Add mkpartition(2).

libc/Makefile

@@ -260,6 +260,7 @@ lstat.o \
 memstat.o \
 mkdirat.o \
 mkdir.o \
+mkpartition.o \
 mktemp.o \
 netdb/endhostent.o \
 netdb/endnetent.o \

libc/include/unistd.h

@@ -368,6 +368,7 @@ int execvpe(const char*, char* const [], char* const []);
 int getdtablesize(void);
 size_t getpagesize(void);
 int memstat(size_t* memused, size_t* memtotal);
+int mkpartition(int fd, off_t start, off_t length);
 size_t preadall(int fd, void* buf, size_t count, off_t off);
 size_t preadleast(int fd, void* buf, size_t least, size_t max, off_t off);
 size_t pwriteall(int fd, const void* buf, size_t count, off_t off);

libc/mkpartition.cpp

@@ -0,0 +1,34 @@
+/*******************************************************************************
+
+    Copyright(C) Jonas 'Sortie' Termansen 2013.
+
+    This file is part of the Sortix C Library.
+
+    The Sortix C Library 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.
+
+    The Sortix C Library 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 the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
+
+    mkpartition.cpp
+    Creates a block device representating a partition of another block device.
+
+*******************************************************************************/
+
+#include <sys/syscall.h>
+
+#include <unistd.h>
+
+DEFN_SYSCALL3(int, sys_mkpartition, SYSCALL_MKPARTITION, int, off_t, off_t);
+
+extern "C" int mkpartition(int fd, off_t start, off_t length)
+{
+	return sys_mkpartition(fd, start, length);
+}

sortix/Makefile

@@ -113,6 +113,7 @@ memorymanagement.o \
 mtable.o \
 net/fs.o \
 panic.o \
+partition.o \
 pci.o \
 pipe.o \
 poll.o \

sortix/include/sortix/syscallnum.h

@@ -132,6 +132,7 @@
 #define SYSCALL_FCHDIRAT 108
 #define SYSCALL_FCHROOT 109
 #define SYSCALL_FCHROOTAT 110
-#define SYSCALL_MAX_NUM 111 /* index of highest constant + 1 */
+#define SYSCALL_MKPARTITION 111
+#define SYSCALL_MAX_NUM 112 /* index of highest constant + 1 */
 
 #endif

sortix/io.cpp

@@ -33,6 +33,7 @@
 #include <sortix/kernel/syscall.h>
 #include <sortix/kernel/process.h>
 #include <sortix/kernel/thread.h>
+#include <sortix/kernel/vnode.h>
 
 #include <sortix/seek.h>
 #include <sortix/dirent.h>
@@ -45,6 +46,7 @@
 #include <errno.h>
 
 #include "io.h"
+#include "partition.h"
 
 namespace Sortix {
 namespace IO {
@@ -886,6 +888,38 @@ static ssize_t sys_pwritev(int fd, const struct iovec* user_iov, int iovcnt,
 	return so_far;
 }
 
+static int sys_mkpartition(int fd, off_t start, off_t length, int flags)
+{
+	int fdflags = 0;
+	if ( flags & O_CLOEXEC ) fdflags |= FD_CLOEXEC;
+	if ( flags & O_CLOFORK ) fdflags |= FD_CLOFORK;
+
+	Ref<Descriptor> desc = CurrentProcess()->GetDescriptor(fd);
+	if ( !desc )
+		return -1;
+
+	int dflags = desc->dflags;
+	Ref<Inode> inner_inode = desc->vnode->inode;
+	desc.Reset();
+
+	Ref<Inode> partition(new Partition(inner_inode, start, length));
+	if ( !partition )
+		return -1;
+	inner_inode.Reset();
+
+	Ref<Vnode> partition_vnode(new Vnode(partition, Ref<Vnode>(NULL), 0, 0));
+	if ( !partition_vnode )
+		return -1;
+	partition.Reset();
+
+	Ref<Descriptor> partition_desc(new Descriptor(partition_vnode, dflags));
+	if ( !partition_desc )
+		return -1;
+	partition_vnode.Reset();
+
+	return CurrentProcess()->GetDTable()->Allocate(partition_desc, fdflags);
+}
+
 void Init()
 {
 	Syscall::Register(SYSCALL_ACCEPT4, (void*) sys_accept4);
@@ -921,6 +955,7 @@ void Init()
 	Syscall::Register(SYSCALL_LISTEN, (void*) sys_listen);
 	Syscall::Register(SYSCALL_MKDIRAT, (void*) sys_mkdirat);
 	Syscall::Register(SYSCALL_MKDIR, (void*) sys_mkdir);
+	Syscall::Register(SYSCALL_MKPARTITION, (void*) sys_mkpartition);
 	Syscall::Register(SYSCALL_OPENAT, (void*) sys_openat);
 	Syscall::Register(SYSCALL_OPEN, (void*) sys_open);
 	Syscall::Register(SYSCALL_PREAD, (void*) sys_pread);

sortix/partition.cpp

@@ -0,0 +1,101 @@
+/*******************************************************************************
+
+    Copyright(C) Jonas 'Sortie' Termansen 2013.
+
+    This file is part of Sortix.
+
+    Sortix is free software: you can redistribute it and/or modify it under the
+    terms of the GNU General Public License as published by the Free Software
+    Foundation, either version 3 of the License, or (at your option) any later
+    version.
+
+    Sortix 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 General Public License for more
+    details.
+
+    You should have received a copy of the GNU General Public License along with
+    Sortix. If not, see <http://www.gnu.org/licenses/>.
+
+    partition.cpp
+    Block device representing a partition of another block device.
+
+*******************************************************************************/
+
+#include <sys/types.h>
+
+#include <errno.h>
+
+#include <sortix/seek.h>
+
+#include <sortix/kernel/platform.h>
+#include <sortix/kernel/refcount.h>
+#include <sortix/kernel/inode.h>
+
+#include "partition.h"
+
+namespace Sortix {
+
+Partition::Partition(Ref<Inode> inner_inode, off_t start, off_t length)
+{
+	this->dev = (dev_t) this;
+	this->ino = (ino_t) this;
+	this->inode_type = INODE_TYPE_FILE;
+	this->inner_inode = inner_inode;
+	this->start = start;
+	this->length = length;
+	this->stat_size = 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_SET )
+		return offset;
+	if ( whence == SEEK_END )
+		// TODO: Avoid underflow and overflow!
+		return length + offset;
+	return errno = EINVAL, -1;
+}
+
+ssize_t Partition::pread(ioctx_t* ctx, uint8_t* buf, size_t count, off_t off)
+{
+	// TODO: Avoid underflow and overflow!
+	off_t end_at = off + count;
+	if ( length <= end_at )
+		return 0;
+	off_t available = length - off;
+	if ( (uintmax_t) available < (uintmax_t) count )
+		count = available;
+	return inner_inode->pread(ctx, buf, count, start + off);
+}
+
+ssize_t Partition::pwrite(ioctx_t* ctx, const uint8_t* buf, size_t count,
+                          off_t off)
+{
+	// TODO: Avoid underflow and overflow!
+	off_t end_at = off + count;
+	if ( length <= end_at )
+		return 0;
+	off_t available = length - off;
+	if ( (uintmax_t) available < (uintmax_t) count )
+		count = available;
+	return inner_inode->pwrite(ctx, buf, count, start + off);
+}
+
+}

sortix/partition.h

@@ -0,0 +1,56 @@
+/*******************************************************************************
+
+    Copyright(C) Jonas 'Sortie' Termansen 2013.
+
+    This file is part of Sortix.
+
+    Sortix is free software: you can redistribute it and/or modify it under the
+    terms of the GNU General Public License as published by the Free Software
+    Foundation, either version 3 of the License, or (at your option) any later
+    version.
+
+    Sortix 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 General Public License for more
+    details.
+
+    You should have received a copy of the GNU General Public License along with
+    Sortix. If not, see <http://www.gnu.org/licenses/>.
+
+    partition.h
+    Block device representing a partition of another block device.
+
+*******************************************************************************/
+
+#ifndef PARTITION_H
+#define PARTITION_H
+
+#include <sortix/kernel/refcount.h>
+#include <sortix/kernel/inode.h>
+
+namespace Sortix {
+
+class Partition : public AbstractInode
+{
+public:
+	Partition(Ref<Inode> inner_inode, off_t start, off_t length);
+	virtual ~Partition();
+
+private:
+	Ref<Inode> inner_inode;
+	off_t start;
+	off_t length;
+
+public:
+	virtual int sync(ioctx_t* ctx);
+	virtual int truncate(ioctx_t* ctx, off_t length);
+	virtual off_t lseek(ioctx_t* ctx, off_t offset, int whence);
+	virtual ssize_t pread(ioctx_t* ctx, uint8_t* buf, size_t count, off_t off);
+	virtual ssize_t pwrite(ioctx_t* ctx, const uint8_t* buf, size_t count,
+	                       off_t off);
+
+};
+
+} // namespace Sortix
+
+#endif