[PATCH 14/17] libtracefs: Add error message when compare fields fail

[Steven Rostedt <rostedt@goodmis.org>]

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

If the processing of comparing fields fail due to not existing or because
they are not compatible to compare, report a proper error message.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 src/tracefs-sqlhist.c | 36 +++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/src/tracefs-sqlhist.c b/src/tracefs-sqlhist.c
index e542eb95c17f..ff0869232a9e 100644
--- a/src/tracefs-sqlhist.c
+++ b/src/tracefs-sqlhist.c
@@ -981,6 +981,38 @@ static void selection_error(struct tep_handle *tep,
 	test_field_exists(tep, sb, expr);
 }
 
+static void compare_error(struct tep_handle *tep,
+			    struct sqlhist_bison *sb, struct expr *expr)
+{
+	struct compare *compare = &expr->compare;
+
+	switch (errno) {
+	case ENODEV:
+	case EBADE:
+		break;
+	default:
+		/* System error */
+		return;
+	}
+
+	/* ENODEV means that an event or field does not exist */
+	if (errno == ENODEV) {
+		if (test_field_exists(tep, sb, compare->lval))
+			return;
+		if (test_field_exists(tep, sb, compare->rval))
+			return;
+		return;
+	}
+
+	/* fields exist, but values are not compatible */
+	sb->line_no = compare->lval->line;
+	sb->line_idx = compare->lval->idx;
+
+	parse_error(sb, compare->lval->field.raw,
+		    "'%s' is not compatible to compare with '%s'\n",
+		    compare->lval->field.raw, compare->rval->field.raw);
+}
+
 static struct tracefs_synth *build_synth(struct tep_handle *tep,
 					 const char *name,
 					 struct sql_table *table)
@@ -1073,8 +1105,10 @@ static struct tracefs_synth *build_synth(struct tep_handle *tep,
 
 		ret = build_compare(synth, start_system, end_system,
 				    &expr->compare);
-		if (ret < 0)
+		if (ret < 0) {
+			compare_error(tep, table->sb, expr);
 			goto free;
+		}
 	}
 
 	for (expr = table->where; expr; expr = expr->next) {
-- 
2.30.2