[lvm-devel] [PATCH 11/12] lvm2app: Reset buffer after retrieving error message

[Tony Asleson]

The error buffer will stack error messages which is fine.  However,
once you retrieve the error messages it doesn't make sense to keep
appending for each additional error message when running in the
context of a library call.

This patch clears and resets the buffer after the user retrieves
the error message.

Signed-off-by: Tony Asleson <tasleson at redhat.com>
---
 lib/log/log.c         | 7 +++++++
 lib/log/lvm-logging.h | 1 +
 liblvm/lvm_base.c     | 9 ++++++++-
 python/liblvm.c       | 5 ++++-
 4 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/lib/log/log.c b/lib/log/log.c
index e0c1e73..25f2264 100644
--- a/lib/log/log.c
+++ b/lib/log/log.c
@@ -170,6 +170,13 @@ const char *stored_errmsg(void)
 	return _lvm_errmsg ? : "";
 }
 
+const char *stored_errmsg_and_clear(void)
+{
+	const char *rc = strdup(stored_errmsg());
+	reset_lvm_errno(1);
+	return rc;
+}
+
 static struct dm_hash_table *_duplicated = NULL;
 
 void reset_log_duplicated(void) {
diff --git a/lib/log/lvm-logging.h b/lib/log/lvm-logging.h
index 52cd895..2f0d843 100644
--- a/lib/log/lvm-logging.h
+++ b/lib/log/lvm-logging.h
@@ -55,6 +55,7 @@ int error_message_produced(void);
 void reset_lvm_errno(int store_errmsg);
 int stored_errno(void);
 const char *stored_errmsg(void);
+const char *stored_errmsg_and_clear(void);
 
 /* Suppress messages to stdout/stderr (1) or everywhere (2) */
 /* Returns previous setting */
diff --git a/liblvm/lvm_base.c b/liblvm/lvm_base.c
index 139cc97..891cdab 100644
--- a/liblvm/lvm_base.c
+++ b/liblvm/lvm_base.c
@@ -115,7 +115,14 @@ int lvm_errno(lvm_t libh)
 
 const char *lvm_errmsg(lvm_t libh)
 {
-	return stored_errmsg();
+	const char *rc = NULL;
+	struct cmd_context *cmd = (struct cmd_context *)libh;
+	const char *msg = stored_errmsg_and_clear();
+	if (msg) {
+		rc = dm_pool_strdup(cmd->mem, msg);
+		free((void *)msg);
+	}
+	return rc;
 }
 
 const char *lvm_vgname_from_pvid(lvm_t libh, const char *pvid)
diff --git a/python/liblvm.c b/python/liblvm.c
index 330ef14..6abd5ff 100644
--- a/python/liblvm.c
+++ b/python/liblvm.c
@@ -141,6 +141,7 @@ static lvobject *_create_py_lv(vgobject *parent, lv_t lv)
 static PyObject *_liblvm_get_last_error(void)
 {
 	PyObject *info;
+	const char *msg = NULL;
 
 	LVM_VALID(NULL);
 
@@ -148,7 +149,9 @@ static PyObject *_liblvm_get_last_error(void)
 		return NULL;
 
 	PyTuple_SetItem(info, 0, PyInt_FromLong((long) lvm_errno(_libh)));
-	PyTuple_SetItem(info, 1, PyString_FromString(lvm_errmsg(_libh)));
+	msg = lvm_errmsg(_libh);
+	PyTuple_SetItem(info, 1, ((msg) ? PyString_FromString(msg) :
+			PyString_FromString("Memory error while retrieving error message")));
 
 	return info;
 }
-- 
1.8.2.1