Kernel/LibC: Update SYS_SEEK to return new offset and implement lseek

kernel/include/kernel/OpenFileDescriptorSet.h

@@ -33,7 +33,7 @@ namespace Kernel
 
 		BAN::ErrorOr<int> fcntl(int fd, int cmd, int extra);
 
-		BAN::ErrorOr<void> seek(int fd, off_t offset, int whence);
+		BAN::ErrorOr<off_t> seek(int fd, off_t offset, int whence);
 		BAN::ErrorOr<off_t> tell(int) const;
 
 		BAN::ErrorOr<void> fstat(int fd, struct stat*) const;

kernel/kernel/OpenFileDescriptorSet.cpp

@@ -207,7 +207,7 @@ namespace Kernel
 		return BAN::Error::from_errno(ENOTSUP);
 	}
 
-	BAN::ErrorOr<void> OpenFileDescriptorSet::seek(int fd, off_t offset, int whence)
+	BAN::ErrorOr<off_t> OpenFileDescriptorSet::seek(int fd, off_t offset, int whence)
 	{
 		TRY(validate_fd(fd));
 
@@ -233,7 +233,7 @@ namespace Kernel
 
 		m_open_files[fd]->offset = new_offset;
 
-		return {};
+		return new_offset;
 	}
 
 	BAN::ErrorOr<off_t> OpenFileDescriptorSet::tell(int fd) const

kernel/kernel/Process.cpp

@@ -1136,8 +1136,7 @@ namespace Kernel
 	BAN::ErrorOr<long> Process::sys_seek(int fd, off_t offset, int whence)
 	{
 		LockGuard _(m_process_lock);
-		TRY(m_open_file_descriptors.seek(fd, offset, whence));
-		return 0;
+		return TRY(m_open_file_descriptors.seek(fd, offset, whence));
 	}
 
 	BAN::ErrorOr<long> Process::sys_tell(int fd)

libc/unistd.cpp

@@ -93,6 +93,11 @@ ssize_t pread(int fildes, void* buf, size_t nbyte, off_t offset)
 	return syscall(SYS_PREAD, fildes, buf, nbyte, offset);
 }
 
+off_t lseek(int fildes, off_t offset, int whence)
+{
+	return syscall(SYS_SEEK, fildes, offset, whence);
+}
+
 int dup(int fildes)
 {
 	return syscall(SYS_DUP, fildes);