C-Hglib

A C library for interfacing with Mercurial's CommandServer.

1. Getting the source

You can clone the packeage from its primary repository c-hglib.

2. First plan

Some steps that I want to do first:

• create an open mechanism between Client (C library) and Server ( Mercurial Command Server)
• close the connection
• readchannel function that will get the channel and the length of message.
• create the _hello function, that will receive the first message, after the connection.

• cmdbuilder, will compute the command that will be sent to CommandServer.

• runcommand, will send the build command to the server and will return the compute message.
• mercurial commands.

How to make it happen:

• Create an open mechanism between Client (C library) and Server ( Mercurial Command Server)
  • First I will try to compute a command that will be execute in the child process.
  • It will be of the form “HGPATH serve --cmdserver pipe --config ui.interactive=True” + “-R path ”
  • I will create two pipes for the bidirectional connection. Then I will fork a new process, where I’ll execute the command that will open the Command Server. In the child process I will redirect the input, the output and the error in to the pipes (for the communication Client-Server). In my case the child process will open the Command Server and the parent process will be the client.
  • The communication will be through the pipes descriptors.
  • The open function will return a Client structure that will contain the pipes descriptors and other useful information.
• Close the connection
  • Will kill the command server and will close the pipe descriptors for a specific Client.
• readchannel function that will get the channel and the length of message.
  • Will read a char (the channel) and a uint (the length). There are chances for a problem to occur over here with the unsigned integer (the Command Server will send to me an integer in big endian form).
  • Most probably I will have to create a conversion mechanism.
• create the _hello function that will receive the first message, after the connection.
  • This function will read the channel and the default data. Then I will check the correctness of data.

• cmdbuilder, will compute the command that will be sent to CommandServer.

  • This function will return a list with a compute command that will be send to CommandServer. This function will be called by all mercurial commands.

• runcommand, will send the build command to the server and will return the compute message.
  • From this function I will sent through pipes the commands and I will receive the specific answers. This will be the function that will make the communication.

3. My starts points will be

• CommandServer

• python-hglib

• chg

4. Directory tree

.
├── hglib
│   ├── main.c
│   ├── Makefile.am
│   ├── utils.c
│   └── utils.h
├── Makefile.am
├── README.md
├── tests
└── Makefile.am