[libc] Implement fcntl() function (#89507)

Fixes #84968. 

Implements the `fcntl()` function defined in the `fcntl.h` header.

6 files changed, 113 insertions, 0 deletions

diff --git a/libc/include/CMakeLists.txt b/libc/include/CMakeLists.txt
index 6dea8e5..6101ec1 100644
--- a/libc/include/CMakeLists.txt
+++ b/libc/include/CMakeLists.txt
@@ -43,6 +43,10 @@ add_gen_header(
   DEPENDS
     .llvm-libc-macros.fcntl_macros
     .llvm-libc-types.mode_t
+    .llvm-libc-types.struct_flock
+    .llvm-libc-types.struct_flock64
+    .llvm-libc-types.off64_t
+    .llvm-libc-types.pid_t
     .llvm-libc-types.off_t
     .llvm_libc_common_h
 )
diff --git a/libc/include/llvm-libc-macros/linux/fcntl-macros.h b/libc/include/llvm-libc-macros/linux/fcntl-macros.h
index 1d4e5bb..8ee9586 100644
--- a/libc/include/llvm-libc-macros/linux/fcntl-macros.h
+++ b/libc/include/llvm-libc-macros/linux/fcntl-macros.h
@@ -67,5 +67,36 @@
 #define F_SETFD 2
 #define F_GETFL 3
 #define F_SETFL 4
+#define F_GETLK 5
+#define F_SETLK 6
+#define F_SETLKW 7
+#define F_SETOWN 8
+#define F_GETOWN 9
+#define F_SETSIG 10
+#define F_GETSIG 11
+#define F_GETLK64 12
+#define F_SETLK64 13
+#define F_SETLKW64 14
+#define F_SETOWN_EX 15
+#define F_GETOWN_EX 16
+
+// Open File Description Locks.
+#define F_OFD_GETLK 36
+#define F_OFD_SETLK 37
+#define F_OFD_SETLKW 38
+
+// Close on succesful
+#define F_CLOEXEC 1
+
+#define F_RDLCK 0
+#define F_WRLCK 1
+#define F_UNLCK 2
+
+// For Large File Support
+#if defined(_LARGEFILE64_SOURCE)
+#define F_GETLK F_GETLK64
+#define F_SETLK F_SETLK64
+#define F_SETLKW F_SETLKW64
+#endif
 
 #endif // LLVM_LIBC_MACROS_LINUX_FCNTL_MACROS_H
diff --git a/libc/include/llvm-libc-types/CMakeLists.txt b/libc/include/llvm-libc-types/CMakeLists.txt
index 16e343d..018b6c5 100644
--- a/libc/include/llvm-libc-types/CMakeLists.txt
+++ b/libc/include/llvm-libc-types/CMakeLists.txt
@@ -60,6 +60,9 @@ add_header(rlim_t HDR rlim_t.h)
 add_header(time_t HDR time_t.h)
 add_header(stack_t HDR stack_t.h)
 add_header(suseconds_t HDR suseconds_t.h)
+add_header(struct_flock HDR struct_flock.h DEPENDS .off_t .pid_t)
+add_header(struct_flock64 HDR struct_flock64.h DEPENDS .off64_t .pid_t)
+add_header(struct_f_owner_ex HDR struct_f_owner_ex.h DEPENDS .pid_t)
 add_header(struct_timeval HDR struct_timeval.h DEPENDS .suseconds_t .time_t)
 add_header(struct_rlimit HDR struct_rlimit.h DEPENDS .rlim_t)
 add_header(struct_rusage HDR struct_rusage.h DEPENDS .struct_timeval)
diff --git a/libc/include/llvm-libc-types/struct_f_owner_ex.h b/libc/include/llvm-libc-types/struct_f_owner_ex.h
new file mode 100644
index 0000000..c9cc85f
--- /dev/null
+++ b/libc/include/llvm-libc-types/struct_f_owner_ex.h
@@ -0,0 +1,25 @@
+//===-- Definition of type struct f_owner_ex ------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_TYPES_STRUCT_F_OWNER_EX_H
+#define LLVM_LIBC_TYPES_STRUCT_F_OWNER_EX_H
+
+#include "llvm-libc-types/pid_t.h"
+
+enum pid_type {
+  F_OWNER_TID = 0,
+  F_OWNER_PID,
+  F_OWNER_PGRP,
+};
+
+struct f_owner_ex {
+  enum pid_type type;
+  pid_t pid;
+};
+
+#endif // LLVM_LIBC_TYPES_STRUCT_F_OWNER_EX_H
diff --git a/libc/include/llvm-libc-types/struct_flock.h b/libc/include/llvm-libc-types/struct_flock.h
new file mode 100644
index 0000000..51c9d27
--- /dev/null
+++ b/libc/include/llvm-libc-types/struct_flock.h
@@ -0,0 +1,25 @@
+//===-- Definition of type struct flock64 ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_TYPES_STRUCT_FLOCK_H
+#define LLVM_LIBC_TYPES_STRUCT_FLOCK_H
+
+#include "llvm-libc-types/off_t.h"
+#include "llvm-libc-types/pid_t.h"
+
+#include <stdint.h>
+
+struct flock {
+  int16_t l_type;
+  int16_t l_whence;
+  off_t l_start;
+  off_t l_len;
+  pid_t l_pid;
+};
+
+#endif // LLVM_LIBC_TYPES_STRUCT_FLOCK_H
diff --git a/libc/include/llvm-libc-types/struct_flock64.h b/libc/include/llvm-libc-types/struct_flock64.h
new file mode 100644
index 0000000..ac50003
--- /dev/null
+++ b/libc/include/llvm-libc-types/struct_flock64.h
@@ -0,0 +1,25 @@
+//===-- Definition of type struct flock64 ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_TYPES_STRUCT_FLOCK64_H
+#define LLVM_LIBC_TYPES_STRUCT_FLOCK64_H
+
+#include "llvm-libc-types/off64_t.h"
+#include "llvm-libc-types/pid_t.h"
+
+#include <stdint.h>
+
+struct flock64 {
+  int16_t l_type;
+  int16_t l_whence;
+  off64_t l_start;
+  off64_t l_len;
+  pid_t l_pid;
+};
+
+#endif // LLVM_LIBC_TYPES_STRUCT_FLOCK64_H