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author | Matt A. Tobin <mattatobin@localhost.localdomain> | 2018-02-02 04:16:08 -0500 |
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committer | Matt A. Tobin <mattatobin@localhost.localdomain> | 2018-02-02 04:16:08 -0500 |
commit | 5f8de423f190bbb79a62f804151bc24824fa32d8 (patch) | |
tree | 10027f336435511475e392454359edea8e25895d /js/src/ctypes/libffi/doc | |
parent | 49ee0794b5d912db1f95dce6eb52d781dc210db5 (diff) | |
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diff --git a/js/src/ctypes/libffi/doc/libffi.info b/js/src/ctypes/libffi/doc/libffi.info new file mode 100755 index 000000000..399093947 --- /dev/null +++ b/js/src/ctypes/libffi/doc/libffi.info @@ -0,0 +1,618 @@ +This is libffi.info, produced by makeinfo version 5.1 from libffi.texi. + +This manual is for Libffi, a portable foreign-function interface +library. + + Copyright (C) 2008, 2010, 2011 Red Hat, Inc. + + Permission is granted to copy, distribute and/or modify this + document under the terms of the GNU General Public License as + published by the Free Software Foundation; either version 2, or (at + your option) any later version. A copy of the license is included + in the section entitled "GNU General Public License". + +INFO-DIR-SECTION Development +START-INFO-DIR-ENTRY +* libffi: (libffi). Portable foreign-function interface library. +END-INFO-DIR-ENTRY + + +File: libffi.info, Node: Top, Next: Introduction, Up: (dir) + +libffi +****** + +This manual is for Libffi, a portable foreign-function interface +library. + + Copyright (C) 2008, 2010, 2011 Red Hat, Inc. + + Permission is granted to copy, distribute and/or modify this + document under the terms of the GNU General Public License as + published by the Free Software Foundation; either version 2, or (at + your option) any later version. A copy of the license is included + in the section entitled "GNU General Public License". + +* Menu: + +* Introduction:: What is libffi? +* Using libffi:: How to use libffi. +* Missing Features:: Things libffi can't do. +* Index:: Index. + + +File: libffi.info, Node: Introduction, Next: Using libffi, Prev: Top, Up: Top + +1 What is libffi? +***************** + +Compilers for high level languages generate code that follow certain +conventions. These conventions are necessary, in part, for separate +compilation to work. One such convention is the "calling convention". +The calling convention is a set of assumptions made by the compiler +about where function arguments will be found on entry to a function. A +calling convention also specifies where the return value for a function +is found. The calling convention is also sometimes called the "ABI" or +"Application Binary Interface". + + Some programs may not know at the time of compilation what arguments +are to be passed to a function. For instance, an interpreter may be +told at run-time about the number and types of arguments used to call a +given function. 'Libffi' can be used in such programs to provide a +bridge from the interpreter program to compiled code. + + The 'libffi' library provides a portable, high level programming +interface to various calling conventions. This allows a programmer to +call any function specified by a call interface description at run time. + + FFI stands for Foreign Function Interface. A foreign function +interface is the popular name for the interface that allows code written +in one language to call code written in another language. The 'libffi' +library really only provides the lowest, machine dependent layer of a +fully featured foreign function interface. A layer must exist above +'libffi' that handles type conversions for values passed between the two +languages. + + +File: libffi.info, Node: Using libffi, Next: Missing Features, Prev: Introduction, Up: Top + +2 Using libffi +************** + +* Menu: + +* The Basics:: The basic libffi API. +* Simple Example:: A simple example. +* Types:: libffi type descriptions. +* Multiple ABIs:: Different passing styles on one platform. +* The Closure API:: Writing a generic function. +* Closure Example:: A closure example. + + +File: libffi.info, Node: The Basics, Next: Simple Example, Up: Using libffi + +2.1 The Basics +============== + +'Libffi' assumes that you have a pointer to the function you wish to +call and that you know the number and types of arguments to pass it, as +well as the return type of the function. + + The first thing you must do is create an 'ffi_cif' object that +matches the signature of the function you wish to call. This is a +separate step because it is common to make multiple calls using a single +'ffi_cif'. The "cif" in 'ffi_cif' stands for Call InterFace. To +prepare a call interface object, use the function 'ffi_prep_cif'. + + -- Function: ffi_status ffi_prep_cif (ffi_cif *CIF, ffi_abi ABI, + unsigned int NARGS, ffi_type *RTYPE, ffi_type **ARGTYPES) + This initializes CIF according to the given parameters. + + ABI is the ABI to use; normally 'FFI_DEFAULT_ABI' is what you want. + *note Multiple ABIs:: for more information. + + NARGS is the number of arguments that this function accepts. + + RTYPE is a pointer to an 'ffi_type' structure that describes the + return type of the function. *Note Types::. + + ARGTYPES is a vector of 'ffi_type' pointers. ARGTYPES must have + NARGS elements. If NARGS is 0, this argument is ignored. + + 'ffi_prep_cif' returns a 'libffi' status code, of type + 'ffi_status'. This will be either 'FFI_OK' if everything worked + properly; 'FFI_BAD_TYPEDEF' if one of the 'ffi_type' objects is + incorrect; or 'FFI_BAD_ABI' if the ABI parameter is invalid. + + If the function being called is variadic (varargs) then +'ffi_prep_cif_var' must be used instead of 'ffi_prep_cif'. + + -- Function: ffi_status ffi_prep_cif_var (ffi_cif *CIF, ffi_abi varabi, + unsigned int NFIXEDARGS, unsigned int varntotalargs, ffi_type + *RTYPE, ffi_type **ARGTYPES) + This initializes CIF according to the given parameters for a call + to a variadic function. In general it's operation is the same as + for 'ffi_prep_cif' except that: + + NFIXEDARGS is the number of fixed arguments, prior to any variadic + arguments. It must be greater than zero. + + NTOTALARGS the total number of arguments, including variadic and + fixed arguments. + + Note that, different cif's must be prepped for calls to the same + function when different numbers of arguments are passed. + + Also note that a call to 'ffi_prep_cif_var' with + NFIXEDARGS=NOTOTALARGS is NOT equivalent to a call to + 'ffi_prep_cif'. + + To call a function using an initialized 'ffi_cif', use the 'ffi_call' +function: + + -- Function: void ffi_call (ffi_cif *CIF, void *FN, void *RVALUE, void + **AVALUES) + This calls the function FN according to the description given in + CIF. CIF must have already been prepared using 'ffi_prep_cif'. + + RVALUE is a pointer to a chunk of memory that will hold the result + of the function call. This must be large enough to hold the + result, no smaller than the system register size (generally 32 or + 64 bits), and must be suitably aligned; it is the caller's + responsibility to ensure this. If CIF declares that the function + returns 'void' (using 'ffi_type_void'), then RVALUE is ignored. + + AVALUES is a vector of 'void *' pointers that point to the memory + locations holding the argument values for a call. If CIF declares + that the function has no arguments (i.e., NARGS was 0), then + AVALUES is ignored. Note that argument values may be modified by + the callee (for instance, structs passed by value); the burden of + copying pass-by-value arguments is placed on the caller. + + +File: libffi.info, Node: Simple Example, Next: Types, Prev: The Basics, Up: Using libffi + +2.2 Simple Example +================== + +Here is a trivial example that calls 'puts' a few times. + + #include <stdio.h> + #include <ffi.h> + + int main() + { + ffi_cif cif; + ffi_type *args[1]; + void *values[1]; + char *s; + ffi_arg rc; + + /* Initialize the argument info vectors */ + args[0] = &ffi_type_pointer; + values[0] = &s; + + /* Initialize the cif */ + if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, 1, + &ffi_type_sint, args) == FFI_OK) + { + s = "Hello World!"; + ffi_call(&cif, puts, &rc, values); + /* rc now holds the result of the call to puts */ + + /* values holds a pointer to the function's arg, so to + call puts() again all we need to do is change the + value of s */ + s = "This is cool!"; + ffi_call(&cif, puts, &rc, values); + } + + return 0; + } + + +File: libffi.info, Node: Types, Next: Multiple ABIs, Prev: Simple Example, Up: Using libffi + +2.3 Types +========= + +* Menu: + +* Primitive Types:: Built-in types. +* Structures:: Structure types. +* Type Example:: Structure type example. + + +File: libffi.info, Node: Primitive Types, Next: Structures, Up: Types + +2.3.1 Primitive Types +--------------------- + +'Libffi' provides a number of built-in type descriptors that can be used +to describe argument and return types: + +'ffi_type_void' + The type 'void'. This cannot be used for argument types, only for + return values. + +'ffi_type_uint8' + An unsigned, 8-bit integer type. + +'ffi_type_sint8' + A signed, 8-bit integer type. + +'ffi_type_uint16' + An unsigned, 16-bit integer type. + +'ffi_type_sint16' + A signed, 16-bit integer type. + +'ffi_type_uint32' + An unsigned, 32-bit integer type. + +'ffi_type_sint32' + A signed, 32-bit integer type. + +'ffi_type_uint64' + An unsigned, 64-bit integer type. + +'ffi_type_sint64' + A signed, 64-bit integer type. + +'ffi_type_float' + The C 'float' type. + +'ffi_type_double' + The C 'double' type. + +'ffi_type_uchar' + The C 'unsigned char' type. + +'ffi_type_schar' + The C 'signed char' type. (Note that there is not an exact + equivalent to the C 'char' type in 'libffi'; ordinarily you should + either use 'ffi_type_schar' or 'ffi_type_uchar' depending on + whether 'char' is signed.) + +'ffi_type_ushort' + The C 'unsigned short' type. + +'ffi_type_sshort' + The C 'short' type. + +'ffi_type_uint' + The C 'unsigned int' type. + +'ffi_type_sint' + The C 'int' type. + +'ffi_type_ulong' + The C 'unsigned long' type. + +'ffi_type_slong' + The C 'long' type. + +'ffi_type_longdouble' + On platforms that have a C 'long double' type, this is defined. On + other platforms, it is not. + +'ffi_type_pointer' + A generic 'void *' pointer. You should use this for all pointers, + regardless of their real type. + + Each of these is of type 'ffi_type', so you must take the address +when passing to 'ffi_prep_cif'. + + +File: libffi.info, Node: Structures, Next: Type Example, Prev: Primitive Types, Up: Types + +2.3.2 Structures +---------------- + +Although 'libffi' has no special support for unions or bit-fields, it is +perfectly happy passing structures back and forth. You must first +describe the structure to 'libffi' by creating a new 'ffi_type' object +for it. + + -- Data type: ffi_type + The 'ffi_type' has the following members: + 'size_t size' + This is set by 'libffi'; you should initialize it to zero. + + 'unsigned short alignment' + This is set by 'libffi'; you should initialize it to zero. + + 'unsigned short type' + For a structure, this should be set to 'FFI_TYPE_STRUCT'. + + 'ffi_type **elements' + This is a 'NULL'-terminated array of pointers to 'ffi_type' + objects. There is one element per field of the struct. + + +File: libffi.info, Node: Type Example, Prev: Structures, Up: Types + +2.3.3 Type Example +------------------ + +The following example initializes a 'ffi_type' object representing the +'tm' struct from Linux's 'time.h'. + + Here is how the struct is defined: + + struct tm { + int tm_sec; + int tm_min; + int tm_hour; + int tm_mday; + int tm_mon; + int tm_year; + int tm_wday; + int tm_yday; + int tm_isdst; + /* Those are for future use. */ + long int __tm_gmtoff__; + __const char *__tm_zone__; + }; + + Here is the corresponding code to describe this struct to 'libffi': + + { + ffi_type tm_type; + ffi_type *tm_type_elements[12]; + int i; + + tm_type.size = tm_type.alignment = 0; + tm_type.type = FFI_TYPE_STRUCT; + tm_type.elements = &tm_type_elements; + + for (i = 0; i < 9; i++) + tm_type_elements[i] = &ffi_type_sint; + + tm_type_elements[9] = &ffi_type_slong; + tm_type_elements[10] = &ffi_type_pointer; + tm_type_elements[11] = NULL; + + /* tm_type can now be used to represent tm argument types and + return types for ffi_prep_cif() */ + } + + +File: libffi.info, Node: Multiple ABIs, Next: The Closure API, Prev: Types, Up: Using libffi + +2.4 Multiple ABIs +================= + +A given platform may provide multiple different ABIs at once. For +instance, the x86 platform has both 'stdcall' and 'fastcall' functions. + + 'libffi' provides some support for this. However, this is +necessarily platform-specific. + + +File: libffi.info, Node: The Closure API, Next: Closure Example, Prev: Multiple ABIs, Up: Using libffi + +2.5 The Closure API +=================== + +'libffi' also provides a way to write a generic function - a function +that can accept and decode any combination of arguments. This can be +useful when writing an interpreter, or to provide wrappers for arbitrary +functions. + + This facility is called the "closure API". Closures are not supported +on all platforms; you can check the 'FFI_CLOSURES' define to determine +whether they are supported on the current platform. + + Because closures work by assembling a tiny function at runtime, they +require special allocation on platforms that have a non-executable heap. +Memory management for closures is handled by a pair of functions: + + -- Function: void *ffi_closure_alloc (size_t SIZE, void **CODE) + Allocate a chunk of memory holding SIZE bytes. This returns a + pointer to the writable address, and sets *CODE to the + corresponding executable address. + + SIZE should be sufficient to hold a 'ffi_closure' object. + + -- Function: void ffi_closure_free (void *WRITABLE) + Free memory allocated using 'ffi_closure_alloc'. The argument is + the writable address that was returned. + + Once you have allocated the memory for a closure, you must construct +a 'ffi_cif' describing the function call. Finally you can prepare the +closure function: + + -- Function: ffi_status ffi_prep_closure_loc (ffi_closure *CLOSURE, + ffi_cif *CIF, void (*FUN) (ffi_cif *CIF, void *RET, void + **ARGS, void *USER_DATA), void *USER_DATA, void *CODELOC) + Prepare a closure function. + + CLOSURE is the address of a 'ffi_closure' object; this is the + writable address returned by 'ffi_closure_alloc'. + + CIF is the 'ffi_cif' describing the function parameters. + + USER_DATA is an arbitrary datum that is passed, uninterpreted, to + your closure function. + + CODELOC is the executable address returned by 'ffi_closure_alloc'. + + FUN is the function which will be called when the closure is + invoked. It is called with the arguments: + CIF + The 'ffi_cif' passed to 'ffi_prep_closure_loc'. + + RET + A pointer to the memory used for the function's return value. + FUN must fill this, unless the function is declared as + returning 'void'. + + ARGS + A vector of pointers to memory holding the arguments to the + function. + + USER_DATA + The same USER_DATA that was passed to 'ffi_prep_closure_loc'. + + 'ffi_prep_closure_loc' will return 'FFI_OK' if everything went ok, + and something else on error. + + After calling 'ffi_prep_closure_loc', you can cast CODELOC to the + appropriate pointer-to-function type. + + You may see old code referring to 'ffi_prep_closure'. This function +is deprecated, as it cannot handle the need for separate writable and +executable addresses. + + +File: libffi.info, Node: Closure Example, Prev: The Closure API, Up: Using libffi + +2.6 Closure Example +=================== + +A trivial example that creates a new 'puts' by binding 'fputs' with +'stdout'. + + #include <stdio.h> + #include <ffi.h> + + /* Acts like puts with the file given at time of enclosure. */ + void puts_binding(ffi_cif *cif, void *ret, void* args[], + void *stream) + { + *(ffi_arg *)ret = fputs(*(char **)args[0], (FILE *)stream); + } + + typedef int (*puts_t)(char *); + + int main() + { + ffi_cif cif; + ffi_type *args[1]; + ffi_closure *closure; + + void *bound_puts; + int rc; + + /* Allocate closure and bound_puts */ + closure = ffi_closure_alloc(sizeof(ffi_closure), &bound_puts); + + if (closure) + { + /* Initialize the argument info vectors */ + args[0] = &ffi_type_pointer; + + /* Initialize the cif */ + if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, 1, + &ffi_type_sint, args) == FFI_OK) + { + /* Initialize the closure, setting stream to stdout */ + if (ffi_prep_closure_loc(closure, &cif, puts_binding, + stdout, bound_puts) == FFI_OK) + { + rc = ((puts_t)bound_puts)("Hello World!"); + /* rc now holds the result of the call to fputs */ + } + } + } + + /* Deallocate both closure, and bound_puts */ + ffi_closure_free(closure); + + return 0; + } + + +File: libffi.info, Node: Missing Features, Next: Index, Prev: Using libffi, Up: Top + +3 Missing Features +****************** + +'libffi' is missing a few features. We welcome patches to add support +for these. + + * Variadic closures. + + * There is no support for bit fields in structures. + + * The closure API is + + * The "raw" API is undocumented. + + Note that variadic support is very new and tested on a relatively +small number of platforms. + + +File: libffi.info, Node: Index, Prev: Missing Features, Up: Top + +Index +***** + + +* Menu: + +* ABI: Introduction. (line 13) +* Application Binary Interface: Introduction. (line 13) +* calling convention: Introduction. (line 13) +* cif: The Basics. (line 14) +* closure API: The Closure API. (line 13) +* closures: The Closure API. (line 13) +* FFI: Introduction. (line 31) +* ffi_call: The Basics. (line 62) +* FFI_CLOSURES: The Closure API. (line 13) +* ffi_closure_alloc: The Closure API. (line 19) +* ffi_closure_free: The Closure API. (line 26) +* ffi_prep_cif: The Basics. (line 16) +* ffi_prep_cif_var: The Basics. (line 39) +* ffi_prep_closure_loc: The Closure API. (line 34) +* ffi_status: The Basics. (line 16) +* ffi_status <1>: The Basics. (line 39) +* ffi_status <2>: The Closure API. (line 34) +* ffi_type: Structures. (line 11) +* ffi_type <1>: Structures. (line 11) +* ffi_type_double: Primitive Types. (line 41) +* ffi_type_float: Primitive Types. (line 38) +* ffi_type_longdouble: Primitive Types. (line 71) +* ffi_type_pointer: Primitive Types. (line 75) +* ffi_type_schar: Primitive Types. (line 47) +* ffi_type_sint: Primitive Types. (line 62) +* ffi_type_sint16: Primitive Types. (line 23) +* ffi_type_sint32: Primitive Types. (line 29) +* ffi_type_sint64: Primitive Types. (line 35) +* ffi_type_sint8: Primitive Types. (line 17) +* ffi_type_slong: Primitive Types. (line 68) +* ffi_type_sshort: Primitive Types. (line 56) +* ffi_type_uchar: Primitive Types. (line 44) +* ffi_type_uint: Primitive Types. (line 59) +* ffi_type_uint16: Primitive Types. (line 20) +* ffi_type_uint32: Primitive Types. (line 26) +* ffi_type_uint64: Primitive Types. (line 32) +* ffi_type_uint8: Primitive Types. (line 14) +* ffi_type_ulong: Primitive Types. (line 65) +* ffi_type_ushort: Primitive Types. (line 53) +* ffi_type_void: Primitive Types. (line 10) +* Foreign Function Interface: Introduction. (line 31) +* void: The Basics. (line 62) +* void <1>: The Closure API. (line 19) +* void <2>: The Closure API. (line 26) + + + +Tag Table: +Node: Top682 +Node: Introduction1429 +Node: Using libffi3061 +Node: The Basics3547 +Node: Simple Example7198 +Node: Types8229 +Node: Primitive Types8512 +Node: Structures10333 +Node: Type Example11207 +Node: Multiple ABIs12473 +Node: The Closure API12844 +Node: Closure Example15788 +Node: Missing Features17397 +Node: Index17850 + +End Tag Table diff --git a/js/src/ctypes/libffi/doc/libffi.texi b/js/src/ctypes/libffi/doc/libffi.texi new file mode 100644 index 000000000..a2b124280 --- /dev/null +++ b/js/src/ctypes/libffi/doc/libffi.texi @@ -0,0 +1,625 @@ +\input texinfo @c -*-texinfo-*- +@c %**start of header +@setfilename libffi.info +@settitle libffi +@setchapternewpage off +@c %**end of header + +@c Merge the standard indexes into a single one. +@syncodeindex fn cp +@syncodeindex vr cp +@syncodeindex ky cp +@syncodeindex pg cp +@syncodeindex tp cp + +@include version.texi + +@copying + +This manual is for Libffi, a portable foreign-function interface +library. + +Copyright @copyright{} 2008, 2010, 2011 Red Hat, Inc. + +@quotation +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU General Public License as published by the +Free Software Foundation; either version 2, or (at your option) any +later version. A copy of the license is included in the +section entitled ``GNU General Public License''. + +@end quotation +@end copying + +@dircategory Development +@direntry +* libffi: (libffi). Portable foreign-function interface library. +@end direntry + +@titlepage +@title Libffi +@page +@vskip 0pt plus 1filll +@insertcopying +@end titlepage + + +@ifnottex +@node Top +@top libffi + +@insertcopying + +@menu +* Introduction:: What is libffi? +* Using libffi:: How to use libffi. +* Missing Features:: Things libffi can't do. +* Index:: Index. +@end menu + +@end ifnottex + + +@node Introduction +@chapter What is libffi? + +Compilers for high level languages generate code that follow certain +conventions. These conventions are necessary, in part, for separate +compilation to work. One such convention is the @dfn{calling +convention}. The calling convention is a set of assumptions made by +the compiler about where function arguments will be found on entry to +a function. A calling convention also specifies where the return +value for a function is found. The calling convention is also +sometimes called the @dfn{ABI} or @dfn{Application Binary Interface}. +@cindex calling convention +@cindex ABI +@cindex Application Binary Interface + +Some programs may not know at the time of compilation what arguments +are to be passed to a function. For instance, an interpreter may be +told at run-time about the number and types of arguments used to call +a given function. @samp{Libffi} can be used in such programs to +provide a bridge from the interpreter program to compiled code. + +The @samp{libffi} library provides a portable, high level programming +interface to various calling conventions. This allows a programmer to +call any function specified by a call interface description at run +time. + +@acronym{FFI} stands for Foreign Function Interface. A foreign +function interface is the popular name for the interface that allows +code written in one language to call code written in another language. +The @samp{libffi} library really only provides the lowest, machine +dependent layer of a fully featured foreign function interface. A +layer must exist above @samp{libffi} that handles type conversions for +values passed between the two languages. +@cindex FFI +@cindex Foreign Function Interface + + +@node Using libffi +@chapter Using libffi + +@menu +* The Basics:: The basic libffi API. +* Simple Example:: A simple example. +* Types:: libffi type descriptions. +* Multiple ABIs:: Different passing styles on one platform. +* The Closure API:: Writing a generic function. +* Closure Example:: A closure example. +@end menu + + +@node The Basics +@section The Basics + +@samp{Libffi} assumes that you have a pointer to the function you wish +to call and that you know the number and types of arguments to pass +it, as well as the return type of the function. + +The first thing you must do is create an @code{ffi_cif} object that +matches the signature of the function you wish to call. This is a +separate step because it is common to make multiple calls using a +single @code{ffi_cif}. The @dfn{cif} in @code{ffi_cif} stands for +Call InterFace. To prepare a call interface object, use the function +@code{ffi_prep_cif}. +@cindex cif + +@findex ffi_prep_cif +@defun ffi_status ffi_prep_cif (ffi_cif *@var{cif}, ffi_abi @var{abi}, unsigned int @var{nargs}, ffi_type *@var{rtype}, ffi_type **@var{argtypes}) +This initializes @var{cif} according to the given parameters. + +@var{abi} is the ABI to use; normally @code{FFI_DEFAULT_ABI} is what +you want. @ref{Multiple ABIs} for more information. + +@var{nargs} is the number of arguments that this function accepts. + +@var{rtype} is a pointer to an @code{ffi_type} structure that +describes the return type of the function. @xref{Types}. + +@var{argtypes} is a vector of @code{ffi_type} pointers. +@var{argtypes} must have @var{nargs} elements. If @var{nargs} is 0, +this argument is ignored. + +@code{ffi_prep_cif} returns a @code{libffi} status code, of type +@code{ffi_status}. This will be either @code{FFI_OK} if everything +worked properly; @code{FFI_BAD_TYPEDEF} if one of the @code{ffi_type} +objects is incorrect; or @code{FFI_BAD_ABI} if the @var{abi} parameter +is invalid. +@end defun + +If the function being called is variadic (varargs) then +@code{ffi_prep_cif_var} must be used instead of @code{ffi_prep_cif}. + +@findex ffi_prep_cif_var +@defun ffi_status ffi_prep_cif_var (ffi_cif *@var{cif}, ffi_abi var{abi}, unsigned int @var{nfixedargs}, unsigned int var{ntotalargs}, ffi_type *@var{rtype}, ffi_type **@var{argtypes}) +This initializes @var{cif} according to the given parameters for +a call to a variadic function. In general it's operation is the +same as for @code{ffi_prep_cif} except that: + +@var{nfixedargs} is the number of fixed arguments, prior to any +variadic arguments. It must be greater than zero. + +@var{ntotalargs} the total number of arguments, including variadic +and fixed arguments. + +Note that, different cif's must be prepped for calls to the same +function when different numbers of arguments are passed. + +Also note that a call to @code{ffi_prep_cif_var} with +@var{nfixedargs}=@var{nototalargs} is NOT equivalent to a call to +@code{ffi_prep_cif}. + +@end defun + + +To call a function using an initialized @code{ffi_cif}, use the +@code{ffi_call} function: + +@findex ffi_call +@defun void ffi_call (ffi_cif *@var{cif}, void *@var{fn}, void *@var{rvalue}, void **@var{avalues}) +This calls the function @var{fn} according to the description given in +@var{cif}. @var{cif} must have already been prepared using +@code{ffi_prep_cif}. + +@var{rvalue} is a pointer to a chunk of memory that will hold the +result of the function call. This must be large enough to hold the +result, no smaller than the system register size (generally 32 or 64 +bits), and must be suitably aligned; it is the caller's responsibility +to ensure this. If @var{cif} declares that the function returns +@code{void} (using @code{ffi_type_void}), then @var{rvalue} is +ignored. + +@var{avalues} is a vector of @code{void *} pointers that point to the +memory locations holding the argument values for a call. If @var{cif} +declares that the function has no arguments (i.e., @var{nargs} was 0), +then @var{avalues} is ignored. Note that argument values may be +modified by the callee (for instance, structs passed by value); the +burden of copying pass-by-value arguments is placed on the caller. +@end defun + + +@node Simple Example +@section Simple Example + +Here is a trivial example that calls @code{puts} a few times. + +@example +#include <stdio.h> +#include <ffi.h> + +int main() +@{ + ffi_cif cif; + ffi_type *args[1]; + void *values[1]; + char *s; + ffi_arg rc; + + /* Initialize the argument info vectors */ + args[0] = &ffi_type_pointer; + values[0] = &s; + + /* Initialize the cif */ + if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, 1, + &ffi_type_sint, args) == FFI_OK) + @{ + s = "Hello World!"; + ffi_call(&cif, puts, &rc, values); + /* rc now holds the result of the call to puts */ + + /* values holds a pointer to the function's arg, so to + call puts() again all we need to do is change the + value of s */ + s = "This is cool!"; + ffi_call(&cif, puts, &rc, values); + @} + + return 0; +@} +@end example + + +@node Types +@section Types + +@menu +* Primitive Types:: Built-in types. +* Structures:: Structure types. +* Type Example:: Structure type example. +@end menu + +@node Primitive Types +@subsection Primitive Types + +@code{Libffi} provides a number of built-in type descriptors that can +be used to describe argument and return types: + +@table @code +@item ffi_type_void +@tindex ffi_type_void +The type @code{void}. This cannot be used for argument types, only +for return values. + +@item ffi_type_uint8 +@tindex ffi_type_uint8 +An unsigned, 8-bit integer type. + +@item ffi_type_sint8 +@tindex ffi_type_sint8 +A signed, 8-bit integer type. + +@item ffi_type_uint16 +@tindex ffi_type_uint16 +An unsigned, 16-bit integer type. + +@item ffi_type_sint16 +@tindex ffi_type_sint16 +A signed, 16-bit integer type. + +@item ffi_type_uint32 +@tindex ffi_type_uint32 +An unsigned, 32-bit integer type. + +@item ffi_type_sint32 +@tindex ffi_type_sint32 +A signed, 32-bit integer type. + +@item ffi_type_uint64 +@tindex ffi_type_uint64 +An unsigned, 64-bit integer type. + +@item ffi_type_sint64 +@tindex ffi_type_sint64 +A signed, 64-bit integer type. + +@item ffi_type_float +@tindex ffi_type_float +The C @code{float} type. + +@item ffi_type_double +@tindex ffi_type_double +The C @code{double} type. + +@item ffi_type_uchar +@tindex ffi_type_uchar +The C @code{unsigned char} type. + +@item ffi_type_schar +@tindex ffi_type_schar +The C @code{signed char} type. (Note that there is not an exact +equivalent to the C @code{char} type in @code{libffi}; ordinarily you +should either use @code{ffi_type_schar} or @code{ffi_type_uchar} +depending on whether @code{char} is signed.) + +@item ffi_type_ushort +@tindex ffi_type_ushort +The C @code{unsigned short} type. + +@item ffi_type_sshort +@tindex ffi_type_sshort +The C @code{short} type. + +@item ffi_type_uint +@tindex ffi_type_uint +The C @code{unsigned int} type. + +@item ffi_type_sint +@tindex ffi_type_sint +The C @code{int} type. + +@item ffi_type_ulong +@tindex ffi_type_ulong +The C @code{unsigned long} type. + +@item ffi_type_slong +@tindex ffi_type_slong +The C @code{long} type. + +@item ffi_type_longdouble +@tindex ffi_type_longdouble +On platforms that have a C @code{long double} type, this is defined. +On other platforms, it is not. + +@item ffi_type_pointer +@tindex ffi_type_pointer +A generic @code{void *} pointer. You should use this for all +pointers, regardless of their real type. +@end table + +Each of these is of type @code{ffi_type}, so you must take the address +when passing to @code{ffi_prep_cif}. + + +@node Structures +@subsection Structures + +Although @samp{libffi} has no special support for unions or +bit-fields, it is perfectly happy passing structures back and forth. +You must first describe the structure to @samp{libffi} by creating a +new @code{ffi_type} object for it. + +@tindex ffi_type +@deftp {Data type} ffi_type +The @code{ffi_type} has the following members: +@table @code +@item size_t size +This is set by @code{libffi}; you should initialize it to zero. + +@item unsigned short alignment +This is set by @code{libffi}; you should initialize it to zero. + +@item unsigned short type +For a structure, this should be set to @code{FFI_TYPE_STRUCT}. + +@item ffi_type **elements +This is a @samp{NULL}-terminated array of pointers to @code{ffi_type} +objects. There is one element per field of the struct. +@end table +@end deftp + + +@node Type Example +@subsection Type Example + +The following example initializes a @code{ffi_type} object +representing the @code{tm} struct from Linux's @file{time.h}. + +Here is how the struct is defined: + +@example +struct tm @{ + int tm_sec; + int tm_min; + int tm_hour; + int tm_mday; + int tm_mon; + int tm_year; + int tm_wday; + int tm_yday; + int tm_isdst; + /* Those are for future use. */ + long int __tm_gmtoff__; + __const char *__tm_zone__; +@}; +@end example + +Here is the corresponding code to describe this struct to +@code{libffi}: + +@example + @{ + ffi_type tm_type; + ffi_type *tm_type_elements[12]; + int i; + + tm_type.size = tm_type.alignment = 0; + tm_type.type = FFI_TYPE_STRUCT; + tm_type.elements = &tm_type_elements; + + for (i = 0; i < 9; i++) + tm_type_elements[i] = &ffi_type_sint; + + tm_type_elements[9] = &ffi_type_slong; + tm_type_elements[10] = &ffi_type_pointer; + tm_type_elements[11] = NULL; + + /* tm_type can now be used to represent tm argument types and + return types for ffi_prep_cif() */ + @} +@end example + + +@node Multiple ABIs +@section Multiple ABIs + +A given platform may provide multiple different ABIs at once. For +instance, the x86 platform has both @samp{stdcall} and @samp{fastcall} +functions. + +@code{libffi} provides some support for this. However, this is +necessarily platform-specific. + +@c FIXME: document the platforms + +@node The Closure API +@section The Closure API + +@code{libffi} also provides a way to write a generic function -- a +function that can accept and decode any combination of arguments. +This can be useful when writing an interpreter, or to provide wrappers +for arbitrary functions. + +This facility is called the @dfn{closure API}. Closures are not +supported on all platforms; you can check the @code{FFI_CLOSURES} +define to determine whether they are supported on the current +platform. +@cindex closures +@cindex closure API +@findex FFI_CLOSURES + +Because closures work by assembling a tiny function at runtime, they +require special allocation on platforms that have a non-executable +heap. Memory management for closures is handled by a pair of +functions: + +@findex ffi_closure_alloc +@defun void *ffi_closure_alloc (size_t @var{size}, void **@var{code}) +Allocate a chunk of memory holding @var{size} bytes. This returns a +pointer to the writable address, and sets *@var{code} to the +corresponding executable address. + +@var{size} should be sufficient to hold a @code{ffi_closure} object. +@end defun + +@findex ffi_closure_free +@defun void ffi_closure_free (void *@var{writable}) +Free memory allocated using @code{ffi_closure_alloc}. The argument is +the writable address that was returned. +@end defun + + +Once you have allocated the memory for a closure, you must construct a +@code{ffi_cif} describing the function call. Finally you can prepare +the closure function: + +@findex ffi_prep_closure_loc +@defun ffi_status ffi_prep_closure_loc (ffi_closure *@var{closure}, ffi_cif *@var{cif}, void (*@var{fun}) (ffi_cif *@var{cif}, void *@var{ret}, void **@var{args}, void *@var{user_data}), void *@var{user_data}, void *@var{codeloc}) +Prepare a closure function. + +@var{closure} is the address of a @code{ffi_closure} object; this is +the writable address returned by @code{ffi_closure_alloc}. + +@var{cif} is the @code{ffi_cif} describing the function parameters. + +@var{user_data} is an arbitrary datum that is passed, uninterpreted, +to your closure function. + +@var{codeloc} is the executable address returned by +@code{ffi_closure_alloc}. + +@var{fun} is the function which will be called when the closure is +invoked. It is called with the arguments: +@table @var +@item cif +The @code{ffi_cif} passed to @code{ffi_prep_closure_loc}. + +@item ret +A pointer to the memory used for the function's return value. +@var{fun} must fill this, unless the function is declared as returning +@code{void}. +@c FIXME: is this NULL for void-returning functions? + +@item args +A vector of pointers to memory holding the arguments to the function. + +@item user_data +The same @var{user_data} that was passed to +@code{ffi_prep_closure_loc}. +@end table + +@code{ffi_prep_closure_loc} will return @code{FFI_OK} if everything +went ok, and something else on error. +@c FIXME: what? + +After calling @code{ffi_prep_closure_loc}, you can cast @var{codeloc} +to the appropriate pointer-to-function type. +@end defun + +You may see old code referring to @code{ffi_prep_closure}. This +function is deprecated, as it cannot handle the need for separate +writable and executable addresses. + +@node Closure Example +@section Closure Example + +A trivial example that creates a new @code{puts} by binding +@code{fputs} with @code{stdout}. + +@example +#include <stdio.h> +#include <ffi.h> + +/* Acts like puts with the file given at time of enclosure. */ +void puts_binding(ffi_cif *cif, void *ret, void* args[], + void *stream) +@{ + *(ffi_arg *)ret = fputs(*(char **)args[0], (FILE *)stream); +@} + +typedef int (*puts_t)(char *); + +int main() +@{ + ffi_cif cif; + ffi_type *args[1]; + ffi_closure *closure; + + void *bound_puts; + int rc; + + /* Allocate closure and bound_puts */ + closure = ffi_closure_alloc(sizeof(ffi_closure), &bound_puts); + + if (closure) + @{ + /* Initialize the argument info vectors */ + args[0] = &ffi_type_pointer; + + /* Initialize the cif */ + if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, 1, + &ffi_type_sint, args) == FFI_OK) + @{ + /* Initialize the closure, setting stream to stdout */ + if (ffi_prep_closure_loc(closure, &cif, puts_binding, + stdout, bound_puts) == FFI_OK) + @{ + rc = ((puts_t)bound_puts)("Hello World!"); + /* rc now holds the result of the call to fputs */ + @} + @} + @} + + /* Deallocate both closure, and bound_puts */ + ffi_closure_free(closure); + + return 0; +@} + +@end example + + +@node Missing Features +@chapter Missing Features + +@code{libffi} is missing a few features. We welcome patches to add +support for these. + +@itemize @bullet +@item +Variadic closures. + +@item +There is no support for bit fields in structures. + +@item +The closure API is + +@c FIXME: ... + +@item +The ``raw'' API is undocumented. +@c argument promotion? +@c unions? +@c anything else? +@end itemize + +Note that variadic support is very new and tested on a relatively +small number of platforms. + +@node Index +@unnumbered Index + +@printindex cp + +@bye diff --git a/js/src/ctypes/libffi/doc/stamp-vti b/js/src/ctypes/libffi/doc/stamp-vti new file mode 100755 index 000000000..378595332 --- /dev/null +++ b/js/src/ctypes/libffi/doc/stamp-vti @@ -0,0 +1,4 @@ +@set UPDATED 25 April 2014 +@set UPDATED-MONTH April 2014 +@set EDITION 3.1 +@set VERSION 3.1 diff --git a/js/src/ctypes/libffi/doc/version.texi b/js/src/ctypes/libffi/doc/version.texi new file mode 100644 index 000000000..378595332 --- /dev/null +++ b/js/src/ctypes/libffi/doc/version.texi @@ -0,0 +1,4 @@ +@set UPDATED 25 April 2014 +@set UPDATED-MONTH April 2014 +@set EDITION 3.1 +@set VERSION 3.1 |