From 18e2559b1e7d8f3f3f5b9c39f942a11d930c595a Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Tue, 28 May 2024 01:08:04 +0300
Subject: [PATCH] Kernel/LibC: Add SYS_TRUNCATE

---
 kernel/include/kernel/OpenFileDescriptorSet.h | 2 ++
 kernel/include/kernel/Process.h               | 2 ++
 kernel/kernel/OpenFileDescriptorSet.cpp       | 6 ++++++
 kernel/kernel/Process.cpp                     | 7 +++++++
 libc/include/sys/syscall.h                    | 1 +
 libc/unistd.cpp                               | 5 +++++
 6 files changed, 23 insertions(+)

diff --git a/kernel/include/kernel/OpenFileDescriptorSet.h b/kernel/include/kernel/OpenFileDescriptorSet.h
index 99386657..43321fe7 100644
--- a/kernel/include/kernel/OpenFileDescriptorSet.h
+++ b/kernel/include/kernel/OpenFileDescriptorSet.h
@@ -36,6 +36,8 @@ namespace Kernel
 		BAN::ErrorOr<off_t> seek(int fd, off_t offset, int whence);
 		BAN::ErrorOr<off_t> tell(int) const;
 
+		BAN::ErrorOr<void> truncate(int fd, off_t length);
+
 		BAN::ErrorOr<void> fstat(int fd, struct stat*) const;
 		BAN::ErrorOr<void> fstatat(int fd, BAN::StringView path, struct stat* buf, int flag);
 		BAN::ErrorOr<void> stat(BAN::StringView absolute_path, struct stat* buf, int flag);
diff --git a/kernel/include/kernel/Process.h b/kernel/include/kernel/Process.h
index 97e9aec8..72df79c8 100644
--- a/kernel/include/kernel/Process.h
+++ b/kernel/include/kernel/Process.h
@@ -138,6 +138,8 @@ namespace Kernel
 		BAN::ErrorOr<long> sys_seek(int fd, off_t offset, int whence);
 		BAN::ErrorOr<long> sys_tell(int fd);
 
+		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);
diff --git a/kernel/kernel/OpenFileDescriptorSet.cpp b/kernel/kernel/OpenFileDescriptorSet.cpp
index bd09d0b0..2043ead3 100644
--- a/kernel/kernel/OpenFileDescriptorSet.cpp
+++ b/kernel/kernel/OpenFileDescriptorSet.cpp
@@ -242,6 +242,12 @@ namespace Kernel
 		return m_open_files[fd]->offset;
 	}
 
+	BAN::ErrorOr<void> OpenFileDescriptorSet::truncate(int fd, off_t length)
+	{
+		TRY(validate_fd(fd));
+		return m_open_files[fd]->inode->truncate(length);
+	}
+
 	static void read_stat_from_inode(BAN::RefPtr<Inode> inode, struct stat* out)
 	{
 		out->st_dev		= inode->dev();
diff --git a/kernel/kernel/Process.cpp b/kernel/kernel/Process.cpp
index 80945b20..9685a2f5 100644
--- a/kernel/kernel/Process.cpp
+++ b/kernel/kernel/Process.cpp
@@ -1145,6 +1145,13 @@ namespace Kernel
 		return TRY(m_open_file_descriptors.tell(fd));
 	}
 
+	BAN::ErrorOr<long> Process::sys_truncate(int fd, off_t length)
+	{
+		LockGuard _(m_process_lock);
+		TRY(m_open_file_descriptors.truncate(fd, length));
+		return 0;
+	}
+
 	BAN::ErrorOr<void> Process::mount(BAN::StringView source, BAN::StringView target)
 	{
 		BAN::String absolute_source, absolute_target;
diff --git a/libc/include/sys/syscall.h b/libc/include/sys/syscall.h
index c2382c15..daebd556 100644
--- a/libc/include/sys/syscall.h
+++ b/libc/include/sys/syscall.h
@@ -73,6 +73,7 @@ __BEGIN_DECLS
 	O(SYS_CONNECT,			connect)		\
 	O(SYS_LISTEN,			listen)			\
 	O(SYS_PSELECT,			pselect)		\
+	O(SYS_TRUNCATE,			truncate)		\
 
 enum Syscall
 {
diff --git a/libc/unistd.cpp b/libc/unistd.cpp
index 689a19c0..3ad3e91b 100644
--- a/libc/unistd.cpp
+++ b/libc/unistd.cpp
@@ -99,6 +99,11 @@ off_t lseek(int fildes, off_t offset, int whence)
 	return syscall(SYS_SEEK, fildes, offset, whence);
 }
 
+int ftruncate(int fildes, off_t length)
+{
+	return syscall(SYS_TRUNCATE, fildes, length);
+}
+
 int dup(int fildes)
 {
 	return syscall(SYS_DUP, fildes);