From 538d304ab289364510eaff37308bb8f4d6293d7b Mon Sep 17 00:00:00 2001
From: Tor Andersson <tor@ghostscript.com>
Date: Sun, 6 Mar 2011 15:14:33 +0000
Subject: Add error message buffer for GUI applications to display the latest
 error stack trace.

---
 apps/win_main.c   | 13 +++++++-
 fitz/base_error.c | 95 +++++++++++++++++++++++++++++++++++++++++--------------
 fitz/fitz.h       |  4 +++
 3 files changed, 87 insertions(+), 25 deletions(-)

diff --git a/apps/win_main.c b/apps/win_main.c
index d3dbb3f8..e217dfbb 100644
--- a/apps/win_main.c
+++ b/apps/win_main.c
@@ -48,9 +48,20 @@ void winwarn(pdfapp_t *app, char *msg)
 
 void winerror(pdfapp_t *app, fz_error error)
 {
+	char msgbuf[160 * 30];
+	int i;
+
 	/* TODO: redirect stderr to a log file and display here */
 	fz_catch(error, "displaying error message to user");
-	MessageBoxA(hwndframe, "An error has occurred.", "MuPDF: Error", MB_ICONERROR);
+
+	fz_strlcpy(msgbuf, "An error has occurred.\n\n", sizeof msgbuf);
+	for (i = 0; i < fz_geterrorcount(); i++)
+	{
+		fz_strlcat(msgbuf, fz_geterrorline(i), sizeof msgbuf);
+		fz_strlcat(msgbuf, "\n", sizeof msgbuf);
+	}
+
+	MessageBoxA(hwndframe, msgbuf, "MuPDF: Error", MB_ICONERROR);
 	exit(1);
 }
 
diff --git a/fitz/base_error.c b/fitz/base_error.c
index 4117bc92..7b21d691 100644
--- a/fitz/base_error.c
+++ b/fitz/base_error.c
@@ -35,16 +35,51 @@ void fz_warn(char *fmt, ...)
 	}
 }
 
+static char errormessage[LINECOUNT][LINELEN];
+static int errorcount = 0;
+
+static void
+fz_emiterror(char what, char *location, char *message)
+{
+	fz_flushwarnings();
+
+	fprintf(stderr, "%c %s%s\n", what, location, message);
+
+	if (errorcount < LINECOUNT)
+	{
+		fz_strlcpy(errormessage[errorcount], location, LINELEN);
+		fz_strlcat(errormessage[errorcount], message, LINELEN);
+		errorcount++;
+	}
+}
+
+int
+fz_geterrorcount(void)
+{
+	return errorcount;
+}
+
+char *
+fz_geterrorline(int n)
+{
+	return errormessage[n];
+}
+
 fz_error
 fz_throwimp(const char *file, int line, const char *func, char *fmt, ...)
 {
 	va_list ap;
-	fz_flushwarnings();
-	fprintf(stderr, "+ %s:%d: %s(): ", file, line, func);
+	char one[LINELEN], two[LINELEN];
+
+	errorcount = 0;
+
+	snprintf(one, sizeof one, "%s:%d: %s(): ", file, line, func);
 	va_start(ap, fmt);
-	vfprintf(stderr, fmt, ap);
+	vsnprintf(two, sizeof two, fmt, ap);
 	va_end(ap);
-	fprintf(stderr, "\n");
+
+	fz_emiterror('+', one, two);
+
 	return -1;
 }
 
@@ -52,12 +87,15 @@ fz_error
 fz_rethrowimp(const char *file, int line, const char *func, fz_error cause, char *fmt, ...)
 {
 	va_list ap;
-	fz_flushwarnings();
-	fprintf(stderr, "| %s:%d: %s(): ", file, line, func);
+	char one[LINELEN], two[LINELEN];
+
+	snprintf(one, sizeof one, "%s:%d: %s(): ", file, line, func);
 	va_start(ap, fmt);
-	vfprintf(stderr, fmt, ap);
+	vsnprintf(two, sizeof two, fmt, ap);
 	va_end(ap);
-	fprintf(stderr, "\n");
+
+	fz_emiterror('|', one, two);
+
 	return cause;
 }
 
@@ -65,24 +103,30 @@ void
 fz_catchimp(const char *file, int line, const char *func, fz_error cause, char *fmt, ...)
 {
 	va_list ap;
-	fz_flushwarnings();
-	fprintf(stderr, "\\ %s:%d: %s(): ", file, line, func);
+	char one[LINELEN], two[LINELEN];
+
+	snprintf(one, sizeof one, "%s:%d: %s(): ", file, line, func);
 	va_start(ap, fmt);
-	vfprintf(stderr, fmt, ap);
+	vsnprintf(two, sizeof two, fmt, ap);
 	va_end(ap);
-	fprintf(stderr, "\n");
+
+	fz_emiterror('\\', one, two);
 }
 
 fz_error
 fz_throwimpx(char *fmt, ...)
 {
 	va_list ap;
-	fz_flushwarnings();
-	fprintf(stderr, "+ ");
+	char buf[LINELEN];
+
+	errorcount = 0;
+
 	va_start(ap, fmt);
-	vfprintf(stderr, fmt, ap);
+	vsnprintf(buf, sizeof buf, fmt, ap);
 	va_end(ap);
-	fprintf(stderr, "\n");
+
+	fz_emiterror('+', "", buf);
+
 	return -1;
 }
 
@@ -90,12 +134,14 @@ fz_error
 fz_rethrowimpx(fz_error cause, char *fmt, ...)
 {
 	va_list ap;
-	fz_flushwarnings();
-	fprintf(stderr, "| ");
+	char buf[LINELEN];
+
 	va_start(ap, fmt);
-	vfprintf(stderr, fmt, ap);
+	vsnprintf(buf, sizeof buf, fmt, ap);
 	va_end(ap);
-	fprintf(stderr, "\n");
+
+	fz_emiterror('|', "", buf);
+
 	return cause;
 }
 
@@ -103,10 +149,11 @@ void
 fz_catchimpx(fz_error cause, char *fmt, ...)
 {
 	va_list ap;
-	fz_flushwarnings();
-	fprintf(stderr, "\\ ");
+	char buf[LINELEN];
+
 	va_start(ap, fmt);
-	vfprintf(stderr, fmt, ap);
+	vsnprintf(buf, sizeof buf, fmt, ap);
 	va_end(ap);
-	fprintf(stderr, "\n");
+
+	fz_emiterror('\\', "", buf);
 }
diff --git a/fitz/fitz.h b/fitz/fitz.h
index 14372efd..72af4532 100644
--- a/fitz/fitz.h
+++ b/fitz/fitz.h
@@ -125,6 +125,10 @@ void fz_catchimpx(fz_error cause, char *fmt, ...) __printflike(2, 3);
 
 #define fz_okay ((fz_error)0)
 
+/* extract the last error stack trace */
+int fz_geterrorcount(void);
+char *fz_geterrorline(int n);
+
 /*
  * Basic runtime and utility functions
  */
-- 
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