/* Copyright (C) 2014 Stony Brook University
This file is part of Graphene Library OS.
Graphene Library OS is free software: you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public License
as published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.
Graphene Library OS is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see . */
/*
* shim_wrapper.c
*
* Implementation of system call "readv" and "writev".
*/
#include
#include
#include
#include
#include
#include
#include
#include
ssize_t shim_do_readv(int fd, const struct iovec* vec, int vlen) {
if (!vec || test_user_memory((void*)vec, sizeof(*vec) * vlen, false))
return -EINVAL;
for (int i = 0; i < vlen; i++) {
if (vec[i].iov_base) {
if (vec[i].iov_base + vec[i].iov_len <= vec[i].iov_base)
return -EINVAL;
if (test_user_memory(vec[i].iov_base, vec[i].iov_len, true))
return -EFAULT;
}
}
struct shim_handle* hdl = get_fd_handle(fd, NULL, NULL);
if (!hdl)
return -EBADF;
int ret = 0;
if (!(hdl->acc_mode & MAY_READ) || !hdl->fs || !hdl->fs->fs_ops || !hdl->fs->fs_ops->read) {
ret = -EACCES;
goto out;
}
ssize_t bytes = 0;
for (int i = 0; i < vlen; i++) {
int b_vec;
if (!vec[i].iov_base)
continue;
b_vec = hdl->fs->fs_ops->read(hdl, vec[i].iov_base, vec[i].iov_len);
if (b_vec < 0) {
ret = bytes ?: b_vec;
goto out;
}
bytes += b_vec;
}
ret = bytes;
out:
put_handle(hdl);
return ret;
}
/*
* Writev can not be implemented as write because :
* writev() has the same requirements as write() with respect to write requests
* of <= PIPE_BUF bytes to a pipe or FIFO: no interleaving and no partial
* writes. Neither of these can be guaranteed in the general case if writev()
* simply calls write() for each struct iovec.
*/
/*
* The problem here is that we have to gaurantee Atomic writev
*
* Upon successful completion, writev() shall return the number of bytes
* actually written. Otherwise, it shall return a value of -1, the file-pointer
* shall remain unchanged, and errno shall be set to indicate an error
*/
ssize_t shim_do_writev(int fd, const struct iovec* vec, int vlen) {
if (!vec || test_user_memory((void*)vec, sizeof(*vec) * vlen, false))
return -EINVAL;
for (int i = 0; i < vlen; i++) {
if (vec[i].iov_base) {
if (vec[i].iov_base + vec[i].iov_len < vec[i].iov_base)
return -EINVAL;
if (test_user_memory(vec[i].iov_base, vec[i].iov_len, false))
return -EFAULT;
}
}
struct shim_handle* hdl = get_fd_handle(fd, NULL, NULL);
if (!hdl)
return -EBADF;
int ret = 0;
if (!(hdl->acc_mode & MAY_WRITE) || !hdl->fs || !hdl->fs->fs_ops || !hdl->fs->fs_ops->write) {
ret = -EACCES;
goto out;
}
ssize_t bytes = 0;
for (int i = 0; i < vlen; i++) {
int b_vec;
if (!vec[i].iov_base)
continue;
b_vec = hdl->fs->fs_ops->write(hdl, vec[i].iov_base, vec[i].iov_len);
if (b_vec < 0) {
ret = bytes ?: b_vec;
goto out;
}
bytes += b_vec;
}
ret = bytes;
out:
put_handle(hdl);
return ret;
}