From 97283416266861534b488c4aced3f5c11aa987ac Mon Sep 17 00:00:00 2001
From: Juan Cruz Viotti <jv@jviotti.com>
Date: Sun, 2 Dec 2018 12:10:42 +0000
Subject: [PATCH] Retry on EPERM when locking and reading

See: https://github.com/electron-userland/electron-json-storage/issues/116
Signed-off-by: Juan Cruz Viotti <jv@jviotti.com>
---
 lib/lock.js    | 17 ++++++++++++++---
 lib/storage.js | 39 ++++++++++++++++++++++++++-------------
 2 files changed, 40 insertions(+), 16 deletions(-)

diff --git a/lib/lock.js b/lib/lock.js
index a38a84a..7f9724e 100644
--- a/lib/lock.js
+++ b/lib/lock.js
@@ -33,7 +33,7 @@ const lockFile = require('lockfile');
  */
 const lockOptions = {
   stale: 10000,
-  retries: Infinity,
+  retries: 1000,
   retryWait: 50
 };
 
@@ -52,8 +52,19 @@ const lockOptions = {
  *   }
  * })
  */
-exports.lock = function(file, callback) {
-  lockFile.lock(file, lockOptions, callback);
+exports.lock = function(file, callback, times) {
+  times = times || 0;
+
+  lockFile.lock(file, lockOptions, function(error) {
+    if (error && error.code === 'EPERM' && times < 10) {
+      setTimeout(function() {
+        exports.unlock(file, callback, times + 1);
+      }, 1000);
+      return;
+    }
+
+    return callback(error);
+  });
 };
 
 /**
diff --git a/lib/storage.js b/lib/storage.js
index 8828cd0..ee7f5f6 100644
--- a/lib/storage.js
+++ b/lib/storage.js
@@ -37,6 +37,31 @@ const path = require('path');
 const utils = require('./utils');
 const lock = require('./lock');
 
+const readFile = function(fileName, callback, times) {
+  times = times || 0;
+
+  fs.readFile(fileName, {
+    encoding: 'utf8'
+  }, function(error, object) {
+    if (!error) {
+      return callback(null, object);
+    }
+
+    if (error.code === 'ENOENT') {
+      return callback(null, JSON.stringify({}));
+    }
+
+    if (error.code === 'EPERM' && times < 10) {
+      setTimeout(function() {
+        readFile(fileName, callback, times + 1);
+      }, 1000);
+      return;
+    }
+
+    return callback(error);
+  });
+};
+
 /**
  * @summary Get the default data path
  * @function
@@ -141,19 +166,7 @@ exports.get = function(key, options, callback) {
       });
     },
     function(callback) {
-      fs.readFile(fileName, {
-        encoding: 'utf8'
-      }, function(error, object) {
-        if (!error) {
-          return callback(null, object);
-        }
-
-        if (error.code === 'ENOENT') {
-          return callback(null, JSON.stringify({}));
-        }
-
-        return callback(error);
-      });
+      readFile(fileName, callback);
     },
     function(object, callback) {
       var objectJSON = {};