Groovy: cloning nodes in an XML document

It’s pretty easy to clone nodes in a XML document using Groovy once XmlParser is used instead of XmlSlurper:

import groovy.xml.XmlUtil

def original = """
<catalog>
   <book id="sample">
      <author>sample</author>
      <title>sample</title>
   </book>
</catalog>
"""

def catalog = new XmlParser().parseText( original )

def sampleBook = catalog.book.find { it.@id == "sample" }

catalog.remove(sampleBook)

3.times {
  def c = sampleBook.clone()
  c.@id = "$it"
  c.author[0].value = "Author $it"
  c.title[0].value = "Title $it"

  catalog.append(c)
}

println XmlUtil.serialize(catalog)


The result is:

<?xml version="1.0" encoding="UTF-8"?><catalog>
  <book id="0">
    <author>Author 0</author>
    <title>Title 0</title>
  </book>
  <book id="1">
    <author>Author 1</author>
    <title>Title 1</title>
  </book>
  <book id="2">
    <author>Author 2</author>
    <title>Title 2</title>
  </book>
</catalog>

 

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Apache: undefined symbol: ap_proxy_location_reverse_map

If you get the following error when starting Apache:

apache2: Syntax error on line ...:
Cannot load mod_proxy_http.so into server:
mod_proxy_http.so: undefined symbol: ap_proxy_location_reverse_map

…then make sure that mod_proxy is enabled, and that it is loaded BEFORE mod_proxy_http. Apache doesn’t support dependency management of modules, so they have to be enabled in the appropriate order.

You might want to disable the modules and reenable them in the right order with a2enmod, or change the order in for instance /etc/sysconfig/apache2

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VMWare Fusion: the path “” is not valid path to the gcc binary.

A common error installing the VMWare tools in a Ubuntu guest is:

Searching for GCC...
the path "" is not valid path to the gcc binary. 
Would you like to change it? [yes]

In some cases, like when using an older version of Fusion with newer version of Ubuntu, an easy workaround is to use the opensource version of the VMWare tools provided by the distribution:

apt-get install open-vm-tools open-vm-tools-desktop
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PHP not working in Apache virtual hosts

I just had the situation where PHP worked fine from the default/main site configured in Apache, but not in a virtual host. Instead of parsing/executing the PHP script, Apache would rather send its source code back to the browser, which would propose to download it.

I found various potentials solutions online, like:

  • Checking if the PHP module was enabled (it was)
  • Setting “php_admin_flag engine” or “php_admin_value”  to “on” (it didn’t help)

What helped was to enable explicitly the PHP handlers in the Directory section of the corresponding vhosts. On OpenSUSE Leap, the file /etc/apache2/conf.d/php7.conf does exactly that, so I could just include it:

<VirtualHost ...>
        DocumentRoot /some/path
        <Directory /some/path>
                Include /etc/apache2/conf.d/php7.conf
                Options ...
                AllowOverride ...
                Require all granted
        </Directory>
</VirtualHost>
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Uploading a file with HTTP PUT in Groovy with Basic Auth

Dependencies:

dependencies {
   compile 'org.codehaus.groovy.modules.http-builder:http-builder:0.7.1'
   compile 'org.apache.httpcomponents:httpmime:4.5'
}

Code:

import groovyx.net.http.HTTPBuilder
import groovyx.net.http.Method
import org.apache.http.client.entity.EntityBuilder
import org.apache.http.util.EntityUtils


class HttpPut {
   File inputFile
   String url
   String username
   String password

   HttpPut withFile(File inputFile) {
       this.inputFile = inputFile
       return this
   }

   HttpPut withUrl(String url) {
       this.url = url
       return this
   }

   HttpPut withCredentials(String username, String password) {
       this.username  = username
       this.password = password
       return this
   }

   void put() {
       def http = new HTTPBuilder(url)

       http.auth.basic(username, password)

       http.request(Method.PUT) { request ->
           request.entity = EntityBuilder.create().setBinary(inputFile.bytes).build()
       }
   }
} 

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Gerrit: robust regular expression to create links from text automatically (commentlink)

When there is a link to a bug tracking ticket in a commit message, and Gerrit is already be configured to make automatically links out of ticket numbers, it results in a mess. There is a bug report about this since quite a while already, but no progress yet.

A workaround is to use a lookbehind regular expression, to ignore ticket numbers that are followed by a double quote or

</a>

, because they are most likely part of a generated URL.

[commentlink "bugtracking"]
       match = \\b([A-Z]+-\\d+)(?!(\"|<\\/a>))
       link = https://bugtracker/tickets/$1

If you need to troubleshoot this kind of issue: it is very cumbersome to test the regex directly in Gerrit, because you have to modify the config file, stop Gerrit, flush the caches and restart it. Since the regex syntax is the onf of Javascript, you can use a tool like https://regex101.com. Just enter as test string a set of lines you want to match, another set that you don’t want to match, enable the “g” option, and experiment with the regular expression until it works as expected. Then you need only to escape the \ and the ” and put it in the Gerrit config file.

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Notepad++: automatic configuration of tabs vs. spaces

Notepad++ is a great text editor with lots of features out of the box, but I miss particularly one: the ability to use automatically tabs or spaces for indentation according to the content of an existing file when opening it.

Luckily enough, it’s easy to add this feature using the Python scripting plugin.

  • Install the Python scripting add on for Notepad++ with the plugin manager
  • Open C:\Program Files (x86)\Notepad++\plugins\PythonScript\scripts\startup.py
  • Append the code below at the bottom of the file
  • Save the file
  • Open Notepad++
  • Choose Plugins -> Python Script -> Configuration
  • Ensure Initialisation is set to ATSTARTUP and save
  • Restart Notepad++
from Npp import *

def indent_auto_detect(arg):
    for i in range(editor.getLineCount()):
        pos = editor.positionFromLine(i)
        indent = editor.getLineIndentPosition(i)-pos
        if indent > 0:
            if ord('\t') == editor.getCharAt(pos):
                console.write("Indentation: Tabs\n")
                editor.setUseTabs(True)
                return
            elif indent in [2, 3, 4, 8]:
                console.write("Indentation: %d spaces\n" % indent)
                editor.setUseTabs(False)
                editor.setIndent(indent)
                return

notepad.clearCallbacks([NOTIFICATION.BUFFERACTIVATED, NOTIFICATION.READY])
notepad.callback(indent_auto_detect, [NOTIFICATION.BUFFERACTIVATED])
notepad.callback(indent_auto_detect, [NOTIFICATION.READY])
console.write("Automatic indentation detection started\n")
indent_auto_detect(None)

The code comes from: https://gist.github.com/patstew/8dc8a4c0b816e2f33204e3e15cd5497e

Posted in Uncategorized | 1 Comment

Configuring Apache to serve multiple domains with a single SSL certificate

Here are some notes on how to configure Apache to server multiple domains with a single SSL certificate. If using a single certificate is not an option, you will have to use SNI, which is not covered in this howto.

# Create root CA
openssl genrsa -out rootCA.key 2048
 
# Self sign the CA cert
openssl req -x509 -new -nodes -key rootCA.key -sha256 -days 1024 -out rootCA.pem

Create the configuration file of the certificate request for all domains (multi.conf):

[req]
distinguished_name = req_distinguished_name
req_extensions = v3_req
prompt = no
 
[req_distinguished_name]
countryName = XY
stateOrProvinceName = XY
localityName = City
organizationName = My organization
organizationalUnitName = My unit
commonName = alias1.domain.com
 
[ v3_req ]
basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment
subjectAltName = @alt_names
 
[alt_names]
DNS.1 = alias1.domain.com
DNS.2 = alias2.domain.com

Be aware that the semantic of the fields in the configuration file changes depending on the value of “prompt”. With “prompt = no”, countryName is the value for the country. Without “prompt”, it set the label that will be displayed when the user is prompted, and a default value can be provided in “countryName_default”. Very confusing…

One of the aliases has to be specified as commonName and again as alternate name, because in some cases only alternate names will be considered.

Now you can create the server key and the corresponding certificate:

openssl genrsa -out multi.key 2048
openssl req -new -out multi.csr -key multi.key -config multi.conf
openssl x509 -req -in multi.csr -CA rootCA.pem -CAkey rootCA.key -CAcreateserial -out multi.crt -days 500 -sha256 -extensions v3_req -extfile multi.conf

Note: the multi.conf file has to be used twice, once to create the request (2nd line), and again to create the certificate (3rd line).

And finally, use it in Apache:

NameVirtualHost *:443
 
SSLCertificateFile /root/ca/multi.crt
SSLCertificateKeyFile /root/ca/multi.key
 
 
<VirtualHost *:443>
    ServerName alias1.domain.com
    ...
</VirtualHost>

<VirtualHost *:443>
    ServerName alias2.domain.com
    ...
</VirtualHost>

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Msys2/pacman: list dependencies with versions

Here is a one-liner to list all the dependencies for an Msys2 package, or for any pacman based system for that matter:

$ pactree -u mingw-w64-x86_64-gcc | xargs -r pacman -Si | gawk '/^Name *:/ {name=$3} /^Version *:/ {version=$3; printf "%s-%s\n",name,version}'
mingw-w64-x86_64-gcc-7.2.0-1
mingw-w64-x86_64-binutils-2.29.1-1
mingw-w64-x86_64-libiconv-1.15-1
mingw-w64-x86_64-zlib-1.2.11-1
mingw-w64-x86_64-bzip2-1.0.6-6
mingw-w64-x86_64-gcc-libs-7.2.0-1
mingw-w64-x86_64-gmp-6.1.2-1
mingw-w64-x86_64-mpc-1.0.3-2
mingw-w64-x86_64-mpfr-3.1.6-1
mingw-w64-x86_64-libwinpthread-git-5.0.0.4850.d1662dc7-1
mingw-w64-x86_64-crt-git-5.0.0.5002.34a7c1c0-1
mingw-w64-x86_64-headers-git-5.0.0.5002.34a7c1c0-1
mingw-w64-x86_64-isl-0.18-1
mingw-w64-x86_64-windows-default-manifest-6.4-3
mingw-w64-x86_64-winpthreads-git-5.0.0.4850.d1662dc7-1

Note: on my system, it works only for installed packages, even using the “-s” option:

$ pacman -Si mingw-w64-i686-qtwebkit
Repository      : mingw32
Name            : mingw-w64-i686-qtwebkit
...

$ pactree -s mingw-w64-i686-qtwebkit
error: package 'mingw-w64-i686-qtwebkit' not found

I don’t know why.

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Getting BLN to work with CyanogenMod / LineageOS

“Backlight Notification” is a great feature of some Android Linux kernels, that allows to use the backlight of the “Menu” and “Back” buttons to signal pending notifications for phones that don’t have a dedicated notification LED.

There is an app called BLN control in the play store from the developer “neldar”, that allows to control this feature. However, if you try to use it on a recent version of CyanogenMod or LineageOS, it will report “This kernel does not support BLN”. This may not be true, the kernel might support it, like in many recent custom ROMs, but the app cannot configure it due to the SELinux (Security-Enhanced Linux). It’s a module that increases the security of Android, but prevents BLN control to work.

One option (that I do not recommend) is to disable SELinux by settings its mode to permissive (“setenforce permissive” as root).

A better option, that doesn’t compromise the security of the phone, is to enable BLN at each boot. For that, enable “adb” in the developer options of the phone, also enable “root” access for adb, then connect to the phone with ADB:

Computer$ adb shell
Phone$ su -
Phone# cat > /data/local/userinit.sh
echo 1 > /sys/devices/virtual/misc/backlightnotification/enabled
[Press CTRL-D]
Phone#

Now reboot the phone, and call or text your phone. The “menu” and “back” buttons should glow until you dismiss the notifications.

Don’t forget to disable the root access and adb in the developer options!

And if the directory “/sys/devices/virtual/misc/backlightnotification” is missing, then the kernel really doesn’t support BLN, sorry for you.

Please let me know in the comments if this worked for you (or not).

Posted in Android | 9 Comments