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phab/src/applications/diffusion/protocol/DiffusionMercurialWireProtocol.php
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DiffusionMercurialWireProtocol.php
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<?php
final class DiffusionMercurialWireProtocol extends Phobject {
public static function getCommandArgs($command) {
// We need to enumerate all of the Mercurial wire commands because the
// argument encoding varies based on the command. "Why?", you might ask,
// "Why would you do this?".
$commands = array(
'batch' => array('cmds', '*'),
'between' => array('pairs'),
'branchmap' => array(),
'branches' => array('nodes'),
'capabilities' => array(),
'changegroup' => array('roots'),
'changegroupsubset' => array('bases heads'),
'debugwireargs' => array('one two *'),
'getbundle' => array('*'),
'heads' => array(),
'hello' => array(),
'known' => array('nodes', '*'),
'listkeys' => array('namespace'),
'lookup' => array('key'),
'pushkey' => array('namespace', 'key', 'old', 'new'),
'stream_out' => array(''),
'unbundle' => array('heads'),
);
if (!isset($commands[$command])) {
throw new Exception(pht("Unknown Mercurial command '%s!", $command));
}
return $commands[$command];
}
public static function isReadOnlyCommand($command) {
$read_only = array(
'between' => true,
'branchmap' => true,
'branches' => true,
'capabilities' => true,
'changegroup' => true,
'changegroupsubset' => true,
'debugwireargs' => true,
'getbundle' => true,
'heads' => true,
'hello' => true,
'known' => true,
'listkeys' => true,
'lookup' => true,
'stream_out' => true,
);
// Notably, the write commands are "pushkey" and "unbundle". The
// "batch" command is theoretically read only, but we require explicit
// analysis of the actual commands.
return isset($read_only[$command]);
}
public static function isReadOnlyBatchCommand($cmds) {
if (!strlen($cmds)) {
// We expect a "batch" command to always have a "cmds" string, so err
// on the side of caution and throw if we don't get any data here. This
// either indicates a mangled command from the client or a programming
// error in our code.
throw new Exception(pht("Expected nonempty '%s' specification!", 'cmds'));
}
// For "batch" we get a "cmds" argument like:
//
// heads ;known nodes=
//
// We need to examine the commands (here, "heads" and "known") to make sure
// they're all read-only.
// NOTE: Mercurial has some code to escape semicolons, but it does not
// actually function for command separation. For example, these two batch
// commands will produce completely different results (the former will run
// the lookup; the latter will fail with a parser error):
//
// lookup key=a:xb;lookup key=z* 0
// lookup key=a:;b;lookup key=z* 0
// ^
// |
// +-- Note semicolon.
//
// So just split unconditionally.
$cmds = explode(';', $cmds);
foreach ($cmds as $sub_cmd) {
$name = head(explode(' ', $sub_cmd, 2));
if (!self::isReadOnlyCommand($name)) {
return false;
}
}
return true;
}
/** If the server version is running 3.4+ it will respond
* with 'bundle2' capability in the format of "bundle2=(url-encoding)".
* Until we maange to properly package up bundles to send back we
* disallow the client from knowing we speak bundle2 by removing it
* from the capabilities listing.
*
* The format of the capabilties string is: "a space separated list
* of strings representing what commands the server supports"
* @link https://www.mercurial-scm.org/wiki/CommandServer#Protocol
*
* @param string $capabilities - The string of capabilities to
* strip the bundle2 capability from. This is expected to be
* the space-separated list of strings resulting from the
* querying the 'capabilties' command.
*
* @return string The resulting space-separated list of capabilities
* which no longer contains the 'bundle2' capability. This is meant
* to replace the original $body to send back to client.
*/
public static function filterBundle2Capability($capabilities) {
$parts = explode(' ', $capabilities);
foreach ($parts as $key => $part) {
if (preg_match('/^bundle2=/', $part)) {
unset($parts[$key]);
break;
}
}
return implode(' ', $parts);
}
}
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