merged branch mrbase/patch-1 (PR #172)

This PR was squashed before being merged into the master branch (closes #172).

Commits
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7a6dfff use getenv before sys_get_temp_dir to allow more flexibility

Discussion
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use getenv before sys_get_temp_dir to allow more flexibility

Using environment settings over system settings enables us to use different tmp dirs pr. virtual host

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by fabpot at 2012-03-22T12:26:32Z

`sys_get_temp_dir()` actually uses the value of the `TMPDIR` environment variable on *nix systems. So, you can already override this value by setting `TMPDIR`. I have added a note about this possibility in the code (see 52d0b22).

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by mrbase at 2012-03-22T12:33:11Z

True, but setting this in a virtualhost will not work, it needs to be set as a "real" env variable to be read.
Doing this would make things work in a shared host env as well.

``` apache
<VirtualHost>
  SetEnv TMPDIR /var/www/..../tmp
</VirtualHost>
```

``` php
echo sys_get_temp_dir();
```
Will not output "/var/www/..../tmp" but "/tmp"

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by fabpot at 2012-03-22T12:51:57Z

understood now. In this case, we just need to add a call to `getenv` for TMPDIR.

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by Exeu at 2012-10-12T14:45:28Z

Why this is not merged?
Currently we are running into the same issue which causes an open base dir restriction.

lib/preferences.php

@@ -12,9 +12,12 @@
 // Without these lines the default caching mechanism is "array" but this uses a lot of memory.
 // If possible, use a disk cache to enable attaching large attachments etc.
 // You can override the default temporary directory by setting the TMPDIR environment variable.
-if (function_exists('sys_get_temp_dir') && is_writable(sys_get_temp_dir())) {
+
+$tmp = getenv('TMPDIR') ? getenv('TMPDIR') : (function_exists('sys_get_temp_dir') ? sys_get_temp_dir() : false);
+
+if ($tmp && is_writable($tmp)) {
     Swift_Preferences::getInstance()
-        -> setTempDir(sys_get_temp_dir())
+        -> setTempDir($tmp)
         -> setCacheType('disk');
 }