[Qemu-devel] [PATCH 6/6] docker: Open dockerfiles in text mode

[Eduardo Habkost]

Instead of treating dockerfile contents as byte sequences, always
open dockerfiles in text mode and treat it as text.

This is not strictly required to make the script compatible with
Python 3, but it's a simpler and safer way than opening
dockerfiles in binary mode and decoding the data data later.

To make the code compatible with both Python 2 and 3, use
io.open(), which accepts a 'encoding' argument on both versions.

Signed-off-by: Eduardo Habkost <address@hidden>
---
 tests/docker/docker.py | 46 ++++++++++++++++++++++++------------------
 1 file changed, 26 insertions(+), 20 deletions(-)

diff --git a/tests/docker/docker.py b/tests/docker/docker.py
index f58af8e894..412a031c1c 100755
--- a/tests/docker/docker.py
+++ b/tests/docker/docker.py
@@ -23,6 +23,7 @@ import argparse
 import tempfile
 import re
 import signal
+import io
 from tarfile import TarFile, TarInfo
 from io import BytesIO
 from shutil import copy, rmtree
@@ -30,7 +31,7 @@ from pwd import getpwuid
 from datetime import datetime,timedelta
 
 try:
-    from typing import List, Union, Tuple
+    from typing import List, Union, Tuple, Text
 except ImportError:
     # needed only to make type annotations work
     pass
@@ -52,13 +53,13 @@ def _fsdecode(name):
         return name # type: ignore
 
 def _text_checksum(text):
-    # type: (bytes) -> str
+    # type: (Text) -> str
     """Calculate a digest string unique to the text content"""
-    return hashlib.sha1(text).hexdigest()
+    return hashlib.sha1(text.encode('utf-8')).hexdigest()
 
 def _file_checksum(filename):
     # type: (str) -> str
-    return _text_checksum(open(filename, 'rb').read())
+    return _text_checksum(io.open(filename, 'r', encoding='utf-8').read())
 
 def _guess_docker_command():
     # type: () -> List[str]
@@ -129,14 +130,14 @@ def _copy_binary_with_libs(src, dest_dir):
             _copy_with_mkdir(l , dest_dir, so_path)
 
 def _read_qemu_dockerfile(img_name):
-    # type: (str) -> str
+    # type: (Text) -> str
     df = os.path.join(os.path.dirname(__file__), "dockerfiles",
                       img_name + ".docker")
-    return open(df, "r").read()
+    return io.open(df, "r", encoding='utf-8').read()
 
 def _dockerfile_preprocess(df):
-    # type: (str) -> str
-    out = ""
+    # type: (Text) -> Text
+    out = u""
     for l in df.splitlines():
         if len(l.strip()) == 0 or l.startswith("#"):
             continue
@@ -149,7 +150,7 @@ def _dockerfile_preprocess(df):
             inlining = _read_qemu_dockerfile(l[len(from_pref):])
             out += _dockerfile_preprocess(inlining)
             continue
-        out += l + "\n"
+        out += l + u"\n"
     return out
 
 class Docker(object):
@@ -220,32 +221,37 @@ class Docker(object):
     def build_image(self,
                     tag,                 # type: str
                     docker_dir,          # type: str
-                    dockerfile,          # type: str
+                    dockerfile,          # type: Text
                     quiet=True,          # type: bool
                     user=False,          # type: bool
                     argv=[],             # type: List[str]
                     extra_files_cksum=[] # List[Tuple[str, bytes]]
                     ):
         # type(...) -> None
-        tmp_df = tempfile.NamedTemporaryFile(dir=docker_dir, suffix=".docker")
+        tmp_ndf = tempfile.NamedTemporaryFile(dir=docker_dir, suffix=".docker")
+        # on Python 2.7, NamedTemporaryFile doesn't support encoding parameter,
+        # so reopen it in text mode:
+        tmp_df = io.open(tmp_ndf.name, mode='w+t', encoding='utf-8')
         tmp_df.write(dockerfile)
 
         if user:
             uid = os.getuid()
             uname = getpwuid(uid).pw_name
-            tmp_df.write("\n")
-            tmp_df.write("RUN id %s 2>/dev/null || useradd -u %d -U %s" %
+            tmp_df.write(u"\n")
+            tmp_df.write(u"RUN id %s 2>/dev/null || useradd -u %d -U %s" %
                          (uname, uid, uname))
 
-        tmp_df.write("\n")
-        tmp_df.write("LABEL com.qemu.dockerfile-checksum=%s" %
-                     _text_checksum(_dockerfile_preprocess(dockerfile)))
+        dockerfile = _dockerfile_preprocess(dockerfile)
+
+        tmp_df.write(u"\n")
+        tmp_df.write(u"LABEL com.qemu.dockerfile-checksum=%s" %
+                     _text_checksum(dockerfile))
         for f, c in extra_files_cksum:
-            tmp_df.write("LABEL com.qemu.%s-checksum=%s" % (f, c))
+            tmp_df.write(u"LABEL com.qemu.%s-checksum=%s" % (f, c))
 
         tmp_df.flush()
 
-        self._do_check(["build", "-t", tag, "-f", tmp_df.name] + argv + \
+        self._do_check(["build", "-t", tag, "-f", tmp_ndf.name] + argv + \
                        [docker_dir],
                        quiet=quiet)
 
@@ -326,7 +332,7 @@ class BuildCommand(SubCommand):
 
     def run(self, args, argv):
         # type: (argparse.Namespace, List[str]) -> int
-        dockerfile = open(args.dockerfile, "rb").read()
+        dockerfile = io.open(args.dockerfile, "r", encoding='utf-8').read()
         tag = args.tag
 
         dkr = Docker()
@@ -519,7 +525,7 @@ class CheckCommand(SubCommand):
                 print("Need a dockerfile for tag:%s" % (tag))
                 return 1
 
-            dockerfile = open(args.dockerfile, "rb").read()
+            dockerfile = io.open(args.dockerfile, "r", encoding='utf-8').read()
 
             if dkr.image_matches_dockerfile(tag, dockerfile):
                 if not args.quiet:
-- 
2.18.0.rc1.1.g3f1ff2140