openpgp: Improve PacketParserResult::as_ref, as_mut, and map.

  - Previously, these method withheld information in the EOF case (and
    in case of `map` this loss is irrecoverable).  Fix this by
    returning a Result instead.

5 files changed, 22 insertions, 21 deletions

diff --git a/autocrypt/src/lib.rs b/autocrypt/src/lib.rs
index 06dbd696..b42e3153 100644
--- a/autocrypt/src/lib.rs
+++ b/autocrypt/src/lib.rs
@@ -686,7 +686,7 @@ impl<'a> AutocryptSetupMessageParser<'a> {
 
         // Recurse into the SEIP packet.
         let mut ppr = self.pp.recurse()?.1;
-        if ppr.as_ref().map(|pp| pp.recursion_depth()) != Some(1) {
+        if ppr.as_ref().map(|pp| pp.recursion_depth()).ok() != Some(1) {
             return Err(
                 Error::MalformedMessage(
                     "SEIP container empty, but expected a Literal Data packet"
diff --git a/openpgp/src/packet_pile.rs b/openpgp/src/packet_pile.rs
index bb505a96..07ca3561 100644
--- a/openpgp/src/packet_pile.rs
+++ b/openpgp/src/packet_pile.rs
@@ -760,7 +760,7 @@ mod test {
             .buffer_unread_content()
             .try_into().unwrap();
 
-        while let Some(pp) = ppp.as_ref() {
+        while let Ok(pp) = ppp.as_ref() {
             eprintln!("{:?}", pp);
             ppp.recurse().unwrap();
         }
diff --git a/openpgp/src/parse.rs b/openpgp/src/parse.rs
index 16c7ec6e..f36f634c 100644
--- a/openpgp/src/parse.rs
+++ b/openpgp/src/parse.rs
@@ -175,6 +175,7 @@ use std::str;
 use std::mem;
 use std::fmt;
 use std::path::Path;
+use std::result::Result as StdResult;
 
 use ::buffered_reader::*;
 
@@ -3315,20 +3316,20 @@ impl<'a> PacketParserResult<'a> {
     }
 
     /// Like `Option::as_ref`().
-    pub fn as_ref(&self) -> Option<&PacketParser<'a>> {
-        if let PacketParserResult::Some(ref pp) = self {
-            Some(pp)
-        } else {
-            None
+    pub fn as_ref(&self)
+                  -> StdResult<&PacketParser<'a>, &PacketParserEOF> {
+        match self {
+            PacketParserResult::Some(pp) => Ok(pp),
+            PacketParserResult::EOF(eof) => Err(eof),
         }
     }
 
     /// Like `Option::as_mut`().
-    pub fn as_mut(&mut self) -> Option<&mut PacketParser<'a>> {
-        if let PacketParserResult::Some(ref mut pp) = self {
-            Some(pp)
-        } else {
-            None
+    pub fn as_mut(&mut self)
+                  -> StdResult<&mut PacketParser<'a>, &mut PacketParserEOF> {
+        match self {
+            PacketParserResult::Some(pp) => Ok(pp),
+            PacketParserResult::EOF(eof) => Err(eof),
         }
     }
 
@@ -3345,12 +3346,12 @@ impl<'a> PacketParserResult<'a> {
     }
 
     /// Like `Option::map`().
-    pub fn map<U, F>(self, f: F) -> Option<U>
+    pub fn map<U, F>(self, f: F) -> StdResult<U, PacketParserEOF>
         where F: FnOnce(PacketParser<'a>) -> U
     {
         match self {
-            PacketParserResult::Some(x) => Some(f(x)),
-            PacketParserResult::EOF(_) => None,
+            PacketParserResult::Some(x) => Ok(f(x)),
+            PacketParserResult::EOF(e) => Err(e),
         }
     }
 }
diff --git a/openpgp/src/parse/packet_pile_parser.rs b/openpgp/src/parse/packet_pile_parser.rs
index 2540026a..78483b82 100644
--- a/openpgp/src/parse/packet_pile_parser.rs
+++ b/openpgp/src/parse/packet_pile_parser.rs
@@ -54,7 +54,7 @@ use buffered_reader::BufferedReader;
 /// #    include_bytes!("../../tests/data/keys/public-key.gpg");
 /// # let mut n = 0;
 /// let mut ppp = PacketPileParser::from_bytes(message_data)?;
-/// while let Some(pp) = ppp.as_ref() {
+/// while let Ok(pp) = ppp.as_ref() {
 ///     eprintln!("{:?}", pp);
 ///     ppp.recurse()?;
 /// #   n += 1;
@@ -198,7 +198,7 @@ impl<'a> PacketPileParser<'a> {
     /// let message_data: &[u8] = // ...
     /// #    include_bytes!("../../tests/data/messages/compressed-data-algo-0.pgp");
     /// let mut ppp = PacketPileParser::from_bytes(message_data)?;
-    /// while let Some(pp) = ppp.as_ref() {
+    /// while let Ok(pp) = ppp.as_ref() {
     ///     // Do something interesting with `pp` here.
     ///
     ///     // Start parsing the next packet, recursing.
@@ -251,7 +251,7 @@ impl<'a> PacketPileParser<'a> {
     /// let message_data: &[u8] = // ...
     /// #    include_bytes!("../../tests/data/messages/compressed-data-algo-0.pgp");
     /// let mut ppp = PacketPileParser::from_bytes(message_data)?;
-    /// while let Some(pp) = ppp.as_ref() {
+    /// while let Ok(pp) = ppp.as_ref() {
     ///     // Do something interesting with `pp` here.
     ///
     ///     // Start parsing the next packet.
@@ -296,7 +296,7 @@ impl<'a> PacketPileParser<'a> {
     /// let message_data: &[u8] = // ...
     /// #    include_bytes!("../../tests/data/messages/compressed-data-algo-0.pgp");
     /// let mut ppp = PacketPileParser::from_bytes(message_data)?;
-    /// while let Some(pp) = ppp.as_ref() {
+    /// while let Ok(pp) = ppp.as_ref() {
     ///     match pp.packet {
     ///         Packet::CompressedData(_) =>
     ///             assert_eq!(ppp.recursion_depth(), Some(0)),
@@ -424,7 +424,7 @@ fn message_parser_reader_interface() {
     let mut ppp = PacketPileParser::from_bytes(
         crate::tests::message("compressed-data-algo-1.gpg")).unwrap();
     let mut count = 0;
-    while let Some(pp) = ppp.as_mut() {
+    while let Ok(pp) = ppp.as_mut() {
         if let Packet::Literal(_) = pp.packet {
             assert_eq!(count, 1); // The *second* packet.
 
diff --git a/tool/src/commands/mod.rs b/tool/src/commands/mod.rs
index 32239d8d..04e84987 100644
--- a/tool/src/commands/mod.rs
+++ b/tool/src/commands/mod.rs
@@ -428,7 +428,7 @@ pub fn split(input: &mut dyn io::Read, prefix: &str)
 
         let old_depth = Some(pp.recursion_depth());
         ppr = pp.recurse()?.1;
-        let new_depth = ppr.as_ref().map(|pp| pp.recursion_depth());
+        let new_depth = ppr.as_ref().map(|pp| pp.recursion_depth()).ok();
 
         // Update pos.
         match old_depth.cmp(&new_depth) {