Save more descriptive error msg from FBS/BKS, relay it up to lldb.

When lldb requests an app launch through FrontBoard/BackBoard,
we get back an NSError object if there was a problem with an
integer error code and a descriptive text string.  debugserver
would log the descriptive text string to the console, but it
would only save the error code value, ask for the
much-less-specific name of that error code, and send that very
generic error word back to lldb.

This patch saves the longer description of the failure when
available, and sends that to lldb.  If unavailable, it falls
back to sending up the generic description of the error code
as it was doing before.

This only impacts the iOS on-device debugserver.

<rdar://problem/49953304>

(cherry picked from commit d44a074)

Author: jasonmolenda

lldb/tools/debugserver/source/MacOSX/MachProcess.mm

@@ -86,7 +86,7 @@ static CFStringRef CopyBundleIDForPath(const char *app_bundle_path,
 #if defined(WITH_BKS) || defined(WITH_FBS)
 #import <Foundation/Foundation.h>
 static const int OPEN_APPLICATION_TIMEOUT_ERROR = 111;
-typedef void (*SetErrorFunction)(NSInteger, DNBError &);
+typedef void (*SetErrorFunction)(NSInteger, std::string, DNBError &);
 typedef bool (*CallOpenApplicationFunction)(NSString *bundleIDNSStr,
                                             NSDictionary *options,
                                             DNBError &error, pid_t *return_pid);
@@ -122,6 +122,7 @@ static bool CallBoardSystemServiceOpenApplication(NSString *bundleIDNSStr,
   mach_port_t client_port = [system_service createClientPort];
   __block dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
   __block ErrorFlavor open_app_error = no_error_enum_value;
+  __block std::string open_app_error_string;
   bool wants_pid = (return_pid != NULL);
   __block pid_t pid_in_block;
 
@@ -159,6 +160,9 @@ static bool CallBoardSystemServiceOpenApplication(NSString *bundleIDNSStr,
              } else {
                const char *error_str =
                    [(NSString *)[bks_error localizedDescription] UTF8String];
+               if (error_str) {
+                 open_app_error_string = error_str;
+               }
                DNBLogThreadedIf(LOG_PROCESS, "In completion handler for send "
                                              "event, got error \"%s\"(%ld).",
                                 error_str ? error_str : "<unknown error>",
@@ -190,7 +194,7 @@ static bool CallBoardSystemServiceOpenApplication(NSString *bundleIDNSStr,
     error.SetError(OPEN_APPLICATION_TIMEOUT_ERROR, DNBError::Generic);
     error.SetErrorString("timed out trying to launch app");
   } else if (open_app_error != no_error_enum_value) {
-    error_function(open_app_error, error);
+    error_function(open_app_error, open_app_error_string, error);
     DNBLogError("unable to launch the application with CFBundleIdentifier '%s' "
                 "bks_error = %u",
                 cstr, open_app_error);
@@ -245,19 +249,19 @@ static bool IsBKSProcess(nub_process_t pid) {
   return app_state != BKSApplicationStateUnknown;
 }
 
-static void SetBKSError(NSInteger error_code, DNBError &error) {
+static void SetBKSError(NSInteger error_code, 
+                        std::string error_description, 
+                        DNBError &error) {
   error.SetError(error_code, DNBError::BackBoard);
   NSString *err_nsstr = ::BKSOpenApplicationErrorCodeToString(
       (BKSOpenApplicationErrorCode)error_code);
-  const char *err_str = NULL;
-  if (err_nsstr == NULL)
-    err_str = "unknown BKS error";
-  else {
+  std::string err_str = "unknown BKS error";
+  if (error_description.empty() == false) {
+    err_str = error_description;
+  } else if (err_nsstr != nullptr) {
     err_str = [err_nsstr UTF8String];
-    if (err_str == NULL)
-      err_str = "unknown BKS error";
   }
-  error.SetErrorString(err_str);
+  error.SetErrorString(err_str.c_str());
 }
 
 static bool BKSAddEventDataToOptions(NSMutableDictionary *options,
@@ -355,19 +359,19 @@ static bool IsFBSProcess(nub_process_t pid) {
 }
 #endif
 
-static void SetFBSError(NSInteger error_code, DNBError &error) {
+static void SetFBSError(NSInteger error_code, 
+                        std::string error_description, 
+                        DNBError &error) {
   error.SetError((DNBError::ValueType)error_code, DNBError::FrontBoard);
   NSString *err_nsstr = ::FBSOpenApplicationErrorCodeToString(
       (FBSOpenApplicationErrorCode)error_code);
-  const char *err_str = NULL;
-  if (err_nsstr == NULL)
-    err_str = "unknown FBS error";
-  else {
+  std::string err_str = "unknown FBS error";
+  if (error_description.empty() == false) {
+    err_str = error_description;
+  } else if (err_nsstr != nullptr) {
     err_str = [err_nsstr UTF8String];
-    if (err_str == NULL)
-      err_str = "unknown FBS error";
   }
-  error.SetErrorString(err_str);
+  error.SetErrorString(err_str.c_str());
 }
 
 static bool FBSAddEventDataToOptions(NSMutableDictionary *options,
@@ -2754,7 +2758,8 @@ static bool FBSAddEventDataToOptions(NSMutableDictionary *options,
           "debugserver timed out waiting for openApplication to complete.");
       attach_err.SetError(OPEN_APPLICATION_TIMEOUT_ERROR, DNBError::Generic);
     } else if (attach_error_code != FBSOpenApplicationErrorCodeNone) {
-      SetFBSError(attach_error_code, attach_err);
+      std::string empty_str;
+      SetFBSError(attach_error_code, empty_str, attach_err);
       DNBLogError("unable to launch the application with CFBundleIdentifier "
                   "'%s' bks_error = %ld",
                   bundleIDStr.c_str(), (NSInteger)attach_error_code);
@@ -2831,7 +2836,8 @@ static bool FBSAddEventDataToOptions(NSMutableDictionary *options,
           "debugserver timed out waiting for openApplication to complete.");
       attach_err.SetError(OPEN_APPLICATION_TIMEOUT_ERROR, DNBError::Generic);
     } else if (attach_error_code != BKSOpenApplicationErrorCodeNone) {
-      SetBKSError(attach_error_code, attach_err);
+      std::string empty_str;
+      SetBKSError(attach_error_code, empty_str, attach_err);
       DNBLogError("unable to launch the application with CFBundleIdentifier "
                   "'%s' bks_error = %ld",
                   bundleIDStr.c_str(), attach_error_code);