From: Mark <markjordanthom@gmail.com>
Date: Thu, 13 Jul 2023 18:23:20 +0000 (-0600)
Subject: correct peek_byte/2 bugs (#1882)
X-Git-Tag: v0.9.2~61
X-Git-Url: https://git.sagredo.dev/?a=commitdiff_plain;h=b051f391455ab10b4f3c29392a7478a0484f633c;p=scryer-prolog.git

correct peek_byte/2 bugs (#1882)
---

diff --git a/src/machine/streams.rs b/src/machine/streams.rs
index 90f927c4..c1b4678e 100644
--- a/src/machine/streams.rs
+++ b/src/machine/streams.rs
@@ -1268,12 +1268,9 @@ impl Stream {
                 }
             }
             Stream::InputFile(ref mut file) => {
-                let mut b = [0u8; 1];
-
-                match file.read(&mut b)? {
-                    1 => {
-                        file.stream.get_mut().file.seek(SeekFrom::Current(-1))?;
-                        Ok(b[0])
+                match file.peek_byte() {
+                    Some(result) => {
+                        Ok(result?)
                     }
                     _ => Err(std::io::Error::new(
                         ErrorKind::UnexpectedEof,
diff --git a/src/machine/system_calls.rs b/src/machine/system_calls.rs
index 7045eff0..ba67067d 100644
--- a/src/machine/system_calls.rs
+++ b/src/machine/system_calls.rs
@@ -2444,7 +2444,11 @@ impl Machine {
                 addr,
             );
 
-            return Ok(());
+            if !self.machine_st.fail {
+                return Ok(());
+            } else {
+                self.machine_st.fail = false;
+            }
         }
 
         let addr = match addr {
diff --git a/src/parser/char_reader.rs b/src/parser/char_reader.rs
index 32854b07..2a1db29f 100644
--- a/src/parser/char_reader.rs
+++ b/src/parser/char_reader.rs
@@ -128,6 +128,19 @@ impl<R: Read> CharReader<R> {
 
         Ok(&self.buf[self.pos..])
     }
+
+    pub fn peek_byte(&mut self) -> Option<io::Result<u8>> {
+        match self.refresh_buffer() {
+            Ok(_buf) => {}
+            Err(e) => return Some(Err(e)),
+        }
+
+        return if let Some(b) = self.buf.get(0).cloned() {
+            Some(Ok(b))
+        } else {
+            None
+        };
+    }
 }
 
 impl<R: Read> CharRead for CharReader<R> {