From aabb868ca6863cb2ac4867f97eb03a854f5c09c1 Mon Sep 17 00:00:00 2001
From: Daniele Varrazzo <daniele.varrazzo@gmail.com>
Date: Wed, 2 Jan 2019 11:04:22 +0100
Subject: [PATCH] Try to annotate a function as raising on returning null

It would be the same semantics of the PyObject* returning functions but
this returns a char* for success.

Currently the annotated function is validated alright but can't validate
the caller just yet, hence the need of a FAKE_RAISE().
---
 psycopg/config.h      |  7 +++++++
 psycopg/cursor_type.c |  5 +++++
 psycopg/utils.c       | 18 ++++++++++++++++--
 psycopg/utils.h       |  6 +++++-
 4 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/psycopg/config.h b/psycopg/config.h
index f98ee408..177782e8 100644
--- a/psycopg/config.h
+++ b/psycopg/config.h
@@ -195,6 +195,13 @@ static double round(double num)
 #define RAISES_NEG
 #endif
 
+#if defined(WITH_CPYCHECKER_NULL_RESULT_SETS_EXCEPTION_ATTRIBUTE)
+#define RAISES_NULL \
+    __attribute__((cpychecker_null_result_sets_exception))
+#else
+#define RAISES_NULL
+#endif
+
 #if defined(WITH_CPYCHECKER_SETS_EXCEPTION_ATTRIBUTE)
 #define RAISES \
     __attribute__((cpychecker_sets_exception))
diff --git a/psycopg/cursor_type.c b/psycopg/cursor_type.c
index 7c3284c2..19b1dc10 100644
--- a/psycopg/cursor_type.c
+++ b/psycopg/cursor_type.c
@@ -88,6 +88,7 @@ psyco_curs_close(cursorObject *self, PyObject *dummy)
         if (!self->query && self->conn->server_version >= 80200) {
             if (!(lname = psycopg_escape_string(
                     self->conn, self->name, -1, NULL, NULL))) {
+                FAKE_RAISE();
                 goto exit;
             }
             PyOS_snprintf(buffer, sizeof(buffer),
@@ -1423,11 +1424,13 @@ psyco_curs_copy_from(cursorObject *self, PyObject *args, PyObject *kwargs)
 
     if (!(quoted_delimiter = psycopg_escape_string(
             self->conn, sep, -1, NULL, NULL))) {
+        FAKE_RAISE();
         goto exit;
     }
 
     if (!(quoted_null = psycopg_escape_string(
             self->conn, null, -1, NULL, NULL))) {
+        FAKE_RAISE();
         goto exit;
     }
 
@@ -1515,11 +1518,13 @@ psyco_curs_copy_to(cursorObject *self, PyObject *args, PyObject *kwargs)
 
     if (!(quoted_delimiter = psycopg_escape_string(
             self->conn, sep, -1, NULL, NULL))) {
+        FAKE_RAISE();
         goto exit;
     }
 
     if (!(quoted_null = psycopg_escape_string(
             self->conn, null, -1, NULL, NULL))) {
+        FAKE_RAISE();
         goto exit;
     }
 
diff --git a/psycopg/utils.c b/psycopg/utils.c
index 01ddf570..995ae55f 100644
--- a/psycopg/utils.c
+++ b/psycopg/utils.c
@@ -47,7 +47,7 @@
  * If tolen is set, it will contain the length of the escaped string,
  * including quotes.
  */
-char *
+RAISES_NULL char *
 psycopg_escape_string(connectionObject *conn, const char *from, Py_ssize_t len,
                        char *to, Py_ssize_t *tolen)
 {
@@ -467,6 +467,8 @@ psyco_GetDecimalType(void)
 }
 
 
+#ifdef WITH_CPYCHECKER_RETURNS_BORROWED_REF_ATTRIBUTE
+
 /* Transfer ownership of an object to another object's state.
  *
  * Work around what seems a bug to the cpychecker which doesn't recognise
@@ -474,10 +476,22 @@ psyco_GetDecimalType(void)
  *
  * See davidmalcolm/gcc-python-plugin#109
  */
-#ifdef WITH_CPYCHECKER_RETURNS_BORROWED_REF_ATTRIBUTE
 STEALS(1) IGNORE_REFCOUNT BORROWED PyObject *
 TO_STATE(PyObject* obj)
 {
     return obj;
 }
+
+/* Fake a function raising an exception.
+ *
+ * Useful to play together with functions with peculiar semantics such as
+ * psycopg_escape_string() which doesn't return a PyObject*, but raises an
+ * exception on NULL. I'm trying to implement a function attribute to raise
+ * on NULL, similar to raise on negative, but haven't finished it yet.
+ */
+RAISES IGNORE_REFCOUNT void
+FAKE_RAISE()
+{
+}
+
 #endif
diff --git a/psycopg/utils.h b/psycopg/utils.h
index 0aa5a10d..c4a0cad3 100644
--- a/psycopg/utils.h
+++ b/psycopg/utils.h
@@ -31,7 +31,7 @@ typedef struct cursorObject cursorObject;
 typedef struct connectionObject connectionObject;
 typedef struct replicationMessageObject replicationMessageObject;
 
-HIDDEN char *psycopg_escape_string(
+HIDDEN RAISES_NULL char *psycopg_escape_string(
     connectionObject *conn,
     const char *from, Py_ssize_t len, char *to, Py_ssize_t *tolen);
 
@@ -58,10 +58,14 @@ HIDDEN RAISES BORROWED PyObject *psyco_set_error(
 
 HIDDEN PyObject *psyco_GetDecimalType(void);
 
+/* Using this macro arbitrarily to check if we are under cpychecker.
+ * Otherwise don't compile this function. */
 #ifdef WITH_CPYCHECKER_RETURNS_BORROWED_REF_ATTRIBUTE
 HIDDEN STEALS(1) IGNORE_REFCOUNT BORROWED PyObject *TO_STATE(PyObject* obj);
+HIDDEN RAISES HIDDEN void FAKE_RAISE(void);
 #else
 #define TO_STATE(x) x
+#define FAKE_RAISE() do {} while (0)
 #endif
 
 #endif /* !defined(UTILS_H) */