From f64c813de84011a84ca21d75a294861a9cc2dfdc Mon Sep 17 00:00:00 2001
From: tzickel <tzickel@users.noreply.github.com>
Date: Mon, 10 Sep 2018 21:46:14 +0300
Subject: [PATCH] bpo-25083: Python can sometimes create incorrect .pyc files
 (GH-8449)

Python 2 never checked for I/O error when reading .py files and
thus could mistake an I/O error for EOF and create incorrect .pyc
files.
This adds an check for this and aborts on an error.
---
 Include/errcode.h                                            | 1 +
 .../2018-07-25-22-47-19.bpo-25083.HT_hXh.rst                 | 2 ++
 Parser/tokenizer.c                                           | 5 +++++
 Python/pythonrun.c                                           | 3 +++
 4 files changed, 11 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2018-07-25-22-47-19.bpo-25083.HT_hXh.rst

diff --git a/Include/errcode.h b/Include/errcode.h
index becec80c8ac..5c5a0f7fa34 100644
--- a/Include/errcode.h
+++ b/Include/errcode.h
@@ -29,6 +29,7 @@ extern "C" {
 #define E_EOFS		23	/* EOF in triple-quoted string */
 #define E_EOLS		24	/* EOL in single-quoted string */
 #define E_LINECONT	25	/* Unexpected characters after a line continuation */
+#define E_IO    	26	/* I/O error */
 
 #ifdef __cplusplus
 }
diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-07-25-22-47-19.bpo-25083.HT_hXh.rst b/Misc/NEWS.d/next/Core and Builtins/2018-07-25-22-47-19.bpo-25083.HT_hXh.rst
new file mode 100644
index 00000000000..0dc44c43b38
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2018-07-25-22-47-19.bpo-25083.HT_hXh.rst	
@@ -0,0 +1,2 @@
+Adding I/O error checking when reading .py files and aborting importing on
+error.
diff --git a/Parser/tokenizer.c b/Parser/tokenizer.c
index 61bfb4e1b7a..c6e61df533e 100644
--- a/Parser/tokenizer.c
+++ b/Parser/tokenizer.c
@@ -1681,6 +1681,11 @@ int
 PyTokenizer_Get(struct tok_state *tok, char **p_start, char **p_end)
 {
     int result = tok_get(tok, p_start, p_end);
+    if (tok->fp && ferror(tok->fp)) {
+        clearerr(tok->fp);
+        result = ERRORTOKEN;
+        tok->done = E_IO;
+    }
     if (tok->decoding_erred) {
         result = ERRORTOKEN;
         tok->done = E_DECODE;
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index 5707c9f5245..2c9f55fbd1d 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -1654,6 +1654,9 @@ err_input(perrdetail *err)
         Py_XDECREF(tb);
         break;
     }
+    case E_IO:
+        msg = "I/O error while reading";
+        break;
     case E_LINECONT:
         msg = "unexpected character after line continuation character";
         break;