Show error message if config file is not readable

[MorrisJobke]

• when the config file is not writable there is a error message shown
• same happens now if the config file is not readable
• fixes white screen if webserver has no read access to config.php #180

cc @adsworth @Mar1u5 @williambargent @LukasReschke @schiessle

[MorrisJobke]

@adsworth the stable9 patch looks like this (because of some refactoring this patch doesn't apply to stable9)

diff --git a/lib/private/config.php b/lib/private/config.php
index 368dafd..2a21cd6 100644
--- a/lib/private/config.php
+++ b/lib/private/config.php
@@ -184,10 +184,11 @@ class Config {

        // Include file and merge config
        foreach ($configFiles as $file) {
-           $filePointer = file_exists($file) ? fopen($file, 'r') : false;
+           $fileExistsAndIsReadable = file_exists($file) && is_readable($file);
+           $filePointer = $fileExistsAndIsReadable ? fopen($file, 'r') : false;
            if($file === $this->configFilePath &&
-               $filePointer === false &&
-               @!file_exists($this->configFilePath)) {
+               $filePointer === false) {
                // Opening the main config might not be possible, e.g. if the wrong
                // permissions are set (likely on a new installation)
                continue;

[schiessle]

seems to be redundant, if $fileExistsAndIsReadable is false, then $filePointer is already false, see https://github.com/nextcloud/server/pull/185/files#diff-e8ccb791da0aa95230141afcf200336dR188

Btw, the old check didn't checked if the config file exists but if the "configFilePath" exists. Don't know in which cases this makes a difference.

[MorrisJobke]

Btw, the old check didn't checked if the config file exists but if the "configFilePath" exists.

$file === $this->configFilePath ;)

[MorrisJobke]

I tested your proposal and also thought about it and you are correct :) I fixed it

[schiessle]

Btw, the old check didn't checked if the config file exists but if the "configFilePath" exists.

$file === $this->configFilePath ;)

This just check if $file equals $this->configFilePath.

The old check evaluated the if-statement to false if $this->configFilePath exists but fopen() returned false. The new check would evaluate the if-statement to true.

But I believe that this is just a theoretical difference. I don't see how this should make a difference and also tested it.

[LukasReschke]

LGTM

[schiessle]

tested, LGTM