NAME

src/exceptions.c - Exceptions

DESCRIPTION

Define the internal interpreter exceptions.

• This is experimental code.
• The enum_class of the Exception isn't fixed.
• The interface isn't fixed.
• Much of this may change in the future.

Functions

*/

#include "parrot/parrot.h" #include "parrot/exceptions.h"

#ifdef PARROT_HAS_GLIBC_BACKTRACE # include <execinfo.h> #endif

/* HEADERIZER HFILE: include/parrot/exceptions.h */

/* HEADERIZER BEGIN: static */

PARROT_WARN_UNUSED_RESULT static opcode_t * create_exception( PARROT_INTERP ) __attribute__nonnull__(1);

PARROT_WARN_UNUSED_RESULT static size_t dest2offset( PARROT_INTERP, NOTNULL(const opcode_t *dest) ) __attribute__nonnull__(1) __attribute__nonnull__(2);

PARROT_WARN_UNUSED_RESULT PARROT_CAN_RETURN_NULL static PMC * find_exception_handler( PARROT_INTERP, NOTNULL(PMC *exception) ) __attribute__nonnull__(1) __attribute__nonnull__(2);

static void run_cleanup_action( PARROT_INTERP, NOTNULL(Stack_Entry_t *e) ) __attribute__nonnull__(1) __attribute__nonnull__(2);

/* HEADERIZER END: static */

#include <stdarg.h>

/*

FUNCDOC: internal_exception

Signal a fatal exception. This involves printing an error message to stderr, and calling Parrot_exit to invoke exit handlers and exit the process with the given exitcode. No error handlers are used, so it is not possible for Parrot bytecode to intercept a fatal error (cf. real_exception). Furthermore, no stack unwinding is done, so the exit handlers run in the current dynamic environment.

*/

PARROT_API PARROT_DOES_NOT_RETURN void internal_exception(int exitcode, NOTNULL(const char *format), ...) { va_list arglist; va_start(arglist, format); vfprintf(stderr, format, arglist); fprintf(stderr, "\n"); /* caution against output swap (with PDB_backtrace) */ fflush(stderr); va_end(arglist); /* * XXX TODO get rid of all the internal_exceptions or call them * with an interpreter arg Parrot_exit(interp, exitcode); */ exit(exitcode); }

/* Panic handler */

#ifndef dumpcore # define dumpcore() \ fprintf(stderr, "Sorry, coredump is not yet implemented " \ "for this platform.\n\n"); \ exit(EXIT_FAILURE); #endif

/*

FUNCDOC: do_panic

Panic handler.

*/

PARROT_DOES_NOT_RETURN void do_panic(NULLOK_INTERP, NULLOK(const char *message), NULLOK(const char *file), unsigned int line) { /* Note: we can't format any floats in here--Parrot_sprintf ** may panic because of floats. ** and we don't use Parrot_sprintf or such, because we are ** already in panic --leo */ fprintf(stderr, "Parrot VM: PANIC: %s!\n", message ? message : "(no message available)");

    fprintf(stderr, "C file %s, line %ud\n",
               file ? file : "(not available)", line);

    fprintf(stderr, "Parrot file (not available), ");
    fprintf(stderr, "line (not available)\n");

    fprintf(stderr, "\n\
We highly suggest you notify the Parrot team if you have not been working on\n\
Parrot.  Use parrotbug (located in parrot's root directory) or send an\n\
e-mail to parrot-porters@perl.org.\n\
Include the entire text of this error message and the text of the script that\n\
generated the error.  If you've made any modifications to Parrot, please\n\
describe them as well.\n\n");

    fprintf(stderr, "Version     : %s\n", PARROT_VERSION);
    fprintf(stderr, "Configured  : %s\n", PARROT_CONFIG_DATE);
    fprintf(stderr, "Architecture: %s\n", PARROT_ARCHNAME);
    fprintf(stderr, "JIT Capable : %s\n", JIT_CAPABLE ? "Yes" : "No");
    if (interp)
        fprintf(stderr, "Interp Flags: %#x\n", (unsigned int)interp->flags);
    else
        fprintf(stderr, "Interp Flags: (no interpreter)\n");
    fprintf(stderr, "Exceptions  : %s\n", "(missing from core)");
    fprintf(stderr, "\nDumping Core...\n");

    dumpcore();
}

/*

FUNCDOC: push_exception

Add the exception handler on the stack.

FUNCDOC: Parrot_push_action

Push an action handler onto the dynamic environment.

FUNCDOC: Parrot_push_mark

Push a cleanup mark onto the dynamic environment.

FUNCDOC: Parrot_pop_mark

Pop items off the dynamic environment up to the mark.

*/

PARROT_API void push_exception(PARROT_INTERP, NOTNULL(PMC *handler)) { if (handler->vtable->base_type != enum_class_Exception_Handler) PANIC(interp, "Tried to set_eh a non Exception_Handler"); stack_push(interp, &interp->dynamic_env, handler, STACK_ENTRY_PMC, STACK_CLEANUP_NULL); }

static void run_cleanup_action(PARROT_INTERP, NOTNULL(Stack_Entry_t *e)) { /* * this is called during normal stack_pop of the control * stack - run the action subroutine with an INTVAL arg of 0 */ PMC * const sub = UVal_pmc(e->entry); Parrot_runops_fromc_args(interp, sub, "vI", 0); }

PARROT_API void Parrot_push_action(PARROT_INTERP, PMC *sub) { if (!VTABLE_isa(interp, sub, const_string(interp, "Sub"))) { real_exception(interp, NULL, 1, "Tried to push a non Sub PMC action"); } stack_push(interp, &interp->dynamic_env, sub, STACK_ENTRY_ACTION, run_cleanup_action); }

PARROT_API void Parrot_push_mark(PARROT_INTERP, INTVAL mark) { stack_push(interp, &interp->dynamic_env, &mark, STACK_ENTRY_MARK, STACK_CLEANUP_NULL); }

PARROT_API void Parrot_pop_mark(PARROT_INTERP, INTVAL mark) { do { const Stack_Entry_t * const e = stack_entry(interp, interp->dynamic_env, 0); if (!e) real_exception(interp, NULL, 1, "Mark %ld not found.", (long)mark); (void)stack_pop(interp, &interp->dynamic_env, NULL, e->entry_type); if (e->entry_type == STACK_ENTRY_MARK) { if (UVal_int(e->entry) == mark) return; } } while (1); }

/*

FUNCDOC: find_exception_handler

Find the exception handler for exception.

*/

PARROT_WARN_UNUSED_RESULT PARROT_CAN_RETURN_NULL static PMC * find_exception_handler(PARROT_INTERP, NOTNULL(PMC *exception)) { char *m; int exit_status, print_location; int depth = 0; Stack_Entry_t *e;

    /* for now, we don't check the exception class and we don't
     * look for matching handlers.  [this is being redesigned anyway.]
     */
    STRING * const message = VTABLE_get_string_keyed_int(interp, exception, 0);

    /* [TODO: replace quadratic search with something linear, hopefully without
       trashing abstraction layers.  -- rgr, 17-Sep-06.] */
    while ((e = stack_entry(interp, interp->dynamic_env, depth)) != NULL) {
        if (e->entry_type == STACK_ENTRY_PMC) {
            PMC * const handler = UVal_pmc(e->entry);
            if (handler && handler->vtable->base_type ==
                    enum_class_Exception_Handler) {
                return handler;
            }
        }
        depth++;
    }

    /* flush interpreter output to get things printed in order */
    PIO_flush(interp, PIO_STDOUT(interp));
    PIO_flush(interp, PIO_STDERR(interp));
    if (interp->debugger) {
        PIO_flush(interp->debugger, PIO_STDOUT(interp->debugger));
        PIO_flush(interp->debugger, PIO_STDERR(interp->debugger));
    }

    m = string_to_cstring(interp, message);
    exit_status = print_location = 1;
    if (m && *m) {
        fputs(m, stderr);
        if (m[strlen(m)-1] != '\n')
            fprintf(stderr, "%c", '\n');
        string_cstring_free(m);
    }
    else {
        if (m)
            string_cstring_free(m); /* coverity fix, m was allocated but was "\0" */
        /* new block for const assignment */
        {
            const INTVAL severity = VTABLE_get_integer_keyed_int(interp, exception, 2);
            if (severity == EXCEPT_exit) {
                print_location = 0;
                exit_status =
                    (int)VTABLE_get_integer_keyed_int(interp, exception, 1);
            }
            else
                fprintf(stderr, "No exception handler and no message\n");
        }
    }
    /* caution against output swap (with PDB_backtrace) */
    fflush(stderr);
    if (print_location)
        PDB_backtrace(interp);
    /*
     * returning NULL from here returns resume address NULL to the
     * runloop, which will terminate the thread function finally
     *
     * XXX this check should better be in Parrot_exit
     */
    if (interp->thread_data && interp->thread_data->tid) {
        /*
         * we should probably detach the thread here
         */
        return NULL;
    }
    /*
     * only main should run the destroy functions - exit handler chain
     * is freed during Parrot_exit
     */
    Parrot_exit(interp, exit_status);
}

/*

FUNCDOC: pop_exception

Pops the topmost exception handler off the stack.

*/

PARROT_API void pop_exception(PARROT_INTERP) { Stack_entry_type type; Parrot_cont *cc;

    PMC * const handler
        = (PMC *)stack_peek(interp, interp->dynamic_env, &type);

    if (! handler
            || type != STACK_ENTRY_PMC
            || handler->vtable->base_type != enum_class_Exception_Handler) {
        real_exception(interp, NULL, E_RuntimeError,
                "No exception to pop.");
    }
    cc = PMC_cont(handler);
    if (cc->to_ctx != CONTEXT(interp->ctx)) {
        real_exception(interp, NULL, E_RuntimeError,
                "No exception to pop.");
    }
    (void)stack_pop(interp, &interp->dynamic_env,
                    NULL, STACK_ENTRY_PMC);
}

/*

FUNCDOC: new_c_exception_handler

Generate an exception handler, that catches PASM level exceptions inside a C function. This could be a separate class too, for now just a private flag bit is set.

*/

PARROT_API PARROT_WARN_UNUSED_RESULT PMC* new_c_exception_handler(PARROT_INTERP, Parrot_exception *jb) { PMC * const handler = pmc_new(interp, enum_class_Exception_Handler); /* * this flag denotes a C exception handler */ PObj_get_FLAGS(handler) |= SUB_FLAG_C_HANDLER; VTABLE_set_pointer(interp, handler, jb); return handler; }

/*

FUNCDOC: push_new_c_exception_handler

Pushes an new C exception handler onto the stack.

*/

PARROT_API void push_new_c_exception_handler(PARROT_INTERP, Parrot_exception *jb) { push_exception(interp, new_c_exception_handler(interp, jb)); }

/*

FUNCDOC: throw_exception

Throw the exception.

*/

PARROT_API PARROT_CAN_RETURN_NULL opcode_t * throw_exception(PARROT_INTERP, PMC *exception, SHIM(void *dest)) { opcode_t *address; PMC * const handler = find_exception_handler(interp, exception);

    if (!handler)
        return NULL;
    /* put the handler aka continuation ctx in the interpreter */
    address = VTABLE_invoke(interp, handler, exception);
    /* address = VTABLE_get_pointer(interp, handler); */
    if (PObj_get_FLAGS(handler) & SUB_FLAG_C_HANDLER) {
        /* its a C exception handler */
        Parrot_exception * const jb = (Parrot_exception *) address;
        longjmp(jb->destination, 1);
    }
    /* return the address of the handler */
    return address;
}

/*

FUNCDOC: rethrow_exception

Rethrow the exception.

*/

PARROT_API PARROT_WARN_UNUSED_RESULT opcode_t * rethrow_exception(PARROT_INTERP, NOTNULL(PMC *exception)) { PMC *handler; opcode_t *address;

    if (exception->vtable->base_type != enum_class_Exception)
        PANIC(interp, "Illegal rethrow");
    handler = find_exception_handler(interp, exception);
    address = VTABLE_invoke(interp, handler, exception);
    /* return the address of the handler */
    return address;
}

/*

FUNCDOC: rethrow_c_exception

Return back to runloop, assumes exception is still in TODO and that this is called from within a handler setup with new_c_exception.

*/

PARROT_DOES_NOT_RETURN void rethrow_c_exception(PARROT_INTERP) { Parrot_exception * const the_exception = interp->exceptions;

    PMC * const exception = PMCNULL;   /* TODO */
    PMC * const handler   = find_exception_handler(interp, exception);

    /* XXX we should only peek for the next handler */
    push_exception(interp, handler);
    /*
     * if there was no user handler, interpreter is already shutdown
     */
    the_exception->resume = VTABLE_get_pointer(interp, handler);
    the_exception->error = VTABLE_get_integer_keyed_int(interp,
            exception, 1);
    the_exception->severity = VTABLE_get_integer_keyed_int(interp,
            exception, 2);
    the_exception->msg = VTABLE_get_string_keyed_int(interp, exception, 0);
    longjmp(the_exception->destination, 1);
}

/*

FUNCDOC: dest2offset

Translate an absolute bytecode location to an offset used for resuming after an exception had occurred.

*/

PARROT_WARN_UNUSED_RESULT static size_t dest2offset(PARROT_INTERP, NOTNULL(const opcode_t *dest)) { size_t offset; /* translate an absolute location in byte_code to an offset * used for resuming after an exception had occurred */ switch (interp->run_core) { case PARROT_SWITCH_CORE: case PARROT_SWITCH_JIT_CORE: case PARROT_CGP_CORE: case PARROT_CGP_JIT_CORE: offset = dest - (const opcode_t *)interp->code->prederef.code; default: offset = dest - interp->code->base.data; } return offset; }

/*

FUNCDOC: create_exception

Create an exception.

*/

PARROT_WARN_UNUSED_RESULT static opcode_t * create_exception(PARROT_INTERP) { PMC *exception; /* exception object */ opcode_t *dest; /* absolute address of handler */ Parrot_exception * const the_exception = interp->exceptions;

    /*
     * if the exception number is in the range of our known exceptions
     * use the precreated exception
     */
    if (the_exception->error <= E_LAST_PYTHON_E &&
            the_exception->error >= 0) {
        exception = interp->exception_list[the_exception->error];
    }
    else {
        /* create an exception object */
        exception = pmc_new(interp, enum_class_Exception);
        /* exception type */
        VTABLE_set_integer_keyed_int(interp, exception, 1,
                the_exception->error);
    }
    /* exception severity */
    VTABLE_set_integer_keyed_int(interp, exception, 2,
            (INTVAL)the_exception->severity);
    if (the_exception->msg) {
        VTABLE_set_string_keyed_int(interp, exception, 0,
                the_exception->msg);
    }
    /* now fill rest of exception, locate handler and get
     * destination of handler
     */
    dest = throw_exception(interp, exception, the_exception->resume);
    return dest;
}

/*

FUNCDOC: handle_exception

Handle an exception.

*/

PARROT_API size_t handle_exception(PARROT_INTERP) { /* absolute address of handler */ const opcode_t * const dest = create_exception(interp);

    return dest2offset(interp, dest);
}

/*

FUNCDOC: new_internal_exception

Create a new internal exception buffer, either by allocating it or by getting one from the free list.

*/

PARROT_API void new_internal_exception(PARROT_INTERP) { Parrot_exception *the_exception;

    if (interp->exc_free_list) {
        the_exception = interp->exc_free_list;
        interp->exc_free_list = the_exception->prev;
    }
    else
        the_exception = mem_allocate_typed(Parrot_exception);
    the_exception->prev = interp->exceptions;
    the_exception->resume = NULL;
    the_exception->msg = NULL;
    interp->exceptions = the_exception;
}

/*

FUNCDOC: free_internal_exception

Place internal exception buffer back on the free list.

*/

PARROT_API void free_internal_exception(PARROT_INTERP) { Parrot_exception * const e = interp->exceptions; interp->exceptions = e->prev; e->prev = interp->exc_free_list; interp->exc_free_list = e; }

void destroy_exception_list(PARROT_INTERP) { really_destroy_exception_list(interp->exceptions); really_destroy_exception_list(interp->exc_free_list); }

void really_destroy_exception_list(NULLOK(Parrot_exception *e)) { while (e != NULL) { Parrot_exception * const prev = e->prev; mem_sys_free(e); e = prev; } }

/*

FUNCDOC: do_exception

Called from interrupt code. Does a longjmp in front of the runloop, which calls handle_exception(), returning the handler address where execution then resumes.

*/

PARROT_API PARROT_DOES_NOT_RETURN void do_exception(PARROT_INTERP, INTVAL severity, long error) { Parrot_exception * const the_exception = interp->exceptions;

    the_exception->error = error;
    the_exception->severity = severity;
    the_exception->msg = NULL;
    the_exception->resume = NULL;
    longjmp(the_exception->destination, 1);
}

/*

FUNCDOC: real_exception

Throws a real exception, with an error message constructed from the format string and arguments. ret_addr is the address from which to resume, if some handler decides that is appropriate, or zero to make the error non-resumable. exitcode is a exception_type_enum value.

See also internal_exception(), which signals fatal errors, and throw_exception, which calls the handler.

*/

PARROT_API PARROT_DOES_NOT_RETURN void real_exception(PARROT_INTERP, NULLOK(void *ret_addr), int exitcode, NOTNULL(const char *format), ...) { STRING *msg; Parrot_exception * const the_exception = interp->exceptions;

    /*
     * if profiling remember end time of lastop and
     * generate entry for exception
     */
    RunProfile * const profile = interp->profile;
    if (profile && Interp_flags_TEST(interp, PARROT_PROFILE_FLAG)) {
        const FLOATVAL now = Parrot_floatval_time();

        profile->data[profile->cur_op].time += now - profile->starttime;
        profile->cur_op = PARROT_PROF_EXCEPTION;
        profile->starttime = now;
        profile->data[PARROT_PROF_EXCEPTION].numcalls++;
    }

    /*
     * make exception message
     */
    if (strchr(format, '%')) {
        va_list arglist;
        va_start(arglist, format);
        msg = Parrot_vsprintf_c(interp, format, arglist);
        va_end(arglist);
    }
    else
        msg = string_make(interp, format, strlen(format),
                NULL, PObj_external_FLAG);
    /* string_from_cstring(interp, format, strlen(format)); */
    /*
     * FIXME classify errors
     */
    if (!the_exception) {
        PIO_eprintf(interp,
                "real_exception (severity:%d error:%d): %Ss\n"
                "likely reason: argument count mismatch in main "
                "(more than 1 param)\n",
                EXCEPT_error, exitcode, msg);
        /* [what if exitcode is a multiple of 256?] */
        exit(exitcode);
    }
    the_exception->severity = EXCEPT_error;
    the_exception->error = exitcode;
    the_exception->msg = msg;
    the_exception->resume = ret_addr;
    if (Interp_debug_TEST(interp, PARROT_BACKTRACE_DEBUG_FLAG)) {
        PIO_eprintf(interp, "real_exception (severity:%d error:%d): %Ss\n",
            EXCEPT_error, exitcode, msg);
        PDB_backtrace(interp);
    }
    /*
     * reenter runloop
     */
    longjmp(the_exception->destination, 1);
}

/*

FUNCDOC: Parrot_init_exceptions

Create exception objects.

*/

void Parrot_init_exceptions(PARROT_INTERP) { int i;

    interp->exception_list = (PMC **)mem_sys_allocate(
            sizeof (PMC*) * (E_LAST_PYTHON_E + 1));
    for (i = 0; i <= E_LAST_PYTHON_E; ++i) {
        PMC * const ex = pmc_new(interp, enum_class_Exception);
        interp->exception_list[i] = ex;
        VTABLE_set_integer_keyed_int(interp, ex, 1, i);
    }
}

/*

FUNCDOC: Parrot_confess

A better version of assert() that gives a backtrace if possible.

*/

PARROT_API PARROT_DOES_NOT_RETURN void Parrot_confess(NOTNULL(const char *cond), NOTNULL(const char *file), unsigned int line) { fprintf(stderr, "%s:%u: failed assertion '%s'\n", file, line, cond); Parrot_print_backtrace(); abort(); }

void Parrot_print_backtrace(void) { #ifdef PARROT_HAS_GLIBC_BACKTRACE # define BACKTRACE_DEPTH 32 /*# define BACKTRACE_VERBOSE */ /* stolen from http://www.delorie.com/gnu/docs/glibc/libc_665.html */ void *array[BACKTRACE_DEPTH]; size_t i; # ifndef BACKTRACE_VERBOSE int ident; char *caller; size_t callerLength; size_t j; # endif

    const size_t size = backtrace (array, BACKTRACE_DEPTH);
    char ** const strings = backtrace_symbols (array, size);

    fprintf (stderr, "Backtrace - Obtained %zd stack frames (max trace depth is %d).\n", size, BACKTRACE_DEPTH);
#  ifndef BACKTRACE_VERBOSE
    for (i = 0; i < size; i++) {
        /* always ident */
        ident = 2;  /* initial indent */
        ident += 2 * i; /* nesting depth */
        fprintf(stderr, "%*s", ident, "");

        /* if the caller was an anon function then strchr won't
        find a '(' in the string and will return NULL */
        caller = strchr(strings[i], '(');
        if (caller) {
            /* skip over the '(' */
            caller++;
            /* find the end of the symbol name */
            callerLength = abs(strchr(caller, '+') - caller);
            /* print just the symbol name */
            for (j = 0; j < callerLength; j++) {
                fputc(caller[j], stderr);
            }
            fprintf(stderr, "\n");
        }
        else {
            fprintf(stderr, "(unknown)\n");
        }
    }
#  else
    for (i = 0; i < size; i++)
        fprintf (stderr, "%s\n", strings[i]);
#  endif

    free (strings);

# undef BACKTRACE_DEPTH #endif /* ifdef PARROT_HAS_GLIBC_BACKTRACE */ }

/*

SEE ALSO

include/parrot/exceptions.h.

*/

/* * Local variables: * c-file-style: "parrot" * End: * vim: expandtab shiftwidth=4: */