From 7f5d78c2d15565dd8a2357268f187045eb3ebc27 Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Fri, 23 Oct 2009 15:27:30 +0000
Subject: improve C error handling interface

git-svn-id: svn+q:///qpdf/trunk@884 71b93d88-0707-0410-a8cf-f5a4172ac649
---
 examples/pdf-linearize.c |  7 +++----
 include/qpdf/Constants.h |  3 +--
 include/qpdf/qpdf-c.h    | 16 +++++++++++++---
 libqpdf/qpdf-c.cc        |  8 +++++++-
 qpdf/qpdf-ctest.c        |  4 ++--
 qpdf/qpdf.testcov        |  3 ++-
 6 files changed, 28 insertions(+), 13 deletions(-)

diff --git a/examples/pdf-linearize.c b/examples/pdf-linearize.c
index d9da913e..78e2483b 100644
--- a/examples/pdf-linearize.c
+++ b/examples/pdf-linearize.c
@@ -24,7 +24,6 @@ int main(int argc, char* argv[])
     int warnings = 0;
     int errors = 0;
     char* p = 0;
-    qpdf_error e = 0;
 
     if ((p = strrchr(argv[0], '/')) != NULL)
     {
@@ -57,11 +56,11 @@ int main(int argc, char* argv[])
 	printf("warning: %s\n",
 	       qpdf_get_error_full_text(qpdf, qpdf_next_warning(qpdf)));
     }
-    e = qpdf_get_error(qpdf);
-    if (e)
+    if (qpdf_has_error(qpdf))
     {
 	errors = 1;
-	printf("error: %s\n", qpdf_get_error_full_text(qpdf, e));
+	printf("error: %s\n",
+	       qpdf_get_error_full_text(qpdf, qpdf_get_error(qpdf)));
     }
     qpdf_cleanup(&qpdf);
     if (errors)
diff --git a/include/qpdf/Constants.h b/include/qpdf/Constants.h
index eb872788..d74cace3 100644
--- a/include/qpdf/Constants.h
+++ b/include/qpdf/Constants.h
@@ -17,8 +17,7 @@
 
 enum qpdf_error_code_e
 {
-    qpdf_e_success = 0,
-    qpdf_e_internal,		/* logic/programming error -- indicates bug */
+    qpdf_e_internal = 1, 	/* logic/programming error -- indicates bug */
     qpdf_e_system,		/* I/O error, memory error, etc. */
     qpdf_e_unsupported,		/* PDF feature not (yet) supported by qpdf */
     qpdf_e_password,		/* incorrect password for encrypted file */
diff --git a/include/qpdf/qpdf-c.h b/include/qpdf/qpdf-c.h
index 0980f1f7..492a72ba 100644
--- a/include/qpdf/qpdf-c.h
+++ b/include/qpdf/qpdf-c.h
@@ -106,9 +106,18 @@ extern "C" {
 
     /* ERROR REPORTING */
 
+    /* Returns 1 if there is an error condition.  The error condition
+     * can be retrieved by a single call to qpdf_get_error.
+     */
+    QPDF_DLL
+    QPDF_BOOL qpdf_has_error(qpdf_data qpdf);
+
     /* Returns the error condition, if any.  The return value is a
-     * pointer to data that will become invalid the next time an error
-     * occurs or after this function is called gain.
+     * pointer to data that will become invalid after the next call to
+     * this function, qpdf_next_warning, or qpdf_destroy.  After this
+     * function is called, qpdf_has_error will return QPDF_FALSE until
+     * the next error condition occurs.  If there is no error
+     * condition, this function returns a null pointer.
      */
     QPDF_DLL
     qpdf_error qpdf_get_error(qpdf_data qpdf);
@@ -133,7 +142,8 @@ extern "C" {
     char const* qpdf_get_error_full_text(qpdf_data q, qpdf_error e);
 
     /* Use these functions to extract individual fields from the
-     * error; see QPDFExc.hh for details. */
+     * error; see QPDFExc.hh for details.  It is invalid for e to be a
+     * null pointer for any of these calls. */
     QPDF_DLL
     enum qpdf_error_code_e qpdf_get_error_code(qpdf_data q, qpdf_error e);
     QPDF_DLL
diff --git a/libqpdf/qpdf-c.cc b/libqpdf/qpdf-c.cc
index 1d1ac735..d0d824b6 100644
--- a/libqpdf/qpdf-c.cc
+++ b/libqpdf/qpdf-c.cc
@@ -128,13 +128,19 @@ QPDF_BOOL qpdf_more_warnings(qpdf_data qpdf)
     }
 }
 
+QPDF_BOOL qpdf_has_error(qpdf_data qpdf)
+{
+    QTC::TC("qpdf", "qpdf-c called qpdf_has_error");
+    return (qpdf->error.getPointer() ? QPDF_TRUE : QPDF_FALSE);
+}
+
 qpdf_error qpdf_get_error(qpdf_data qpdf)
 {
     if (qpdf->error.getPointer())
     {
 	qpdf->tmp_error.exc = qpdf->error;
 	qpdf->error = 0;
-	QTC::TC("qpdf", "qpdf-c qpdf_next_error returned error");
+	QTC::TC("qpdf", "qpdf-c qpdf_get_error returned error");
 	return &qpdf->tmp_error;
     }
     else
diff --git a/qpdf/qpdf-ctest.c b/qpdf/qpdf-ctest.c
index 422aff15..08663cde 100644
--- a/qpdf/qpdf-ctest.c
+++ b/qpdf/qpdf-ctest.c
@@ -18,9 +18,9 @@ static void report_errors()
 	printf("  pos : %ld\n", qpdf_get_error_file_position(qpdf, e));
 	printf("  text: %s\n", qpdf_get_error_message_detail(qpdf, e));
     }
-    e = qpdf_get_error(qpdf);
-    if (e)
+    if (qpdf_has_error(qpdf))
     {
+	e = qpdf_get_error(qpdf);
 	printf("error: %s\n", qpdf_get_error_full_text(qpdf, e));
 	printf("  code: %d\n", qpdf_get_error_code(qpdf, e));
 	printf("  file: %s\n", qpdf_get_error_filename(qpdf, e));
diff --git a/qpdf/qpdf.testcov b/qpdf/qpdf.testcov
index 811bddff..4d4c537a 100644
--- a/qpdf/qpdf.testcov
+++ b/qpdf/qpdf.testcov
@@ -121,7 +121,7 @@ QPDF_Stream ignore non-dictionary DecodeParms 0
 qpdf-c called qpdf_init 0
 qpdf-c called qpdf_cleanup 0
 qpdf-c called qpdf_more_warnings 0
-qpdf-c qpdf_next_error returned error 0
+qpdf-c qpdf_get_error returned error 0
 qpdf-c qpdf_next_warning returned warning 0
 qpdf-c called qpdf_set_suppress_warnings 0
 qpdf-c called qpdf_set_ignore_xref_streams 0
@@ -172,3 +172,4 @@ qpdf-c called qpdf_set_static_aes_IV 0
 QPDF_encryption stream crypt filter 0
 QPDF ERR object stream with wrong type 0
 QPDF object gone after xref reconstruction 0
+qpdf-c called qpdf_has_error 0
-- 
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