))
goto efault;
if (__put_user(0, dirent->d_name + namlen))
goto efault;
buf->previous = dirent;
dirent = (void __user *)dirent + reclen;
buf->current_dir = dirent;
buf->count -= reclen;
return 0;
efault:
buf->error = -EFAULT;
return -EFAULT;
}
SYSCALL_DEFINE3(getdents64, unsigned int, fd,
struct linux_dirent64 __user *, dirent, unsigned int, count)
{
struct fd f;
struct linux_dirent64 __user * lastdirent;
struct getdents_callback64 buf;
int error;
if (!access_ok(VERIFY_WRITE, dirent, count))
return -EFAULT;
f = fdget(fd);
if (!f.file)
return -EBADF;
buf.current_dir = dirent;
buf.previous = NULL;
buf.count = count;
buf.error = 0;
buf.ctx.actor = filldir64;
error = iterate_dir(f.file, &buf.ctx);
if (error >= 0)
error = buf.error;
lastdirent = buf.previous;
if (lastdirent) {
typeof(lastdirent->d_off) d_off = buf.ctx.pos;
if (__put_user(d_off, &lastdirent->d_off))
error = -EFAULT;
else
error = count - buf.count;
}
fdput(f);
return error;
}