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https://gerrit.wikimedia.org/r/mediawiki/extensions/Scribunto
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6b4cfd5b94
In Lua, a table entry with a nil value is the same as a table entry that doesn't exist. So when serializing for transfer to PHP, these keys will be skipped. For a table as an associative array this isn't much of a problem, but for a table as a list it means we have missing indexes. Some of Lua's functions for handling "lists" (i.e. tables with numeric keys) also have a problem when the list contains nils. To work around these issues when passing argument lists and return value lists, pass the number of elements along with the sparse list. On the PHP end we can use this to fill in the missing nulls, and on the Lua end we can pass this count to unpack() to avoid the problems on the Lua side. Change-Id: I858e3905a06e377693301da2b8bc534808f00e3e
152 lines
4.1 KiB
Plaintext
152 lines
4.1 KiB
Plaintext
The Lua standalone engine has a message-based protocol for communicating between
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PHP and Lua.
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Messages start with a 16 byte header. The first 8 bytes are the body length in
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hexadecimal. The second 8 bytes are (length * 2 - 1) also in hexadecimal.
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For messages passed from PHP to Lua, the body is encoded as a Lua expression.
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The expression may reference a table in a variable called "chunks", which
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contains an array of functions.
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Messages passed from Lua to PHP have their body encoded in PHP serialize() format.
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They may include instances of function objects which have an "id" member for
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passing back to Lua as an index in the chunk table.
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The expressions encoded into the message bodies are associative arrays. The "op"
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member of the array gives the operation to be performed by the message.
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Every request message demands exactly one response message in reply. When a
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request message is sent, the responder does not need to send the corresponding
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response message as its next message. It may instead send its own request
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message. In this way, a stack of pending requests can be accumulated. This
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mechanism allows re-entrant and recursive calls.
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All numerically-indexed arrays should start from index 1 unless otherwise
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specified. Note that the number of values in an array may not match what Lua's
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'#' operator returns if the array contains nils.
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== Request messages sent from PHP to Lua ==
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=== loadString ===
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Load some executable Lua code (a "chunk") and return the resulting function ID.
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Message parameters:
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* op: "loadString"
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* text: The string to load
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* chunkName: The name of the string, for use in error messages
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On success, the response message is:
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* op: "return"
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* nvalues: 1
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* values: An array with a single element with the ID in it
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On failure, the response message is:
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* op: "error"
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* value: The error message
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=== call ===
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Call a Lua function.
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Message parameters:
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* op: "call"
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* id: The chunk ID
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* nargs: Number of arguments, including nils
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* args: The argument array
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On success, the response message is:
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* op: "return"
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* nvalues: Number of return values, including nils
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* values: All return values as an array
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On failure, the response message is:
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* op: "error"
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* value: The value given to error(), usually an error message
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* trace: A table giving a backtrace of the stack as it was when error() was
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called, in a similar format to the one used by debug.getinfo(). Element 1 of
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the table is the function that called error(), element 2 is the function that
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called that, and so on.
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=== registerLibrary ===
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Register a set of functions in the sandbox environment.
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Message parameters:
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* op: "registerLibrary"
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* name: The global variable name to register. May contain "." characters to
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specify a global variable subtable.
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* functions: An associative array mapping function name to ID
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On success, the response message is:
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* op: "return"
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* nvalues: 0
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* values: An empty array
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On failure the response message is:
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* op: "error"
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* value: The error message
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=== getStatus ===
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Get status information about the Lua process.
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Message parameters:
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* op: "getStatus"
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On success, the response message is:
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* op: "return"
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* nvalues: 1
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* values: An array with a single element, which is an associative array mapping
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status key to value. The status keys are:
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** pid: The process identifier
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** time: The amount of user and system time spent by the process, measured in clock ticks
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** vsize: The virtual memory size in bytes
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** rss: The resident set size in bytes
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On failure, the response message is:
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* op: "return"
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* nvalues: 0
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* values: An empty array
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=== quit ===
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Request graceful shutdown.
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Message parameters:
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* op: "quit"
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No return message will be sent.
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== Request messages sent from Lua to PHP ==
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=== call ===
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Call a PHP function.
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Message parameters:
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* op: "call"
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* id: The function ID given by registerLibrary
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* nargs: Number of arguments, including nils
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* args: An array giving the function arguments
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On success, the response message is:
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* op: "return"
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* nvalues: Number of return values, including nils
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* values: All return values as an array
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On failure the response message is:
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* op: "error"
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* value: The error message
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