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🐛 Fix missing execution permission bit in execFile override

Consider an electron application that uses `execFile` to run a script
that lives within the application code base:

```coffee
child_process = require 'child_process'
child_process.execFile __dirname + '/script.sh', (error) ->
  throw error if error?
```

An application like this will fail when being packaged in an `asar` with
an following error:

```
Error: spawn EACCES
```

Electron overrides certain `fs` functions to make them work within an
`asar` package. In the case of `execFile`, the file to be executed is
extracted from the `asar` package into a temporary file and ran from
there.

The problem is that during the extraction, the original permissions of
the file are lost.

We workaround this by:

1. Extending `asar.stat` to return whether a file is executable or not,
  which is information that's already saved in the `asar` header.

2. Setting execution permissions on the extracted file if the above
  property holds true.

Fixes: #3512
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Juan Cruz Viotti
Juan Cruz Viotti committed Nov 26, 2015
1 parent bf5e9e4 commit 585ff9062cbf92ca65fcc50607e8f2b751f9d05e
Showing with 16 additions and 0 deletions.
  1. +1 −0 atom/common/api/atom_api_asar.cc
  2. +3 −0 atom/common/asar/archive.cc
  3. +1 −0 atom/common/asar/archive.h
  4. +11 −0 atom/common/lib/asar.coffee
@@ -54,6 +54,7 @@ class Archive : public mate::Wrappable {
mate::Dictionary dict(isolate, v8::Object::New(isolate));
dict.Set("size", stats.size);
dict.Set("offset", stats.offset);
dict.Set("executable", stats.executable);
dict.Set("isFile", stats.is_file);
dict.Set("isDirectory", stats.is_directory);
dict.Set("isLink", stats.is_link);
@@ -107,6 +107,9 @@ bool FillFileInfoWithNode(Archive::FileInfo* info,
return false;
info->offset += header_size;

info->executable = false;
node->GetBoolean("executable", &info->executable);

return true;
}

@@ -27,6 +27,7 @@ class Archive {
struct FileInfo {
FileInfo() : size(0), offset(0) {}
bool unpacked;
bool executable;
uint32 size;
uint64 offset;
};
@@ -1,5 +1,6 @@
asar = process.binding 'atom_common_asar'
child_process = require 'child_process'
fs = require 'fs'
path = require 'path'
util = require 'util'

@@ -83,6 +84,11 @@ overrideAPISync = (module, name, arg = 0) ->
newPath = archive.copyFileOut filePath
notFoundError asarPath, filePath unless newPath

stat = archive.stat filePath

if stat.executable
fs.chmodSync(newPath, 0o755)

arguments[arg] = newPath
old.apply this, arguments

@@ -102,6 +108,11 @@ overrideAPI = (module, name, arg = 0) ->
newPath = archive.copyFileOut filePath
return notFoundError asarPath, filePath, callback unless newPath

stat = archive.stat filePath

if stat.executable
fs.chmodSync(newPath, 0o755)

arguments[arg] = newPath
old.apply this, arguments

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