From fdc10e4e5f5abfcfdcda903ca7bd2668debe25d7 Mon Sep 17 00:00:00 2001
From: deepak1556 <hop2deep@gmail.com>
Date: Wed, 18 Mar 2015 22:16:37 +0530
Subject: [PATCH] Allow reading empty file from asar archive

---
 atom/common/lib/asar.coffee   |  42 ++++++++++++++++++++++------------
 spec/asar-spec.coffee         |  13 +++++++++++
 spec/fixtures/asar/empty.asar | Bin 0 -> 60 bytes
 3 files changed, 40 insertions(+), 15 deletions(-)
 create mode 100644 spec/fixtures/asar/empty.asar

diff --git a/atom/common/lib/asar.coffee b/atom/common/lib/asar.coffee
index 38ac2fc3b727..1b3326e8d7d2 100644
--- a/atom/common/lib/asar.coffee
+++ b/atom/common/lib/asar.coffee
@@ -3,6 +3,8 @@ child_process = require 'child_process'
 path = require 'path'
 util = require 'util'
 
+kEmptyBufferLength = 0
+
 # Cache asar archive objects.
 cachedArchives = {}
 getOrCreateArchive = (p) ->
@@ -228,12 +230,17 @@ exports.wrapFsWithAsar = (fs) ->
     flag = options.flag || 'r'
     encoding = options.encoding
 
-    buffer = new Buffer(info.size)
-    open archive.path, flag, (error, fd) ->
-      return callback error if error
-      fs.read fd, buffer, 0, info.size, info.offset, (error) ->
-        fs.close fd, ->
-          callback error, if encoding then buffer.toString encoding else buffer
+    bufferLength = info.size || kEmptyBufferLength
+    buffer = new Buffer(bufferLength)
+
+    if info.size
+      open archive.path, flag, (error, fd) ->
+        return callback error if error
+        fs.read fd, buffer, 0, info.size, info.offset, (error, bytesRead, buf) ->
+          fs.close fd, ->
+            callback error, if encoding then buf.toString encoding, 0 ,bytesRead else buf
+    else
+      callback null, buffer
 
   openSync = fs.openSync
   readFileSync = fs.readFileSync
@@ -257,15 +264,20 @@ exports.wrapFsWithAsar = (fs) ->
     flag = options.flag || 'r'
     encoding = options.encoding
 
-    buffer = new Buffer(info.size)
-    fd = openSync archive.path, flag
-    try
-      fs.readSync fd, buffer, 0, info.size, info.offset
-    catch e
-      throw e
-    finally
-      fs.closeSync fd
-    if encoding then buffer.toString encoding else buffer
+    bufferLength = info.size || kEmptyBufferLength
+    buffer = new Buffer(bufferLength)
+
+    if info.size
+      fd = openSync archive.path, flag
+      try
+        bytesRead = fs.readSync fd, buffer, 0, info.size, info.offset
+      catch e
+        throw e
+      finally
+        fs.closeSync fd
+      if encoding then buffer.toString encoding, 0, bytesRead else buffer
+    else
+      buffer
 
   readdir = fs.readdir
   fs.readdir = (p, callback) ->
diff --git a/spec/asar-spec.coffee b/spec/asar-spec.coffee
index 222faf9a5e2e..624461245b2b 100644
--- a/spec/asar-spec.coffee
+++ b/spec/asar-spec.coffee
@@ -15,6 +15,12 @@ describe 'asar package', ->
         file3 = path.join fixtures, 'asar', 'a.asar', 'file3'
         assert.equal fs.readFileSync(file3).toString(), 'file3\n'
 
+      it 'reads from a empty file', ->
+        file = path.join fixtures, 'asar', 'empty.asar', 'file1'
+        buffer = fs.readFileSync(file)
+        assert.equal buffer.length, 0
+        assert.equal buffer.toString(), ''
+
       it 'reads a linked file', ->
         p = path.join fixtures, 'asar', 'a.asar', 'link1'
         assert.equal fs.readFileSync(p).toString(), 'file1\n'
@@ -38,6 +44,13 @@ describe 'asar package', ->
           assert.equal String(content), 'file1\n'
           done()
 
+      it 'reads from a empty file', (done) ->
+        p = path.join fixtures, 'asar', 'empty.asar', 'file1'
+        fs.readFile p, (err, content) ->
+          assert.equal err, null
+          assert.equal String(content), ''
+          done()
+
       it 'reads a linked file', (done) ->
         p = path.join fixtures, 'asar', 'a.asar', 'link1'
         fs.readFile p, (err, content) ->
diff --git a/spec/fixtures/asar/empty.asar b/spec/fixtures/asar/empty.asar
new file mode 100644
index 0000000000000000000000000000000000000000..10cddfb67654e9b2bc455529148a04045060ec50
GIT binary patch
literal 60
zcmZQ!U|=u-Vgn%72I6X^w9K5;VkIjG!w|$M&a6sRvNF(7%1=uxPAyTgQZi7gt*vDM
E0ATbEY5)KL

literal 0
HcmV?d00001