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- /*
- * Duktape 1.x compatible module loading framework
- */
- #include "duktape.h"
- #include "duk_module_duktape.h"
- /* (v)snprintf() is missing before MSVC 2015. Note that _(v)snprintf() does
- * NOT NUL terminate on truncation, but that's OK here.
- * http://stackoverflow.com/questions/2915672/snprintf-and-visual-studio-2010
- */
- #if defined(_MSC_VER) && (_MSC_VER < 1900)
- #define snprintf _snprintf
- #endif
- #if 0 /* Enable manually */
- #define DUK__ASSERT(x) do { \
- if (!(x)) { \
- fprintf(stderr, "ASSERTION FAILED at %s:%d: " #x "\n", __FILE__, __LINE__); \
- fflush(stderr); \
- } \
- } while (0)
- #define DUK__ASSERT_TOP(ctx,val) do { \
- DUK__ASSERT(duk_get_top((ctx)) == (val)); \
- } while (0)
- #else
- #define DUK__ASSERT(x) do { (void) (x); } while (0)
- #define DUK__ASSERT_TOP(ctx,val) do { (void) ctx; (void) (val); } while (0)
- #endif
- static void duk__resolve_module_id(duk_context *ctx, const char *req_id, const char *mod_id) {
- duk_uint8_t buf[DUK_COMMONJS_MODULE_ID_LIMIT];
- duk_uint8_t *p;
- duk_uint8_t *q;
- duk_uint8_t *q_last; /* last component */
- duk_int_t int_rc;
- DUK__ASSERT(req_id != NULL);
- /* mod_id may be NULL */
- /*
- * A few notes on the algorithm:
- *
- * - Terms are not allowed to begin with a period unless the term
- * is either '.' or '..'. This simplifies implementation (and
- * is within CommonJS modules specification).
- *
- * - There are few output bound checks here. This is on purpose:
- * the resolution input is length checked and the output is never
- * longer than the input. The resolved output is written directly
- * over the input because it's never longer than the input at any
- * point in the algorithm.
- *
- * - Non-ASCII characters are processed as individual bytes and
- * need no special treatment. However, U+0000 terminates the
- * algorithm; this is not an issue because U+0000 is not a
- * desirable term character anyway.
- */
- /*
- * Set up the resolution input which is the requested ID directly
- * (if absolute or no current module path) or with current module
- * ID prepended (if relative and current module path exists).
- *
- * Suppose current module is 'foo/bar' and relative path is './quux'.
- * The 'bar' component must be replaced so the initial input here is
- * 'foo/bar/.././quux'.
- */
- if (mod_id != NULL && req_id[0] == '.') {
- int_rc = snprintf((char *) buf, sizeof(buf), "%s/../%s", mod_id, req_id);
- } else {
- int_rc = snprintf((char *) buf, sizeof(buf), "%s", req_id);
- }
- if (int_rc >= (duk_int_t) sizeof(buf) || int_rc < 0) {
- /* Potentially truncated, NUL not guaranteed in any case.
- * The (int_rc < 0) case should not occur in practice.
- */
- goto resolve_error;
- }
- DUK__ASSERT(strlen((const char *) buf) < sizeof(buf)); /* at most sizeof(buf) - 1 */
- /*
- * Resolution loop. At the top of the loop we're expecting a valid
- * term: '.', '..', or a non-empty identifier not starting with a period.
- */
- p = buf;
- q = buf;
- for (;;) {
- duk_uint_fast8_t c;
- /* Here 'p' always points to the start of a term.
- *
- * We can also unconditionally reset q_last here: if this is
- * the last (non-empty) term q_last will have the right value
- * on loop exit.
- */
- DUK__ASSERT(p >= q); /* output is never longer than input during resolution */
- q_last = q;
- c = *p++;
- if (c == 0) {
- goto resolve_error;
- } else if (c == '.') {
- c = *p++;
- if (c == '/') {
- /* Term was '.' and is eaten entirely (including dup slashes). */
- goto eat_dup_slashes;
- }
- if (c == '.' && *p == '/') {
- /* Term was '..', backtrack resolved name by one component.
- * q[-1] = previous slash (or beyond start of buffer)
- * q[-2] = last char of previous component (or beyond start of buffer)
- */
- p++; /* eat (first) input slash */
- DUK__ASSERT(q >= buf);
- if (q == buf) {
- goto resolve_error;
- }
- DUK__ASSERT(*(q - 1) == '/');
- q--; /* Backtrack to last output slash (dups already eliminated). */
- for (;;) {
- /* Backtrack to previous slash or start of buffer. */
- DUK__ASSERT(q >= buf);
- if (q == buf) {
- break;
- }
- if (*(q - 1) == '/') {
- break;
- }
- q--;
- }
- goto eat_dup_slashes;
- }
- goto resolve_error;
- } else if (c == '/') {
- /* e.g. require('/foo'), empty terms not allowed */
- goto resolve_error;
- } else {
- for (;;) {
- /* Copy term name until end or '/'. */
- *q++ = c;
- c = *p++;
- if (c == 0) {
- /* This was the last term, and q_last was
- * updated to match this term at loop top.
- */
- goto loop_done;
- } else if (c == '/') {
- *q++ = '/';
- break;
- } else {
- /* write on next loop */
- }
- }
- }
- eat_dup_slashes:
- for (;;) {
- /* eat dup slashes */
- c = *p;
- if (c != '/') {
- break;
- }
- p++;
- }
- }
- loop_done:
- /* Output #1: resolved absolute name. */
- DUK__ASSERT(q >= buf);
- duk_push_lstring(ctx, (const char *) buf, (size_t) (q - buf));
- /* Output #2: last component name. */
- DUK__ASSERT(q >= q_last);
- DUK__ASSERT(q_last >= buf);
- duk_push_lstring(ctx, (const char *) q_last, (size_t) (q - q_last));
- return;
- resolve_error:
- (void) duk_type_error(ctx, "cannot resolve module id: %s", (const char *) req_id);
- }
- /* Stack indices for better readability. */
- #define DUK__IDX_REQUESTED_ID 0 /* module id requested */
- #define DUK__IDX_REQUIRE 1 /* current require() function */
- #define DUK__IDX_REQUIRE_ID 2 /* the base ID of the current require() function, resolution base */
- #define DUK__IDX_RESOLVED_ID 3 /* resolved, normalized absolute module ID */
- #define DUK__IDX_LASTCOMP 4 /* last component name in resolved path */
- #define DUK__IDX_DUKTAPE 5 /* Duktape object */
- #define DUK__IDX_MODLOADED 6 /* Duktape.modLoaded[] module cache */
- #define DUK__IDX_UNDEFINED 7 /* 'undefined', artifact of lookup */
- #define DUK__IDX_FRESH_REQUIRE 8 /* new require() function for module, updated resolution base */
- #define DUK__IDX_EXPORTS 9 /* default exports table */
- #define DUK__IDX_MODULE 10 /* module object containing module.exports, etc */
- static duk_ret_t duk__require(duk_context *ctx) {
- const char *str_req_id; /* requested identifier */
- const char *str_mod_id; /* require.id of current module */
- duk_int_t pcall_rc;
- /* NOTE: we try to minimize code size by avoiding unnecessary pops,
- * so the stack looks a bit cluttered in this function. DUK__ASSERT_TOP()
- * assertions are used to ensure stack configuration is correct at each
- * step.
- */
- /*
- * Resolve module identifier into canonical absolute form.
- */
- str_req_id = duk_require_string(ctx, DUK__IDX_REQUESTED_ID);
- duk_push_current_function(ctx);
- duk_get_prop_string(ctx, -1, "id");
- str_mod_id = duk_get_string(ctx, DUK__IDX_REQUIRE_ID); /* ignore non-strings */
- duk__resolve_module_id(ctx, str_req_id, str_mod_id);
- str_req_id = NULL;
- str_mod_id = NULL;
- /* [ requested_id require require.id resolved_id last_comp ] */
- DUK__ASSERT_TOP(ctx, DUK__IDX_LASTCOMP + 1);
- /*
- * Cached module check.
- *
- * If module has been loaded or its loading has already begun without
- * finishing, return the same cached value (module.exports). The
- * value is registered when module load starts so that circular
- * references can be supported to some extent.
- */
- duk_push_global_stash(ctx);
- duk_get_prop_string(ctx, -1, "\xff" "module:Duktape");
- duk_remove(ctx, -2); /* Lookup stashed, original 'Duktape' object. */
- duk_get_prop_string(ctx, DUK__IDX_DUKTAPE, "modLoaded"); /* Duktape.modLoaded */
- duk_require_type_mask(ctx, DUK__IDX_MODLOADED, DUK_TYPE_MASK_OBJECT);
- DUK__ASSERT_TOP(ctx, DUK__IDX_MODLOADED + 1);
- duk_dup(ctx, DUK__IDX_RESOLVED_ID);
- if (duk_get_prop(ctx, DUK__IDX_MODLOADED)) {
- /* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded Duktape.modLoaded[id] ] */
- duk_get_prop_string(ctx, -1, "exports"); /* return module.exports */
- return 1;
- }
- DUK__ASSERT_TOP(ctx, DUK__IDX_UNDEFINED + 1);
- /* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded undefined ] */
- /*
- * Module not loaded (and loading not started previously).
- *
- * Create a new require() function with 'id' set to resolved ID
- * of module being loaded. Also create 'exports' and 'module'
- * tables but don't register exports to the loaded table yet.
- * We don't want to do that unless the user module search callbacks
- * succeeds in finding the module.
- */
- /* Fresh require: require.id is left configurable (but not writable)
- * so that is not easy to accidentally tweak it, but it can still be
- * done with Object.defineProperty().
- *
- * XXX: require.id could also be just made non-configurable, as there
- * is no practical reason to touch it (at least from Ecmascript code).
- */
- duk_push_c_function(ctx, duk__require, 1 /*nargs*/);
- duk_push_string(ctx, "name");
- duk_push_string(ctx, "require");
- duk_def_prop(ctx, DUK__IDX_FRESH_REQUIRE, DUK_DEFPROP_HAVE_VALUE); /* not writable, not enumerable, not configurable */
- duk_push_string(ctx, "id");
- duk_dup(ctx, DUK__IDX_RESOLVED_ID);
- duk_def_prop(ctx, DUK__IDX_FRESH_REQUIRE, DUK_DEFPROP_HAVE_VALUE | DUK_DEFPROP_SET_CONFIGURABLE); /* a fresh require() with require.id = resolved target module id */
- /* Module table:
- * - module.exports: initial exports table (may be replaced by user)
- * - module.id is non-writable and non-configurable, as the CommonJS
- * spec suggests this if possible
- * - module.filename: not set, defaults to resolved ID if not explicitly
- * set by modSearch() (note capitalization, not .fileName, matches Node.js)
- * - module.name: not set, defaults to last component of resolved ID if
- * not explicitly set by modSearch()
- */
- duk_push_object(ctx); /* exports */
- duk_push_object(ctx); /* module */
- duk_push_string(ctx, "exports");
- duk_dup(ctx, DUK__IDX_EXPORTS);
- duk_def_prop(ctx, DUK__IDX_MODULE, DUK_DEFPROP_HAVE_VALUE | DUK_DEFPROP_SET_WRITABLE | DUK_DEFPROP_SET_CONFIGURABLE); /* module.exports = exports */
- duk_push_string(ctx, "id");
- duk_dup(ctx, DUK__IDX_RESOLVED_ID); /* resolved id: require(id) must return this same module */
- duk_def_prop(ctx, DUK__IDX_MODULE, DUK_DEFPROP_HAVE_VALUE); /* module.id = resolved_id; not writable, not enumerable, not configurable */
- duk_compact(ctx, DUK__IDX_MODULE); /* module table remains registered to modLoaded, minimize its size */
- DUK__ASSERT_TOP(ctx, DUK__IDX_MODULE + 1);
- /* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded undefined fresh_require exports module ] */
- /* Register the module table early to modLoaded[] so that we can
- * support circular references even in modSearch(). If an error
- * is thrown, we'll delete the reference.
- */
- duk_dup(ctx, DUK__IDX_RESOLVED_ID);
- duk_dup(ctx, DUK__IDX_MODULE);
- duk_put_prop(ctx, DUK__IDX_MODLOADED); /* Duktape.modLoaded[resolved_id] = module */
- /*
- * Call user provided module search function and build the wrapped
- * module source code (if necessary). The module search function
- * can be used to implement pure Ecmacsript, pure C, and mixed
- * Ecmascript/C modules.
- *
- * The module search function can operate on the exports table directly
- * (e.g. DLL code can register values to it). It can also return a
- * string which is interpreted as module source code (if a non-string
- * is returned the module is assumed to be a pure C one). If a module
- * cannot be found, an error must be thrown by the user callback.
- *
- * Because Duktape.modLoaded[] already contains the module being
- * loaded, circular references for C modules should also work
- * (although expected to be quite rare).
- */
- duk_push_string(ctx, "(function(require,exports,module){");
- /* Duktape.modSearch(resolved_id, fresh_require, exports, module). */
- duk_get_prop_string(ctx, DUK__IDX_DUKTAPE, "modSearch"); /* Duktape.modSearch */
- duk_dup(ctx, DUK__IDX_RESOLVED_ID);
- duk_dup(ctx, DUK__IDX_FRESH_REQUIRE);
- duk_dup(ctx, DUK__IDX_EXPORTS);
- duk_dup(ctx, DUK__IDX_MODULE); /* [ ... Duktape.modSearch resolved_id last_comp fresh_require exports module ] */
- pcall_rc = duk_pcall(ctx, 4 /*nargs*/); /* -> [ ... source ] */
- DUK__ASSERT_TOP(ctx, DUK__IDX_MODULE + 3);
- if (pcall_rc != DUK_EXEC_SUCCESS) {
- /* Delete entry in Duktape.modLoaded[] and rethrow. */
- goto delete_rethrow;
- }
- /* If user callback did not return source code, module loading
- * is finished (user callback initialized exports table directly).
- */
- if (!duk_is_string(ctx, -1)) {
- /* User callback did not return source code, so module loading
- * is finished: just update modLoaded with final module.exports
- * and we're done.
- */
- goto return_exports;
- }
- /* Finish the wrapped module source. Force module.filename as the
- * function .fileName so it gets set for functions defined within a
- * module. This also ensures loggers created within the module get
- * the module ID (or overridden filename) as their default logger name.
- * (Note capitalization: .filename matches Node.js while .fileName is
- * used elsewhere in Duktape.)
- */
- duk_push_string(ctx, "\n})"); /* Newline allows module last line to contain a // comment. */
- duk_concat(ctx, 3);
- if (!duk_get_prop_string(ctx, DUK__IDX_MODULE, "filename")) {
- /* module.filename for .fileName, default to resolved ID if
- * not present.
- */
- duk_pop(ctx);
- duk_dup(ctx, DUK__IDX_RESOLVED_ID);
- }
- pcall_rc = duk_pcompile(ctx, DUK_COMPILE_EVAL);
- if (pcall_rc != DUK_EXEC_SUCCESS) {
- goto delete_rethrow;
- }
- pcall_rc = duk_pcall(ctx, 0); /* -> eval'd function wrapper (not called yet) */
- if (pcall_rc != DUK_EXEC_SUCCESS) {
- goto delete_rethrow;
- }
- /* Module has now evaluated to a wrapped module function. Force its
- * .name to match module.name (defaults to last component of resolved
- * ID) so that it is shown in stack traces too. Note that we must not
- * introduce an actual name binding into the function scope (which is
- * usually the case with a named function) because it would affect the
- * scope seen by the module and shadow accesses to globals of the same name.
- * This is now done by compiling the function as anonymous and then forcing
- * its .name without setting a "has name binding" flag.
- */
- duk_push_string(ctx, "name");
- if (!duk_get_prop_string(ctx, DUK__IDX_MODULE, "name")) {
- /* module.name for .name, default to last component if
- * not present.
- */
- duk_pop(ctx);
- duk_dup(ctx, DUK__IDX_LASTCOMP);
- }
- duk_def_prop(ctx, -3, DUK_DEFPROP_HAVE_VALUE | DUK_DEFPROP_FORCE);
- /*
- * Call the wrapped module function.
- *
- * Use a protected call so that we can update Duktape.modLoaded[resolved_id]
- * even if the module throws an error.
- */
- /* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded undefined fresh_require exports module mod_func ] */
- DUK__ASSERT_TOP(ctx, DUK__IDX_MODULE + 2);
- duk_dup(ctx, DUK__IDX_EXPORTS); /* exports (this binding) */
- duk_dup(ctx, DUK__IDX_FRESH_REQUIRE); /* fresh require (argument) */
- duk_get_prop_string(ctx, DUK__IDX_MODULE, "exports"); /* relookup exports from module.exports in case it was changed by modSearch */
- duk_dup(ctx, DUK__IDX_MODULE); /* module (argument) */
- DUK__ASSERT_TOP(ctx, DUK__IDX_MODULE + 6);
- /* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded undefined fresh_require exports module mod_func exports fresh_require exports module ] */
- pcall_rc = duk_pcall_method(ctx, 3 /*nargs*/);
- if (pcall_rc != DUK_EXEC_SUCCESS) {
- /* Module loading failed. Node.js will forget the module
- * registration so that another require() will try to load
- * the module again. Mimic that behavior.
- */
- goto delete_rethrow;
- }
- /* [ requested_id require require.id resolved_id last_comp Duktape Duktape.modLoaded undefined fresh_require exports module result(ignored) ] */
- DUK__ASSERT_TOP(ctx, DUK__IDX_MODULE + 2);
- /* fall through */
- return_exports:
- duk_get_prop_string(ctx, DUK__IDX_MODULE, "exports");
- duk_compact(ctx, -1); /* compact the exports table */
- return 1; /* return module.exports */
- delete_rethrow:
- duk_dup(ctx, DUK__IDX_RESOLVED_ID);
- duk_del_prop(ctx, DUK__IDX_MODLOADED); /* delete Duktape.modLoaded[resolved_id] */
- (void) duk_throw(ctx); /* rethrow original error */
- return 0; /* not reachable */
- }
- void duk_module_duktape_init(duk_context *ctx) {
- /* Stash 'Duktape' in case it's modified. */
- duk_push_global_stash(ctx);
- duk_get_global_string(ctx, "Duktape");
- duk_put_prop_string(ctx, -2, "\xff" "module:Duktape");
- duk_pop(ctx);
- /* Register `require` as a global function. */
- duk_eval_string(ctx,
- "(function(req){"
- "var D=Object.defineProperty;"
- "D(req,'name',{value:'require'});"
- "D(this,'require',{value:req,writable:true,configurable:true});"
- "D(Duktape,'modLoaded',{value:Object.create(null),writable:true,configurable:true});"
- "})");
- duk_push_c_function(ctx, duk__require, 1 /*nargs*/);
- duk_call(ctx, 1);
- duk_pop(ctx);
- }
- #undef DUK__ASSERT
- #undef DUK__ASSERT_TOP
- #undef DUK__IDX_REQUESTED_ID
- #undef DUK__IDX_REQUIRE
- #undef DUK__IDX_REQUIRE_ID
- #undef DUK__IDX_RESOLVED_ID
- #undef DUK__IDX_LASTCOMP
- #undef DUK__IDX_DUKTAPE
- #undef DUK__IDX_MODLOADED
- #undef DUK__IDX_UNDEFINED
- #undef DUK__IDX_FRESH_REQUIRE
- #undef DUK__IDX_EXPORTS
- #undef DUK__IDX_MODULE
|