fune/xpcom/base/nsObjCExceptions.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

// Undo the damage that exception_defines.h does.
#undef try
#undef catch

#ifndef nsObjCExceptions_h_
#define nsObjCExceptions_h_

#import <Foundation/Foundation.h>

#ifdef DEBUG
#import <ExceptionHandling/NSExceptionHandler.h>
#endif

#if defined(__cplusplus)
#include "nsICrashReporter.h"
#include "nsCOMPtr.h"
#include "nsServiceManagerUtils.h"
#endif

#include <unistd.h>
#include <signal.h>
#include "nsError.h"

// Undo the damage that exception_defines.h does.
#undef try
#undef catch

/* NOTE: Macros that claim to abort no longer abort, see bug 486574.
 * If you actually want to log and abort, call "nsObjCExceptionLogAbort"
 * from an exception handler. At some point we will fix this by replacing
 * all macros in the tree with appropriately-named macros.
 */

// See Mozilla bug 163260.
// This file can only be included in an Objective-C context.

__attribute__((unused))
static void
nsObjCExceptionLog(NSException* aException)
{
  NSLog(@"Mozilla has caught an Obj-C exception [%@: %@]",
        [aException name], [aException reason]);

#if defined(__cplusplus)
  // Attach exception info to the crash report.
  nsCOMPtr<nsICrashReporter> crashReporter =
    do_GetService("@mozilla.org/toolkit/crash-reporter;1");
  if (crashReporter) {
    crashReporter->AppendObjCExceptionInfoToAppNotes(static_cast<void*>(aException));
  }
#endif

#ifdef DEBUG
  @try {
    // Try to get stack information out of the exception. 10.5 returns the stack
    // info with the callStackReturnAddresses selector.
    NSArray* stackTrace = nil;
    if ([aException respondsToSelector:@selector(callStackReturnAddresses)]) {
      NSArray* addresses = (NSArray*)
        [aException performSelector:@selector(callStackReturnAddresses)];
      if ([addresses count]) {
        stackTrace = addresses;
      }
    }

    // 10.4 doesn't respond to callStackReturnAddresses so we'll try to pull the
    // stack info out of the userInfo. It might not be there, sadly :(
    if (!stackTrace) {
      stackTrace = [[aException userInfo] objectForKey:NSStackTraceKey];
    }

    if (stackTrace) {
      // The command line should look like this:
      //   /usr/bin/atos -p <pid> -printHeader <stack frame addresses>
      NSMutableArray* args =
        [NSMutableArray arrayWithCapacity:[stackTrace count] + 3];

      [args addObject:@"-p"];
      int pid = [[NSProcessInfo processInfo] processIdentifier];
      [args addObject:[NSString stringWithFormat:@"%d", pid]];

      [args addObject:@"-printHeader"];

      unsigned int stackCount = [stackTrace count];
      unsigned int stackIndex = 0;
      for (; stackIndex < stackCount; stackIndex++) {
        unsigned long address =
          [[stackTrace objectAtIndex:stackIndex] unsignedLongValue];
        [args addObject:[NSString stringWithFormat:@"0x%lx", address]];
      }

      NSPipe* outPipe = [NSPipe pipe];

      NSTask* task = [[NSTask alloc] init];
      [task setLaunchPath:@"/usr/bin/atos"];
      [task setArguments:args];
      [task setStandardOutput:outPipe];
      [task setStandardError:outPipe];

      NSLog(@"Generating stack trace for Obj-C exception...");

      // This will throw an exception if the atos tool cannot be found, and in
      // that case we'll just hit our @catch block below.
      [task launch];

      [task waitUntilExit];
      [task release];

      NSData* outData =
        [[outPipe fileHandleForReading] readDataToEndOfFile];
      NSString* outString =
        [[NSString alloc] initWithData:outData encoding:NSUTF8StringEncoding];

      NSLog(@"Stack trace:\n%@", outString);

      [outString release];
    } else {
      NSLog(@"<No stack information available for Obj-C exception>");
    }
  }
  @catch (NSException* exn) {
    NSLog(@"Failed to generate stack trace for Obj-C exception [%@: %@]",
          [exn name], [exn reason]);
  }
#endif
}

__attribute__((unused))
static void
nsObjCExceptionAbort()
{
  // We need to raise a mach-o signal here, the Mozilla crash reporter on
  // Mac OS X does not respond to POSIX signals. Raising mach-o signals directly
  // is tricky so we do it by just derefing a null pointer.
  int* foo = nullptr;
  *foo = 1;
}

__attribute__((unused))
static void
nsObjCExceptionLogAbort(NSException* aException)
{
  nsObjCExceptionLog(aException);
  nsObjCExceptionAbort();
}

#define NS_OBJC_TRY(_e, _fail)                     \
@try { _e; }                                       \
@catch(NSException *_exn) {                        \
  nsObjCExceptionLog(_exn);                        \
  _fail;                                           \
}

#define NS_OBJC_TRY_EXPR(_e, _fail)                \
({                                                 \
   typeof(_e) _tmp;                                \
   @try { _tmp = (_e); }                           \
   @catch(NSException *_exn) {                     \
     nsObjCExceptionLog(_exn);                     \
     _fail;                                        \
   }                                               \
   _tmp;                                           \
})

#define NS_OBJC_TRY_EXPR_NULL(_e)                  \
NS_OBJC_TRY_EXPR(_e, 0)

#define NS_OBJC_TRY_IGNORE(_e)                     \
NS_OBJC_TRY(_e, )

// To reduce code size the abort versions do not reuse above macros. This allows
// catch blocks to only contain one call.

#define NS_OBJC_TRY_ABORT(_e)                      \
@try { _e; }                                       \
@catch(NSException *_exn) {                        \
  nsObjCExceptionLog(_exn);                        \
}

#define NS_OBJC_TRY_EXPR_ABORT(_e)                 \
({                                                 \
   typeof(_e) _tmp;                                \
   @try { _tmp = (_e); }                           \
   @catch(NSException *_exn) {                     \
     nsObjCExceptionLog(_exn);                     \
   }                                               \
   _tmp;                                           \
})

// For wrapping blocks of Obj-C calls. Does not actually terminate.
#define NS_OBJC_BEGIN_TRY_ABORT_BLOCK @try {
#define NS_OBJC_END_TRY_ABORT_BLOCK   } @catch(NSException *_exn) {             \
                                        nsObjCExceptionLog(_exn);               \
                                      }

// Same as above ABORT_BLOCK but returns a value after the try/catch block to
// suppress compiler warnings. This allows us to avoid having to refactor code
// to get scoping right when wrapping an entire method.

#define NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NIL @try {
#define NS_OBJC_END_TRY_ABORT_BLOCK_NIL   } @catch(NSException *_exn) {         \
                                            nsObjCExceptionLog(_exn);           \
                                          }                                     \
                                          return nil;

#define NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSNULL @try {
#define NS_OBJC_END_TRY_ABORT_BLOCK_NSNULL   } @catch(NSException *_exn) {      \
                                               nsObjCExceptionLog(_exn);        \
                                             }                                  \
                                             return nullptr;

#define NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT @try {
#define NS_OBJC_END_TRY_ABORT_BLOCK_NSRESULT   } @catch(NSException *_exn) {    \
                                                 nsObjCExceptionLog(_exn);      \
                                               }                                \
                                               return NS_ERROR_FAILURE;

#define NS_OBJC_BEGIN_TRY_ABORT_BLOCK_RETURN    @try {
#define NS_OBJC_END_TRY_ABORT_BLOCK_RETURN(_rv) } @catch(NSException *_exn) {   \
                                                  nsObjCExceptionLog(_exn);\
                                                }                               \
                                                return _rv;

#endif // nsObjCExceptions_h_