From 23968c9f1116ab35d2f7c45be40ae18896517b79 Mon Sep 17 00:00:00 2001
From: Anton Kling <anton@kling.gg>
Date: Sat, 23 Nov 2024 15:55:21 +0100
Subject: vfs: Support O_TRUNC

---
 kernel/fs/vfs.c             | 6 +++++-
 userland/libc/stdio/fopen.c | 5 +----
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/kernel/fs/vfs.c b/kernel/fs/vfs.c
index 25e2423..0d03dce 100644
--- a/kernel/fs/vfs.c
+++ b/kernel/fs/vfs.c
@@ -287,7 +287,11 @@ int vfs_open(const char *file, int flags, int mode) {
   }
 
   // FIXME: Maybe it is sometimes a TTY?
-  return vfs_create_fd(flags, mode, 0 /*is_tty*/, inode, NULL);
+  int rc = vfs_create_fd(flags, mode, 0 /*is_tty*/, inode, NULL);
+  if (flags & O_TRUNC) {
+    vfs_ftruncate(rc, 0);
+  }
+  return rc;
 }
 
 int vfs_close_process(process_t *p, int fd) {
diff --git a/userland/libc/stdio/fopen.c b/userland/libc/stdio/fopen.c
index fe0b5cf..38ccbf1 100644
--- a/userland/libc/stdio/fopen.c
+++ b/userland/libc/stdio/fopen.c
@@ -18,7 +18,7 @@ FILE *fopen(const char *pathname, const char *mode) {
       flag |= O_READ;
       break;
     case 'w':
-      flag |= O_WRITE;
+      flag |= O_WRITE | O_TRUNC;
       break;
     case 'a':
       flag |= O_APPEND;
@@ -36,9 +36,6 @@ FILE *fopen(const char *pathname, const char *mode) {
     close(fd);
     return NULL;
   }
-  if(flag & O_WRITE) {
-    ftruncate(fd, 0);
-  }
   r->has_control_over_the_fd = 1;
   return r;
 }
-- 
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