[PLAT-2016] Fix Swift fatal error message reporting

Bugsnag/BugsnagCrashSentry.m

@@ -26,7 +26,7 @@ - (void)install:(BugsnagConfiguration *)config
     BugsnagErrorReportSink *sink = [[BugsnagErrorReportSink alloc] initWithApiClient:apiClient configuration:config notifier:notifier];
     BSG_KSCrash *ksCrash = [BSG_KSCrash sharedInstance];
     ksCrash.sink = sink;
-    ksCrash.introspectMemory = YES;
+    ksCrash.introspectMemory = NO;
     ksCrash.onCrash = onCrash;
     ksCrash.maxStoredReports = (int)config.maxPersistedEvents;
 

Bugsnag/KSCrash/Source/KSCrash/Recording/BSG_KSCrashReport.c

@@ -965,6 +965,27 @@ void bsg_kscrw_i_writeNotableAddresses(
     writer->endContainer(writer);
 }
 
+/** Write the message from the `__crash_info` Mach section into the report.
+ *
+ * @param writer The writer.
+ *
+ * @param key The object key.
+ *
+ * @param address The address of the first frame in the backtrace.
+ */
+void bsg_kscrw_i_writeCrashInfoMessage(const BSG_KSCrashReportWriter *const writer,
+                                       const char *key, uintptr_t address) {
+    BSG_Mach_Header_Info *image = bsg_mach_headers_image_at_address(address);
+    if (!image) {
+        BSG_KSLOG_ERROR("Could not locate mach header info");
+        return;
+    }
+    const char *message = bsg_mach_headers_get_crash_info_message(image);
+    if (message) {
+        writer->addStringElement(writer, key, message);
+    }
+}
+
 /** Write information about a thread to the report.
  *
  * @param writer The writer.
@@ -1021,6 +1042,10 @@ void bsg_kscrw_i_writeThread(const BSG_KSCrashReportWriter *const writer,
                     writer, BSG_KSCrashField_NotableAddresses, machineContext);
             }
         }
+        if (isCrashedThread && backtrace && backtraceLength) {
+            bsg_kscrw_i_writeCrashInfoMessage(writer, BSG_KSCrashField_CrashInfoMessage,
+                                              backtrace[0]);
+        }
     }
     writer->endContainer(writer);
 }

Bugsnag/KSCrash/Source/KSCrash/Recording/BSG_KSCrashReportFields.h

@@ -95,6 +95,7 @@
 #define BSG_KSCrashField_Backtrace "backtrace"
 #define BSG_KSCrashField_Basic "basic"
 #define BSG_KSCrashField_Crashed "crashed"
+#define BSG_KSCrashField_CrashInfoMessage "crash_info_message"
 #define BSG_KSCrashField_CurrentThread "current_thread"
 #define BSG_KSCrashField_DispatchQueue "dispatch_queue"
 #define BSG_KSCrashField_NotableAddresses "notable_addresses"

Bugsnag/KSCrash/Source/KSCrash/Recording/Tools/BSG_KSMachHeaders.m → Bugsnag/KSCrash/Source/KSCrash/Recording/Tools/BSG_KSMachHeaders.c

@@ -1,16 +1,36 @@
 //
-//  BSG_KSMachHeaders.m
+//  BSG_KSMachHeaders.c
 //  Bugsnag
 //
 //  Created by Robin Macharg on 04/05/2020.
 //  Copyright © 2020 Bugsnag. All rights reserved.
 //
 
-#import <mach-o/dyld.h>
-#import <dlfcn.h>
-#import <Foundation/Foundation.h>
-#import "BSG_KSDynamicLinker.h"
-#import "BSG_KSMachHeaders.h"
+#include "BSG_KSMachHeaders.h"
+
+#include "BSG_KSDynamicLinker.h"
+#include "BSG_KSMach.h"
+
+#include <dispatch/dispatch.h>
+#include <dlfcn.h>
+#include <mach-o/dyld.h>
+#include <stdlib.h>
+
+// Copied from https://github.com/apple/swift/blob/swift-5.0-RELEASE/include/swift/Runtime/Debug.h#L28-L40
+
+#define CRASHREPORTER_ANNOTATIONS_VERSION 5
+#define CRASHREPORTER_ANNOTATIONS_SECTION "__crash_info"
+
+struct crashreporter_annotations_t {
+    uint64_t version;          // unsigned long
+    uint64_t message;          // char *
+    uint64_t signature_string; // char *
+    uint64_t backtrace;        // char *
+    uint64_t message2;         // char *
+    uint64_t thread;           // uint64_t
+    uint64_t dialog_mode;      // unsigned int
+    uint64_t abort_cause;      // unsigned int
+};
 
 // MARK: - Mach Header Linked List
 
@@ -255,3 +275,66 @@ uintptr_t bsg_mach_headers_image_at_base_of_image_index(const struct mach_header
 
     return 0;
 }
+static uintptr_t bsg_mach_header_info_get_section_addr_named(const BSG_Mach_Header_Info *header, const char *name) {
+    uintptr_t cmdPtr = bsg_mach_headers_first_cmd_after_header(header->header);
+    if (!cmdPtr) {
+        return 0;
+    }
+    for (uint32_t i = 0; i < header->header->ncmds; i++) {
+        const struct load_command *loadCmd = (struct load_command *)cmdPtr;
+        if (loadCmd->cmd == LC_SEGMENT) {
+            const struct segment_command *segment = (void *)cmdPtr;
+            char *sectionPtr = (void *)(cmdPtr + sizeof(*segment));
+            for (uint32_t i = 0; i < segment->nsects; i++) {
+                struct section *section = (void *)sectionPtr;
+                if (strcmp(name, section->sectname) == 0) {
+                    return section->addr + header->slide;
+                }
+                sectionPtr += sizeof(*section);
+            }
+        } else if (loadCmd->cmd == LC_SEGMENT_64) {
+            const struct segment_command_64 *segment = (void *)cmdPtr;
+            char *sectionPtr = (void *)(cmdPtr + sizeof(*segment));
+            for (uint32_t i = 0; i < segment->nsects; i++) {
+                struct section_64 *section = (void *)sectionPtr;
+                if (strcmp(name, section->sectname) == 0) {
+                    return (uintptr_t)section->addr + header->slide;
+                }
+                sectionPtr += sizeof(*section);
+            }
+        }
+        cmdPtr += loadCmd->cmdsize;
+    }
+    return 0;
+}
+
+const char *bsg_mach_headers_get_crash_info_message(const BSG_Mach_Header_Info *header) {
+    struct crashreporter_annotations_t info;
+    uintptr_t sectionAddress = bsg_mach_header_info_get_section_addr_named(header, CRASHREPORTER_ANNOTATIONS_SECTION);
+    if (!sectionAddress) {
+        return NULL;
+    }
+    if (bsg_ksmachcopyMem((void *)sectionAddress, &info, sizeof(info)) != KERN_SUCCESS) {
+        return NULL;
+    }
+    // Version 4 was in use until iOS 9 / Swift 2.0 when the version was bumped to 5.
+    if (info.version > CRASHREPORTER_ANNOTATIONS_VERSION) {
+        return NULL;
+    }
+    if (!info.message) {
+        return NULL;
+    }
+    // Probe the string to ensure it's safe to read.
+    for (uintptr_t i = 0; i < 500; i++) {
+        char c;
+        if (bsg_ksmachcopyMem((void *)(info.message + i), &c, sizeof(c)) != KERN_SUCCESS) {
+            // String is not readable.
+            return NULL;
+        }
+        if (c == '\0') {
+            // Found end of string.
+            return (const char *)info.message;
+        }
+    }
+    return NULL;
+}

Bugsnag/KSCrash/Source/KSCrash/Recording/Tools/BSG_KSMachHeaders.h

@@ -99,4 +99,11 @@ uintptr_t bsg_mach_headers_first_cmd_after_header(const struct mach_header *head
  */
 uintptr_t bsg_mach_headers_image_at_base_of_image_index(const struct mach_header *header);
 
+/** Get the __crash_info message of the specified image.
+ *
+ * @param header The header to get commands for.
+ * @return The __crash_info message, or NULL if no readable message could be found.
+ */
+const char *bsg_mach_headers_get_crash_info_message(const BSG_Mach_Header_Info *header);
+
 #endif /* BSG_KSMachHeaders_h */

Bugsnag/Payload/BugsnagError+Private.h

@@ -23,6 +23,9 @@ NS_ASSUME_NONNULL_BEGIN
 
 + (BugsnagError *)errorFromJson:(NSDictionary *)json;
 
+/// Parses the `__crash_info` message and updates the `errorClass` and `errorMessage` as appropriate.
+- (void)updateWithCrashInfoMessage:(NSString *)crashInfoMessage;
+
 - (NSDictionary *)toDictionary;
 
 @end

Bugsnag/Payload/BugsnagError.m

@@ -6,14 +6,16 @@
 //  Copyright © 2020 Bugsnag. All rights reserved.
 //
 
-#import "BugsnagError.h"
+#import "BugsnagError+Private.h"
 
+#import "BSG_KSCrashReportFields.h"
+#import "BugsnagCollections.h"
 #import "BugsnagKeys.h"
+#import "BugsnagLogger.h"
 #import "BugsnagStackframe+Private.h"
 #import "BugsnagStacktrace.h"
-#import "BugsnagCollections.h"
-#import "RegisterErrorData.h"
-#import "BugsnagThread.h"
+#import "BugsnagThread+Private.h"
+
 
 NSString *_Nonnull BSGSerializeErrorType(BSGErrorType errorType) {
     switch (errorType) {
@@ -87,12 +89,6 @@ - (instancetype)initWithEvent:(NSDictionary *)event errorReportingThread:(Bugsna
         _type = BSGErrorTypeCocoa;
 
         if (![[event valueForKeyPath:@"user.state.didOOM"] boolValue]) {
-            NSArray *threadDict = [event valueForKeyPath:@"crash.threads"];
-            RegisterErrorData *data = [RegisterErrorData errorDataFromThreads:threadDict];
-            if (data) {
-                _errorClass = data.errorClass;
-                _errorMessage = data.errorMessage;
-            }
             _stacktrace = thread.stacktrace;
         }
     }
@@ -132,6 +128,36 @@ + (BugsnagError *)errorFromJson:(NSDictionary *)json {
     return error;
 }
 
+- (void)updateWithCrashInfoMessage:(NSString *)crashInfoMessage {
+    @try {
+        // Messages that match this pattern should override the errorClass (and errorMessage if there is enough information.)
+        NSString *pattern = @"^(Assertion failed|Fatal error|Precondition failed): ((.+): )?file .+, line \\d+\n$";
+        NSRegularExpression *regex = [[NSRegularExpression alloc] initWithPattern:pattern options:NSRegularExpressionCaseInsensitive error:nil];
+        NSArray<NSTextCheckingResult *> *matches = [regex matchesInString:crashInfoMessage options:0 range:NSMakeRange(0, crashInfoMessage.length)];
+        if (matches.count != 1 || matches[0].numberOfRanges != 4) {
+            if (!self.errorMessage.length) {
+                // It's better to fall back to the raw string than have an empty errorMessage.
+                self.errorMessage = crashInfoMessage;
+            }
+            return;
+        }
+        NSRange errorClassRange = [matches[0] rangeAtIndex:1];
+        if (errorClassRange.location != NSNotFound) {
+            self.errorClass = [crashInfoMessage substringWithRange:errorClassRange];
+        }
+        NSRange errorMessageRange = [matches[0] rangeAtIndex:3];
+        if (errorMessageRange.location != NSNotFound) {
+            self.errorMessage = [crashInfoMessage substringWithRange:errorMessageRange];
+        }
+    } @catch (NSException *exception) {
+        bsg_log_err(@"Exception thrown while parsing crash info message: %@", exception);
+        if (!self.errorMessage.length) {
+            // It's better to fall back to the raw string than have an empty errorMessage.
+            self.errorMessage = crashInfoMessage;
+        }
+    }
+}
+
 - (NSDictionary *)findErrorReportingThread:(NSDictionary *)event {
     NSArray *threads = [event valueForKeyPath:@"crash.threads"];
 

Bugsnag/Payload/BugsnagEvent.m

@@ -8,6 +8,8 @@
 
 #import "BugsnagPlatformConditional.h"
 
+#import "BugsnagEvent+Private.h"
+
 #if BSG_PLATFORM_IOS
 #import "BSGUIKit.h"
 #include <sys/utsname.h>
@@ -27,7 +29,6 @@
 #import "BugsnagConfiguration+Private.h"
 #import "BugsnagDeviceWithState+Private.h"
 #import "BugsnagError+Private.h"
-#import "BugsnagEvent+Private.h"
 #import "BugsnagHandledState.h"
 #import "BugsnagKeys.h"
 #import "BugsnagMetadata+Private.h"
@@ -36,7 +37,7 @@
 #import "BugsnagStacktrace+Private.h"
 #import "BugsnagThread+Private.h"
 #import "BugsnagUser+Private.h"
-#import "RegisterErrorData.h"
+
 
 static NSString *const DEFAULT_EXCEPTION_TYPE = @"cocoa";
 
@@ -267,7 +268,7 @@ - (instancetype)initWithOOMData:(NSDictionary *)event {
  * @return a BugsnagEvent containing the parsed information
  */
 - (instancetype)initWithKSCrashData:(NSDictionary *)event {
-    NSDictionary *error = [event valueForKeyPath:@"crash.error"];
+    NSMutableDictionary *error = [[event valueForKeyPath:@"crash.error"] mutableCopy];
     NSString *errorType = error[BSGKeyType];
 
     // Always assume that a report coming from KSCrash is by default an unhandled error.
@@ -333,6 +334,11 @@ - (instancetype)initWithKSCrashData:(NSDictionary *)event {
 
     NSArray<BugsnagError *> *errors = @[[[BugsnagError alloc] initWithEvent:event errorReportingThread:errorReportingThread]];
 
+    if (errorReportingThread.crashInfoMessage) {
+        [errors[0] updateWithCrashInfoMessage:errorReportingThread.crashInfoMessage];
+        error[@"crashInfo"] = errorReportingThread.crashInfoMessage;
+    }
+
     BugsnagHandledState *handledState;
     if (recordedState) {
         handledState = [[BugsnagHandledState alloc] initWithDictionary:recordedState];

Bugsnag/Payload/BugsnagThread+Private.h

@@ -18,6 +18,8 @@ NS_ASSUME_NONNULL_BEGIN
 
 + (instancetype)threadFromJson:(NSDictionary *)json;
 
+@property (readonly) NSString *crashInfoMessage;
+
 + (NSDictionary *)enhanceThreadInfo:(NSDictionary *)thread
                               depth:(NSUInteger)depth
                           errorType:(nullable NSString *)errorType;

Bugsnag/Payload/BugsnagThread.m

@@ -6,8 +6,9 @@
 //  Copyright © 2020 Bugsnag. All rights reserved.
 //
 
-#import "BugsnagThread.h"
+#import "BugsnagThread+Private.h"
 
+#import "BSG_KSCrashReportFields.h"
 #import "BugsnagCollections.h"
 #import "BugsnagStackframe+Private.h"
 #import "BugsnagStacktrace+Private.h"
@@ -56,13 +57,13 @@ - (instancetype)initWithId:(NSString *)id
 
 - (instancetype)initWithThread:(NSDictionary *)thread binaryImages:(NSArray *)binaryImages {
     if (self = [super init]) {
-        _errorReportingThread = [thread[@"crashed"] boolValue];
-        self.id = [thread[@"index"] stringValue];
-        self.type = BSGThreadTypeCocoa;
-
-        NSArray *backtrace = thread[@"backtrace"][@"contents"];
+        _errorReportingThread = [thread[@(BSG_KSCrashField_Crashed)] boolValue];
+        _id = [thread[@(BSG_KSCrashField_Index)] stringValue];
+        _type = BSGThreadTypeCocoa;
+        _crashInfoMessage = [thread[@(BSG_KSCrashField_CrashInfoMessage)] copy];
+        NSArray *backtrace = thread[@(BSG_KSCrashField_Backtrace)][@(BSG_KSCrashField_Contents)];
         BugsnagStacktrace *frames = [[BugsnagStacktrace alloc] initWithTrace:backtrace binaryImages:binaryImages];
-        self.stacktrace = frames.trace;
+        _stacktrace = [frames.trace copy];
     }
     return self;
 }