openpgp: Unify Message and writer::Stack, hide writers.

  - Previously, Message::new returned a writer::Stack, and Message was
    just an empty struct.  Unify the types.  This makes sense, because
    if you have a message, and encrypt it, you get a message.

  - Make the writer module private.  This is an implementation detail.

5 files changed, 41 insertions, 54 deletions

diff --git a/openpgp/src/serialize/stream/padding.rs b/openpgp/src/serialize/stream/padding.rs
index db190253..3b08aa50 100644
--- a/openpgp/src/serialize/stream/padding.rs
+++ b/openpgp/src/serialize/stream/padding.rs
@@ -51,6 +51,7 @@ use crate::serialize::{
     stream::{
         writer,
         Cookie,
+        Message,
         PartialBodyFilter,
     },
 };
@@ -132,26 +133,26 @@ pub struct Padder<'a, P: Fn(u64) -> u64 + 'a> {
 
 impl<'a, P: Fn(u64) -> u64 + 'a> Padder<'a, P> {
     /// Creates a new padder with the given policy.
-    pub fn new(inner: writer::Stack<'a, Cookie>, p: P)
-               -> Result<writer::Stack<'a, Cookie>> {
+    pub fn new(inner: Message<'a, Cookie>, p: P)
+               -> Result<Message<'a, Cookie>> {
         let mut inner = writer::BoxStack::from(inner);
         let level = inner.cookie_ref().level + 1;
 
         // Packet header.
         CTB::new(Tag::CompressedData).serialize(&mut inner)?;
-        let mut inner: writer::Stack<'a, Cookie>
-            = PartialBodyFilter::new(writer::Stack::from(inner),
+        let mut inner: Message<'a, Cookie>
+            = PartialBodyFilter::new(Message::from(inner),
                                      Cookie::new(level));
 
         // Compressed data header.
         inner.as_mut().write_u8(CompressionAlgorithm::Zip.into())?;
 
         // Create an appropriate filter.
-        let inner: writer::Stack<'a, Cookie> =
+        let inner: Message<'a, Cookie> =
             writer::ZIP::new(inner, Cookie::new(level),
                              writer::CompressionLevel::none());
 
-        Ok(writer::Stack::from(Box::new(Self {
+        Ok(Message::from(Box::new(Self {
             inner: inner.into(),
             policy: p,
         })))
diff --git a/openpgp/src/serialize/stream/partial_body.rs b/openpgp/src/serialize/stream/partial_body.rs
index e5aef8ca..24e0ea52 100644
--- a/openpgp/src/serialize/stream/partial_body.rs
+++ b/openpgp/src/serialize/stream/partial_body.rs
@@ -10,7 +10,10 @@ use crate::Result;
 use crate::packet::header::BodyLength;
 use crate::serialize::{
     log2,
-    stream::writer,
+    stream::{
+        writer,
+        Message,
+    },
     write_byte,
     Marshal,
 };
@@ -48,8 +51,8 @@ const PARTIAL_BODY_FILTER_BUFFER_THRESHOLD : usize = 4 * 1024 * 1024;
 
 impl<'a, C: 'a> PartialBodyFilter<'a, C> {
     /// Returns a new partial body encoder.
-    pub fn new(inner: writer::Stack<'a, C>, cookie: C)
-               -> writer::Stack<'a, C> {
+    pub fn new(inner: Message<'a, C>, cookie: C)
+               -> Message<'a, C> {
         Self::with_limits(inner, cookie,
                           PARTIAL_BODY_FILTER_BUFFER_THRESHOLD,
                           PARTIAL_BODY_FILTER_MAX_CHUNK_SIZE)
@@ -57,10 +60,10 @@ impl<'a, C: 'a> PartialBodyFilter<'a, C> {
     }
 
     /// Returns a new partial body encoder with the given limits.
-    pub fn with_limits(inner: writer::Stack<'a, C>, cookie: C,
+    pub fn with_limits(inner: Message<'a, C>, cookie: C,
                        buffer_threshold: usize,
                        max_chunk_size: usize)
-                       -> Result<writer::Stack<'a, C>> {
+                       -> Result<Message<'a, C>> {
         if buffer_threshold.count_ones() != 1 {
             return Err(Error::InvalidArgument(
                 "buffer_threshold is not a power of two".into()).into());
@@ -76,7 +79,7 @@ impl<'a, C: 'a> PartialBodyFilter<'a, C> {
                 "max_chunk_size exceeds limit".into()).into());
         }
 
-        Ok(writer::Stack::from(Box::new(PartialBodyFilter {
+        Ok(Message::from(Box::new(PartialBodyFilter {
             inner: Some(inner.into()),
             cookie,
             buffer: Vec::with_capacity(buffer_threshold),
diff --git a/openpgp/src/serialize/stream/writer/mod.rs b/openpgp/src/serialize/stream/writer/mod.rs
index 2141ca98..1006f0f5 100644
--- a/openpgp/src/serialize/stream/writer/mod.rs
+++ b/openpgp/src/serialize/stream/writer/mod.rs
@@ -23,14 +23,11 @@ use crate::{
     Result,
     crypto::SessionKey,
 };
+use super::Message;
 
-/// A stack of writers.
-#[derive(Debug)]
-pub struct Stack<'a, C>(BoxStack<'a, C>);
-
-impl<'a, C> Stack<'a, C> {
+impl<'a, C> Message<'a, C> {
     pub(crate) fn from(bs: BoxStack<'a, C>) -> Self {
-        Stack(bs)
+        Message(bs)
     }
 
     pub(crate) fn as_ref(&self) -> &BoxStack<'a, C> {
@@ -40,23 +37,9 @@ impl<'a, C> Stack<'a, C> {
     pub(crate) fn as_mut(&mut self) -> &mut BoxStack<'a, C> {
         &mut self.0
     }
-
-    /// Finalizes this writer, returning the underlying writer.
-    pub fn finalize_one(self) -> Result<Option<Stack<'a, C>>> {
-        Ok(self.0.into_inner()?.map(|bs| Self::from(bs)))
-    }
-
-    /// Finalizes all writers, tearing down the whole stack.
-    pub fn finalize(self) -> Result<()> {
-        let mut stack = self;
-        while let Some(s) = stack.finalize_one()? {
-            stack = s;
-        }
-        Ok(())
-    }
 }
 
-impl<'a, C> io::Write for Stack<'a, C> {
+impl<'a, C> io::Write for Message<'a, C> {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         self.0.write(buf)
     }
@@ -66,8 +49,8 @@ impl<'a, C> io::Write for Stack<'a, C> {
     }
 }
 
-impl<'a, C> From<Stack<'a, C>> for BoxStack<'a, C> {
-    fn from(s: Stack<'a, C>) -> Self {
+impl<'a, C> From<Message<'a, C>> for BoxStack<'a, C> {
+    fn from(s: Message<'a, C>) -> Self {
         s.0
     }
 }
@@ -214,9 +197,9 @@ pub struct Identity<'a, C> {
 
 impl<'a, C: 'a> Identity<'a, C> {
     /// Makes an identity writer.
-    pub fn new(inner: Stack<'a, C>, cookie: C)
-                  -> Stack<'a, C> {
-        Stack::from(Box::new(Self{inner: Some(inner.into()), cookie }))
+    pub fn new(inner: Message<'a, C>, cookie: C)
+                  -> Message<'a, C> {
+        Message::from(Box::new(Self{inner: Some(inner.into()), cookie }))
     }
 }
 
@@ -294,8 +277,8 @@ pub struct Generic<W: io::Write, C> {
 
 impl<'a, W: 'a + io::Write, C: 'a> Generic<W, C> {
     /// Wraps an `io::Write`r.
-    pub fn new(inner: W, cookie: C) -> Stack<'a, C> {
-        Stack::from(Box::new(Self::new_unboxed(inner.into(), cookie)))
+    pub fn new(inner: W, cookie: C) -> Message<'a, C> {
+        Message::from(Box::new(Self::new_unboxed(inner.into(), cookie)))
     }
 
     fn new_unboxed(inner: W, cookie: C) -> Self {
@@ -378,11 +361,11 @@ pub struct Encryptor<'a, C: 'a> {
 
 impl<'a, C: 'a> Encryptor<'a, C> {
     /// Makes an encrypting writer.
-    pub fn new(inner: Stack<'a, C>, cookie: C, algo: SymmetricAlgorithm,
+    pub fn new(inner: Message<'a, C>, cookie: C, algo: SymmetricAlgorithm,
                key: &[u8])
-        -> Result<Stack<'a, C>>
+        -> Result<Message<'a, C>>
     {
-        Ok(Stack::from(Box::new(Encryptor {
+        Ok(Message::from(Box::new(Encryptor {
             inner: Generic::new_unboxed(
                 symmetric::Encryptor::new(algo, key, inner.into())?,
                 cookie),
@@ -449,12 +432,12 @@ pub struct AEADEncryptor<'a, C: 'a> {
 
 impl<'a, C: 'a> AEADEncryptor<'a, C> {
     /// Makes an encrypting writer.
-    pub fn new(inner: Stack<'a, C>, cookie: C,
+    pub fn new(inner: Message<'a, C>, cookie: C,
                cipher: SymmetricAlgorithm, aead: AEADAlgorithm,
                chunk_size: usize, iv: &[u8], key: &SessionKey)
-        -> Result<Stack<'a, C>>
+        -> Result<Message<'a, C>>
     {
-        Ok(Stack::from(Box::new(AEADEncryptor {
+        Ok(Message::from(Box::new(AEADEncryptor {
             inner: Generic::new_unboxed(
                 aead::Encryptor::new(1, cipher, aead, chunk_size, iv, key,
                                      inner.into())?,
diff --git a/openpgp/src/serialize/stream/writer/writer_bzip2.rs b/openpgp/src/serialize/stream/writer/writer_bzip2.rs
index 62affd0c..1f5b6cdf 100644
--- a/openpgp/src/serialize/stream/writer/writer_bzip2.rs
+++ b/openpgp/src/serialize/stream/writer/writer_bzip2.rs
@@ -3,7 +3,7 @@ use std::fmt;
 use std::io;
 
 use crate::Result;
-use super::{Generic, Stack, BoxStack, Stackable, CompressionLevel};
+use super::{Generic, Message, BoxStack, Stackable, CompressionLevel};
 
 /// BZing writer.
 pub struct BZ<'a, C: 'a> {
@@ -12,10 +12,10 @@ pub struct BZ<'a, C: 'a> {
 
 impl<'a, C: 'a> BZ<'a, C> {
     /// Makes a BZ compressing writer.
-    pub fn new<L>(inner: Stack<'a, C>, cookie: C, level: L) -> Stack<'a, C>
+    pub fn new<L>(inner: Message<'a, C>, cookie: C, level: L) -> Message<'a, C>
         where L: Into<Option<CompressionLevel>>
     {
-        Stack::from(Box::new(BZ {
+        Message::from(Box::new(BZ {
             inner: Generic::new_unboxed(
                 BzEncoder::new(inner.into(),
                                level.into().unwrap_or_default().into()),
diff --git a/openpgp/src/serialize/stream/writer/writer_deflate.rs b/openpgp/src/serialize/stream/writer/writer_deflate.rs
index 387b3f2c..b2cdd74f 100644
--- a/openpgp/src/serialize/stream/writer/writer_deflate.rs
+++ b/openpgp/src/serialize/stream/writer/writer_deflate.rs
@@ -3,7 +3,7 @@ use std::fmt;
 use std::io;
 
 use crate::Result;
-use super::{Generic, Stack, BoxStack, Stackable, CompressionLevel};
+use super::{Generic, Message, BoxStack, Stackable, CompressionLevel};
 
 /// ZIPing writer.
 pub struct ZIP<'a, C: 'a> {
@@ -12,10 +12,10 @@ pub struct ZIP<'a, C: 'a> {
 
 impl<'a, C: 'a> ZIP<'a, C> {
     /// Makes a ZIP compressing writer.
-    pub fn new<L>(inner: Stack<'a, C>, cookie: C, level: L) -> Stack<'a, C>
+    pub fn new<L>(inner: Message<'a, C>, cookie: C, level: L) -> Message<'a, C>
         where L: Into<Option<CompressionLevel>>
     {
-        Stack::from(Box::new(ZIP {
+        Message::from(Box::new(ZIP {
             inner: Generic::new_unboxed(
                 DeflateEncoder::new(inner.into(),
                                     level.into().unwrap_or_default().into()),
@@ -80,10 +80,10 @@ pub struct ZLIB<'a, C: 'a> {
 
 impl<'a, C: 'a> ZLIB<'a, C> {
     /// Makes a ZLIB compressing writer.
-    pub fn new<L>(inner: Stack<'a, C>, cookie: C, level: L) -> Stack<'a, C>
+    pub fn new<L>(inner: Message<'a, C>, cookie: C, level: L) -> Message<'a, C>
         where L: Into<Option<CompressionLevel>>
     {
-        Stack::from(Box::new(ZLIB {
+        Message::from(Box::new(ZLIB {
             inner: Generic::new_unboxed(
                 ZlibEncoder::new(inner.into(),
                                  level.into().unwrap_or_default().into()),