Latest version:
http://mozilla.org/scriptable/typelib_file.html
This version:
http://mozilla.org/scriptable/typelib_file_v1_d1.html
Record fields with type boolean occupy one bit, not one byte. A value of 1 represents true and a value of 0 represents false.
All integer fields with multibyte precision are stored in little-endian order, e.g. for a uint16 field, the low-order byte is stored in the file followed by the high-order byte.
TypeLibHeader {
char magic[16];
uint8 major_version;
uint8 minor_version;
uint16 num_interfaces;
uint32 file_length;
InterfaceDirectoryEntry* interface_directory;
uint8* data_pool;
}
The first 16 bytes of the file always contain the following values:(hex) 58 50 43 4f 4d 0a 54 79 70 65 4c 69 62 0d 0a 1a (C notation) X P C O M \n T y p e L i b \r \n \032This signature both identifies the file as an XPCOM typelib file and provides for immediate detection of common file-transfer problems, i.e. treatment of a binary file as if it was a text file. The CR-LF sequence catches file transformations that alter newline sequences. The control-Z character stops file display under MS-DOS. The linefeed in the sixth character checks for the inverse of the CR-LF translation problem. (A nod to the PNG folks for the inspiration behind using these special characters in the header.)
These are the major and minor version numbers of the typelib file format. For this specification major_version is 0x01 and minor_version is 0x00. TypeLib files that share the same major version but have different minor versions are compatible. Changes to the major version represent typelib file formats that are not backward-compatible with parsers designed only to read earlier major versions. If a typelib file is encountered with a major version for which support is not available, the rest of the file should not be parsed.
This indicates the number of InterfaceDirectoryEntry records that are at the offset indicated by the interface_directory field.
This field specifies a zero-relative byte offset from the beginning of the file. It identifies the start of an array of InterfaceDirectoryEntry records. If num_interfaces is zero, then this field should also be zero. The value of this field should be a multiple of 4, i.e. the interface directory must be aligned on a 4-byte boundary. (This is to guarantee aligned access if the typelib file is mmap'ed into memory.)
Total length of the typelib file, in bytes. This value can be compared to the length of the file reported by the OS so as to detect file truncation.
The data pool is a heap-like storage area that is the container for most kinds of typelib data including, but not limited to InterfaceDescriptor, MethodDescriptor, ParamDescriptor, and TypeDescriptor records. Note that, unlike most file offsets in a typelib, the value of data_pool is relative to the beginning of the file.
InterfaceDirectoryEntry {
uint128 iid;
InterfaceDescriptor* interface_descriptor;
}
The iid field contains a 128-bit value representing the interface ID. The iid is created from an IID by concatenating the individual bytes of an IID in a particular order. For example, this IID:{00112233-4455-6677-8899-aabbccddeeff}is converted to the 128-bit value0xffeeddccbbaa88996677445500112233Note that the byte storage order corresponds to the layout of the nsIID C-struct on a little-endian architecture.All InterfaceDirectoryEntry objects must appear sorted in increasing order of iid, so as to facilitate a binary search of the array.
This is a byte offset from the beginning of the file to the corresponding InterfaceDescriptor object.
InterfaceDescriptor {
String name;
InterfaceDescriptor* parent_interface;
uint16 num_methods;
MethodDescriptor method_descriptors[num_methods];
}
The human-readable name of this interface, e.g. "nsISupports", stored using the String record format.
As a space-saving measure, an interface's methods can be specified by composing the methods of an interface from which it is derived with additional methods it defines. In this case, the method_descriptors array does not list any methods that the interface inherits from its parent and the parent_interface field contains a byte offset to the InterfaceDescriptor of its parent interface. Note: the XPIDL compiler is not required to compress interface descriptions in this manner - it's purely a space optimization.
The number of methods in the method_descriptors array.
This is a byte offset from the beginning of the data pool to an array of MethodDescriptor objects. The length of the array is determined by the num_methods field.
MethodDescriptor {
boolean is_getter;
boolean is_setter;
uint6 reserved;
String* name;
uint8 num_args;
ParamDescriptor params[num_args];
ParamDescriptor result;
}
This field is used to allow interface methods to act as property getters for object-oriented languages such as JavaScript. For example, if there was an XPCOM method named "get_Banjo", you could access a "Banjo" property on an interface like this: 'myInterface.Banjo'. If is_getter is true, then the "get_" prefix should be stripped off the method's name by the XPIDL compiler.
This field is used to allow interface methods to act as property setters for object-oriented languages such as JavaScript. For example, if there was an XPCOM method named "set_Banjo", you could assign to a "Banjo" property on an interface like this: 'myInterface.Banjo = 3'. If is_setter is true, then the "set_" prefix should be stripped off the method's name by the XPIDL compiler.
The human-readable name of this method, e.g. "getWindow", stored in the String record format.
The number of arguments that the method consumes. Also, the number of elements in the params array.
This is a byte offset from the beginning of the data pool to an array of ParamDescriptor objects. The length of the array is determined by the num_args field.
This is a byte offset from the beginning of the data pool to a single ParamDescriptor object that identifies the type of the method return value.
ParamDescriptor {
boolean in;
boolean out;
uint6 reserved;
TypeDescriptor type;
}
If in is true, it indicates that the parameter is to be passed from caller to callee.
If out is true, it indicates that the parameter is to be passed from callee to caller. Out parameters must have pointer type. It is possible for a parameter to have both out and in bits set.
A 6-bit field reserved for future use.
The type of the method parameter.
To efficiently describe all the type categories listed above, there are several different variants of TypeDescriptor records:
union TypeDescriptor {The first byte of all these TypeDescriptor variants has the identical layout:
SimpleTypeDescriptor;
InterfaceTypeDescriptor;
InterfaceIsTypeDescriptor;
}
TypeDescriptorPrefix {
boolean is_pointer;
boolean is_unique_pointer;
boolean is_reference;
uint5 tag;
}
This field is true only when representing C pointer/reference types.
This field cannot have a value of true unless is_pointer is also true. The unique_pointer field indicates if the parameter value can be aliased to another parameter value. If unique_pointer is true, it must not be possible to reach the memory pointed at by this argument value from any other argument to the method.
This field cannot have a value of true unless is_pointer is also true. This field is true if the parameter is a reference, which is to say, it's a pointer that can't have a value of NULL.
The tag field indicates which of the variant TypeDescriptor records is being used, and hence the way any remaining fields should be parsed.
Value in tag field TypeDescriptor variant to use 0..15 SimpleTypeDescriptor 16 InterfaceTypeDescriptor 17 InterfaceIsTypeDescriptor 18..31 reserved
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InterfaceTypeDescriptor {
boolean is_pointer;
boolean is_unique_pointer;
boolean is_reference;
uint5 tag;
InterfaceDescriptor* interface;
}
When this field is false, the represented type is an interface pointer. When is_pointer is true, the represented type is a pointer to an interface pointer.
The tag field must have the decimal value 16.
InterfaceIsTypeDescriptor {
boolean is_pointer;
boolean is_unique_pointer;
boolean is_reference;
uint5 tag;
uint8 arg_num;
}
The tag field must have the decimal value 17.
The index of the method argument that describes the type of the interface pointer. The specified method argument must have type nsIID*.
String {
uint16 length;
char bytes[];
}
The length of the string, in characters (not bytes).
Unicode string encoded in UTF-8 format, with no null-termination. The length of the bytes array, measured in Unicode characters (not bytes), is reported by the length field.