/* 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 . */
/*
* fs.c
*
* This file contains codes for implementation of 'str' filesystem.
*/
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
int str_open(struct shim_handle* hdl, struct shim_dentry* dent, int flags) {
struct shim_str_data* data = dent->data;
/* when str file is opened, it must have a data */
if (!dent->data)
return -ENOENT;
REF_INC(data->ref_count);
hdl->dentry = dent;
hdl->flags = flags;
return 0;
}
int str_dput(struct shim_dentry* dent) {
struct shim_str_data* data = dent->data;
if (!data || REF_DEC(data->ref_count) > 1)
return 0;
if (data->str) {
free(data->str);
data->str = NULL;
}
data->len = 0;
data->buf_size = 0;
free(dent->data);
dent->data = NULL;
return 0;
}
int str_close(struct shim_handle* hdl) {
if (hdl->flags & (O_WRONLY | O_RDWR)) {
int ret = str_flush(hdl);
if (ret < 0)
return ret;
}
str_dput(hdl->dentry);
return 0;
}
ssize_t str_read(struct shim_handle* hdl, void* buf, size_t count) {
ssize_t ret = 0;
if (!(hdl->acc_mode & MAY_READ)) {
ret = -EACCES;
goto out;
}
struct shim_str_handle* strhdl = &hdl->info.str;
assert(hdl->dentry);
assert(strhdl->data);
struct shim_str_data* data = strhdl->data;
if (!data->str) {
debug("str_data has no str\n");
ret = -EACCES;
goto out;
}
if (!strhdl->ptr)
strhdl->ptr = data->str;
off_t offset = strhdl->ptr - data->str;
size_t remain = data->len - offset;
if (count >= remain) {
memcpy(buf, strhdl->ptr, remain);
strhdl->ptr += remain;
ret = remain;
goto out;
}
memcpy(buf, strhdl->ptr, count);
strhdl->ptr += count;
ret = count;
out:
return ret;
}
ssize_t str_write(struct shim_handle* hdl, const void* buf, size_t count) {
if (!(hdl->acc_mode & MAY_WRITE))
return -EACCES;
struct shim_str_handle* strhdl = &hdl->info.str;
assert(hdl->dentry);
assert(strhdl->data);
struct shim_str_data* data = strhdl->data;
if (!data->str || strhdl->ptr + count > data->str + data->buf_size) {
int newlen = 0;
if (data->str) {
newlen = data->buf_size * 2;
while (strhdl->ptr + count > data->str + newlen) {
newlen *= 2;
}
} else {
newlen = count;
}
char* newbuf = malloc(newlen);
if (!newbuf)
return -ENOMEM;
if (data->str) {
memcpy(newbuf, data->str, data->len);
free(data->str);
}
strhdl->ptr = newbuf + (strhdl->ptr - data->str);
data->str = newbuf;
data->buf_size = newlen;
}
memcpy(strhdl->ptr, buf, count);
strhdl->ptr += count;
data->dirty = true;
if (strhdl->ptr >= data->str + data->len)
data->len = strhdl->ptr - data->str;
return count;
}
off_t str_seek(struct shim_handle* hdl, off_t offset, int whence) {
struct shim_str_handle* strhdl = &hdl->info.str;
assert(hdl->dentry);
assert(strhdl->data);
struct shim_str_data* data = strhdl->data;
switch (whence) {
case SEEK_SET:
if (offset < 0)
return -EINVAL;
strhdl->ptr = data->str;
if (strhdl->ptr > data->str + data->len)
strhdl->ptr = data->str + data->len;
break;
case SEEK_CUR:
if (offset >= 0) {
strhdl->ptr += offset;
if (strhdl->ptr > data->str + data->len)
strhdl->ptr = data->str + data->len;
} else {
strhdl->ptr -= offset;
if (strhdl->ptr < data->str)
strhdl->ptr = data->str;
}
break;
case SEEK_END:
if (offset < 0)
return -EINVAL;
strhdl->ptr = data->str + data->len - offset;
if (strhdl->ptr < data->str)
strhdl->ptr = data->str;
break;
}
return strhdl->ptr - data->str;
}
int str_flush(struct shim_handle* hdl) {
struct shim_str_handle* strhdl = &hdl->info.str;
assert(hdl->dentry);
assert(strhdl->data);
struct shim_str_data* data = strhdl->data;
if (!data->dirty)
return 0;
if (!data->modify)
return -EACCES;
return data->modify(hdl);
}
struct shim_fs_ops str_fs_ops = {
.close = &str_close,
.read = &str_read,
.write = &str_write,
.seek = &str_seek,
.flush = &str_flush,
};
struct shim_d_ops str_d_ops = {
.open = &str_open,
.dput = &str_dput,
};