Exception handling changes

In preparation for work on progressive loading, update the exception
handling scheme slightly.

Until now, exceptions (as thrown with fz_throw, and caught with
fz_try/fz_catch) have merely had an informative string. They have
never had anything that can be compared to see if an error is of
a particular type.

We now introduce error codes; when we fz_throw, we now always
give an error code, and can optionally (using fz_throw_message)
give both an error code and an informative string.

When we fz_rethrow from within a fz_catch, both the error code and
the error message is maintained. Using fz_rethrow_message we can
'improve' the error message, but the code is maintained.

The error message can be read out using fz_caught_message() and the
error code can be read as fz_caught().

Currently we only define a 'generic' error. This will expand in future
versions to include other error types that may be tested for.

8 files changed, 25 insertions, 25 deletions

diff --git a/apps/jstest_main.c b/apps/jstest_main.c
index f01eabfc..2003ad55 100644
--- a/apps/jstest_main.c
+++ b/apps/jstest_main.c
@@ -326,7 +326,7 @@ main(int argc, char *argv[])
 			scriptname = argv[fz_optind++];
 			script = fopen(scriptname, "rb");
 			if (script == NULL)
-				fz_throw(ctx, "cannot open script: %s", scriptname);
+				fz_throw(ctx, FZ_ERROR_GENERIC, "cannot open script: %s", scriptname);
 
 			do
 			{
diff --git a/apps/mudraw.c b/apps/mudraw.c
index 366cdb8a..57bd4be2 100644
--- a/apps/mudraw.c
+++ b/apps/mudraw.c
@@ -271,7 +271,7 @@ static void drawpage(fz_context *ctx, fz_document *doc, int pagenum)
 	}
 	fz_catch(ctx)
 	{
-		fz_throw(ctx, "cannot load page %d in file '%s'", pagenum, filename);
+		fz_rethrow_message(ctx, "cannot load page %d in file '%s'", pagenum, filename);
 	}
 
 	if (mujstest_file)
@@ -396,7 +396,7 @@ static void drawpage(fz_context *ctx, fz_document *doc, int pagenum)
 		{
 			fz_drop_display_list(ctx, list);
 			fz_free_page(doc, page);
-			fz_throw(ctx, "cannot draw page %d in file '%s'", pagenum, filename);
+			fz_rethrow_message(ctx, "cannot draw page %d in file '%s'", pagenum, filename);
 		}
 	}
 
@@ -485,7 +485,7 @@ static void drawpage(fz_context *ctx, fz_document *doc, int pagenum)
 		sprintf(buf, output, pagenum);
 		file = fopen(buf, "wb");
 		if (file == NULL)
-			fz_throw(ctx, "cannot open file '%s': %s", buf, strerror(errno));
+			fz_throw(ctx, FZ_ERROR_GENERIC, "cannot open file '%s': %s", buf, strerror(errno));
 		out = fz_new_output_with_file(ctx, file);
 
 		fz_bound_page(doc, page, &bounds);
@@ -983,13 +983,13 @@ int main(int argc, char **argv)
 				}
 				fz_catch(ctx)
 				{
-					fz_throw(ctx, "cannot open document: %s", filename);
+					fz_rethrow_message(ctx, "cannot open document: %s", filename);
 				}
 
 				if (fz_needs_password(doc))
 				{
 					if (!fz_authenticate_password(doc, password))
-						fz_throw(ctx, "cannot authenticate password: %s", filename);
+						fz_throw(ctx, FZ_ERROR_GENERIC, "cannot authenticate password: %s", filename);
 					if (mujstest_file)
 						fprintf(mujstest_file, "PASSWORD %s\n", password);
 				}
diff --git a/apps/pdfapp.c b/apps/pdfapp.c
index 7371ea0c..e76c6c7c 100644
--- a/apps/pdfapp.c
+++ b/apps/pdfapp.c
@@ -178,7 +178,7 @@ void pdfapp_open(pdfapp_t *app, char *filename, int reload)
 			{
 				password = winpassword(app, filename);
 				if (!password)
-					fz_throw(ctx, "Needs a password");
+					fz_throw(ctx, FZ_ERROR_GENERIC, "Needs a password");
 				okay = fz_authenticate_password(app->doc, password);
 				if (!okay)
 					pdfapp_warn(app, "Invalid password.");
diff --git a/apps/pdfclean.c b/apps/pdfclean.c
index 3c1e810e..c437b819 100644
--- a/apps/pdfclean.c
+++ b/apps/pdfclean.c
@@ -212,7 +212,7 @@ int pdfclean_main(int argc, char **argv)
 		xref = pdf_open_document_no_run(ctx, infile);
 		if (pdf_needs_password(xref))
 			if (!pdf_authenticate_password(xref, password))
-				fz_throw(ctx, "cannot authenticate password: %s", infile);
+				fz_throw(ctx, FZ_ERROR_GENERIC, "cannot authenticate password: %s", infile);
 
 		/* Only retain the specified subset of the pages */
 		if (subset)
diff --git a/apps/pdfextract.c b/apps/pdfextract.c
index 78a61f14..6e8e4aec 100644
--- a/apps/pdfextract.c
+++ b/apps/pdfextract.c
@@ -120,7 +120,7 @@ static void savefont(pdf_obj *dict, int num)
 
 		obj = pdf_dict_gets(obj, "Subtype");
 		if (obj && !pdf_is_name(obj))
-			fz_throw(ctx, "Invalid font descriptor subtype");
+			fz_throw(ctx, FZ_ERROR_GENERIC, "Invalid font descriptor subtype");
 
 		subtype = pdf_to_name(obj);
 		if (!strcmp(subtype, "Type1C"))
@@ -130,7 +130,7 @@ static void savefont(pdf_obj *dict, int num)
 		else if (!strcmp(subtype, "OpenType"))
 			ext = "otf";
 		else
-			fz_throw(ctx, "Unhandled font type '%s'", subtype);
+			fz_throw(ctx, FZ_ERROR_GENERIC, "Unhandled font type '%s'", subtype);
 	}
 
 	if (!stream)
@@ -146,15 +146,15 @@ static void savefont(pdf_obj *dict, int num)
 
 	f = fopen(name, "wb");
 	if (!f)
-		fz_throw(ctx, "Error creating font file");
+		fz_throw(ctx, FZ_ERROR_GENERIC, "Error creating font file");
 
 	len = fz_buffer_storage(ctx, buf, &data);
 	n = fwrite(data, 1, len, f);
 	if (n < len)
-		fz_throw(ctx, "Error writing font file");
+		fz_throw(ctx, FZ_ERROR_GENERIC, "Error writing font file");
 
 	if (fclose(f) < 0)
-		fz_throw(ctx, "Error closing font file");
+		fz_throw(ctx, FZ_ERROR_GENERIC, "Error closing font file");
 
 	fz_drop_buffer(ctx, buf);
 }
@@ -164,7 +164,7 @@ static void showobject(int num)
 	pdf_obj *obj;
 
 	if (!doc)
-		fz_throw(ctx, "no file specified");
+		fz_throw(ctx, FZ_ERROR_GENERIC, "no file specified");
 
 	obj = pdf_load_object(doc, num, 0);
 
@@ -207,7 +207,7 @@ int pdfextract_main(int argc, char **argv)
 	doc = pdf_open_document_no_run(ctx, infile);
 	if (pdf_needs_password(doc))
 		if (!pdf_authenticate_password(doc, password))
-			fz_throw(ctx, "cannot authenticate password: %s", infile);
+			fz_throw(ctx, FZ_ERROR_GENERIC, "cannot authenticate password: %s", infile);
 
 	if (fz_optind == argc)
 	{
diff --git a/apps/pdfinfo.c b/apps/pdfinfo.c
index fa21431e..79743892 100644
--- a/apps/pdfinfo.c
+++ b/apps/pdfinfo.c
@@ -576,7 +576,7 @@ gatherresourceinfo(int page, pdf_obj *rsrc, int show)
 	pageref = xref->page_refs[page-1];
 
 	if (!pageobj)
-		fz_throw(ctx, "cannot retrieve info from page %d", page);
+		fz_throw(ctx, FZ_ERROR_GENERIC, "cannot retrieve info from page %d", page);
 
 	font = pdf_dict_gets(rsrc, "Font");
 	if (show & FONTS && font)
@@ -644,7 +644,7 @@ gatherpageinfo(int page, int show)
 	pageref = xref->page_refs[page-1];
 
 	if (!pageobj)
-		fz_throw(ctx, "cannot retrieve info from page %d", page);
+		fz_throw(ctx, FZ_ERROR_GENERIC, "cannot retrieve info from page %d", page);
 
 	gatherdimensions(page, pageref, pageobj);
 
@@ -1008,7 +1008,7 @@ int pdfinfo_main(int argc, char **argv)
 			xref = pdf_open_document_no_run(ctx, filename);
 			if (pdf_needs_password(xref))
 				if (!pdf_authenticate_password(xref, password))
-					fz_throw(ctx, "cannot authenticate password: %s", filename);
+					fz_throw(ctx, FZ_ERROR_GENERIC, "cannot authenticate password: %s", filename);
 			pagecount = pdf_count_pages(xref);
 
 			showglobalinfo();
diff --git a/apps/pdfposter.c b/apps/pdfposter.c
index 050a497f..ed3a4bda 100644
--- a/apps/pdfposter.c
+++ b/apps/pdfposter.c
@@ -170,7 +170,7 @@ int pdfposter_main(int argc, char **argv)
 	xref = pdf_open_document_no_run(ctx, infile);
 	if (pdf_needs_password(xref))
 		if (!pdf_authenticate_password(xref, password))
-			fz_throw(ctx, "cannot authenticate password: %s", infile);
+			fz_throw(ctx, FZ_ERROR_GENERIC, "cannot authenticate password: %s", infile);
 
 	/* Only retain the specified subset of the pages */
 	decimatepages(xref);
diff --git a/apps/pdfshow.c b/apps/pdfshow.c
index 586a2fc6..78e3fd08 100644
--- a/apps/pdfshow.c
+++ b/apps/pdfshow.c
@@ -22,7 +22,7 @@ static void usage(void)
 static void showtrailer(void)
 {
 	if (!doc)
-		fz_throw(ctx, "no file specified");
+		fz_throw(ctx, FZ_ERROR_GENERIC, "no file specified");
 	printf("trailer\n");
 	pdf_fprint_obj(stdout, pdf_trailer(doc), 0);
 	printf("\n");
@@ -33,10 +33,10 @@ static void showencrypt(void)
 	pdf_obj *encrypt;
 
 	if (!doc)
-		fz_throw(ctx, "no file specified");
+		fz_throw(ctx, FZ_ERROR_GENERIC, "no file specified");
 	encrypt = pdf_dict_gets(pdf_trailer(doc), "Encrypt");
 	if (!encrypt)
-		fz_throw(ctx, "document not encrypted");
+		fz_throw(ctx, FZ_ERROR_GENERIC, "document not encrypted");
 	printf("encryption dictionary\n");
 	pdf_fprint_obj(stdout, pdf_resolve_indirect(encrypt), 0);
 	printf("\n");
@@ -45,7 +45,7 @@ static void showencrypt(void)
 static void showxref(void)
 {
 	if (!doc)
-		fz_throw(ctx, "no file specified");
+		fz_throw(ctx, FZ_ERROR_GENERIC, "no file specified");
 	pdf_print_xref(doc);
 	printf("\n");
 }
@@ -57,7 +57,7 @@ static void showpagetree(void)
 	int i;
 
 	if (!doc)
-		fz_throw(ctx, "no file specified");
+		fz_throw(ctx, FZ_ERROR_GENERIC, "no file specified");
 
 	count = pdf_count_pages(doc);
 	for (i = 0; i < count; i++)
@@ -123,7 +123,7 @@ static void showobject(int num, int gen)
 	pdf_obj *obj;
 
 	if (!doc)
-		fz_throw(ctx, "no file specified");
+		fz_throw(ctx, FZ_ERROR_GENERIC, "no file specified");
 
 	obj = pdf_load_object(doc, num, gen);