From 6ed1435aebf7fb813bdba82b2589edcab8650ca4 Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Mon, 2 Dec 2024 03:59:23 +0200
Subject: [PATCH] Kernel/LibC: Implement tcgetpgrp

---
 kernel/include/kernel/Process.h                |  1 +
 kernel/kernel/Process.cpp                      | 18 ++++++++++++++++++
 userspace/libraries/LibC/include/sys/syscall.h |  1 +
 userspace/libraries/LibC/unistd.cpp            |  5 +++++
 4 files changed, 25 insertions(+)

diff --git a/kernel/include/kernel/Process.h b/kernel/include/kernel/Process.h
index de0cf334..0044d586 100644
--- a/kernel/include/kernel/Process.h
+++ b/kernel/include/kernel/Process.h
@@ -179,6 +179,7 @@ namespace Kernel
 		BAN::ErrorOr<long> sys_sigpending(sigset_t* set);
 		BAN::ErrorOr<long> sys_sigprocmask(int how, const sigset_t* set, sigset_t* oset);
 
+		BAN::ErrorOr<long> sys_tcgetpgrp(int fd);
 		BAN::ErrorOr<long> sys_tcsetpgrp(int fd, pid_t pgid);
 
 		BAN::ErrorOr<long> sys_termid(char*);
diff --git a/kernel/kernel/Process.cpp b/kernel/kernel/Process.cpp
index 27527f0e..76846a07 100644
--- a/kernel/kernel/Process.cpp
+++ b/kernel/kernel/Process.cpp
@@ -2012,6 +2012,24 @@ namespace Kernel
 		return 0;
 	}
 
+	BAN::ErrorOr<long> Process::sys_tcgetpgrp(int fd)
+	{
+		LockGuard _(m_process_lock);
+
+		if (!m_controlling_terminal)
+			return BAN::Error::from_errno(ENOTTY);
+
+		auto inode = TRY(m_open_file_descriptors.inode_of(fd));
+		if (!inode->is_tty())
+			return BAN::Error::from_errno(ENOTTY);
+
+		auto* tty = static_cast<TTY*>(inode.ptr());
+		if (tty != m_controlling_terminal.ptr())
+			return BAN::Error::from_errno(ENOTTY);
+
+		return tty->foreground_pgrp();
+	}
+
 	BAN::ErrorOr<long> Process::sys_tcsetpgrp(int fd, pid_t pgrp)
 	{
 		LockGuard _(m_process_lock);
diff --git a/userspace/libraries/LibC/include/sys/syscall.h b/userspace/libraries/LibC/include/sys/syscall.h
index 29f865bc..f8073c6f 100644
--- a/userspace/libraries/LibC/include/sys/syscall.h
+++ b/userspace/libraries/LibC/include/sys/syscall.h
@@ -39,6 +39,7 @@ __BEGIN_DECLS
 	O(SYS_DUP,				dup)			\
 	O(SYS_DUP2,				dup2)			\
 	O(SYS_KILL,				kill)			\
+	O(SYS_TCGETPGRP,		tcgetpgrp)		\
 	O(SYS_TCSETPGRP,		tcsetpgrp)		\
 	O(SYS_GET_PID,			getpid)			\
 	O(SYS_GET_PGID,			getpgid)		\
diff --git a/userspace/libraries/LibC/unistd.cpp b/userspace/libraries/LibC/unistd.cpp
index efc577df..48c04bad 100644
--- a/userspace/libraries/LibC/unistd.cpp
+++ b/userspace/libraries/LibC/unistd.cpp
@@ -483,6 +483,11 @@ pid_t getpgid(pid_t pid)
 	return syscall(SYS_GET_PGID, pid);
 }
 
+int tcgetpgrp(int fildes)
+{
+	return syscall(SYS_TCGETPGRP, fildes);
+}
+
 int seteuid(uid_t uid)
 {
 	return syscall(SYS_SET_EUID, uid);