Geoff Garside

Checking git staged files for tabs before committing

2010-01-10T19:42:00+00:00

I recently cocked up a bunch of files in a project I'm working on because I'd inadvertently changed the language indentation from Soft Tabs to Tabs in TextMate. When I finally noticed this I was a might bit annoyed, not least because I'd have to change all the files and thereby nuke half of the git blame history. The first step of this was to find the files with the tab characters in them, a quick google revealed this

$ TAB=$(printf "\t")
$ grep -Hnr "$TAB" *

which helped me solve the initial problem. I then decided I'd write a rake task for my project so I can check for tab indented files in the future more easily. I aimed to make this Ruby 1.8 and Ruby 1.9 friendly and came up with the following function

 1 def check_for_tabs_in(srcfile)
 2   line_number = 0
 3   File.readlines(srcfile).each do |line|
 4     line_number += 1
 5     if line.index("\t")
 6       found << "#{srcfile}:#{line_number}\t#{line}"
 7     end
 8   end
 9 end
10 
11 namespace :check_tabs do
12   task :all => [:source, :tests]
13   task :source do
14     Dir.glob("Source/**/*.[hm]").each do |srcfile|
15      check_for_tabs_in srcfile
16     end
17   end
18   task :tests do
19     Dir.glob("Test/Units/*.[hm]").each do |srcfile|
20       check_for_tabs_in srcfile
21     end
22   end
23 end

which left me feeling quite happy, then it struck me. What if git could warn me if I was about to commit files with tabs and let me know what files were affected so I could go and fix them. Well, the code was already there above, but I hardly wanted a git hook to call my rake file, so I rolled the function straight into the hook file. Then to make the error output look better I cached the list of found lines and printed the at the end of the message, the result is this lovely life saving snippet of code.

 1 #!/usr/bin/env ruby
 2 
 3 found = []
 4 `git diff --cached --name-only`.split("\n").each do |srcfile|
 5   line_number = 0
 6   File.readlines(srcfile).each do |line|
 7     line_number += 1
 8     if line.index("\t")
 9       found << "#{srcfile}:#{line_number}\t#{line}"
10     end
11   end
12 end
13 
14 unless found.empty?
15   puts "Error: Attempt to add file with tab indentation"
16   puts ""
17   puts "This project uses spaces rather than tabs for indendation,"
18   puts "please fix the lines of the following files and then re-add"
19   puts "the files to the index and re-commit.\n\n"
20   puts found.join("\n")
21   exit 1
22 end
23 
24 exit 0

feel free to use it yourself.

Running Stompserver with Daemontools

2009-10-23T08:57:00+01:00

I've been messing around with chef recently and needed to setup a stompserver for the chef indexer. As I normally have daemontools installed on my servers anyway I thought I'd have a go at running stompserver under daemontools rather than runit.

My instructions will deviate a little from the prescribed daemontools configuration. I'm running FreeBSD and using the sysutils/daemontools port which runs out of /var/service rather than /service. This should be the only difference between my instructions and those for a Linux based operating system.

I'm assuming you've already got daemontools installed and that its running.

Installing Stompserver

Stompserver is a RubyGem which requires Ruby and RubyGems to be installed. On FreeBSD the following commands will install Ruby and RubyGems

cd /usr/ports/lang/ruby18
make install clean
cd /usr/ports/devel/ruby-gems
make install clean

or if you've got portupgrade installed then you'll already have lang/ruby18 so we just need the gems

portinstall devel/ruby-gems

Now that we've got Ruby and RubyGems we can install stompserver with

gem install stompserver --no-ri --no-rdoc

I've added the --no-ri --no-rdoc as I'm going to be running this on a server and don't want the docs as well.

Creating the Stompserver directory

To begin with we need a place to keep all the run, env, log files and directories which daemontools will use to run the server. I've opted for /usr/local/etc/stompserver and a working directory of /var/db/stompserver

mkdir -p /usr/local/etc/stompserver
cd /usr/local/etc/stompserver
mkdir -p env log/main
mkdir /var/db/stompserver

Creating a user for the stompserver

This is short and sweet really, but we'll chown the folders as well

pw useradd stompserver -d /nonexistent -s /sbin/nologin
chown -R stompserver:stompserver log/main
chown -R stompserver:stompserver /var/db/stompserver

The `run` scripts

Starting off with the multilog run file

cat < EOF > log/run
#!/bin/sh
exec setuidgid stompserver \
multilog \
    t \
    ${MAXFILESIZE+"s$MAXFILESIZE"} \
    ${MAXLOGFILES+"n$MAXLOGFILES"} \
    ${PROCESSOR+"!$PROCESSOR"} \
    ./main
EOF
chmod 755 log/run

now for the stompserver run file. First lets set some env variables we'll use in the run file

echo localhost > env/HOST
echo 61613 > env/PORT
echo memory > env/QUEUETYPE
echo 0 > env/SECONDS
echo /var/db/stompserver > env/WORKING_DIR

and now the run file

cat < EOF > run
exec 2>&1
envdir ./env \
sh -c '
    exec \
    setuidgid stompserver \
    /usr/local/bin/stompserver \
        ${PORT+"-p$PORT"} ${HOST+"-b$HOST"} \
        ${QUEUETYPE+"-q$QUEUETYPE"} \
        ${WORKING_DIR+"-w$WORKING_DIR"} \
        ${DEBUG+"-d"} \
        ${AUTH+"-a"} \
        ${SECONDS+"-c$SECONDS"}
'
EOF
chmod 755 run

its worth noting that if you set either env/DEBUG or env/AUTH then debug or auth flags will be set when the stompserver is run.

Starting the Stompserver

Now it is only required to link the stompserver directory into the daemontools service directory

ln -s /usr/local/etc/stompserver /var/service

you can check that its working with

svstat /var/service/stompserver
ps aux | grep stompserver

Handling arguments with execve

2009-09-13T11:53:00+01:00

As I mentioned in my previous post I've been working on a project at work which required me to be managing shell commands from a C program. The solution I documented worked fine so long as you knew all of the arguments at compile time. Another popular requirement would be to generate a command string and have this passed to the external program. Unfortunately this adds some complications.

Here is the main executing body of our program from last time.

 1 pid_t pid;
 2 int status;
 3 char *envp[] = { NULL };
 4 char *argv[] = { "./test_args", "hello", "there", NULL };
 5 
 6 switch ( pid = fork() ) {
 7   case -1:
 8     perror("fork()");
 9     exit(EXIT_FAILURE);
10   case 0: // in the child
11     status = execve("./test_args", argv, envp);
12     exit(status); // only happens if execve(2) fails
13   default: // in parent
14     if ( waitpid(pid, &status, 0) < 0 ) {
15       perror("waitpid()");
16       exit(EXIT_FAILURE);
17     }
18 
19     if ( WIFEXITED(status) ) {
20       // return status from child, ie ./test_args
21       exit( WEXITSTATUS(status) );
22     }
23     exit(EXIT_FAILURE);
24 }

So say we wanted to throw "hello there world" as arguments to test_args. We could changes line 4 to read

char *argv[] = { "./test_args", "hello there world", NULL };

and I would forgive you for thinking that test args would get 4 arguments, in fact it only gets 2. The second argument is just the full string. If you look at the line above this is actually fairly obvious.

Generating our arguments

So in order for this to work we have to preprocess the "hello there world" string into an argv** list. Unfortunately its now been a while since I had to do this so I won't be going into great detail as to how the function evolved. So I'll just splat it straight down and then go through it.

 1 static char** argv_from_string(char *cmd, char *args) {
 2  int i, spaces = 0, argc = 0, len = strlen(args);
 3  char **argv;
 4 
 5  for ( i = 0; i < len; i++ )
 6      if ( isspace(args[i]) ) spaces++;
 7 
 8  // add 1 for cmd, 1 for NULL and 1 as spaces will be one short
 9  argv = (char**) malloc ( (spaces + 3) * sizeof(char*) );
10  argv[argc++] = cmd;
11  argv[argc++] = args;
12 
13  for ( i = 0; i < len; i++ ) {
14      if ( isspace(args[i]) ) {
15          args[i] = '\0';
16          if ( i + 1 < len )
17            argv[argc++] = args + i + 1;
18      }
19  }
20 
21  argv[argc] = (char*)NULL;
22  return argv;
23 }

The algorithm is quite simple, lines 4 and 5 count the number of spaces in the argument string. This tells us how big we need to make the argv list. Once we know how big the argument list is we need to allocate the memory for that list.

NOTE that whatever function calls this will need to free the memory allocated by it. This is slightly bad form, but I felt it was acceptable in this case.

Next the arguments are added to the list using the argv[argc++] lines. On line 10 the first argument is added to the list, over the course of lines 12 to 18 the spaces within the argument string are replaced with null characters to terminate the strings. The starts of the new strings are then added to the argv list. Finally on line 20 the null sentinel is added at the end of the argv list.

NOTE the char *args contents are permanently changed by argv_from_string, if the calling function does not want to alter its argument string it should duplicate it and pass the clone to argv_from_string.

Using `argv_from_string`

Now I've already alluded to two issues when calling argv_from_string. The caller needs to ensure its memory is freed and potentially make a clone of the argument string before passing it if it cares about it being modified. So then to use this new function we need to change the main executing body above to

 1 pid_t pid;
 2 int status;
 3 char *args, **argv = NULL;
 4 char *envp[] = { NULL };
 5 
 6 switch ( pid = fork() ) {
 7   case -1:
 8     perror("fork()");
 9     exit(EXIT_FAILURE);
10   case 0: // in the child
11     args = strdup(cmd); // cmd is our argument string
12     argv = argv_from_string("./test_args", args);
13 
14     status = execve("./test_args", argv, envp);
15 
16     // only happens if execve(2) fails
17     free( args );
18     free( argv );
19     exit(status);
20   default: // in parent
21     if ( waitpid(pid, &status, 0) < 0 ) {
22       perror("waitpid()");
23       exit(EXIT_FAILURE);
24     }
25 
26     if ( WIFEXITED(status) ) {
27       // return status from child, ie ./test_args
28       exit( WEXITSTATUS(status) );
29     }
30     exit(EXIT_FAILURE);
31 }

the main body of changes are on lines 3 to 4 and 10 to 20. On lines 3 and 4 we've altered our variable list to include a string called args and an array of strings called argv. Now the real work begins on line 10, here we duplicate the string of arguments we received, this is so we don't trample the contents. We then pass this string of arguments to argv_from_string with the name of the program we are executing.

The execve(2) call itself hasn't changed, but should it fail we first cleanup the argument list and duplicated arguments string before exiting.

Now you might wonder why I chose to do all of this in the forked child instead of doing this before calling fork(2). My reasoning for this is that the external program I am executing is likely to be short lived and so memory created in its space will be freed by the operating system when its done. Also by keeping all of this in only the child I don't have to worry about freeing the memory in the parent or in the event that fork(2) fails.

Well I hope thats been useful for you.

XML Demolisher

2009-08-28T11:25:00+01:00

The majority of people familiar with Ruby have at one time or another used the Builder library to generate XML files. Builder is nice in that it provides a very ruby-ish interface to writing XML.

For example the following Builder code

 1 require 'builder'
 2 
 3 people = [
 4   { :firstname => 'Enoch', :lastname => 'Root',
 5     :phone => '01234 567 8900', :email => 'enoch@example.com',
 6     :active => true },
 7   { :firstname => 'Randy', :lastname => 'Waterhouse',
 8     :phone => '01234 567 8901', :email => 'randy@example.com',
 9     :active => false },
10 ]
11 
12 File.open('addressbook.xml', 'w') do |file|
13   xml = Builder::XmlMarkup.new(:target => file, :indent => 2)
14   xml.instruct!
15   
16   xml.addressbook do
17     people.each do |person|
18       xml.person do
19         xml.firstname person[:firstname]
20         xml.lastname  person[:lastname]
21         xml.contact do
22           xml.phone person[:phone]
23           xml.email person[:email]
24         end
25         xml.active person[:active] ? 'YES' : 'NO'
26       end
27     end
28   end
29 end

will generate this XML

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <addressbook>
 3   <person>
 4     <firstname>Enoch</firstname>
 5     <lastname>Root</lastname>
 6     <contact>
 7       <phone>01234 567 8900</phone>
 8       <email>enoch@example.com</email>
 9     </contact>
10     <active>YES</active>
11   </person>
12   <person>
13     <firstname>Randy</firstname>
14     <lastname>Waterhouse</lastname>
15     <contact>
16       <phone>01234 567 8901</phone>
17       <email>randy@example.com</email>
18     </contact>
19     <active>NO</active>
20   </person>
21 </addressbook>

nice and easy huh, despite me complicating it by using an array of people in the ruby code you can see how the XML is being put together. Now with the likes of REXML and Hpricot you can, with out a great deal of effort, extract pieces of this XML file back out and re-create the original array. The trouble is that neither of these projects are that well designed for this kind of process as I discovered.

What I was needing to do was export vast amounts of data into a portable format and then either import it back into the same system or potentially another system. Unfortunately coping with differences between how some other system might want to store that data was very tricky with the normal pick and choose method XML parsing. What I really wanted was something like Builder but the other way round. This was actually a lot simpler to achieve than I thought and with only a couple of hours work I had some code do just that.

Demolisher

So Demolisher was born, first onto GitHub and then properly, after adding tests, to Rubyforge. So to proceed with our addressbook example a bit more, how would you get the information back out?

 1 require 'demolisher'
 2 people = []
 3 
 4 xml = Demolisher.demolish('addressbook.xml')
 5 xml.addressbook do
 6   xml.person do
 7     person = {}
 8 
 9     person[:firstname] = xml.firstname
10     person[:lastname]  = xml.lastname
11     person[:active] = xml.active?
12     xml.contact do
13       person[:phone] = xml.phone
14       person[:email] = xml.email
15     end
16 
17     people << person
18   end
19 end

notice the active? call, if you append a ? to the end of an element name then it will return true provided the contents of the element are "t", "y", "true", "yes" or 1. This is case insensitive.

As I found it common in my import/export code to have little wrapped elements for logical grouping like the contact element above I also added a shorthand approach to accessing sub elements. You can get the contact phone using xml.contact.phone as well as the block method, so it could also be written as (lines 11 and 12)

 1 require 'demolisher'
 2 people = []
 3 
 4 xml = Demolisher.demolish('addressbook.xml')
 5 xml.addressbook do
 6   xml.person do
 7     person = {}
 8 
 9     person[:firstname] = xml.firstname
10     person[:lastname]  = xml.lastname
11     person[:phone] = xml.contact.phone
12     person[:email] = xml.contact.email
13     person[:active] = xml.active?
14 
15     people << person
16   end
17 end

I hope you like it and have some more fun demolishing XML data files. You can view the rdoc for only the tiniest bit more information, hey I told you it was pretty simple.

Using execve for the first time

2009-08-28T00:20:00+01:00

Recently I've been working on a project at work which required me to be managing shell commands from a C program. It's quite an interesting project, when its ready I hope to do a bit of a post on it. I've got quite a limited history of C experience but I do quite enjoy working with the language. Nowhere in my past experience with it had I ever been invoking other programs within my code, so this was definitely a learning experience for me.

For the purposes of any examples here is the source for the program I will be invoking as test_args

 1 #include <stdio.h>
 2 
 3 int main(int argc, char **argv) {
 4  FILE *log;
 5  int i;
 6 
 7  log = fopen("./out.txt", "a+"); // assume it worked
 8  fprintf(log, "Called with %d args as: ", argc);
 9  
10  for ( i = 0; i < argc ; i++ ) {
11      fprintf(log, "\"");
12      fprintf(log, argv[i]);
13      fprintf(log, "\"");
14      fprintf(log, " ");
15  }
16 
17  fprintf(log, "\n");
18 
19  return 0;
20 }

I've opted to write the arguments passed to the program to a text file for the sake of simplicity.

execve(2) and friends

The main system call to invoke an external program within your code is execve(2). Now that I've said that I'm going to retract nearly all of it. From the manpage

execve() transforms the calling process into a new process.

we see something a bit different, and initially for me a source of confusion. To begin with I was simply calling execve(2) in my code and letting it do its thing. This is not correct as any veteran of execve(2) knows and will probably baulk at my stupidity for not getting it right away.

So what does the manpage mean in this case, well as I found out to my cost, it means exactly what it says. The moment execve(2) is entered, provided it doesn't encounter an error, your program becomes the program invoked by execve(2). It will run to the end of that invoked program and return you whatever that program would if you'd run it yourself. This was my first tripping point and I quickly found out that I needed to fork(2) my way around it. As an example, most definitely not to be followed, here is what I had started with

1 int ret;
2 char *envp[] = { NULL };
3 char *argv[] = { "./test_args", "hello", "there", NULL };
4 
5 ret = execve("./test_args", argv, envp);
6 
7 // do things based on ret from test_args down here

as I've described, with the exception of an error, nothing after the execve(2) would be run.

Now I mentioned friends, execve(2) is wrapped by a number of functions such as execl, execle, execlp, execv, execvp and execvP which are documented in exec(3). These functions primarily offer a selection of different ways to wrap up the call to execve(2) for your convenience. I won't touch on these again as you can look into them yourself.

Another friend of execve(2) is system(2), this function takes a command string and passes it to sh(1) the default shell for interpretation and execution. For small commands it can be a quick way of getting things done but for my needs I didn't feel like it gave me enough control.

fork(2)ing around to keep in your program

So I needed to first fork(2) my program before calling execve(2) to invoke the external program. Now the important thing to remember about fork(2) is that your program branches into a child and parent. The parent is your controlling process and the child is what you will offer up to the gods of execve(2) to be transformed into the program you wish to invoke.

Here follows a crude example...

 1 pid_t pid;
 2 int status;
 3 char *envp[] = { NULL };
 4 char *argv[] = { "./test_args", "hello", "there", NULL };
 5 
 6 switch ( pid = fork() ) {
 7   case -1:
 8     perror("fork()");
 9     exit(EXIT_FAILURE);
10   case 0: // in the child
11     status = execve("./test_args", argv, envp);
12     exit(status); // only happens if execve(2) fails
13   default: // in parent
14     if ( waitpid(pid, &status, 0) < 0 ) {
15       perror("waitpid()");
16       exit(EXIT_FAILURE);
17     }
18 
19     if ( WIFEXITED(status) ) {
20       // return status from child, ie ./test_args
21       exit( WEXITSTATUS(status) );
22     }
23     exit(EXIT_FAILURE);
24 }

So again we setup the envp and argv string arrays to pass to execve(2) but before that we declare a variable of type pid_t. This is a type to store Process Identifiers, PIDs, which are returned from fork(2).

I've opted for a switch statement here, you could equally use an if but I prefer the readability and clarity of the switch.

So we fork our process and save the returned PID value as we'll need this in the parent. If our PID has a value of -1 then fork(2) has failed. Now we have the fun part, the child will always get a 0 return value from fork(2), if you want the PID in the child you can call getpid(2). So inside the child we make the call to execve(2) and capture the result of the call in the event of an error. From this point on the child is test_args and not our main program. Now the fork(2) call will return the value of the PID for the child to the parent, so we can catch this with the default case. In this rather simple example we wait for the child process to complete with waitpid(2) which will fill in our status variable with the return value of the child. Next we check the status to ensure the child exited and didn't crash or die, we then return the status code or indicate failure.

Thats the basic gist of using execve(2) to invoke external programs in your code. In a later post I'll describe how I went about handling more free form argument lists.

I'm Expert Staff apparently

2009-08-27T23:06:00+01:00

Rather recently the company I work for went through a bit of a re-branding and structural reorganisation. So now Open Hosting is a division of a new parent company M247 Ltd. Part of this re-branding was the creation of a couple of new divisions, one of which is Ice Colo through which our data centre services are being sold.

Now a while ago I'd rather foolishly agreed to allow myself to be photographed as part of some generic PR effort, this resulted in the following image

which was at least not quite as bemusing as

which I think is fantastic and cheesy at the same time.

Anyway I digress, the first picture found its way into I believe Data Centre Management magazine as part of a piece on the data centre we've built in Manchester.

Expert staff

With the creation of the Ice Colo brand came the inevitable website where once again you can see the image of my lovely self as part of the auto scrolling schpiel under Expert Staff. Wonderful eh, guess I've now got a reputation to live up to.

Marketing Idea for Apple

2009-08-27T22:28:00+01:00

Portrait style banner, fresh green apple at the bottom with a bite taken out of it. Text reads

They're just better for you ;)

as added bonus, have people standing outside Microsoft stores selling bushels of apples.

RSpec with MacRuby, part 2

2009-07-24T16:35:00+01:00

RSpec with MacRuby, part 2

RSpec with MacRuby, part 1

2009-07-24T16:35:00+01:00

RSpec with MacRuby, part 1

Failure in the GPS

2009-05-26T14:36:00+01:00

I swear, sometimes it's as if Hollywood sets out with "failure" plugged right into the GPS.

A Joss Whedon-less 'Buffy' movie: Worst idea ever of the year

Harsh highlighting

2009-04-02T13:23:00+01:00

Just read about the Harsh ERb/HAML highlighter, it looks quite cool. Also because it uses UltraViolet it can be powered by my version of the Oniguruma gem.

Initialising Cocoa NSValueTransformers

2009-03-26T02:09:00+00:00

Just a quicky, I created my first custom Value Transformer this evening. Normally to register your transformer you have to do something like the following

 1 + (void)initialize
 2 {
 3     [self initialiseValueTransformers];
 4 }
 5 + (void)initialiseValueTransformers
 6 {
 7     LoginStatusTransformer *loginStatusTransformer =
 8         [[[LoginStatusTransformer alloc] init] autorelease];
 9     [LoginStatusTransformer setValueTransformer:loginStatusTransformer
10         forName:@"LoginStatusTransformer"];
11 }

which hurt that part of my brain which likes clean code because of all the repetition.

So I cooked up a nice little pre-processor macro to tidy it up

1 #define init_transformer(klass) \
2     klass *vt##klass = [[[klass alloc] init] autorelease]; \
3     [klass setValueTransformer:vt##klass forName:@""#klass]

so now I have

1 + (void)initialiseValueTransformers
2 {
3     init_transformer(LoginStatusTransformer);
4 }

which will be expanded out to

1 + (void)initialiseValueTransformers
2 {
3     LoginStatusTransformer *vtLoginStatusTransformer =
4         [[[LoginStatusTransformer alloc] init] autorelease];
5     [LoginStatusTransformer setValueTransformer:vtLoginStatusTransformer 
6         forName:@"LoginStatusTransformer"];
7 }

it seems to be working for me at the moment, any bugs in the macro please let me know.

Update

Ben Stiglitz pointed out that if you use the class name as the transformer name there is no need to register it and Keith Duncan mentioned that theres no need to call [super initialize] so I've updated the sample to reflect this.

Tweaking RDiscount

2009-03-16T03:12:00+00:00

As I mentioned in my previous post I'd had some issues with Pygments and RDiscount. I have been using Pygments to highlight my code blocks in my blog. Unfortunately right after using a code block with linenos none of the markdown was being parsed anymore.

The Discount library upon which RDiscount is based has the ability to output a debug tree which shows the different blocks within the document. Things like paragraphs, quotes, code blocks and so on. Using this I was able to determine that the HTML block which contained the highlighted code was the last block being detected.

The Pygments highlighted source with line numbers is actually rendered in a table. This table closes with

</td></tr></table>

and herein lay the problem. The Discount library detects the closing HTML tag with the following function

 1 static Line *
 2 htmlblock(Paragraph *p, char *tag)
 3 {
 4     Line *t = p->text, *ret;
 5     int closesize;
 6     char close[MAXTAG+4];
 7  
 8     if ( selfclose(t, tag) || (strlen(tag) >= MAXTAG) ) {
 9         ret = t->next;
10         t->next = 0;
11         return ret;
12     }
13  
14     closesize = sprintf(close, "</%s>", tag);
15  
16     for ( ; t ; t = t->next) {
17         if ( strncasecmp(T(t->text), close, closesize) == 0 ) {
18             ret = t->next;
19             t->next = 0;
20             return ret;
21         }
22     }
23     return 0;
24 }

which as you might be able to tell, on line 17, checks the line for the presence of the HTML closing element. In the case of the Pygments closing element, this was not on its own line. While looking for </table> it would only read up to </td></t from the line before giving up.

Testing with a pre-pygmentised file and pushing the </table> onto its own new line confirmed that this was the problem.

But how do we fix it?

Well I started out looking for C string searching functions, of course strstr was the first candidate. Replacing line 17 of the aforementioned htmlblock() function with

if ( strstr(T(t->text), close) != NULL ) {

seemed like a good idea, but running the RDiscount test suite revealed my naivety of the solution. With my change text such as </table> was matched breaking HTML code examples, this wasn't good enough.

I spent much longer than I really should have trying other solutions before having the critical Eureka moment. I should add that prior to this moment I'd learnt of the more suitable strcasestr() function to better match the strncasecmp() function originally used.

At any rate my Eureka was realising that I was only ever going to need to search a string of closing tags, and that these closing tags would never be preceded by white space. Initially was thinking of using the CTYPE isspace macro, but a far simpler solution also struck me.

A closing tag, or string of closing tags will always start with a <, so provided the line started with < and then contained the respective closing tag I could reasonably safely assume the HTML block was being closed.

So I next transformed line 17 of htmlblock() to

if ( T(t->text)[0] == '<' && strcasestr(T(t->text), close) != NULL ) {

and re-ran the RDiscount test suite to see if the tests passed, they did. Next I added a snippet of the Pygments table to one of the test files with some extra markdown after it, updated the expected output file as well and re-ran the test suite. Again it all passed perfectly.

Once this was all done, I committed my changes to a branch of the fork I'd made of RDiscount and pushed them up to my fork on GitHub.

As I final test I updated the Discount source as well and re-ran it over the file to output the debug tree again. I was pleased to see all the right blocks of the file being shown, lovely.

Update

My fork has been merged with the master and been refined as well.

Changing the blogging gear

2009-03-16T02:44:00+00:00

I've recently been working on merging my two blogs together into one. One of them I host myself, the other is with Tumblr. One has stagnated quite severely with the last update April 1st, 2008, the other only seems to get periodic and occasionally small updates.

Twitter has played a large part in the lack of updates to both of these sites. Through Twitter I can post short thoughts, URLs to items of potential interest and frequently have a more live dialogue with a group of people. I also don't plug either of my blogs to any degree really, I provide links to them, but I don't go telling people to read them.

So what, you may ask, is the point in merging them at all? Well I still want to blog, but the point of blogging has changed. I now see blogging as a platform from which I can propose my thoughts or detail my current exploits when they merit it. My recent head injury was one such item mainly because I was asked for further details on it and it wouldn't fit the Twitter 140 character limit. The post on MySQL Replication was asked for by a friend of mine, while it was simplistic it helped me iron the process down in my head as well.

So as the game is changing a bit I've been through all of my old blog posts, correcting spelling mistakes as well as changing some grammar here and there. Its a bit vain I know, but some of it read really poorly, I also went and wrapped nearly all of the code blogs so they'd be parsed by Pygments. I had some fun with that, especially with RDiscount which I am using to parse the Markdown post files. I managed to sort out those problems though and now I'm just down to sorting out some niggly little bits before I close down the other two and redirect them to one location.

Setting up MySQL Master Slave Replication

2009-03-10T14:07:00+00:00

Today I was asked to set up a MySQL Replication server to allow for failover on one of the services we operate.

A friend of mine also asked me to document the procedure as its been a while since he'd done it and couldn't remember. So here goes....

The Setup

I'll be doing all of this on FreeBSD 7.1 servers and I'll be installing things from ports and then setting up the replication part.

Installing MySQL is pretty much a breeze, I do tend to do this first though

cat <<EOF > /etc/make.conf
.if ${.CURDIR:M*/databases/mysql5*}
BUILD_OPTIMIZED=YES
.endif
EOF

to ensure that MySQL is built to run as quickly as possible. Then you have the simple commands to install the server, assuming you use ports-mgmt/portupgrade

portinstall databases/mysql50-server

once that has been done on each server then we can begin setting up the replication service.

Instruct the Master

First we need to tell the master that it is a master, we also need to make sure that it'll listen for slaves. So we need to add some things to the configuration file. You can use /etc/my.cnf which is pretty global but I've opted for /var/db/mysql/my.cnf

1 [mysqld]
2 bind-address      = 192.168.0.10
3 server-id         = 1

now, it will listen and it knows its the master.

Next we need to instruct it where to keep the binary log file for replaying to the slaves so in the same file

1 log-bin           = mysql-bin
2 expire-logs-days  = 20
3 max_binlog_size   = 104857600

so the binary log file will be written to /var/db/mysql/mysql-bin, entries older than 20 days should be dropped and it shouldn't grow bigger than 100 megabytes.

Finally we tell it exactly which databases we want to replicate, can you ignore this if you don't want to be specific. Again in the same file

1 binlog-do-db      = testdb
2 binlog-ignore-db  = mysql,test

so only our testdb table will be binary logged, additionally mysql and test databases will be ignored.

Now you can restart your MySQL master server, to check that things are working you can connect to the server and run

mysql> SHOW MASTER STATUS;
+------------------+----------+---------------+-----------------------+
| File             | Position | Binlog_Do_DB  | Binlog_Ignore_DB      |
+------------------+----------+---------------+-----------------------+
| mysql-bin.000001 |       98 | testdb,testdb | mysql,test,mysql,test | 
+------------------+----------+---------------+-----------------------+
1 row in set (0.01 sec)

and you should get something like above. You can also check to make sure the server is listening for connections with

sockstat | grep mysql | grep tcp4
mysql    mysqld     90119 13 tcp4   192.168.0.10:3306   *:*

Creating a replication user

So we need to setup an account on the master server for the slave to use to authenticate itself. To do this we create a REPLICATION SLAVE using the following MySQL statement

GRANT REPLICATION SLAVE ON *.* TO 'slave'@'slavehost' IDENTIFIED BY 'slavepass';

we'll set these values on the slave as well so that it can authenticate to the master.

Instructing the Slave

Again I'll be keeping my configuration in /var/db/mysql/my.cnf, so for the slave we need to tell it that it isn't top of the food chain and also who is. To do this we add

1 [mysqld]
2 bind-address          = 192.168.0.11
3 server-id             = 2

to tell the Slave to listen for connections, this is so that external services which perhaps only need read access to the database can use the slave and save the master for writes.

Next we must inform the Slave of its masters address and its authentication credentials for use when addressing the Master

1 master-host           = 192.168.0.10
2 master-user           = slave
3 master-password       = slavepass
4 master-connect-retry  = 60

Finally as we only want one database to be replicated, in my case at least, add the following line to the configuration file

1 replicate-do-db       = testdb

so that only the testdb database will be replicated.

Copying the database to the Slave

Firstly we need to know where in the binlog we are at the moment, so on the master server run the following command

mysql> SHOW MASTER STATUS;
+------------------+----------+---------------+-----------------------+
| File             | Position | Binlog_Do_DB  | Binlog_Ignore_DB      |
+------------------+----------+---------------+-----------------------+
| mysql-bin.000001 |   327128 | testdb,testdb | mysql,test,mysql,test | 
+------------------+----------+---------------+-----------------------+

remember the File and Position values as we'll need these to resynchronised the databases once the slave has a copy of the data.

Using mysqldump create a copy of the master database to put onto the slave

mysqldump --opt --databases testdb > /root/master-databases.sql

Now copy the /root/master-databases.sql file to the slave and then import it, assuming you copied it to /root/master-databases.sql on the slave as well

mysql < /root/master-databases.sql

Now we need to synchronise the two copies. On the slave load up the mysql client

mysql> STOP SLAVE;
mysql> CHANGE MASTER TO MASTER_HOST = '192.168.0.10',
    -> MASTER_USER = 'slave_user', MASTER_PASSWORD = 'slave_pass',
    -> MASTER_LOG_FILE = 'mysql-bin.000001', MASTER_LOG_POS = 327128;
mysql> START SLAVE;

and the changes will be synchronised between the two servers.

A quick test

Now its a good idea to make some test insertions into the master database and then check to see if they exist on the slave as well. I'll leave this part up to you...

So what happened to me on Friday the 6th of March?

2009-03-09T18:47:00+00:00

As so many of these tales unravel it all started with alcohol. I'd been invited out by Claire for her brother Neils fiancé Alices birthday drinks do. This is only the second time I've met Alice, the first time at their engagement party. I've known Neil for a while as he used to work at the same company I'm at now.

At any rate over the course of the night quite a few drinks where consumed.

Towards the end of the evening, one or two people had started to go home, I felt a bit dizzy quite rapidly. Normally I get a slowly increasing buzz which I know well and use as a good indicator of when to stop drinking. I made my way to the toilets to get some water on my face, unfortunately there was a queue of people coming out of the toilets, so I decided to go back up the spiral staircase to get some air instead. The next couple of events are bit more patchy. I recall standing under the staircase, possibly letting some people past, something also makes me think I might have sat down under the stairs, maybe I was waiting to get into the toilets to splash my face. Things just sort of get a bit black and hazy from there.

The next thing I remember is seeing Claire and the woman from the coat desk standing over me. Claire was pressing some blue paper towels to my forehead. I don't specifically recall the first couple of questions but they were along the lines of "are you alright" and "how many fingers am I holding up". Then we came to the slightly more tricky questions of did I remember what happened. As you can probably guess at this point, I wasn't completely sure. I'd apparently been unconscious for a minute or so as well.

After a few minutes the ambulance "drunk bus" arrived, and the paramedics had a look over me, took my blood pressure, checked my blood sugar and took my details. They said the wound seemed superficial but that someone should keep an eye on me and asked if I'd come with anyone else, I said no and that I'd met up with every body at the bar. Once they'd finished collecting my details the paramedic and I wandered back over to my friends and told them that I should be alright but that someone should keep an eye on me over night as it could be worse than it looked. If I started having blurred vision or started vomiting I should be taken to hospital to be checked out fully.

Everyone came back out of the bar a few minutes later to decide what to do next, I think the party was winding down so most opted to return home. So we said farewell to each other amidst various Harry Potter comments. Claire offered to take me back to her house and keep an eye on me so we headed off in the direction of the tube. On the way back, before we caught the tube, she checked with one of her house mates that was away for the weekend to see if I could sleep in their bed for the night. Fortunately the tube is quite direct though the whole time I was wishing I had a hat to cover up my stupid forehead. When we got off the tube we had a rather pleasant walk to her house, it was good to chat without the noise of the bar.

When we got to her house Claire stuck some bandages to my forehead and chin so that I wouldn't bleed all over her house mates pillow. We each then went to bed, as I couldn't quite sleep yet I posted a picture on twitter and then answered a few questions about it before finally putting head down to sleep.

Around eight in the morning I woke up and checked my bandages, it was good having them there as my chin had bled a bit during the night. I left them in place and then lay back down in the bed for a bit to rest and run through the evening. After a little while I checked the internet to find some tips on speeding up the healing process. Vitamin C, Zinc and protein all seemed like best things to get, so I decided that I'd have a fry up with Orange Juice when I got home. The best hangover cure if ever there was one. A tasty multivitamin can follow that up for the Zinc. I also did some "Brain Training" as I figured it might help.

Some time later I got up again and carefully remove the bandages from my face, I managed to loosen the scab on my chin from the bandage with water so I didn't tear it all off. At the same time I noticed some abrasions on the side of my face, quite shallow though and they'd scabbed up pretty quickly by the looks of things, a bit swollen though.

Around 9.30 Claire came down to check on me, by this time I was feeling reasonably well, as she needed to pack up to go to a ball in the evening I decided I would make my way back home. She gave me some directions back to the tube station and I remembered most of it from the walk the opposite direction the night before.

I got a couple of strange looks from people on the tube but mainly I kept my head down to avoid everyone. When I got back to Mile End I went into the new Tesco got my fry up supplies and some plasters. Then I had a nice big fry up when I got back to my flat.

Later that day I discovered a couple other party injuries, a decent sized but shallow cut on my shoulder and a skinned and bruised knee. None of it, bar the knee, is giving me any real pain and I've not had any dizziness or vomiting since the event.

So what actually happened?

Well the best I can piece together is that my head collided with the spiral staircase by the toilets, though its difficult to work out exactly how I got the gash I did from that. The cut on my chin did swell up a little but, but as I've no pain in my jaw I don't think I hit it very hard at all. I've also no neck pains so I don't think I fell down the stairs at all. I suppose its possible that I just stood up into the edge of a stair, that would probably explain the vertical nature of the gash though its not a straight wound.

But I wanna see a picture!!!

Ok fine, Jason took a pretty good one of it the other night.

Proxying through complex situations

2009-02-06T16:54:00+00:00

I was recently in need of access to my Windows XP desktop machine which is has been left at my parents house due to lack of space anywhere I've lived in London. I had previously set up a port forwarding rule on their home router to push any RDP connections through to my desktop. Annoyingly as I found these didn't want to work. I don't know what is wrong with my parents router but it won't forward any ports, this might have something to do with the DMZ which is also turned on. I've never been a big fan of remote router access so I got on to their file server via SSH, installed elinks with SpiderMonkey javascript support and attempted to connect to the router to see if I'd set up the port forwarding. This didn't work as the javascript location.replace is apparently not a function. This left me a bit stumped as to how I might be able to pull this off.

After a bit of searching through the SSH manpage I gave the following a try

ssh -D 8080 -f -C -q -N parents-fileserver

this created a SOCKS proxy through which I could tunnel into their local network and view the routers management interface. It was after a bit of unsuccessful playing here that I found out their router doesn't always forward ports properly. This left me in a bit of conundrum.

Netcat

I would say that the majority of Unix people would have heard of Netcat, aka nc. Netcat is a networking tool which lets you do just about anything you could possibly want to with TCP or UDP. So I wondered if I could create an instance of nc to listen on the RDP port and then somehow pass that through to my desktop machine. A very quick google turned up this command

$ nc -l -p 3389 | nc 10.0.0.10 3389 | nc -b -l -p 3389

though many of the command switches had disappeared or their combinations were now invalid I turned it into this

$ nc -l 3389 | nc 10.0.0.10 3389 | nc -l 3389

and tried to connect up to my desktop. This command should create an instance of nc that listens on the RDP port and pipes whatever it gets through to another instance of nc which is connected to my desktop machine, this again pipes whatever it gets back through the listening port.

This didn't work... at all.

So a bit more googling turned up this on the freebsd mailing lists

$ mkfifo /tmp/fifo
$ nc -l 3389 < /tmp/fifo | nc 10.0.0.10 3389 > /tmp/fifo

this should again pipe anything hitting the server RDP port to the desktop RDP port, the desktop RDP traffic gets written into /tmp/fifo which is then sent back to the originating client.

This also didn't work... at all.

So now I was at a bit of a loss, but the freebsd mailing list entry mentioned a website from which they were basing their experiment on, so I went to check that out. The bottom of the page mentioned an alternative solution using a program called socat. Ok, I thought, lets give that a try and installed that.

So I ran the following command to create the socat proxy

$ socat tcp4-listen:3389,reuseaddr,fork TCP:10.0.0.10:3389

This worked... very, very well.

So now when I need to get into my desktop machine I can SSH to the file server and setup the proxy, do what I need to and then shut it down when I'm done.

Ruby on Rails on Vimeo

2009-01-28T09:21:00+00:00

Ruby on Rails on Vimeo

This is brilliant to watch, it starts off in SVN and around 5:10 I think its been moved into git. At around 6:05 you might also spot a recognisable avatar ;-)

My first Nu script

2009-01-17T00:49:00+00:00

I get bored, quite easily and my desktop picture is no exception to this. Thankfully in Mac OS X, I believe Windows too, you can have a rotating desktop picture. By rotating, I don't mean spinning, rather I mean you provide a directory of images and the OS displays them in a random order. So every 5 minutes I get another image.

Occasionally it will display and image which I am very bored of, or just don't like. In this case I then have to flip through the images in my Desktop Pictures directory to find the offending image and remove it. Every time I had to do this I was sure there was an easier way. A couple months ago I found that the ~/Library/Preferences/com.apple.desktop.plist file contained the information which I required to get the image file name, and more portably the path used for the Desktop Pictures. Originally I wrote up a small bash script to grep the information I needed from the defaults read output, but I never liked this. The reason I never liked this was that the ChangePath and LastName property list keys appeared something like three times in the file. So I was having to tail the grep output to only select the last one, as this is the one I cared about.

What I really wanted was a way to use the defaults program to access a slightly more complicated key structure than it would allow.

Along came Nu

Nu is a lisp like language written by Tim Burks which allows access to the Cocoa and Foundation API's in a scripting like shell (through nush).

The most I'd really used Nu for at this point was just playing around with the Cocoa API's, messing with functions and seeing how things worked. This is one of the most frequent uses I have of Nu because it lets me essentially debug interactively in a sensible way.

Given my rather amateur usage of Nu so far I wanted to try and use it in its own right. Given my issues with the defaults program for accessing complex key paths, and knowing an NSDictionary would do this easily I thought this would be a good little dip in the sparkling Nu waters.

The script below is what I came up with, it is pretty simple, and pretty self explanatory if you already know the Cocoa API's. As a simple walkthrough though

Check to see if the script was called with the "-rm" argument
1. Set shouldOfferToRemove to true if it did, nil if not
Read in the com.apple.desktop.plist file contents
Get the dictionary for the Background/default key
Extract the ChangePath value which is the path to the Desktop Pictures directory.
Extract the LastName value which is the file name of the image file
Print the name of the image file
Prompt the user to delete the file if requested
1. Delete the file if instructed

The most complicated portion of the script is the part where the response to either delete or leave the file is read.

1 (set input (((NSString alloc)
2     initWithData:((NSFileHandle fileHandleWithStandardInput) availableData)
3     encoding:NSUTF8StringEncoding)
4         stringByTrimmingCharactersInSet:
5             (NSCharacterSet whitespaceAndNewlineCharacterSet)))

this section could be broken down a bit to something more like the following

1 (set stdin (NSFileHandle fileHandleWithStandardInput))
2 (set inputData (stdin availableData))
3 (set inputString ((NSString alloc) initWithData:inputData
4   encoding:NSUTF8StringEncoding))
5 (set trimSet (NSCharacterSet whitespaceAndNewlineCharacterSet))
6 (set input (inputString stringByTrimmingCharactersInSet:trimSet))

which does give a better indication of the operations being carried out, firstly a file handle to the input stream is obtained, then the availableData is read. The availableData returns whatever the user types before hitting Enter. The next couple of lines convert the NSData into an NSString and then trim any whitespace or newline characters in the string. This lets the script more easily compare the input against "y" and "Y".

So without further ado, here is the script (also on gist)

 1 #!/usr/bin/env nush
 2 ; Useful script for when you have a rotating background on Mac OS X
 3 ; this script will tell you which image is currently being displayed.
 4 ; If you add -rm when calling the command then it will provide you with
 5 ; prompt to let you delete the background.
 6 ;
 7 ; Installation:
 8 ;  Copy this into something like ~/bin/current_background and then
 9 ;  $ chmod 750 ~/bin/current_background
10 ;  then use :D
11 ;
12 ; Usage: (assuming you call it current_background)
13 ; Show the current background image filename
14 ;  $ current_background
15 ;  Current desktop image is background-1.jpg
16 ; Show and optionally delete the current background image file
17 ;  $ current_background -rm
18 ;  Current desktop image is background-1.jpg
19 ;  Are you sure you want to delete background-1.jpg [y/N]: 
20 ;  y
21 ;  Background background-1.jpg has been deleted
22 ;
23 ; Bugs:
24 ;  1. When prompting for user input I can't seem to flush stdout manually
25 ;     so I have to print a new line character in order to show the prompt.
26 ;
27 
28 (set processInfo (NSProcessInfo processInfo))
29 (set args (processInfo arguments))
30 
31 (if (and (eq (args count) 3) (eq (args objectAtIndex:2) "-rm"))
32     (set shouldOfferToRemove t)
33     (else (set shouldOfferToRemove nil)))
34 
35 ;; Get the dictionary
36 (set plist ("~/Library/Preferences/com.apple.desktop.plist" stringByExpandingTildeInPath))
37 (set prefs (NSDictionary dictionaryWithContentsOfFile:plist))
38 
39 ;; Drill down to the dictionary key we care about
40 (set default ((prefs valueForKey:"Background") valueForKey:"default"))
41 
42 ;; Extract the fields we need
43 (set changePath (default valueForKey:"ChangePath"))
44 (set currentImage (default valueForKey:"LastName"))
45 
46 ;; Print the information
47 (puts "Current desktop image is #{currentImage}")
48 
49 ;; Offer to delete
50 (if (eq t shouldOfferToRemove)
51     (print "Are you sure you want to delete #{currentImage} [y/N]: \n")
52     (set input (((NSString alloc)
53         initWithData:((NSFileHandle fileHandleWithStandardInput) availableData)
54         encoding:NSUTF8StringEncoding)
55             stringByTrimmingCharactersInSet:
56                 (NSCharacterSet whitespaceAndNewlineCharacterSet)))
57     (if (or (input isEqualToString:"y") (input isEqualToString:"Y"))
58         (set fm (NSFileManager defaultManager))
59         (set path (changePath stringByAppendingPathComponent:currentImage))
60         (if (fm removeFileAtPath:path handler:nil)
61             (puts "Background #{currentImage} has been deleted")
62             (else (puts "Background #{currentImage} could not be deleted")))
63         (else
64             (puts "Background #{currentImage} has not been deleted"))))

What the Fedora developers failed to realize

2009-01-13T10:26:00+00:00

What the Fedora developers failed to realize, however, is that the USS Leonidas was a derelict vessel that the Union army obtained to intentionally sink

Source: Regarding the Fedora 11 codename

Apple Wish: Xcode Building Embedded Projects

2009-01-04T01:43:00+00:00

I've been spending quite a lot of my time recently using Apple's Xcode just hacking on things which scratch a bit of an itch I get from time to time. Mainly I've been working on developing Mac OS frameworks for a couple purposes and I recently wanted to make a GUI demo app which used my framework, so I created a new project and use a git submodule to import the framework project. This all worked just fine, I was able to hook in the framework project to the demo project, set up the framework as a dependency of the GUI app and slapped the old Build button and got two errors.

Seems Xcode first builds the framework into Framework/build/Debug/Framework.framework and then the GUI app into build/Debug/Gui.app which means the GUI app can't find the framework to get the headers from.

What are our options?

Well what is required is for the build directories of both projects to be the same. You've got a couple of choices here. You can set an Xcode wide preference and build all projects into a specific directory, or you can set the build directory in each of the projects (or just one) to make them the same. Lets explore the latter for the sake of argument as its the least disruptive to other projects.

Option 1

The first option, which is advocated in Xcode 3 Unleashed, is to place the two projects in the same directory. In this case you have two .xcodeproj files in your project directory, which therefore use the same build directory. The downside to this method is that it doesn't work terribly well with git submodules as each submodule has to exist as a separate folder.

So because of the requirement to use git submodules this method isn't really that feasible.

Option 2

A second option might be to change the sub project to build into ../build which is the build directory of the primary project. This has the benefit of keeping the build results in the logical place of the primary project. The down side is that you have to modify the submodule in order to make it work. While in most cases if you git pull on the submodule to update the source it shouldn't break it but it is a nuisance none the less. So for this reason I also don't really like this option either.

Option 3

The final option would be to change our GUI project to use the build directory to use the build directory of the framework project. This keeps us from having to modify the submodule but I personally don't like this solution as it means our primary project in this case is building into the space of a sub project.

What would be better?

So why is this a wishlist item? Well I'd personally like to be able to override the sub project build directory in the primary project. So you'd be able to Get Info on the Framework.xcodeproj in your Groups & Files pane and change the build directory. This would then either build the sub project and then copy those contents into the primary projects build directory, or else just have the project when its being built by the primary build into the primary build directory.

Update: A Stop Gap

Played around a bit further and I believe the Frameworks Search Paths build configuration setting is possibly an appropriate solution. You can set this to say Framework/build/Debug for your Debug configuration and then the compiler can find your framework project correctly for compiling. All the changes are happily in your primary project and it makes sense that it should have to search into the Framework directory for the right files. I'm a bit happier now :-)

A boy with pointy ears

2008-12-16T17:13:00+00:00

Next we see a much shorter growing up story – one of a boy with pointy ears. He starts off small and cute with pointy ears. Then gets bigger (but still with the ears), and turns into someone that modern viewers might recognise as Sylar from Heroes.

Star Trek trailer: all 12-year-olds and whizz-bang action

But better to be addicted to smartphones...

2008-12-10T18:07:00+00:00

But better to be addicted to smartphones and gismos than cocaine or sex, I suppose. Well, I don’t know, the result is the same after all, very little sleep, great expense and horrific mess everywhere.

The New Adventures of Mr Stephen Fry

My iPod is inspired

2008-11-13T13:58:00+00:00

The other morning my iPod played the following songs:

Follow the Cops Back Home by Placebo
Evergreen by Faithless
Starting Over by The Crystal Method
Angels by Within Temptation

I'm still not quite sure why these songs flow so well into each other but the sequence really is superb.

Jeff Dunham - Achmed the Dead Terrorist

2008-10-31T18:27:00+00:00

Jeff Dunham - Achmed the Dead Terrorist (via KrowBatellio)

Not very PC but still quite hilarious.

Geoff Garside

Checking git staged files for tabs before committing

Running Stompserver with Daemontools

Installing Stompserver

Creating the Stompserver directory

Creating a user for the stompserver

The run scripts

Starting the Stompserver

Handling arguments with execve

Generating our arguments

Using argv_from_string

XML Demolisher

Demolisher

Using execve for the first time

execve(2) and friends

fork(2)ing around to keep in your program

I'm Expert Staff apparently

Expert staff

Marketing Idea for Apple

RSpec with MacRuby, part 2

RSpec with MacRuby, part 1

Failure in the GPS

Harsh highlighting

Initialising Cocoa NSValueTransformers

Update

Tweaking RDiscount

But how do we fix it?

Update

Changing the blogging gear

Setting up MySQL Master Slave Replication

The Setup

Instruct the Master

Creating a replication user

Instructing the Slave

Copying the database to the Slave

A quick test

So what happened to me on Friday the 6th of March?

So what actually happened?

But I wanna see a picture!!!

Proxying through complex situations

Netcat

Ruby on Rails on Vimeo

My first Nu script

Along came Nu

What the Fedora developers failed to realize

Apple Wish: Xcode Building Embedded Projects

What are our options?

Option 1

Option 2

Option 3

What would be better?

Update: A Stop Gap

A boy with pointy ears

But better to be addicted to smartphones...

My iPod is inspired

Jeff Dunham - Achmed the Dead Terrorist

The `run` scripts

Using `argv_from_string`