From a3c6635f3ea114095a921d97b0410c843c4cab3b Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Thu, 27 Oct 2022 07:43:55 +0200
Subject: [PATCH] Kernel, libc: Add O_APPEND and stub out O_CREAT and O_TRUNC

---
 kernel/src/sys/stdio.cpp  | 22 ++++++++++++++++++++++
 libs/libc/include/fcntl.h |  6 ++++++
 2 files changed, 28 insertions(+)

diff --git a/kernel/src/sys/stdio.cpp b/kernel/src/sys/stdio.cpp
index ec806a4b..b4ed6d44 100644
--- a/kernel/src/sys/stdio.cpp
+++ b/kernel/src/sys/stdio.cpp
@@ -17,6 +17,9 @@
 #define OPEN_NONBLOCK 4
 #define OPEN_CLOEXEC 8
 #define OPEN_DIRECTORY 16
+#define OPEN_TRUNCATED 32
+#define OPEN_CREATE 64
+#define OPEN_APPEND 128
 
 #define SEEK_SET 0
 #define SEEK_CUR 1
@@ -154,6 +157,8 @@ void sys_open(Context* context, const char* filename, int flags)
     VFS::Node* node = VFS::resolve_path(kfilename);
     if (!node)
     {
+        bool create = (flags & OPEN_CREATE) > 0;
+        if (create) kwarnln("FIXME: open(O_CREAT) is not implemented");
         kfree(kfilename);
         context->rax = -ENOENT;
         return;
@@ -173,6 +178,17 @@ void sys_open(Context* context, const char* filename, int flags)
 
     bool only_directory = (flags & OPEN_DIRECTORY) > 0;
 
+    bool truncate = (flags & OPEN_TRUNCATED) > 0;
+    if (truncate)
+    {
+        kfree(kfilename);
+        kerrorln("FIXME: open(O_TRUNC) is not implemented");
+        context->rax = -ENOTSUP;
+        return;
+    }
+
+    bool append = (flags & OPEN_APPEND) > 0;
+
     if (only_directory && node->type != VFS_DIRECTORY)
     {
         kfree(kfilename);
@@ -188,6 +204,12 @@ void sys_open(Context* context, const char* filename, int flags)
 
     kfree(kfilename);
     current_task->files[fd].open(node, can_read, can_write, able_to_block, close_on_exec);
+
+    if (append && current_task->files[fd].node()->type != VFS_DEVICE)
+    {
+        current_task->files[fd].seek((long)current_task->files[fd].length());
+    }
+
     context->rax = fd;
     return;
 }
diff --git a/libs/libc/include/fcntl.h b/libs/libc/include/fcntl.h
index fa306abe..6e801bd6 100644
--- a/libs/libc/include/fcntl.h
+++ b/libs/libc/include/fcntl.h
@@ -13,6 +13,12 @@
 #define O_CLOEXEC 8
 /* Refuse to open the file if it is not a directory. */
 #define O_DIRECTORY 16
+/* Truncate the file on open. */
+#define O_TRUNC 32
+/* Create the file if it doesn't exist. */
+#define O_CREAT 64
+/* Open the file for appending. */
+#define O_APPEND 128
 
 /* Duplicate a file descriptor. */
 #define F_DUPFD 0