Kernel/LibC: Implement all stat family functions with fstatat

This patch gets rid of 2 unnecessary syscalls!

kernel/include/kernel/Process.h

@@ -146,9 +146,7 @@ namespace Kernel
 
 		BAN::ErrorOr<long> sys_truncate(int fd, off_t length);
 
-		BAN::ErrorOr<long> sys_fstat(int fd, struct stat*);
 		BAN::ErrorOr<long> sys_fstatat(int fd, const char* path, struct stat* buf, int flag);
-		BAN::ErrorOr<long> sys_stat(const char* path, struct stat* buf, int flag);
 
 		BAN::ErrorOr<long> sys_realpath(const char* path, char* buffer);
 

kernel/kernel/Process.cpp

@@ -1400,33 +1400,6 @@ namespace Kernel
 		return {};
 	}
 
-	static void read_stat_from_inode(BAN::RefPtr<Inode> inode, struct stat* out)
-	{
-		out->st_dev		= inode->dev();
-		out->st_ino		= inode->ino();
-		out->st_mode	= inode->mode().mode;
-		out->st_nlink	= inode->nlink();
-		out->st_uid		= inode->uid();
-		out->st_gid		= inode->gid();
-		out->st_rdev	= inode->rdev();
-		out->st_size	= inode->size();
-		out->st_atim	= inode->atime();
-		out->st_mtim	= inode->mtime();
-		out->st_ctim	= inode->ctime();
-		out->st_blksize	= inode->blksize();
-		out->st_blocks	= inode->blocks();
-	}
-
-	BAN::ErrorOr<long> Process::sys_fstat(int fd, struct stat* buf)
-	{
-		LockGuard _(m_process_lock);
-		TRY(validate_pointer_access(buf, sizeof(struct stat), true));
-
-		auto inode = TRY(m_open_file_descriptors.inode_of(fd));
-		read_stat_from_inode(inode, buf);
-		return 0;
-	}
-
 	BAN::ErrorOr<long> Process::sys_fstatat(int fd, const char* path, struct stat* buf, int flags)
 	{
 		if (flags & ~AT_SYMLINK_NOFOLLOW)
@@ -1435,27 +1408,35 @@ namespace Kernel
 			flags = O_NOFOLLOW;
 
 		LockGuard _(m_process_lock);
+		if (path)
+			TRY(validate_string_access(path));
 		TRY(validate_pointer_access(buf, sizeof(struct stat), true));
 
-		auto parent_file = TRY(m_open_file_descriptors.file_of(fd));
+		VirtualFileSystem::File parent_file;
-		auto inode = TRY(VirtualFileSystem::get().file_from_relative_path(parent_file, m_credentials, path, flags)).inode;
+		if (path && path[0] == '/')
-		read_stat_from_inode(inode, buf);
+			parent_file = VirtualFileSystem::get().root_file();
-		return 0;
+		else if (fd == AT_FDCWD)
-	}
+			parent_file = TRY(m_working_directory.clone());
+		else
+			parent_file = TRY(m_open_file_descriptors.file_of(fd));
 
-	BAN::ErrorOr<long> Process::sys_stat(const char* path, struct stat* buf, int flags)
+		const auto inode = path
-	{
+			? TRY(VirtualFileSystem::get().file_from_relative_path(parent_file, m_credentials, path, flags)).inode
-		if (flags & ~AT_SYMLINK_NOFOLLOW)
+			: parent_file.inode;
-			return BAN::Error::from_errno(EINVAL);
+		buf->st_dev		= inode->dev();
-		if (flags == AT_SYMLINK_NOFOLLOW)
+		buf->st_ino		= inode->ino();
-			flags = O_NOFOLLOW;
+		buf->st_mode	= inode->mode().mode;
+		buf->st_nlink	= inode->nlink();
+		buf->st_uid		= inode->uid();
+		buf->st_gid		= inode->gid();
+		buf->st_rdev	= inode->rdev();
+		buf->st_size	= inode->size();
+		buf->st_atim	= inode->atime();
+		buf->st_mtim	= inode->mtime();
+		buf->st_ctim	= inode->ctime();
+		buf->st_blksize	= inode->blksize();
+		buf->st_blocks	= inode->blocks();
 
-		LockGuard _(m_process_lock);
-		TRY(validate_pointer_access(buf, sizeof(struct stat), true));
-
-		auto absolute_path = TRY(absolute_path_of(path));
-		auto inode = TRY(VirtualFileSystem::get().file_from_absolute_path(m_credentials, absolute_path, flags)).inode;
-		read_stat_from_inode(inode, buf);
 		return 0;
 	}
 

userspace/libraries/LibC/include/sys/syscall.h

@@ -20,7 +20,6 @@ __BEGIN_DECLS
 	O(SYS_EXEC,				exec)			\
 	O(SYS_SLEEP,			sleep)			\
 	O(SYS_WAIT,				wait)			\
-	O(SYS_FSTAT,			fstat)			\
 	O(SYS_READ_DIR,			readdir)		\
 	O(SYS_SET_UID,			setuid)			\
 	O(SYS_SET_GID,			setgid)			\
@@ -47,7 +46,6 @@ __BEGIN_DECLS
 	O(SYS_FCNTL,			fcntl)			\
 	O(SYS_NANOSLEEP,		nanosleep)		\
 	O(SYS_FSTATAT,			fstatat)		\
-	O(SYS_STAT,				stat)			\
 	O(SYS_SYNC,				sync)			\
 	O(SYS_MMAP,				mmap)			\
 	O(SYS_MUNMAP,			munmap) 		\

userspace/libraries/LibC/sys/stat.cpp

@@ -1,6 +1,5 @@
 #include <BAN/Assert.h>
 
-#include <errno.h>
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/syscall.h>
@@ -20,7 +19,7 @@ int fchmod(int fildes, mode_t mode)
 
 int fstat(int fildes, struct stat* buf)
 {
-	return syscall(SYS_FSTAT, fildes, buf);
+	return fstatat(fildes, nullptr, buf, 0);
 }
 
 int fstatat(int fd, const char* __restrict path, struct stat* __restrict buf, int flag)
@@ -30,12 +29,12 @@ int fstatat(int fd, const char* __restrict path, struct stat* __restrict buf, in
 
 int lstat(const char* __restrict path, struct stat* __restrict buf)
 {
-	return syscall(SYS_STAT, path, buf, AT_SYMLINK_NOFOLLOW);
+	return fstatat(AT_FDCWD, path, buf, AT_SYMLINK_NOFOLLOW);
 }
 
 int stat(const char* __restrict path, struct stat* __restrict buf)
 {
-	return syscall(SYS_STAT, path, buf, 0);
+	return fstatat(AT_FDCWD, path, buf, 0);
 }
 
 mode_t umask(mode_t cmask)