From aec5a09cafb63cedfbe595674aaa7ff59187bbe1 Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Mon, 3 Jun 2024 03:36:25 +0300
Subject: [PATCH] Kernel/LibC: Implement SYS_ISATTY and isatty()

---
 kernel/include/kernel/Process.h | 2 ++
 kernel/kernel/Process.cpp       | 9 +++++++++
 libc/include/sys/syscall.h      | 1 +
 libc/unistd.cpp                 | 5 +++++
 4 files changed, 17 insertions(+)

diff --git a/kernel/include/kernel/Process.h b/kernel/include/kernel/Process.h
index ac010ed3..84bc6b96 100644
--- a/kernel/include/kernel/Process.h
+++ b/kernel/include/kernel/Process.h
@@ -162,6 +162,8 @@ namespace Kernel
 		BAN::ErrorOr<long> sys_smo_delete(SharedMemoryObjectManager::Key);
 		BAN::ErrorOr<long> sys_smo_map(SharedMemoryObjectManager::Key);
 
+		BAN::ErrorOr<long> sys_isatty(int fildes);
+
 		BAN::ErrorOr<long> sys_tty_ctrl(int fildes, int command, int flags);
 
 		BAN::ErrorOr<long> sys_signal(int, void (*)(int));
diff --git a/kernel/kernel/Process.cpp b/kernel/kernel/Process.cpp
index abc02a7d..ac737e58 100644
--- a/kernel/kernel/Process.cpp
+++ b/kernel/kernel/Process.cpp
@@ -1433,6 +1433,15 @@ namespace Kernel
 		return m_mapped_regions.back()->vaddr();
 	}
 
+	BAN::ErrorOr<long> Process::sys_isatty(int fildes)
+	{
+		LockGuard _(m_process_lock);
+		auto inode = TRY(m_open_file_descriptors.inode_of(fildes));
+		if (!inode->is_tty())
+			return BAN::Error::from_errno(ENOTTY);
+		return 0;
+	}
+
 	BAN::ErrorOr<long> Process::sys_tty_ctrl(int fildes, int command, int flags)
 	{
 		LockGuard _(m_process_lock);
diff --git a/libc/include/sys/syscall.h b/libc/include/sys/syscall.h
index 429e4351..a720c1a8 100644
--- a/libc/include/sys/syscall.h
+++ b/libc/include/sys/syscall.h
@@ -77,6 +77,7 @@ __BEGIN_DECLS
 	O(SYS_SMO_CREATE,		smo_create)		\
 	O(SYS_SMO_DELETE,		smo_delete)		\
 	O(SYS_SMO_MAP,			smo_map)		\
+	O(SYS_ISATTY,			isatty)			\
 
 enum Syscall
 {
diff --git a/libc/unistd.cpp b/libc/unistd.cpp
index 3ad3e91b..e7405bc9 100644
--- a/libc/unistd.cpp
+++ b/libc/unistd.cpp
@@ -114,6 +114,11 @@ int dup2(int fildes, int fildes2)
 	return syscall(SYS_DUP2, fildes, fildes2);
 }
 
+int isatty(int fildes)
+{
+	return syscall(SYS_ISATTY, fildes) >= 0;
+}
+
 int execl(const char* pathname, const char* arg0, ...)
 {
 	if (arg0 == nullptr)