/* * linux/fs/read_write.c * * Copyright (C) 1991, 1992 Linus Torvalds */ #include <linux/slab.h> #include <linux/stat.h> #include <linux/fcntl.h> #include <linux/file.h> #include <linux/uio.h> #include <linux/fsnotify.h> #include <linux/security.h> #include <linux/module.h> #include <linux/syscalls.h> #include <linux/pagemap.h> #include <linux/splice.h> #include "read_write.h" #include <asm/uaccess.h> #include <asm/unistd.h> const struct file_operations generic_ro_fops = { .llseek = generic_file_llseek, .read = do_sync_read, .aio_read = generic_file_aio_read, .mmap = generic_file_readonly_mmap, .splice_read = generic_file_splice_read, }; EXPORT_SYMBOL(generic_ro_fops); static inline int unsigned_offsets(struct file *file) { return file->f_mode & FMODE_UNSIGNED_OFFSET; } static loff_t lseek_execute(struct file *file, struct inode *inode, loff_t offset, loff_t maxsize) { if (offset < 0 && !unsigned_offsets(file)) return -EINVAL; if (offset > maxsize) return -EINVAL; if (offset != file->f_pos) { file->f_pos = offset; file->f_version = 0; } return offset; } /** * generic_file_llseek_size - generic llseek implementation for regular files * @file: file structure to seek on * @offset: file offset to seek to * @origin: type of seek * @size: max size of file system * * This is a variant of generic_file_llseek that allows passing in a custom * file size. * * Synchronization: * SEEK_SET and SEEK_END are unsynchronized (but atomic on 64bit platforms) * SEEK_CUR is synchronized against other SEEK_CURs, but not read/writes. * read/writes behave like SEEK_SET against seeks. */ loff_t generic_file_llseek_size(struct file *file, loff_t offset, int origin, loff_t maxsize) { struct inode *inode = file->f_mapping->host; switch (origin) { case SEEK_END: offset += i_size_read(inode); break; case SEEK_CUR: /* * Here we special-case the lseek(fd, 0, SEEK_CUR) * position-querying operation. Avoid rewriting the "same" * f_pos value back to the file because a concurrent read(), * write() or lseek() might have altered it */ if (offset == 0) return file->f_pos; /* * f_lock protects against read/modify/write race with other * SEEK_CURs. Note that parallel writes and reads behave * like SEEK_SET. */ spin_lock(&file->f_lock); offset = lseek_execute(file, inode, file->f_pos + offset, maxsize); spin_unlock(&file->f_lock); return offset; case SEEK_DATA: /* * In the generic case the entire file is data, so as long as * offset isn't at the end of the file then the offset is data. */ if (offset >= i_size_read(inode)) return -ENXIO; break; case SEEK_HOLE: /* * There is a virtual hole at the end of the file, so as long as * offset isn't i_size or larger, return i_size. */ if (offset >= i_size_read(inode)) return -ENXIO; offset = i_size_read(inode); break; } return lseek_execute(file, inode, offset, maxsize); } EXPORT_SYMBOL(generic_file_llseek_size); /** * generic_file_llseek - generic llseek implementation for regular files * @file: file structure to seek on * @offset: file offset to seek to * @origin: type of seek * * This is a generic implemenation of ->llseek useable for all normal local * filesystems. It just updates the file offset to the value specified by * @offset and @origin under i_mutex. */ loff_t generic_file_llseek(struct file *file, loff_t offset, int origin) { struct inode *inode = file->f_mapping->host; return generic_file_llseek_size(file, offset, origin, inode->i_sb->s_maxbytes); } EXPORT_SYMBOL(generic_file_llseek); /** * noop_llseek - No Operation Performed llseek implementation * @file: file structure to seek on * @offset: file offset to seek to * @origin: type of seek * * This is an implementation of ->llseek useable for the rare special case when * userspace expects the seek to succeed but the (device) file is actually not * able to perform the seek. In this case you use noop_llseek() instead of * falling back to the default implementation of ->llseek. */ loff_t noop_llseek(struct file *file, loff_t offset, int origin) { return file->f_pos; } EXPORT_SYMBOL(noop_llseek); loff_t no_llseek(struct file *file, loff_t offset, int origin) { return -ESPIPE; } EXPORT_SYMBOL(no_llseek); loff_t default_llseek(struct file *file, loff_t offset, int origin) { struct inode *inode = file->f_path.dentry->d_inode; loff_t retval; mutex_lock(&inode->i_mutex); switch (origin) { case SEEK_END: offset += i_size_read(inode); break; case SEEK_CUR: if (offset == 0) { retval = file->f_pos; goto out; } offset += file->f_pos; break; case SEEK_DATA: /* * In the generic case the entire file is data, so as * long as offset isn't at the end of the file then the * offset is data. */ if (offset >= inode->i_size) { retval = -ENXIO; goto out; } break; case SEEK_HOLE: /* * There is a virtual hole at the end of the file, so * as long as offset isn't i_size or larger, return * i_size. */ if (offset >= inode->i_size) { retval = -ENXIO; goto out; } offset = inode->i_size; break; } retval = -EINVAL; if (offset >= 0 || unsigned_offsets(file)) { if (offset != file->f_pos) { file->f_pos = offset; file->f_version = 0; } retval = offset; } out: mutex_unlock(&inode->i_mutex); return retval; } EXPORT_SYMBOL(default_llseek); loff_t vfs_llseek(struct file *file, loff_t offset, int origin) { loff_t (*fn)(struct file *, loff_t, int); fn = no_llseek; if (file->f_mode & FMODE_LSEEK) { if (file->f_op && file->f_op->llseek) fn = file->f_op->llseek; } return fn(file, offset, origin); } EXPORT_SYMBOL(vfs_llseek); SYSCALL_DEFINE3(lseek, unsigned int, fd, off_t, offset, unsigned int, origin) { off_t retval; struct file * file; int fput_needed; retval = -EBADF; file = fget_light(fd, &fput_needed); if (!file) goto bad; retval = -EINVAL; if (origin <= SEEK_MAX) { loff_t res = vfs_llseek(file, offset, origin); retval = res; if (res != (loff_t)retval) retval = -EOVERFLOW; /* LFS: should only happen on 32 bit platforms */ } fput_light(file, fput_needed); bad: return retval; } #ifdef __ARCH_WANT_SYS_LLSEEK SYSCALL_DEFINE5(llseek, unsigned int, fd, unsigned long, offset_high, unsigned long, offset_low, loff_t __user *, result, unsigned int, origin) { int retval; struct file * file; loff_t offset; int fput_needed; retval = -EBADF; file = fget_light(fd, &fput_needed); if (!file) goto bad; retval = -EINVAL; if (origin > SEEK_MAX) goto out_putf; offset = vfs_llseek(file, ((loff_t) offset_high << 32) | offset_low, origin); retval = (int)offset; if (offset >= 0) { retval = -EFAULT; if (!copy_to_user(result, &offset, sizeof(offset))) retval = 0; } out_putf: fput_light(file, fput_needed); bad: return retval; } #endif /* * rw_verify_area doesn't like huge counts. We limit * them to something that fits in "int" so that others * won't have to do range checks all the time. */ int rw_verify_area(int read_write, struct file *file, loff_t *ppos, size_t count) { struct inode *inode; loff_t pos; int retval = -EINVAL; inode = file->f_path.dentry->d_inode; if (unlikely((ssize_t) count < 0)) return retval; pos = *ppos; if (unlikely(pos < 0)) { if (!unsigned_offsets(file)) return retval; if (count >= -pos) /* both values are in 0..LLONG_MAX */ return -EOVERFLOW; } else if (unlikely((loff_t) (pos + count) < 0)) { if (!unsigned_offsets(file)) return retval; } if (unlikely(inode->i_flock && mandatory_lock(inode))) { retval = locks_mandatory_area( read_write == READ ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE, inode, file, pos, count); if (retval < 0) return retval; } retval = security_file_permission(file, read_write == READ ? MAY_READ : MAY_WRITE); if (retval) return retval; return count > MAX_RW_COUNT ? MAX_RW_COUNT : count; } static void wait_on_retry_sync_kiocb(struct kiocb *iocb) { set_current_state(TASK_UNINTERRUPTIBLE); if (!kiocbIsKicked(iocb)) schedule(); else kiocbClearKicked(iocb); __set_current_state(TASK_RUNNING); } ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos) { struct iovec iov = { .iov_base = buf, .iov_len = len }; struct kiocb kiocb; ssize_t ret; init_sync_kiocb(&kiocb, filp); kiocb.ki_pos = *ppos; kiocb.ki_left = len; kiocb.ki_nbytes = len; for (;;) { ret = filp->f_op->aio_read(&kiocb, &iov, 1, kiocb.ki_pos); if (ret != -EIOCBRETRY) break; wait_on_retry_sync_kiocb(&kiocb); } if (-EIOCBQUEUED == ret) ret = wait_on_sync_kiocb(&kiocb); *ppos = kiocb.ki_pos; return ret; } EXPORT_SYMBOL(do_sync_read); ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos) { ssize_t ret; if (!(file->f_mode & FMODE_READ)) return -EBADF; if (!file->f_op || (!file->f_op->read && !file->f_op->aio_read)) return -EINVAL; if (unlikely(!access_ok(VERIFY_WRITE, buf, count))) return -EFAULT; ret = rw_verify_area(READ, file, pos, count); if (ret >= 0) { count = ret; if (file->f_op->read) ret = file->f_op->read(file, buf, count, pos); else ret = do_sync_read(file, buf, count, pos); if (ret > 0) { fsnotify_access(file); add_rchar(current, ret); } inc_syscr(current); } return ret; } EXPORT_SYMBOL(vfs_read); ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos) { struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = len }; struct kiocb kiocb; ssize_t ret; init_sync_kiocb(&kiocb, filp); kiocb.ki_pos = *ppos; kiocb.ki_left = len; kiocb.ki_nbytes = len; for (;;) { ret = filp->f_op->aio_write(&kiocb, &iov, 1, kiocb.ki_pos); if (ret != -EIOCBRETRY) break; wait_on_retry_sync_kiocb(&kiocb); } if (-EIOCBQUEUED == ret) ret = wait_on_sync_kiocb(&kiocb); *ppos = kiocb.ki_pos; return ret; } EXPORT_SYMBOL(do_sync_write); ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos) { ssize_t ret; if (!(file->f_mode & FMODE_WRITE)) return -EBADF; if (!file->f_op || (!file->f_op->write && !file->f_op->aio_write)) return -EINVAL; if (unlikely(!access_ok(VERIFY_READ, buf, count))) return -EFAULT; ret = rw_verify_area(WRITE, file, pos, count); if (ret >= 0) { count = ret; if (file->f_op->write) ret = file->f_op->write(file, buf, count, pos); else ret = do_sync_write(file, buf, count, pos); if (ret > 0) { fsnotify_modify(file); add_wchar(current, ret); } inc_syscw(current); } return ret; } EXPORT_SYMBOL(vfs_write); static inline loff_t file_pos_read(struct file *file) { return file->f_pos; } static inline void file_pos_write(struct file *file, loff_t pos) { file->f_pos = pos; } SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count) { 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_read(file, buf, count, &pos); file_pos_write(file, pos); fput_light(file, fput_needed); } return ret; } SYSCALL_DEFINE3(write, unsigned int, fd, const char __user *, buf, size_t, count) { 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_write(file, buf, count, &pos); file_pos_write(file, pos); fput_light(file, fput_needed); } return ret; } SYSCALL_DEFINE(pread64)(unsigned int fd, char __user *buf, size_t count, loff_t pos) { struct file *file; ssize_t ret = -EBADF; int fput_needed; if (pos < 0) return -EINVAL; file = fget_light(fd, &fput_needed); if (file) { ret = -ESPIPE; if (file->f_mode & FMODE_PREAD) ret = vfs_read(file, buf, count, &pos); fput_light(file, fput_needed); } return ret; } #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS asmlinkage long SyS_pread64(long fd, long buf, long count, loff_t pos) { return SYSC_pread64((unsigned int) fd, (char __user *) buf, (size_t) count, pos); } SYSCALL_ALIAS(sys_pread64, SyS_pread64); #endif SYSCALL_DEFINE(pwrite64)(unsigned int fd, const char __user *buf, size_t count, loff_t pos) { struct file *file; ssize_t ret = -EBADF; int fput_needed; if (pos < 0) return -EINVAL; file = fget_light(fd, &fput_needed); if (file) { ret = -ESPIPE; if (file->f_mode & FMODE_PWRITE) ret = vfs_write(file, buf, count, &pos); fput_light(file, fput_needed); } return ret; } #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS asmlinkage long SyS_pwrite64(long fd, long buf, long count, loff_t pos) { return SYSC_pwrite64((unsigned int) fd, (const char __user *) buf, (size_t) count, pos); } SYSCALL_ALIAS(sys_pwrite64, SyS_pwrite64); #endif /* * Reduce an iovec's length in-place. Return the resulting number of segments */ unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to) { unsigned long seg = 0; size_t len = 0; while (seg < nr_segs) { seg++; if (len + iov->iov_len >= to) { iov->iov_len = to - len; break; } len += iov->iov_len; iov++; } return seg; } EXPORT_SYMBOL(iov_shorten); ssize_t do_sync_readv_writev(struct file *filp, const struct iovec *iov, unsigned long nr_segs, size_t len, loff_t *ppos, iov_fn_t fn) { struct kiocb kiocb; ssize_t ret; init_sync_kiocb(&kiocb, filp); kiocb.ki_pos = *ppos; kiocb.ki_left = len; kiocb.ki_nbytes = len; for (;;) { ret = fn(&kiocb, iov, nr_segs, kiocb.ki_pos); if (ret != -EIOCBRETRY) break; wait_on_retry_sync_kiocb(&kiocb); } if (ret == -EIOCBQUEUED) ret = wait_on_sync_kiocb(&kiocb); *ppos = kiocb.ki_pos; return ret; } /* Do it by hand, with file-ops */ ssize_t do_loop_readv_writev(struct file *filp, struct iovec *iov, unsigned long nr_segs, loff_t *ppos, io_fn_t fn) { struct iovec *vector = iov; ssize_t ret = 0; 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(filp, base, len, ppos); if (nr < 0) { if (!ret) ret = nr; break; } ret += nr; if (nr != len) break; } return ret; } /* A write operation does a read from user space and vice versa */ #define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ) ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector, unsigned long nr_segs, unsigned long fast_segs, struct iovec *fast_pointer, struct iovec **ret_pointer, int check_access) { unsigned long seg; ssize_t ret; struct iovec *iov = fast_pointer; /* * SuS says "The readv() function *may* fail if the iovcnt argument * was less than or equal to 0, or greater than {IOV_MAX}. Linux has * traditionally returned zero for zero segments, so... */ if (nr_segs == 0) { ret = 0; goto out; } /* * First get the "struct iovec" from user memory and * verify all the pointers */ if (nr_segs > UIO_MAXIOV) { ret = -EINVAL; goto out; } if (nr_segs > fast_segs) { iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL); if (iov == NULL) { ret = -ENOMEM; goto out; } } if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector))) { ret = -EFAULT; goto out; } /* * According to the Single Unix Specification we should return EINVAL * if an element length is < 0 when cast to ssize_t or if the * total length would overflow the ssize_t return value of the * system call. * * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the * overflow case. */ ret = 0; for (seg = 0; seg < nr_segs; seg++) { void __user *buf = iov[seg].iov_base; ssize_t len = (ssize_t)iov[seg].iov_len; /* see if we we're about to use an invalid len or if * it's about to overflow ssize_t */ if (len < 0) { ret = -EINVAL; goto out; } if (check_access && unlikely(!access_ok(vrfy_dir(type), buf, len))) { ret = -EFAULT; goto out; } if (len > MAX_RW_COUNT - ret) { len = MAX_RW_COUNT - ret; iov[seg].iov_len = len; } ret += len; } out: *ret_pointer = iov; return ret; } static ssize_t do_readv_writev(int type, struct file *file, const struct iovec __user * uvector, unsigned long nr_segs, loff_t *pos) { size_t tot_len; struct iovec iovstack[UIO_FASTIOV]; struct iovec *iov = iovstack; ssize_t ret; io_fn_t fn; iov_fn_t fnv; if (!file->f_op) { ret = -EINVAL; goto out; } ret = rw_copy_check_uvector(type, uvector, nr_segs, ARRAY_SIZE(iovstack), iovstack, &iov, 1); if (ret <= 0) goto out; tot_len = ret; ret = rw_verify_area(type, file, pos, tot_len); if (ret < 0) goto out; fnv = NULL; if (type == READ) { fn = file->f_op->read; fnv = file->f_op->aio_read; } else { fn = (io_fn_t)file->f_op->write; fnv = file->f_op->aio_write; } if (fnv) ret = do_sync_readv_writev(file, iov, nr_segs, tot_len, pos, fnv); else ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn); out: if (iov != iovstack) kfree(iov); if ((ret + (type == READ)) > 0) { if (type == READ) fsnotify_access(file); else fsnotify_modify(file); } return ret; } 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->aio_read && !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->aio_write && !file->f_op->write)) return -EINVAL; return do_readv_writev(WRITE, file, vec, vlen, pos); } EXPORT_SYMBOL(vfs_writev); SYSCALL_DEFINE3(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) add_rchar(current, ret); inc_syscr(current); return ret; } SYSCALL_DEFINE3(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) add_wchar(current, ret); inc_syscw(current); return ret; } static inline loff_t pos_from_hilo(unsigned long high, unsigned long low) { #define HALF_LONG_BITS (BITS_PER_LONG / 2) return (((loff_t)high << HALF_LONG_BITS) << HALF_LONG_BITS) | low; } SYSCALL_DEFINE5(preadv, unsigned long, fd, const struct iovec __user *, vec, unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h) { loff_t pos = pos_from_hilo(pos_h, pos_l); struct file *file; ssize_t ret = -EBADF; int fput_needed; if (pos < 0) return -EINVAL; file = fget_light(fd, &fput_needed); if (file) { ret = -ESPIPE; if (file->f_mode & FMODE_PREAD) ret = vfs_readv(file, vec, vlen, &pos); fput_light(file, fput_needed); } if (ret > 0) add_rchar(current, ret); inc_syscr(current); return ret; } SYSCALL_DEFINE5(pwritev, unsigned long, fd, const struct iovec __user *, vec, unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h) { loff_t pos = pos_from_hilo(pos_h, pos_l); struct file *file; ssize_t ret = -EBADF; int fput_needed; if (pos < 0) return -EINVAL; file = fget_light(fd, &fput_needed); if (file) { ret = -ESPIPE; if (file->f_mode & FMODE_PWRITE) ret = vfs_writev(file, vec, vlen, &pos); fput_light(file, fput_needed); } if (ret > 0) add_wchar(current, ret); inc_syscw(current); 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, fl; /* * 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 = -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; /* * 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; in_inode = in_file->f_path.dentry->d_inode; out_inode = out_file->f_path.dentry->d_inode; retval = rw_verify_area(WRITE, out_file, &out_file->f_pos, count); if (retval < 0) goto fput_out; count = retval; if (!max) max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes); pos = *ppos; if (unlikely(pos + count > max)) { retval = -EOVERFLOW; if (pos >= max) goto fput_out; count = max - pos; } fl = 0; #if 0 /* * We need to debate whether we can enable this or not. The * man page documents EAGAIN return for the output at least, * and the application is arguably buggy if it doesn't expect * EAGAIN on a non-blocking file descriptor. */ if (in_file->f_flags & O_NONBLOCK) fl = SPLICE_F_NONBLOCK; #endif retval = do_splice_direct(in_file, ppos, out_file, count, fl); if (retval > 0) { add_rchar(current, retval); add_wchar(current, retval); } inc_syscr(current); inc_syscw(current); 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; } SYSCALL_DEFINE4(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); } SYSCALL_DEFINE4(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); }