exceptions.h

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#pragma once
#include "except.h"
#include <wsutil/ws_assert.h>
 
/* Wireshark has only one exception group, to make these macros simple */
#define XCEPT_GROUP_WIRESHARK 1
 
#define BoundsError     1
 
#define ContainedBoundsError    2
 
#define ReportedBoundsError 3
 
#define FragmentBoundsError 4
 
#define TypeError       5
 
#define DissectorError      6
 
#define ScsiBoundsError     7
 
#define OutOfMemoryError    8
 
#define ReassemblyError         9
 
/*
 * Catch errors that, if you're calling a subdissector and catching
 * exceptions from the subdissector, and possibly dissecting more
 * stuff after the subdissector returns or fails, mean it makes
 * sense to continue dissecting:
 *
 * BoundsError indicates a configuration problem (the capture was
 * set up to throw away data, and it did); there's no point in
 * trying to dissect any more data, as there's no more data to dissect.
 *
 * FragmentBoundsError indicates a configuration problem (reassembly
 * wasn't enabled or couldn't be done); there's no point in trying
 * to dissect any more data, as there's no more data to dissect.
 *
 * OutOfMemoryError indicates what its name suggests; there's no point
 * in trying to dissect any more data, as you're probably not going to
 * have any more memory to use when dissecting them.
 *
 * Other errors indicate that there's some sort of problem with
 * the packet; you should continue dissecting data, as it might
 * be OK, and, even if it's not, you should report its problem
 * separately.
 */
#define CATCH_NONFATAL_ERRORS \
    CATCH4(ReportedBoundsError, ContainedBoundsError, ScsiBoundsError, ReassemblyError)
 
/*
 * Catch all bounds-checking errors.
 */
#define CATCH_BOUNDS_ERRORS \
    CATCH5(BoundsError, FragmentBoundsError, ReportedBoundsError, \
           ContainedBoundsError, ScsiBoundsError)
 
/*
 * Catch all bounds-checking errors, and catch dissector bugs.
 * Should only be used at the top level, so that dissector bugs
 * go all the way to the top level and get reported immediately.
 */
#define CATCH_BOUNDS_AND_DISSECTOR_ERRORS \
    CATCH7(BoundsError, FragmentBoundsError, ContainedBoundsError, \
           ReportedBoundsError, ScsiBoundsError, DissectorError, \
           ReassemblyError)
 
/* Usage:
 *
 * TRY {
 *  code;
 * }
 *
 * CATCH(exception) {
 *  code;
 * }
 *
 * CATCH2(exception1, exception2) {
 *  code;
 * }
 *
 * CATCH3(exception1, exception2, exception3) {
 *  code;
 * }
 *
 * CATCH4(exception1, exception2, exception3, exception4) {
 *  code;
 * }
 *
 * CATCH5(exception1, exception2, exception3, exception4, exception5) {
 *  code;
 * }
 *
 * CATCH6(exception1, exception2, exception3, exception4, exception5, exception6) {
 *  code;
 * }
 *
 * CATCH7(exception1, exception2, exception3, exception4, exception5, exception6, exception7) {
 *  code;
 * }
 *
 * CATCH_NONFATAL_ERRORS {
 *  code;
 * }
 *
 * CATCH_BOUNDS_ERRORS {
 *  code;
 * }
 *
 * CATCH_BOUNDS_AND_DISSECTOR_ERRORS {
 *  code;
 * }
 *
 * CATCH_ALL {
 *  code;
 * }
 *
 * FINALLY {
 *  code;
 * }
 *
 * ENDTRY;
 *
 * ********* Never use 'goto' or 'return' inside the TRY, CATCH*, or
 * ********* FINALLY blocks. Execution must proceed through ENDTRY before
 * ********* branching out.
 *
 * This is really something like:
 *
 * {
 *  caught = false:
 *  x = setjmp();
 *  if (x == 0) {
 *      <TRY code>
 *  }
 *  if (!caught && x == 1) {
 *      caught = true;
 *      <CATCH(1) code>
 *  }
 *  if (!caught && x == 2) {
 *      caught = true;
 *      <CATCH(2) code>
 *  }
 *  if (!caught && (x == 3 || x == 4)) {
 *      caught = true;
 *      <CATCH2(3,4) code>
 *  }
 *  if (!caught && (x == 5 || x == 6 || x == 7)) {
 *      caught = true;
 *      <CATCH3(5,6,7) code>
 *  }
 *  if (!caught && x != 0) {
 *      caught = true;
 *      <CATCH_ALL code>
 *  }
 *  <FINALLY code>
 *  if(!caught) {
 *          RETHROW(x)
 *  }
 * }<ENDTRY tag>
 *
 * All CATCH's must precede a CATCH_ALL.
 * FINALLY must occur after any CATCH or CATCH_ALL.
 * ENDTRY marks the end of the TRY code.
 * TRY and ENDTRY are the mandatory parts of a TRY block.
 * CATCH, CATCH_ALL, and FINALLY are all optional (although
 * you'll probably use at least one, otherwise why "TRY"?)
 *
 * GET_MESSAGE  returns string ptr to exception message
 *      when exception is thrown via THROW_MESSAGE()
 *
 * To throw/raise an exception.
 *
 * THROW(exception)
 * RETHROW              rethrow the caught exception
 *
 * A cleanup callback is a function called in case an exception occurs
 * and is not caught. It should be used to free any dynamically-allocated data.
 * A pop or call_and_pop should occur at the same statement-nesting level
 * as the push.
 *
 * CLEANUP_CB_PUSH(func, data)
 * CLEANUP_CB_POP
 * CLEANUP_CB_CALL_AND_POP
 */
 
/* we do up to three passes through the bit of code after except_try_push(),
 * and except_state is used to keep track of where we are.
 */
#define EXCEPT_CAUGHT   1 /* exception has been caught, no need to rethrow at
                           * ENDTRY */
 
#define EXCEPT_RETHROWN 2 /* the exception was rethrown from a CATCH
                           * block. Don't reenter the CATCH blocks, but do
                           * execute FINALLY and rethrow at ENDTRY */
 
#define EXCEPT_FINALLY  4 /* we've entered the FINALLY block - don't allow
                           * RETHROW, and don't reenter FINALLY if a
                           * different exception is thrown */
 
#define TRY \
{\
    except_t *volatile exc; \
    volatile int except_state = 0; \
    static const except_id_t catch_spec[] = { \
        { XCEPT_GROUP_WIRESHARK, XCEPT_CODE_ANY } }; \
    except_try_push(catch_spec, 1, &exc); \
                                                   \
    if(except_state & EXCEPT_CAUGHT)               \
        except_state |= EXCEPT_RETHROWN;           \
    except_state &= ~EXCEPT_CAUGHT;                \
                                                   \
    if (except_state == 0 && exc == 0)             \
        /* user's code goes here */
 
#define ENDTRY \
    /* rethrow the exception if necessary */ \
    if(!(except_state&EXCEPT_CAUGHT) && exc != 0)  \
        except_rethrow(exc);                 \
    except_try_pop();\
}
 
/* the (except_state |= EXCEPT_CAUGHT) in the below is a way of setting
 * except_state before the user's code, without disrupting the user's code if
 * it's a one-liner.
 */
#define CATCH(x) \
    if (except_state == 0 && exc != 0 && \
        exc->except_id.except_code == (x) && \
        (except_state |= EXCEPT_CAUGHT)) \
        /* user's code goes here */
 
#define CATCH2(x,y) \
    if (except_state == 0 && exc != 0 && \
        (exc->except_id.except_code == (x) || \
         exc->except_id.except_code == (y)) && \
        (except_state|=EXCEPT_CAUGHT)) \
        /* user's code goes here */
 
#define CATCH3(x,y,z) \
    if (except_state == 0 && exc != 0 && \
        (exc->except_id.except_code == (x) || \
         exc->except_id.except_code == (y) || \
         exc->except_id.except_code == (z)) && \
        (except_state|=EXCEPT_CAUGHT)) \
        /* user's code goes here */
 
#define CATCH4(w,x,y,z) \
    if (except_state == 0 && exc != 0 && \
        (exc->except_id.except_code == (w) || \
         exc->except_id.except_code == (x) || \
         exc->except_id.except_code == (y) || \
         exc->except_id.except_code == (z)) && \
        (except_state|=EXCEPT_CAUGHT)) \
        /* user's code goes here */
 
#define CATCH5(v,w,x,y,z) \
    if (except_state == 0 && exc != 0 && \
        (exc->except_id.except_code == (v) || \
         exc->except_id.except_code == (w) || \
         exc->except_id.except_code == (x) || \
         exc->except_id.except_code == (y) || \
         exc->except_id.except_code == (z)) && \
        (except_state|=EXCEPT_CAUGHT)) \
        /* user's code goes here */
 
#define CATCH6(u,v,w,x,y,z) \
    if (except_state == 0 && exc != 0 && \
        (exc->except_id.except_code == (u) || \
         exc->except_id.except_code == (v) || \
         exc->except_id.except_code == (w) || \
         exc->except_id.except_code == (x) || \
         exc->except_id.except_code == (y) || \
         exc->except_id.except_code == (z)) && \
        (except_state|=EXCEPT_CAUGHT)) \
        /* user's code goes here */
 
#define CATCH7(t,u,v,w,x,y,z) \
    if (except_state == 0 && exc != 0 && \
        (exc->except_id.except_code == (t) || \
         exc->except_id.except_code == (u) || \
         exc->except_id.except_code == (v) || \
         exc->except_id.except_code == (w) || \
         exc->except_id.except_code == (x) || \
         exc->except_id.except_code == (y) || \
         exc->except_id.except_code == (z)) && \
        (except_state|=EXCEPT_CAUGHT)) \
        /* user's code goes here */
 
#define CATCH_ALL \
    if (except_state == 0 && exc != 0 && \
        (except_state|=EXCEPT_CAUGHT)) \
        /* user's code goes here */
 
#define FINALLY \
    if( !(except_state & EXCEPT_FINALLY) && (except_state|=EXCEPT_FINALLY)) \
        /* user's code goes here */
 
#define THROW(x) \
    except_throw(XCEPT_GROUP_WIRESHARK, (x), NULL)
 
#define THROW_ON(cond, x) G_STMT_START { \
    if ((cond)) \
        except_throw(XCEPT_GROUP_WIRESHARK, (x), NULL); \
} G_STMT_END
 
#define THROW_MESSAGE(x, y) \
    except_throw(XCEPT_GROUP_WIRESHARK, (x), (y))
 
#define THROW_MESSAGE_ON(cond, x, y) G_STMT_START { \
    if ((cond)) \
        except_throw(XCEPT_GROUP_WIRESHARK, (x), (y)); \
} G_STMT_END
 
/* Throws a formatted message, its memory is cleared after catching it. */
#define THROW_FORMATTED(x, ...) \
    except_throwf(XCEPT_GROUP_WIRESHARK, (x), __VA_ARGS__)
 
/* Like THROW_FORMATTED, but takes a va_list as an argument */
#define VTHROW_FORMATTED(x, format, args) \
    except_vthrowf(XCEPT_GROUP_WIRESHARK, (x), format, args)
 
#define GET_MESSAGE         except_message(exc)
 
#define RETHROW                                     \
{                                                   \
    /* check we're in a catch block */          \
    ws_assert(except_state == EXCEPT_CAUGHT);    \
    /* we can't use except_rethrow here, as that pops a catch block \
     * off the stack, and we don't want to do that, because we want to \
     * execute the FINALLY {} block first.     \
     * except_throw doesn't provide an interface to rethrow an existing \
     * exception; however, longjmping back to except_try_push() has the \
     * desired effect.              \
     *                      \
     * Note also that THROW and RETHROW should provide much the same \
     * functionality in terms of which blocks to enter, so any messing \
     * about with except_state in here would indicate that THROW is \
     * doing the wrong thing.                   \
     */                     \
    longjmp(except_ch.except_jmp,1);            \
}
 
#define EXCEPT_CODE         except_code(exc)
 
/* Register cleanup functions in case an exception is thrown and not caught.
 * From the Kazlib documentation, with modifications for use with the
 * Wireshark-specific macros:
 *
 * CLEANUP_PUSH(func, arg)
 *
 *  The call to CLEANUP_PUSH shall be matched with a call to
 *  CLEANUP_CALL_AND_POP or CLEANUP_POP which must occur in the same
 *  statement block at the same level of nesting. This requirement allows
 *  an implementation to provide a CLEANUP_PUSH macro which opens up a
 *  statement block and a CLEANUP_POP which closes the statement block.
 *  The space for the registered pointers can then be efficiently
 *  allocated from automatic storage.
 *
 *  The CLEANUP_PUSH macro registers a cleanup handler that will be
 *  called if an exception subsequently occurs before the matching
 *  CLEANUP_[CALL_AND_]POP is executed, and is not intercepted and
 *  handled by a try-catch region that is nested between the two.
 *
 *  The first argument to CLEANUP_PUSH is a pointer to the cleanup
 *  handler, a function that returns nothing and takes a single
 *  argument of type void*. The second argument is a void* value that
 *  is registered along with the handler.  This value is what is passed
 *  to the registered handler, should it be called.
 *
 *  Cleanup handlers are called in the reverse order of their nesting:
 *  inner handlers are called before outer handlers.
 *
 *  The program shall not leave the cleanup region between
 *  the call to the macro CLEANUP_PUSH and the matching call to
 *  CLEANUP_[CALL_AND_]POP by means other than throwing an exception,
 *  or calling CLEANUP_[CALL_AND_]POP.
 *
 *  Within the call to the cleanup handler, it is possible that new
 *  exceptions may happen.  Such exceptions must be handled before the
 *  cleanup handler terminates. If the call to the cleanup handler is
 *  terminated by an exception, the behavior is undefined. The exception
 *  which triggered the cleanup is not yet caught; thus the program
 *  would be effectively trying to replace an exception with one that
 *  isn't in a well-defined state.
 *
 *
 * CLEANUP_POP and CLEANUP_CALL_AND_POP
 *
 *  A call to the CLEANUP_POP or CLEANUP_CALL_AND_POP macro shall match
 *  each call to CLEANUP_PUSH which shall be in the same statement block
 *  at the same nesting level.  It shall match the most recent such a
 *  call that is not matched by a previous CLEANUP_[CALL_AND_]POP at
 *  the same level.
 *
 *  These macros causes the registered cleanup handler to be removed. If
 *  CLEANUP_CALL_AND_POP is called, the cleanup handler is called.
 *  In that case, the registered context pointer is passed to the cleanup
 *  handler. If CLEANUP_POP is called, the cleanup handler is not called.
 *
 *  The program shall not leave the region between the call to the
 *  macro CLEANUP_PUSH and the matching call to CLEANUP_[CALL_AND_]POP
 *  other than by throwing an exception, or by executing the
 *  CLEANUP_CALL_AND_POP.
 *
 */
 
 
#define CLEANUP_PUSH(f,a)       except_cleanup_push((f),(a))
#define CLEANUP_POP         except_cleanup_pop(0)
#define CLEANUP_CALL_AND_POP        except_cleanup_pop(1)
 
/* Variants to allow nesting of except_cleanup_push w/o "shadowing" variables */
#define CLEANUP_PUSH_PFX(pfx,f,a)   except_cleanup_push_pfx(pfx,(f),(a))
#define CLEANUP_POP_PFX(pfx)        except_cleanup_pop_pfx(pfx,0)
#define CLEANUP_CALL_AND_POP_PFX(pfx)   except_cleanup_pop_pfx(pfx,1)
 
/*
 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 8
 * tab-width: 8
 * indent-tabs-mode: t
 * End:
 *
 * vi: set shiftwidth=8 tabstop=8 noexpandtab:
 * :indentSize=8:tabSize=8:noTabs=false:
 */