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![Jens Axboe](/assets/img/avatar_default.png)
Also corrects a few comments. Patch mainly from Ingo, changes by me. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Jens Axboe <axboe@suse.de>
768 lines
16 KiB
C
768 lines
16 KiB
C
/*
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* linux/fs/read_write.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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#include <linux/slab.h>
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#include <linux/stat.h>
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#include <linux/fcntl.h>
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#include <linux/file.h>
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#include <linux/uio.h>
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#include <linux/smp_lock.h>
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#include <linux/fsnotify.h>
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#include <linux/security.h>
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#include <linux/module.h>
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#include <linux/syscalls.h>
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#include <linux/pagemap.h>
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#include <asm/uaccess.h>
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#include <asm/unistd.h>
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const struct file_operations generic_ro_fops = {
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.llseek = generic_file_llseek,
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.read = generic_file_read,
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.mmap = generic_file_readonly_mmap,
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.sendfile = generic_file_sendfile,
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};
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EXPORT_SYMBOL(generic_ro_fops);
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loff_t generic_file_llseek(struct file *file, loff_t offset, int origin)
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{
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long long retval;
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struct inode *inode = file->f_mapping->host;
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mutex_lock(&inode->i_mutex);
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switch (origin) {
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case 2:
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offset += inode->i_size;
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break;
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case 1:
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offset += file->f_pos;
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}
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retval = -EINVAL;
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if (offset>=0 && offset<=inode->i_sb->s_maxbytes) {
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if (offset != file->f_pos) {
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file->f_pos = offset;
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file->f_version = 0;
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}
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retval = offset;
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}
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mutex_unlock(&inode->i_mutex);
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return retval;
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}
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EXPORT_SYMBOL(generic_file_llseek);
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loff_t remote_llseek(struct file *file, loff_t offset, int origin)
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{
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long long retval;
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lock_kernel();
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switch (origin) {
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case 2:
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offset += i_size_read(file->f_dentry->d_inode);
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break;
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case 1:
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offset += file->f_pos;
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}
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retval = -EINVAL;
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if (offset>=0 && offset<=file->f_dentry->d_inode->i_sb->s_maxbytes) {
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if (offset != file->f_pos) {
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file->f_pos = offset;
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file->f_version = 0;
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}
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retval = offset;
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}
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unlock_kernel();
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return retval;
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}
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EXPORT_SYMBOL(remote_llseek);
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loff_t no_llseek(struct file *file, loff_t offset, int origin)
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{
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return -ESPIPE;
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}
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EXPORT_SYMBOL(no_llseek);
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loff_t default_llseek(struct file *file, loff_t offset, int origin)
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{
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long long retval;
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lock_kernel();
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switch (origin) {
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case 2:
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offset += i_size_read(file->f_dentry->d_inode);
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break;
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case 1:
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offset += file->f_pos;
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}
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retval = -EINVAL;
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if (offset >= 0) {
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if (offset != file->f_pos) {
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file->f_pos = offset;
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file->f_version = 0;
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}
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retval = offset;
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}
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unlock_kernel();
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return retval;
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}
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EXPORT_SYMBOL(default_llseek);
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loff_t vfs_llseek(struct file *file, loff_t offset, int origin)
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{
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loff_t (*fn)(struct file *, loff_t, int);
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fn = no_llseek;
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if (file->f_mode & FMODE_LSEEK) {
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fn = default_llseek;
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if (file->f_op && file->f_op->llseek)
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fn = file->f_op->llseek;
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}
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return fn(file, offset, origin);
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}
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EXPORT_SYMBOL(vfs_llseek);
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asmlinkage off_t sys_lseek(unsigned int fd, off_t offset, unsigned int origin)
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{
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off_t retval;
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struct file * file;
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int fput_needed;
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retval = -EBADF;
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file = fget_light(fd, &fput_needed);
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if (!file)
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goto bad;
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retval = -EINVAL;
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if (origin <= 2) {
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loff_t res = vfs_llseek(file, offset, origin);
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retval = res;
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if (res != (loff_t)retval)
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retval = -EOVERFLOW; /* LFS: should only happen on 32 bit platforms */
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}
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fput_light(file, fput_needed);
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bad:
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return retval;
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}
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#ifdef __ARCH_WANT_SYS_LLSEEK
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asmlinkage long sys_llseek(unsigned int fd, unsigned long offset_high,
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unsigned long offset_low, loff_t __user * result,
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unsigned int origin)
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{
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int retval;
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struct file * file;
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loff_t offset;
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int fput_needed;
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retval = -EBADF;
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file = fget_light(fd, &fput_needed);
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if (!file)
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goto bad;
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retval = -EINVAL;
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if (origin > 2)
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goto out_putf;
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offset = vfs_llseek(file, ((loff_t) offset_high << 32) | offset_low,
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origin);
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retval = (int)offset;
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if (offset >= 0) {
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retval = -EFAULT;
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if (!copy_to_user(result, &offset, sizeof(offset)))
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retval = 0;
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}
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out_putf:
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fput_light(file, fput_needed);
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bad:
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return retval;
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}
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#endif
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/*
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* rw_verify_area doesn't like huge counts. We limit
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* them to something that fits in "int" so that others
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* won't have to do range checks all the time.
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*/
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#define MAX_RW_COUNT (INT_MAX & PAGE_CACHE_MASK)
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int rw_verify_area(int read_write, struct file *file, loff_t *ppos, size_t count)
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{
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struct inode *inode;
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loff_t pos;
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if (unlikely((ssize_t) count < 0))
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goto Einval;
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pos = *ppos;
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if (unlikely((pos < 0) || (loff_t) (pos + count) < 0))
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goto Einval;
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inode = file->f_dentry->d_inode;
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if (unlikely(inode->i_flock && MANDATORY_LOCK(inode))) {
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int retval = locks_mandatory_area(
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read_write == READ ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE,
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inode, file, pos, count);
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if (retval < 0)
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return retval;
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}
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return count > MAX_RW_COUNT ? MAX_RW_COUNT : count;
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Einval:
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return -EINVAL;
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}
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static void wait_on_retry_sync_kiocb(struct kiocb *iocb)
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{
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set_current_state(TASK_UNINTERRUPTIBLE);
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if (!kiocbIsKicked(iocb))
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schedule();
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else
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kiocbClearKicked(iocb);
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__set_current_state(TASK_RUNNING);
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}
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ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
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{
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struct kiocb kiocb;
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ssize_t ret;
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init_sync_kiocb(&kiocb, filp);
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kiocb.ki_pos = *ppos;
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while (-EIOCBRETRY ==
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(ret = filp->f_op->aio_read(&kiocb, buf, len, kiocb.ki_pos)))
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wait_on_retry_sync_kiocb(&kiocb);
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if (-EIOCBQUEUED == ret)
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ret = wait_on_sync_kiocb(&kiocb);
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*ppos = kiocb.ki_pos;
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return ret;
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}
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EXPORT_SYMBOL(do_sync_read);
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ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
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{
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ssize_t ret;
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if (!(file->f_mode & FMODE_READ))
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return -EBADF;
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if (!file->f_op || (!file->f_op->read && !file->f_op->aio_read))
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return -EINVAL;
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if (unlikely(!access_ok(VERIFY_WRITE, buf, count)))
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return -EFAULT;
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ret = rw_verify_area(READ, file, pos, count);
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if (ret >= 0) {
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count = ret;
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ret = security_file_permission (file, MAY_READ);
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if (!ret) {
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if (file->f_op->read)
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ret = file->f_op->read(file, buf, count, pos);
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else
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ret = do_sync_read(file, buf, count, pos);
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if (ret > 0) {
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fsnotify_access(file->f_dentry);
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current->rchar += ret;
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}
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current->syscr++;
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}
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}
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return ret;
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}
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EXPORT_SYMBOL(vfs_read);
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ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
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{
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struct kiocb kiocb;
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ssize_t ret;
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init_sync_kiocb(&kiocb, filp);
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kiocb.ki_pos = *ppos;
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while (-EIOCBRETRY ==
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(ret = filp->f_op->aio_write(&kiocb, buf, len, kiocb.ki_pos)))
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wait_on_retry_sync_kiocb(&kiocb);
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if (-EIOCBQUEUED == ret)
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ret = wait_on_sync_kiocb(&kiocb);
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*ppos = kiocb.ki_pos;
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return ret;
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}
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EXPORT_SYMBOL(do_sync_write);
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ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
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{
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ssize_t ret;
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if (!(file->f_mode & FMODE_WRITE))
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return -EBADF;
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if (!file->f_op || (!file->f_op->write && !file->f_op->aio_write))
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return -EINVAL;
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if (unlikely(!access_ok(VERIFY_READ, buf, count)))
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return -EFAULT;
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ret = rw_verify_area(WRITE, file, pos, count);
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if (ret >= 0) {
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count = ret;
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ret = security_file_permission (file, MAY_WRITE);
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if (!ret) {
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if (file->f_op->write)
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ret = file->f_op->write(file, buf, count, pos);
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else
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ret = do_sync_write(file, buf, count, pos);
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if (ret > 0) {
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fsnotify_modify(file->f_dentry);
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current->wchar += ret;
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}
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current->syscw++;
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}
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}
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return ret;
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}
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EXPORT_SYMBOL(vfs_write);
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static inline loff_t file_pos_read(struct file *file)
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{
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return file->f_pos;
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}
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static inline void file_pos_write(struct file *file, loff_t pos)
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{
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file->f_pos = pos;
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}
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asmlinkage ssize_t sys_read(unsigned int fd, char __user * buf, size_t count)
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{
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struct file *file;
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ssize_t ret = -EBADF;
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int fput_needed;
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file = fget_light(fd, &fput_needed);
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if (file) {
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loff_t pos = file_pos_read(file);
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ret = vfs_read(file, buf, count, &pos);
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file_pos_write(file, pos);
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fput_light(file, fput_needed);
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(sys_read);
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asmlinkage ssize_t sys_write(unsigned int fd, const char __user * buf, size_t count)
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{
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struct file *file;
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ssize_t ret = -EBADF;
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int fput_needed;
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file = fget_light(fd, &fput_needed);
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if (file) {
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loff_t pos = file_pos_read(file);
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ret = vfs_write(file, buf, count, &pos);
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file_pos_write(file, pos);
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fput_light(file, fput_needed);
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}
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return ret;
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}
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asmlinkage ssize_t sys_pread64(unsigned int fd, char __user *buf,
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size_t count, loff_t pos)
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{
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struct file *file;
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ssize_t ret = -EBADF;
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int fput_needed;
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if (pos < 0)
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return -EINVAL;
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file = fget_light(fd, &fput_needed);
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if (file) {
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ret = -ESPIPE;
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if (file->f_mode & FMODE_PREAD)
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ret = vfs_read(file, buf, count, &pos);
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fput_light(file, fput_needed);
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}
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return ret;
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}
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asmlinkage ssize_t sys_pwrite64(unsigned int fd, const char __user *buf,
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size_t count, loff_t pos)
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{
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struct file *file;
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ssize_t ret = -EBADF;
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int fput_needed;
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if (pos < 0)
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return -EINVAL;
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file = fget_light(fd, &fput_needed);
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if (file) {
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ret = -ESPIPE;
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if (file->f_mode & FMODE_PWRITE)
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ret = vfs_write(file, buf, count, &pos);
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fput_light(file, fput_needed);
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}
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return ret;
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}
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/*
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* Reduce an iovec's length in-place. Return the resulting number of segments
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*/
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unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
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{
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unsigned long seg = 0;
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size_t len = 0;
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while (seg < nr_segs) {
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seg++;
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if (len + iov->iov_len >= to) {
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iov->iov_len = to - len;
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break;
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}
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len += iov->iov_len;
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iov++;
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}
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return seg;
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}
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EXPORT_SYMBOL(iov_shorten);
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/* A write operation does a read from user space and vice versa */
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#define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)
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static ssize_t do_readv_writev(int type, struct file *file,
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const struct iovec __user * uvector,
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unsigned long nr_segs, loff_t *pos)
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{
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typedef ssize_t (*io_fn_t)(struct file *, char __user *, size_t, loff_t *);
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typedef ssize_t (*iov_fn_t)(struct file *, const struct iovec *, unsigned long, loff_t *);
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size_t tot_len;
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struct iovec iovstack[UIO_FASTIOV];
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struct iovec *iov=iovstack, *vector;
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ssize_t ret;
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int seg;
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io_fn_t fn;
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iov_fn_t fnv;
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/*
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* SuS says "The readv() function *may* fail if the iovcnt argument
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* was less than or equal to 0, or greater than {IOV_MAX}. Linux has
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* traditionally returned zero for zero segments, so...
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*/
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ret = 0;
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if (nr_segs == 0)
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goto out;
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/*
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* First get the "struct iovec" from user memory and
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* verify all the pointers
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*/
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ret = -EINVAL;
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if (nr_segs > UIO_MAXIOV)
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goto out;
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if (!file->f_op)
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goto out;
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if (nr_segs > UIO_FASTIOV) {
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ret = -ENOMEM;
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iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
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if (!iov)
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goto out;
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}
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ret = -EFAULT;
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if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector)))
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goto out;
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/*
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* Single unix specification:
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* We should -EINVAL if an element length is not >= 0 and fitting an
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* ssize_t. The total length is fitting an ssize_t
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*
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* Be careful here because iov_len is a size_t not an ssize_t
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*/
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tot_len = 0;
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ret = -EINVAL;
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for (seg = 0; seg < nr_segs; seg++) {
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void __user *buf = iov[seg].iov_base;
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ssize_t len = (ssize_t)iov[seg].iov_len;
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if (len < 0) /* size_t not fitting an ssize_t .. */
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goto out;
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if (unlikely(!access_ok(vrfy_dir(type), buf, len)))
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goto Efault;
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tot_len += len;
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if ((ssize_t)tot_len < 0) /* maths overflow on the ssize_t */
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goto out;
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}
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if (tot_len == 0) {
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ret = 0;
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goto out;
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}
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ret = rw_verify_area(type, file, pos, tot_len);
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if (ret < 0)
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goto out;
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ret = security_file_permission(file, type == READ ? MAY_READ : MAY_WRITE);
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if (ret)
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goto out;
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fnv = NULL;
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if (type == READ) {
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fn = file->f_op->read;
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fnv = file->f_op->readv;
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} else {
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fn = (io_fn_t)file->f_op->write;
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fnv = file->f_op->writev;
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}
|
|
if (fnv) {
|
|
ret = fnv(file, iov, nr_segs, pos);
|
|
goto out;
|
|
}
|
|
|
|
/* Do it by hand, with file-ops */
|
|
ret = 0;
|
|
vector = iov;
|
|
while (nr_segs > 0) {
|
|
void __user * base;
|
|
size_t len;
|
|
ssize_t nr;
|
|
|
|
base = vector->iov_base;
|
|
len = vector->iov_len;
|
|
vector++;
|
|
nr_segs--;
|
|
|
|
nr = fn(file, base, len, pos);
|
|
|
|
if (nr < 0) {
|
|
if (!ret) ret = nr;
|
|
break;
|
|
}
|
|
ret += nr;
|
|
if (nr != len)
|
|
break;
|
|
}
|
|
out:
|
|
if (iov != iovstack)
|
|
kfree(iov);
|
|
if ((ret + (type == READ)) > 0) {
|
|
if (type == READ)
|
|
fsnotify_access(file->f_dentry);
|
|
else
|
|
fsnotify_modify(file->f_dentry);
|
|
}
|
|
return ret;
|
|
Efault:
|
|
ret = -EFAULT;
|
|
goto out;
|
|
}
|
|
|
|
ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
|
|
unsigned long vlen, loff_t *pos)
|
|
{
|
|
if (!(file->f_mode & FMODE_READ))
|
|
return -EBADF;
|
|
if (!file->f_op || (!file->f_op->readv && !file->f_op->read))
|
|
return -EINVAL;
|
|
|
|
return do_readv_writev(READ, file, vec, vlen, pos);
|
|
}
|
|
|
|
EXPORT_SYMBOL(vfs_readv);
|
|
|
|
ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
|
|
unsigned long vlen, loff_t *pos)
|
|
{
|
|
if (!(file->f_mode & FMODE_WRITE))
|
|
return -EBADF;
|
|
if (!file->f_op || (!file->f_op->writev && !file->f_op->write))
|
|
return -EINVAL;
|
|
|
|
return do_readv_writev(WRITE, file, vec, vlen, pos);
|
|
}
|
|
|
|
EXPORT_SYMBOL(vfs_writev);
|
|
|
|
asmlinkage ssize_t
|
|
sys_readv(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
|
|
{
|
|
struct file *file;
|
|
ssize_t ret = -EBADF;
|
|
int fput_needed;
|
|
|
|
file = fget_light(fd, &fput_needed);
|
|
if (file) {
|
|
loff_t pos = file_pos_read(file);
|
|
ret = vfs_readv(file, vec, vlen, &pos);
|
|
file_pos_write(file, pos);
|
|
fput_light(file, fput_needed);
|
|
}
|
|
|
|
if (ret > 0)
|
|
current->rchar += ret;
|
|
current->syscr++;
|
|
return ret;
|
|
}
|
|
|
|
asmlinkage ssize_t
|
|
sys_writev(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
|
|
{
|
|
struct file *file;
|
|
ssize_t ret = -EBADF;
|
|
int fput_needed;
|
|
|
|
file = fget_light(fd, &fput_needed);
|
|
if (file) {
|
|
loff_t pos = file_pos_read(file);
|
|
ret = vfs_writev(file, vec, vlen, &pos);
|
|
file_pos_write(file, pos);
|
|
fput_light(file, fput_needed);
|
|
}
|
|
|
|
if (ret > 0)
|
|
current->wchar += ret;
|
|
current->syscw++;
|
|
return ret;
|
|
}
|
|
|
|
static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
|
|
size_t count, loff_t max)
|
|
{
|
|
struct file * in_file, * out_file;
|
|
struct inode * in_inode, * out_inode;
|
|
loff_t pos;
|
|
ssize_t retval;
|
|
int fput_needed_in, fput_needed_out;
|
|
|
|
/*
|
|
* Get input file, and verify that it is ok..
|
|
*/
|
|
retval = -EBADF;
|
|
in_file = fget_light(in_fd, &fput_needed_in);
|
|
if (!in_file)
|
|
goto out;
|
|
if (!(in_file->f_mode & FMODE_READ))
|
|
goto fput_in;
|
|
retval = -EINVAL;
|
|
in_inode = in_file->f_dentry->d_inode;
|
|
if (!in_inode)
|
|
goto fput_in;
|
|
if (!in_file->f_op || !in_file->f_op->sendfile)
|
|
goto fput_in;
|
|
retval = -ESPIPE;
|
|
if (!ppos)
|
|
ppos = &in_file->f_pos;
|
|
else
|
|
if (!(in_file->f_mode & FMODE_PREAD))
|
|
goto fput_in;
|
|
retval = rw_verify_area(READ, in_file, ppos, count);
|
|
if (retval < 0)
|
|
goto fput_in;
|
|
count = retval;
|
|
|
|
retval = security_file_permission (in_file, MAY_READ);
|
|
if (retval)
|
|
goto fput_in;
|
|
|
|
/*
|
|
* Get output file, and verify that it is ok..
|
|
*/
|
|
retval = -EBADF;
|
|
out_file = fget_light(out_fd, &fput_needed_out);
|
|
if (!out_file)
|
|
goto fput_in;
|
|
if (!(out_file->f_mode & FMODE_WRITE))
|
|
goto fput_out;
|
|
retval = -EINVAL;
|
|
if (!out_file->f_op || !out_file->f_op->sendpage)
|
|
goto fput_out;
|
|
out_inode = out_file->f_dentry->d_inode;
|
|
retval = rw_verify_area(WRITE, out_file, &out_file->f_pos, count);
|
|
if (retval < 0)
|
|
goto fput_out;
|
|
count = retval;
|
|
|
|
retval = security_file_permission (out_file, MAY_WRITE);
|
|
if (retval)
|
|
goto fput_out;
|
|
|
|
if (!max)
|
|
max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
|
|
|
|
pos = *ppos;
|
|
retval = -EINVAL;
|
|
if (unlikely(pos < 0))
|
|
goto fput_out;
|
|
if (unlikely(pos + count > max)) {
|
|
retval = -EOVERFLOW;
|
|
if (pos >= max)
|
|
goto fput_out;
|
|
count = max - pos;
|
|
}
|
|
|
|
retval = in_file->f_op->sendfile(in_file, ppos, count, file_send_actor, out_file);
|
|
|
|
if (retval > 0) {
|
|
current->rchar += retval;
|
|
current->wchar += retval;
|
|
}
|
|
current->syscr++;
|
|
current->syscw++;
|
|
|
|
if (*ppos > max)
|
|
retval = -EOVERFLOW;
|
|
|
|
fput_out:
|
|
fput_light(out_file, fput_needed_out);
|
|
fput_in:
|
|
fput_light(in_file, fput_needed_in);
|
|
out:
|
|
return retval;
|
|
}
|
|
|
|
asmlinkage ssize_t sys_sendfile(int out_fd, int in_fd, off_t __user *offset, size_t count)
|
|
{
|
|
loff_t pos;
|
|
off_t off;
|
|
ssize_t ret;
|
|
|
|
if (offset) {
|
|
if (unlikely(get_user(off, offset)))
|
|
return -EFAULT;
|
|
pos = off;
|
|
ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
|
|
if (unlikely(put_user(pos, offset)))
|
|
return -EFAULT;
|
|
return ret;
|
|
}
|
|
|
|
return do_sendfile(out_fd, in_fd, NULL, count, 0);
|
|
}
|
|
|
|
asmlinkage ssize_t sys_sendfile64(int out_fd, int in_fd, loff_t __user *offset, size_t count)
|
|
{
|
|
loff_t pos;
|
|
ssize_t ret;
|
|
|
|
if (offset) {
|
|
if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
|
|
return -EFAULT;
|
|
ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
|
|
if (unlikely(put_user(pos, offset)))
|
|
return -EFAULT;
|
|
return ret;
|
|
}
|
|
|
|
return do_sendfile(out_fd, in_fd, NULL, count, 0);
|
|
}
|