Add chroot(2), fchroot(2) and fchrootat(2).

libc/Makefile

@@ -172,6 +172,7 @@ canonicalize_file_name.o \
 chdir.o \
 chmod.o \
 chown.o \
+chroot.o \
 close.o \
 confstr.o \
 $(CPUDIR)/calltrace.o \
@@ -204,6 +205,8 @@ fchmodat.o \
 fchmod.o \
 fchownat.o \
 fchown.o \
+fchrootat.o \
+fchroot.o \
 fcloseall.o \
 fcntl.o \
 fddir-sortix.o \

libc/chroot.cpp

@@ -0,0 +1,31 @@
+/*******************************************************************************
+
+    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/>.
+
+    chroot.cpp
+    Changes the root directory.
+
+*******************************************************************************/
+
+#include <fcntl.h>
+#include <unistd.h>
+
+extern "C" int chroot(const char* path)
+{
+	return fchrootat(AT_FDCWD, path);
+}

libc/fchroot.cpp

@@ -0,0 +1,33 @@
+/*******************************************************************************
+
+    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/>.
+
+    fchroot.cpp
+    Changes the root directory.
+
+*******************************************************************************/
+
+#include <sys/syscall.h>
+#include <unistd.h>
+
+DEFN_SYSCALL1(int, sys_fchroot, SYSCALL_FCHROOT, int);
+
+extern "C" int fchroot(int fd)
+{
+	return sys_fchroot(fd);
+}

libc/fchrootat.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/>.
+
+    fchrootat.cpp
+    Changes the root directory.
+
+*******************************************************************************/
+
+#include <sys/syscall.h>
+
+#include <unistd.h>
+
+DEFN_SYSCALL2(int, sys_fchrootat, SYSCALL_FCHROOTAT, int, const char*);
+
+extern "C" int fchrootat(int dirfd, const char* path)
+{
+	return sys_fchrootat(dirfd, path);
+}

libc/include/unistd.h

@@ -302,6 +302,7 @@ int access(const char*, int);
 unsigned alarm(unsigned);
 int chdir(const char*);
 int chown(const char*, uid_t, gid_t);
+int chroot(const char*);
 int close(int);
 size_t confstr(int, char*, size_t);
 int dup2(int, int);
@@ -319,6 +320,8 @@ int fchdir(int);
 int fchdirat(int, const char*);
 int fchown(int, uid_t, gid_t);
 int fchownat(int, const char*, uid_t, gid_t, int);
+int fchroot(int);
+int fchrootat(int, const char*);
 int fsync(int);
 int ftruncate(int, off_t);
 char* getcwd(char*, size_t);

sortix/include/sortix/kernel/process.h

@@ -120,6 +120,7 @@ public:
 	Ref<Descriptor> GetDescriptor(int fd);
 	// TODO: This should be removed, don't call it.
 	Ref<Descriptor> Open(ioctx_t* ctx, const char* path, int flags, mode_t mode = 0);
+	void SetRoot(Ref<Descriptor> newroot);
 	void SetCWD(Ref<Descriptor> newcwd);
 
 private:

sortix/include/sortix/syscallnum.h

@@ -130,6 +130,8 @@
 #define SYSCALL_TIMENS 106
 #define SYSCALL_UMASK 107
 #define SYSCALL_FCHDIRAT 108
-#define SYSCALL_MAX_NUM 109 /* index of highest constant + 1 */
+#define SYSCALL_FCHROOT 109
+#define SYSCALL_FCHROOTAT 110
+#define SYSCALL_MAX_NUM 111 /* index of highest constant + 1 */
 
 #endif

sortix/io.cpp

@@ -390,6 +390,35 @@ static int sys_chdir(const char* path)
 	return sys_fchdirat(AT_FDCWD, path);
 }
 
+static int sys_fchroot(int fd)
+{
+	Process* process = CurrentProcess();
+	Ref<Descriptor> desc = process->GetDescriptor(fd);
+	if ( !desc )
+		return -1;
+	if ( !S_ISDIR(desc->type) )
+		return errno = ENOTDIR, -1;
+	process->SetRoot(desc);
+	return 0;
+}
+
+static int sys_fchrootat(int dirfd, const char* path)
+{
+	char* pathcopy = GetStringFromUser(path);
+	if ( !pathcopy )
+		return -1;
+	ioctx_t ctx; SetupUserIOCtx(&ctx);
+	const char* relpath = pathcopy;
+	Ref<Descriptor> from = PrepareLookup(&relpath, dirfd);
+	Ref<Descriptor> desc = from->open(&ctx, relpath, O_READ | O_DIRECTORY);
+	from.Reset();
+	delete[] pathcopy;
+	if ( !desc )
+		return -1;
+	CurrentProcess()->SetRoot(desc);
+	return 0;
+}
+
 static int sys_fchown(int fd, uid_t owner, gid_t group)
 {
 	Ref<Descriptor> desc = CurrentProcess()->GetDescriptor(fd);
@@ -876,6 +905,8 @@ void Init()
 	Syscall::Register(SYSCALL_FCHMOD, (void*) sys_fchmod);
 	Syscall::Register(SYSCALL_FCHOWNAT, (void*) sys_fchownat);
 	Syscall::Register(SYSCALL_FCHOWN, (void*) sys_fchown);
+	Syscall::Register(SYSCALL_FCHROOTAT, (void*) sys_fchrootat);
+	Syscall::Register(SYSCALL_FCHROOT, (void*) sys_fchroot);
 	Syscall::Register(SYSCALL_FCNTL, (void*) sys_fcntl);
 	Syscall::Register(SYSCALL_FSTATAT, (void*) sys_fstatat);
 	Syscall::Register(SYSCALL_FSTAT, (void*) sys_fstat);

sortix/process.cpp

@@ -546,6 +546,13 @@ namespace Sortix
 		return cwd;
 	}
 
+	void Process::SetRoot(Ref<Descriptor> newroot)
+	{
+		ScopedLock lock(&ptrlock);
+		assert(newroot);
+		root = newroot;
+	}
+
 	void Process::SetCWD(Ref<Descriptor> newcwd)
 	{
 		ScopedLock lock(&ptrlock);