Rework error handling

Previously, various error handling functions were defined, but not all
of them were even used. The new error handling functions handle the most
common cases:

- Assertions. These can be handled with `ASSERT()`, which gives the
  error location for debugging.

- Errors we don't know how to handle, like GetNewWindow returning NULL.
  These can be handled with `EXIT_INTERNAL()`, which gives the error
  location for debugging.

- Out of memory conditions. These can be handled with `ShowMemError()`.

- System errors in response to user operations. These can be handled
  with `ShowError()`.

macos/choose_directory.c

@@ -47,7 +47,8 @@ static void SelectCurrentDirectory(struct ChooseDirReply *reply)
 	ci.dirInfo.ioDrDirID = LMGetCurDirStore();
 	err = PBGetCatInfoSync(&ci);
 	if (err != 0) {
-		ExitErrorOS(kErrUnknown, err);
+		ShowError(kErrNone, kErrNone, err, NULL);
+		return;
 	}
 	directory = reply->directory;
 	directory->vRefNum = ci.dirInfo.ioVRefNum;
@@ -99,10 +100,10 @@ Boolean ChooseDirectory(FSSpec *directory)
 	switch (cdreply.status) {
 	case kCDChild:
 		BlockMoveData(&sfreply.sfFile, directory, sizeof(FSSpec));
-		return 1;
+		return true;
 	case kCDCurrent:
-		return 1;
+		return true;
 	default:
-		return 0;
+		return false;
 	}
 }

macos/error.c

@@ -3,73 +3,120 @@
 // Mozilla Public License, version 2.0. See LICENSE.txt for details.
 #include "macos/error.h"
 
+#include "lib/defs.h"
 #include "macos/main.h"
+#include "macos/pstrbuilder.h"
 #include "macos/resources.h"
-#include "macos/strutil.h"
 
 #include <Dialogs.h>
 #include <TextUtils.h>
 
-void ExitError(ErrorCode errCode)
+enum {
+	// OK
+	kStrOK = 1,
+	// Quit
+	kStrQuit,
+	// An error of type ^2 occurred.
+	kStrErrorCode,
+	// Error at: ^1:^2
+	kStrErrorAt,
+	// Assertion: ^1
+	kStrAssertion,
+	// An internal error occurred.
+	kStrInternal,
+	// An unknown error occurred.
+	kStrUnknown,
+	// (Base value for error messages.)
+	kStrMessageBase
+};
+
+static void AppendErrorArray(struct PStrBuilder *str, int sep, int strNum,
+                             int paramCount, const unsigned char *const *params)
 {
 	Str255 message;
 
-	GetIndString(message, rSTRS_Errors, errCode);
+	if (str->data[0] > 0 && sep != 0) {
-	if (message[0] == 0) {
+		PStrAppendChar(str, sep);
-		GetIndString(message, rSTRS_Errors, kErrUnknown);
+	}
+	GetIndString(message, rSTRS_Errors, strNum);
+	if (message[0] == 0) {
+		PStrAppendChar(str, '?');
+	} else {
+		PStrAppendSubstitute(str, message, paramCount, params);
 	}
-	ParamText(message, NULL, NULL, NULL);
-	Alert(rAlrtError, NULL);
-	QuitApp();
 }
 
-void ExitErrorOS(ErrorCode errCode, short osErr)
+static void AppendError0(struct PStrBuilder *str, int sep, int strNum)
 {
-	Str255 message;
+	AppendErrorArray(str, sep, strNum, 0, NULL);
-
-	GetIndString(message, rSTRS_Errors, errCode);
-	if (message[0] == 0) {
-		GetIndString(message, rSTRS_Errors, kErrUnknown);
-	}
-	StrAppendFormat(message, "\p\rError code: %d", osErr);
-	ParamText(message, NULL, NULL, NULL);
-	Alert(rAlrtError, NULL);
-	QuitApp();
 }
 
-void ExitMemError(void)
+static void AppendError1(struct PStrBuilder *str, int sep, int strNum,
+                         const unsigned char *strParam)
 {
-	ExitErrorOS(kErrOutOfMemory, MemError());
+	AppendErrorArray(str, sep, strNum, 1, &strParam);
+}
+
+static void AppendError2(struct PStrBuilder *str, int sep, int strNum,
+                         const unsigned char *strParam, int intParam)
+{
+	unsigned char num[16];
+	const unsigned char *params[2];
+
+	params[0] = strParam;
+	NumToString(intParam, num);
+	params[1] = num;
+	AppendErrorArray(str, sep, strNum, 2, params);
+}
+
+static void ShowErrorAlert(const unsigned char *message, int button)
+{
+	Str255 buttonText;
+
+	GetIndString(buttonText, rSTRS_Errors, button);
+	ParamText(message, buttonText, NULL, NULL);
+	Alert(rAlrtError, NULL);
 }
 
 void ExitAssert(const unsigned char *file, int line,
-                const unsigned char *message)
+                const unsigned char *assertion)
 {
-	Str255 dmessage;
+	struct PStrBuilder str;
 
-	GetIndString(dmessage, rSTRS_Errors, kErrInternal);
+	PStrInit(&str);
-	StrAppendFormat(dmessage, "\p\rError at: %S:%d", file, line);
+	AppendError0(&str, 0, kStrInternal);
-	if (message != NULL) {
+	if (file != NULL) {
-		StrAppendFormat(dmessage, "\p: %S", message);
+		AppendError2(&str, '\r', kStrErrorAt, file, line);
 	}
-	ParamText(dmessage, NULL, NULL, NULL);
+	if (assertion != NULL) {
-	Alert(rAlrtError, NULL);
+		AppendError1(&str, '\r', kStrAssertion, assertion);
+	}
+	ShowErrorAlert(str.data, kStrQuit);
 	QuitApp();
 }
 
-void ShowError(const struct ErrorParams *p)
+void ShowError(ErrorCode err1, ErrorCode err2, short osErr,
+               const unsigned char *strParam)
 {
-	Str255 message;
+	struct PStrBuilder str;
 
-	GetIndString(message, rSTRS_Errors, p->err);
+	PStrInit(&str);
-	if (message[0] == 0) {
+	if (err1 != kErrNone) {
-		GetIndString(message, rSTRS_Errors, kErrUnknown);
+		AppendError1(&str, ' ', kStrMessageBase - 1 + err1, strParam);
-	} else if (p->strParam != NULL) {
-		StrSubstitute(message, p->strParam);
 	}
-	if (p->osErr != NULL) {
+	if (err2 != kErrNone) {
-		StrAppendFormat(message, "\p\rError code: %d", p->osErr);
+		AppendError1(&str, ' ', kStrMessageBase - 1 + err2, strParam);
 	}
-	ParamText(message, NULL, NULL, NULL);
+	if (osErr != 0) {
-	Alert(rAlrtError, NULL);
+		AppendError2(&str, ' ', kStrErrorCode, NULL, osErr);
+	}
+	if (str.data[0] == 0) {
+		AppendError0(&str, ' ', kStrUnknown);
+	}
+	ShowErrorAlert(str.data, kStrOK);
+}
+
+void ShowMemError(void)
+{
+	ShowError(kErrOutOfMemory, kErrNone, MemError(), NULL);
 }

macos/error.h

@@ -6,32 +6,34 @@
 
 // Error codes, corresponding to messages in a STR# resource. This should be
 // kept in sync with STR# rSTRS_Errors in resources.r.
-typedef enum {
+typedef enum ErrorCode {
-	// An unknown error occurred.
+	// (no error)
-	kErrUnknown = 1,
+	kErrNone,
-	// An internal error occurred.
-	kErrInternal,
 	// Out of memory.
 	kErrOutOfMemory,
 	// Could not save project "^1".
 	kErrCouldNotSaveProject,
+	// Could not read project "^1".
+	kErrCouldNotReadProject,
+	// The project file is damaged.
+	kErrProjectDamaged,
+	// The project file is from an unknown version of SyncFiles.
+	kErrProjectUnknownVersion,
+	// Could not query volume parameters.
+	kErrVolumeQuery,
+	// Could not create alias.
+	kErrAlias,
+	// Could not get directory path.
+	kErrDirPath
 } ErrorCode;
 
-// ExitError shows an error dialog with the given error message, then quits the
+// ExitAssert shows an assertion error and quits the program. Either the file or
-// program.
+// the assertion may be NULL.
-void ExitError(ErrorCode errCode);
-
-// ExitErrorOS shows an error dialog with the given error message and an OS
-// error code, then quits the program.
-void ExitErrorOS(ErrorCode errCode, short osErr);
-
-// ExitMemError shows an out of memory error and quits the program.
-void ExitMemError(void);
-
-// ExitAssert shows an assertion error and quits the program. The message may be
-// NULL.
 void ExitAssert(const unsigned char *file, int line,
-                const unsigned char *message);
+                const unsigned char *assertion);
+
+// EXIT_INTERNAL shows an internal error message and quits the program.
+#define EXIT_INTERNAL() ExitAssert("\p" __FILE__, __LINE__, NULL)
 
 // EXIT_ASSERT shows an assertion error and quits the program. The message may
 // be NULL.
@@ -45,24 +47,13 @@ void ExitAssert(const unsigned char *file, int line,
 			ExitAssert("\p" __FILE__, __LINE__, "\p" #p); \
 	} while (0)
 
-// An ErrorParams contains the parameters for displaying en error alert window.
+// ShowMemError shows an out of memory error to the user.
-// This structure should be zeroed before use, in case additional fields are
+void ShowMemError(void);
-// added.
-struct ErrorParams {
-	// The application error code. If this is zero, it will be treated as
-	// kErrInternal.
-	ErrorCode err;
 
-	// The OS error code. This is displayed at the end of the error message,
+// ShowError shows an error alert window to the user. The error codes are
-	// unless it is zero.
+// displayed if they are not 0. If osErr is not 0, then it is displayed as well.
-	short osErr;
+// Any ^1 parameters in the error messages are replaced with strParam.
-
+void ShowError(ErrorCode err1, ErrorCode err2, short osErr,
-	// If the error messages contain any string substitutions like "^1", those
+               const unsigned char *strParam);
-	// substitutions are replaced with this string.
-	const unsigned char *strParam;
-};
-
-// ShowError shows an error alert window to the user.
-void ShowError(const struct ErrorParams *p);
 
 #endif

macos/project.c

@@ -130,11 +130,11 @@ void ProjectNew(void)
 
 	project = (ProjectHandle)NewHandle(sizeof(struct Project));
 	if (project == NULL) {
-		EXIT_ASSERT(NULL);
+		EXIT_INTERNAL();
 	}
 	window = GetNewCWindow(rWIND_Project, NULL, (WindowPtr)-1);
 	if (window == NULL) {
-		EXIT_ASSERT(NULL);
+		EXIT_INTERNAL();
 	}
 	windowWidth = window->portRect.right - window->portRect.left;
 	SetWRefCon(window, (long)project);
@@ -145,7 +145,7 @@ void ProjectNew(void)
 	for (i = 0; i < 2; i++) {
 		control = GetNewControl(rCNTL_ChooseFolder, window);
 		if (control == NULL) {
-			EXIT_ASSERT(NULL);
+			EXIT_INTERNAL();
 		}
 		controlWidth =
 			(*control)->contrlRect.right - (*control)->contrlRect.left;
@@ -453,7 +453,6 @@ static void ProjectSave(WindowRef window, ProjectHandle project,
 	Str255 name;
 	StandardFileReply reply;
 	OSErr err;
-	struct ErrorParams errp;
 	FSSpec spec;
 	ScriptCode script;
 
@@ -483,11 +482,7 @@ static void ProjectSave(WindowRef window, ProjectHandle project,
 	return;
 
 error:
-	memset(&errp, 0, sizeof(errp));
+	ShowError(kErrCouldNotSaveProject, kErrNone, err, reply.sfFile.name);
-	errp.err = kErrCouldNotSaveProject;
-	errp.osErr = err;
-	errp.strParam = reply.sfFile.name;
-	ShowError(&errp);
 }
 
 void ProjectCommand(WindowRef window, ProjectHandle project, int menuID,
@@ -569,7 +564,8 @@ static Boolean VolumeDoesSupportIDs(short vRefNum)
 	hb.ioParam.ioReqCount = sizeof(parms);
 	err = PBHGetVolParms(&hb, false);
 	if (err != noErr) {
-		ExitErrorOS(kErrUnknown, err);
+		ShowError(kErrVolumeQuery, kErrNone, err, NULL);
+		return false;
 	}
 	return (parms.vMAttrib & (1ul << bHasFileIDs)) != 0;
 }
@@ -591,15 +587,21 @@ static void ProjectChooseDir(WindowRef window, ProjectHandle project,
 	if (VolumeDoesSupportIDs(directory.vRefNum)) {
 		err = NewAlias(NULL, &directory, &alias);
 		if (err != noErr) {
-			ExitErrorOS(kErrUnknown, err);
+			ShowError(kErrAlias, kErrNone, err, NULL);
+			return;
 		}
 	} else {
 		alias = NULL;
 	}
 	err = GetDirPath(&directory, &pathLength, &path);
 	if (err != noErr) {
-		ExitErrorOS(kErrUnknown, err);
+		ShowError(kErrDirPath, kErrNone, err, NULL);
+		if (alias != NULL) {
+			DisposeHandle((Handle)alias);
+		}
+		return;
 	}
+
 	projectp = *project;
 	dirp = &projectp->dirs[whichDir];
 	if (dirp->path != NULL) {

macos/pstrbuilder.c

@@ -5,6 +5,12 @@
 
 #include <string.h>
 
+void PStrInit(struct PStrBuilder *buf)
+{
+	buf->data[0] = 0;
+	buf->truncated = 0;
+}
+
 static void PStrAppendMem(struct PStrBuilder *buf, const unsigned char *src,
                           int slen)
 {
@@ -35,6 +41,11 @@ static void PStrAppendMem(struct PStrBuilder *buf, const unsigned char *src,
 	buf->data[0] = dlen + slen;
 }
 
+void PStrAppendChar(struct PStrBuilder *buf, unsigned char c)
+{
+	PStrAppendMem(buf, &c, 1);
+}
+
 void PStrAppend(struct PStrBuilder *buf, const unsigned char *src)
 {
 	PStrAppendMem(buf, src + 1, src[0]);

macos/pstrbuilder.h

@@ -29,6 +29,12 @@ struct PStrBuilder {
 	Boolean truncated;
 };
 
+// PStrInit initializes a string buffer.
+void PStrInit(struct PStrBuilder *buf);
+
+// PStrAppendChar appends a single character to the buffer.
+void PStrAppendChar(struct PStrBuilder *buf, unsigned char c);
+
 // PStrAppend appends a string to the buffer.
 void PStrAppend(struct PStrBuilder *buf, const unsigned char *src);
 

macos/resources.r

@@ -119,10 +119,21 @@ resource 'BNDL' (128, purgeable) {
 };
 
 resource 'STR#' (rSTRS_Errors) {{
-	"An unknown error occurred.",
+	"OK",
+	"Quit",
+	"An error of type ^2 occurred.",
+	"Error at: ^1:^2",
+	"Assertion: ^1",
 	"An internal error occurred.",
+	"An unknown error occurred.",
 	"Out of memory.",
 	"Could not save project “^1”.",
+	"Could not read project “^1”.",
+	"The project file is damaged.",
+	"The project file is from an unknown version of SyncFiles.",
+	"Could not query volume parameters.",
+	"Could not create alias.",
+	"Could not get directory path.",
 }};
 
 resource 'WIND' (rWIND_Project, preload, purgeable) {