From 38f2afdc026507956e28d00ab02f4fd235d8a846 Mon Sep 17 00:00:00 2001
From: Sebastian Harl <sh@tokkee.org>
Date: Thu, 20 Feb 2014 22:48:43 +0100
Subject: [PATCH] data: Let sdb_data_format() return the number of bytes
 written.

---
 src/core/data.c         | 25 +++++++++++--------------
 src/include/core/data.h |  4 +++-
 t/core/data_test.c      |  4 ++--
 3 files changed, 16 insertions(+), 17 deletions(-)

diff --git a/src/core/data.c b/src/core/data.c
index a0c2be1..bf1f55e 100644
--- a/src/core/data.c
+++ b/src/core/data.c
@@ -117,23 +117,22 @@ sdb_data_strlen(sdb_data_t *datum)
 int
 sdb_data_format(sdb_data_t *datum, char *buf, size_t buflen)
 {
+	int ret = -1;
+
 	if ((! datum) || (! buf))
 		return -1;
 
 	switch (datum->type) {
 		case SDB_TYPE_INTEGER:
-			snprintf(buf, buflen, "%"PRIi64, datum->data.integer);
+			ret = snprintf(buf, buflen, "%"PRIi64, datum->data.integer);
 			break;
 		case SDB_TYPE_DECIMAL:
-			snprintf(buf, buflen, "%a", datum->data.decimal);
+			ret = snprintf(buf, buflen, "%a", datum->data.decimal);
 			break;
 		case SDB_TYPE_STRING:
-			if (! datum->data.string) {
-				strncpy(buf, "\"NULL\"", buflen);
-				buf[buflen - 1] = '\0';
-				return 0;
-			}
-			{
+			if (! datum->data.string)
+				ret = snprintf(buf, buflen, "\"NULL\"");
+			else {
 				char tmp[2 * strlen(datum->data.string) + 1];
 				size_t i, pos;
 
@@ -149,7 +148,7 @@ sdb_data_format(sdb_data_t *datum, char *buf, size_t buflen)
 					++pos;
 				}
 				tmp[pos] = '\0';
-				snprintf(buf, buflen, "\"%s\"", tmp);
+				ret = snprintf(buf, buflen, "\"%s\"", tmp);
 			}
 			break;
 		case SDB_TYPE_DATETIME:
@@ -159,7 +158,7 @@ sdb_data_format(sdb_data_t *datum, char *buf, size_t buflen)
 							datum->data.datetime))
 					return -1;
 				tmp[sizeof(tmp) - 1] = '\0';
-				snprintf(buf, buflen, "\"%s\"", tmp);
+				ret = snprintf(buf, buflen, "\"%s\"", tmp);
 			}
 			break;
 		case SDB_TYPE_BINARY:
@@ -185,14 +184,12 @@ sdb_data_format(sdb_data_t *datum, char *buf, size_t buflen)
 					++pos;
 				}
 				tmp[pos] = '\0';
-				snprintf(buf, buflen, "\"%s\"", tmp);
+				ret = snprintf(buf, buflen, "\"%s\"", tmp);
 			}
 			break;
-		default:
-			return -1;
 	}
 	buf[buflen - 1] = '\0';
-	return 0;
+	return ret;
 } /* sdb_data_format */
 
 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */
diff --git a/src/include/core/data.h b/src/include/core/data.h
index 01d323b..230c1c9 100644
--- a/src/include/core/data.h
+++ b/src/include/core/data.h
@@ -117,7 +117,9 @@ sdb_data_strlen(sdb_data_t *datum);
  * calling this function.
  *
  * Returns:
- *  - 0 on success
+ *  - the number of characters written to the buffer (excluding the terminated
+ *    null byte) or the number of characters which would have been written in
+ *    case the output was truncated
  *  - a negative value else
  */
 int
diff --git a/t/core/data_test.c b/t/core/data_test.c
index 8af042a..4d2efed 100644
--- a/t/core/data_test.c
+++ b/t/core/data_test.c
@@ -160,8 +160,8 @@ START_TEST(test_format)
 		memset(buf, (int)'A', sizeof(buf));
 
 		check = sdb_data_format(datum, buf, sizeof(buf) - 1);
-		fail_unless(! check,
-				"sdb_data_format(type=%s) = %d; expected: 0",
+		fail_unless(check > 0,
+				"sdb_data_format(type=%s) = %d; expected: >0",
 				SDB_TYPE_TO_STRING(datum->type), check);
 		fail_unless(! strcmp(buf, golden_data[i].expected),
 				"sdb_data_format(type=%s) used wrong format: %s; expected: %s",
-- 
2.30.2