sortix-mirror/kernel/partition.cpp
Jonas 'Sortie' Termansen 3c43f71084 Implement file descriptor passing.
This change refactors the Unix socket / pipe backend to have a ring buffer
containing segments, where each segment has an optional leading ancillary
buffer containing control messages followed by a normal data buffer.

The SCM_RIGHTS control message has been implemented which transfers file
descriptors to the receiving process. File descriptors are reference counted
and cycles are prevented using the following restrictions:

1) Unix sockets cannot be sent on themselves (on either end).
2) Unix sockets themselves being sent cannot be sent on.
3) Unix sockets cannot send a Unix socket being sent on.

This is a compatible ABI change.
2021-12-31 22:24:11 +01:00

129 lines
3.4 KiB
C++

/*
* Copyright (c) 2013, 2015, 2017 Jonas 'Sortie' Termansen.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* partition.cpp
* Block device representing a partition of another block device.
*/
#include <sys/types.h>
#include <assert.h>
#include <errno.h>
#include <sortix/seek.h>
#include <sortix/stat.h>
#include <sortix/kernel/inode.h>
#include <sortix/kernel/ioctx.h>
#include <sortix/kernel/kernel.h>
#include <sortix/kernel/refcount.h>
#include "partition.h"
namespace Sortix {
Partition::Partition(Ref<Inode> inner_inode, off_t start, off_t length)
{
assert(0 <= start);
assert(0 <= length);
assert(length <= OFF_MAX - start);
assert(!(inner_inode->type & S_IFNEVERWRAP));
assert(S_ISBLK(inner_inode->type) || S_ISREG(inner_inode->type));
this->dev = (dev_t) this;
this->ino = (ino_t) this;
this->type = inner_inode->type;
this->inode_type = INODE_TYPE_FILE;
this->inner_inode = inner_inode;
this->start = start;
this->length = length;
}
Partition::~Partition()
{
}
int Partition::sync(ioctx_t* ctx)
{
return inner_inode->sync(ctx);
}
int Partition::truncate(ioctx_t* /*ctx*/, off_t new_length)
{
if ( new_length != length )
return errno = EPERM, -1;
return 0;
}
off_t Partition::lseek(ioctx_t* /*ctx*/, off_t offset, int whence)
{
if ( whence == SEEK_END && offset == 0 )
return length;
return errno = EINVAL, -1;
}
ssize_t Partition::pread(ioctx_t* ctx, uint8_t* buf, size_t count, off_t off)
{
if ( off < 0 )
return errno = EINVAL, -1;
if ( length <= off )
return 0;
off_t available = length - off;
if ( (uintmax_t) available < (uintmax_t) count )
count = available;
if ( count == 0 )
return 0;
off_t final_offset;
if ( __builtin_add_overflow(start, off, &final_offset) )
return errno = EOVERFLOW, -1;
assert(start <= final_offset);
assert(final_offset < start + length);
return inner_inode->pread(ctx, buf, count, final_offset);
}
ssize_t Partition::pwrite(ioctx_t* ctx, const uint8_t* buf, size_t count,
off_t off)
{
if ( off < 0 )
return errno = EINVAL, -1;
if ( length <= off )
return count ? (errno = EFBIG, -1) : 0;
off_t available = length - off;
if ( (uintmax_t) available < (uintmax_t) count )
count = available;
if ( count == 0 )
return 0;
off_t final_offset;
if ( __builtin_add_overflow(start, off, &final_offset) )
return errno = EOVERFLOW, -1;
assert(start <= final_offset);
assert(final_offset < start + length);
return inner_inode->pwrite(ctx, buf, count, final_offset);
}
int Partition::stat(ioctx_t* ctx, struct stat* st)
{
if ( inner_inode->stat(ctx, st) < 0 )
return -1;
struct stat myst;
if ( !ctx->copy_from_src(&myst, st, sizeof(myst)) )
return -1;
myst.st_size = length;
myst.st_blocks = length / 512;
if ( !ctx->copy_to_dest(st, &myst, sizeof(myst)) )
return -1;
return 0;
}
}