From 79cef7c0344a50f2052e8972a263685dbf8f61ac Mon Sep 17 00:00:00 2001
From: jD91mZM2 <me@krake.one>
Date: Sun, 7 Oct 2018 15:22:13 +0200
Subject: [PATCH] Adopt linux' O_APPEND behavior
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According to `man open`:

> The file is opened in append mode. Before each write(2), the file offset
is positioned at the end of the file, as if with lseek(2). The modi‐
fication of the file offset and the write operation are performed as a
single atomic step.
---
 src/mount/redox/resource.rs | 19 +++++++++++--------
 src/mount/redox/scheme.rs   | 18 +++---------------
 2 files changed, 14 insertions(+), 23 deletions(-)

diff --git a/src/mount/redox/resource.rs b/src/mount/redox/resource.rs
index 9d7c75af62..81f057fe6c 100644
--- a/src/mount/redox/resource.rs
+++ b/src/mount/redox/resource.rs
@@ -3,7 +3,7 @@ use std::time::{SystemTime, UNIX_EPOCH};
 
 use syscall::data::TimeSpec;
 use syscall::error::{Error, Result, EBADF, EBUSY, EINVAL, EISDIR, EPERM};
-use syscall::flag::{O_ACCMODE, O_RDONLY, O_WRONLY, O_RDWR, F_GETFL, F_SETFL, MODE_PERM};
+use syscall::flag::{O_ACCMODE, O_APPEND, O_RDONLY, O_WRONLY, O_RDWR, F_GETFL, F_SETFL, MODE_PERM};
 use syscall::{Stat, SEEK_SET, SEEK_CUR, SEEK_END};
 
 use disk::Disk;
@@ -191,13 +191,13 @@ pub struct FileResource {
 }
 
 impl FileResource {
-    pub fn new(path: String, block: u64, flags: usize, seek: u64, uid: u32) -> FileResource {
+    pub fn new(path: String, block: u64, flags: usize, uid: u32) -> FileResource {
         FileResource {
-            path: path,
-            block: block,
-            flags: flags,
-            seek: seek,
-            uid: uid,
+            path,
+            block,
+            flags,
+            seek: 0,
+            uid,
             fmap: None
         }
     }
@@ -255,7 +255,10 @@ impl<D: Disk> Resource<D> for FileResource {
     }
 
     fn write(&mut self, buf: &[u8], fs: &mut FileSystem<D>) -> Result<usize> {
-        if self.flags & O_ACCMODE == O_RDWR || self.flags & O_ACCMODE == O_WRONLY {
+        if self.flags & O_WRONLY == O_WRONLY {
+            if self.flags & O_APPEND == O_APPEND {
+                self.seek = fs.node_len(self.block)?;
+            }
             let mtime = SystemTime::now().duration_since(UNIX_EPOCH).unwrap();
             let count = fs.write_node(self.block, self.seek, buf, mtime.as_secs(), mtime.subsec_nanos())?;
             self.seek += count as u64;
diff --git a/src/mount/redox/scheme.rs b/src/mount/redox/scheme.rs
index a5ce3be516..5c827b28a0 100644
--- a/src/mount/redox/scheme.rs
+++ b/src/mount/redox/scheme.rs
@@ -7,7 +7,7 @@ use std::time::{SystemTime, UNIX_EPOCH};
 
 use syscall::data::{Stat, StatVfs, TimeSpec};
 use syscall::error::{Error, Result, EACCES, EEXIST, EISDIR, ENOTDIR, ENOTEMPTY, EPERM, ENOENT, EBADF, ELOOP, EINVAL};
-use syscall::flag::{O_APPEND, O_CREAT, O_DIRECTORY, O_STAT, O_EXCL, O_TRUNC, O_ACCMODE, O_RDONLY, O_WRONLY, O_RDWR, MODE_PERM, O_SYMLINK, O_NOFOLLOW};
+use syscall::flag::{O_CREAT, O_DIRECTORY, O_STAT, O_EXCL, O_TRUNC, O_ACCMODE, O_RDONLY, O_WRONLY, O_RDWR, MODE_PERM, O_SYMLINK, O_NOFOLLOW};
 use syscall::scheme::Scheme;
 
 use BLOCK_SIZE;
@@ -321,13 +321,7 @@ impl<D: Disk> Scheme for FileScheme<D> {
                     fs.node_set_len(node.0, 0)?;
                 }
 
-                let seek = if flags & O_APPEND == O_APPEND {
-                    fs.node_len(node.0)?
-                } else {
-                    0
-                };
-
-                Box::new(FileResource::new(path.to_string(), node.0, flags, seek, uid))
+                Box::new(FileResource::new(path.to_string(), node.0, flags, uid))
             },
             None => if flags & O_CREAT == O_CREAT {
                 let mut last_part = String::new();
@@ -361,13 +355,7 @@ impl<D: Disk> Scheme for FileScheme<D> {
                         if dir {
                             Box::new(DirResource::new(path.to_string(), node.0, None, uid))
                         } else {
-                            let seek = if flags & O_APPEND == O_APPEND {
-                                fs.node_len(node.0)?
-                            } else {
-                                0
-                            };
-
-                            Box::new(FileResource::new(path.to_string(), node.0, flags, seek, uid))
+                            Box::new(FileResource::new(path.to_string(), node.0, flags, uid))
                         }
                     } else {
                         return Err(Error::new(EPERM));