From 8bf64918e36044021b276e4aebf41aac1c76bee3 Mon Sep 17 00:00:00 2001
From: Frost Ming <mianghong@gmail.com>
Date: Fri, 20 Apr 2018 21:19:38 +0800
Subject: [PATCH 1/3] Do not destroy lock early

---
 pipenv/core.py    | 2 --
 pipenv/project.py | 8 --------
 2 files changed, 10 deletions(-)

diff --git a/pipenv/core.py b/pipenv/core.py
index 9e761ff7..d8948b4c 100644
--- a/pipenv/core.py
+++ b/pipenv/core.py
@@ -1000,8 +1000,6 @@ def do_lock(
             )
             sys.exit(1)
         cached_lockfile = project.lockfile_content
-    if write:
-        project.destroy_lockfile()
     if write:
         # Alert the user of progress.
         click.echo(
diff --git a/pipenv/project.py b/pipenv/project.py
index 70e05006..ade9cd87 100644
--- a/pipenv/project.py
+++ b/pipenv/project.py
@@ -668,14 +668,6 @@ class Project(object):
             return found_source
         raise SourceNotFound(name or url)
 
-    def destroy_lockfile(self):
-        """Deletes the lockfile."""
-        try:
-            return os.remove(self.lockfile_location)
-
-        except OSError:
-            pass
-
     def get_package_name_in_pipfile(self, package_name, dev=False):
         """Get the equivalent package name in pipfile"""
         key = 'dev-packages' if dev else 'packages'

From bd057000b2ce4a1af8466f6f9745bf3ad9d49249 Mon Sep 17 00:00:00 2001
From: Tzu-ping Chung <uranusjr@gmail.com>
Date: Fri, 27 Apr 2018 15:13:23 +0800
Subject: [PATCH 2/3] Implement utility to write to lockfile atomically

---
 pipenv/core.py  |  3 ++-
 pipenv/utils.py | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/pipenv/core.py b/pipenv/core.py
index 423176e1..f6bebbcb 100644
--- a/pipenv/core.py
+++ b/pipenv/core.py
@@ -25,6 +25,7 @@ import six
 from .cmdparse import ScriptEmptyError
 from .project import Project, SourceNotFound
 from .utils import (
+    atomic_open_for_write,
     convert_deps_from_pip,
     convert_deps_to_pip,
     is_required_version,
@@ -1165,7 +1166,7 @@ def do_lock(
             ]
     if write:
         # Write out the lockfile.
-        with open(project.lockfile_location, 'w') as f:
+        with atomic_open_for_write(project.lockfile_location) as f:
             simplejson.dump(
                 lockfile, f, indent=4, separators=(',', ': '), sort_keys=True
             )
diff --git a/pipenv/utils.py b/pipenv/utils.py
index 10e3ae75..4e7fc028 100644
--- a/pipenv/utils.py
+++ b/pipenv/utils.py
@@ -1323,3 +1323,41 @@ def split_argument(req, short=None, long_=None):
             index, more_req = remaining_line[0], ' '.join(remaining_line[1:])
             req = '{0} {1}'.format(req, more_req)
     return req, index
+
+
+@contextmanager
+def atomic_open_for_write(target, binary=False):
+    """Atomically open `target` for writing.
+
+    This is based on Lektor's `atomic_open()` utility, but simplified a lot
+    to handle only writing, and skip many multi-process/thread edge cases
+    handled by Werkzeug.
+
+    How this works:
+
+    * Create a temp file (in the same directory of the actual target), and
+      yield for surrounding code to write to it.
+    * If some thing goes wrong, try to remove the temp file. The actual target
+      is not touched whatsoever.
+    * If everything goes well, close the temp file, and replace the actual
+      target with this new file.
+    """
+    fd, tmp = tempfile.mkstemp(
+        dir=os.path.dirname(target),
+        prefix='.__atomic-write',
+    )
+    os.chmod(tmp, 0o644)
+    f = os.fdopen(fd, 'wb' if binary else 'w')
+    try:
+        yield f
+    except BaseException:
+        f.close()
+        try:
+            os.remove(tmp)
+        except OSError:
+            pass
+        raise
+    else:
+        f.close()
+        os.remove(target)       # This is needed on Windows.
+        os.rename(tmp, target)  # No os.replace() on Python 2.

From 0944eb56d84ee1060a8e8b8292f36839d761c66c Mon Sep 17 00:00:00 2001
From: Tzu-ping Chung <uranusjr@gmail.com>
Date: Fri, 27 Apr 2018 15:31:46 +0800
Subject: [PATCH 3/3] Ignore errors when removing old file

---
 pipenv/utils.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/pipenv/utils.py b/pipenv/utils.py
index 4e7fc028..2c815b6f 100644
--- a/pipenv/utils.py
+++ b/pipenv/utils.py
@@ -1359,5 +1359,8 @@ def atomic_open_for_write(target, binary=False):
         raise
     else:
         f.close()
-        os.remove(target)       # This is needed on Windows.
+        try:
+            os.remove(target)   # This is needed on Windows.
+        except OSError:
+            pass
         os.rename(tmp, target)  # No os.replace() on Python 2.