[ulogd2 PATCH v4 22/32] output: SQLITE3: improve mapping of fields to DB columns

[Jeremy Sowden <jeremy@xxxxxxxxxx>]

Currently, we derive a field-name by replacing all the underscores in a
DB column-name with full-stops and use the field-name to find the
matching input-key.  However, every time we create a new insert SQL
statement, we derive the column-names by copying the field-names to a
buffer, replacing all the full-stops with underscores, and then
appending the buffer containing the column-name to the one containing
the statments.

Apart from the inefficiency, `strncpy` is used to do the copies, which
leads gcc to complain:

  ulogd_output_SQLITE3.c:234:17: warning: `strncpy` output may be truncated copying 31 bytes from a string of length 31

Instead, leave the underscores in the field-name, but copy it once to a
buffer in which the underscores are replaced and use this to find the
input-key.

Signed-off-by: Jeremy Sowden <jeremy@xxxxxxxxxx>
---
 output/sqlite3/ulogd_output_SQLITE3.c | 23 +++++++----------------
 1 file changed, 7 insertions(+), 16 deletions(-)

diff --git a/output/sqlite3/ulogd_output_SQLITE3.c b/output/sqlite3/ulogd_output_SQLITE3.c
index e3040a8a2fac..c61694a51d47 100644
--- a/output/sqlite3/ulogd_output_SQLITE3.c
+++ b/output/sqlite3/ulogd_output_SQLITE3.c
@@ -214,8 +214,6 @@ sqlite3_createstmt(struct ulogd_pluginstance *pi)
 {
 	struct sqlite3_priv *priv = (void *)pi->private;
 	struct field *f;
-	char buf[ULOGD_MAX_KEYLEN + 1];
-	char *underscore;
 	char *stmt_pos;
 	int i, cols = 0;
 
@@ -231,13 +229,7 @@ sqlite3_createstmt(struct ulogd_pluginstance *pi)
 	stmt_pos += sprintf(stmt_pos, "insert into %s (", table_ce(pi));
 
 	tailq_for_each(f, priv->fields, link) {
-		strncpy(buf, f->name, ULOGD_MAX_KEYLEN);
-
-		while ((underscore = strchr(buf, '.')))
-			*underscore = '_';
-
-		stmt_pos += sprintf(stmt_pos, "%s,", buf);
-
+		stmt_pos += sprintf(stmt_pos, "%s,", f->name);
 		cols++;
 	}
 
@@ -271,10 +263,15 @@ sqlite3_createstmt(struct ulogd_pluginstance *pi)
 static struct ulogd_key *
 ulogd_find_key(struct ulogd_pluginstance *pi, const char *name)
 {
+	char buf[ULOGD_MAX_KEYLEN + 1] = "";
 	unsigned int i;
 
+	/* replace all underscores with dots */
+	for (i = 0; i < sizeof(buf) - 1 && name[i]; ++i)
+		buf[i] = name[i] != '_' ? name[i] : '.';
+
 	for (i = 0; i < pi->input.num_keys; i++) {
-		if (strcmp(pi->input.keys[i].name, name) == 0)
+		if (strcmp(pi->input.keys[i].name, buf) == 0)
 			return &pi->input.keys[i];
 	}
 
@@ -323,7 +320,6 @@ sqlite3_init_db(struct ulogd_pluginstance *pi)
 
 	for (col = 0; col < num_cols; col++) {
 		struct field *f;
-		char *underscore;
 
 		/* prepend it to the linked list */
 		if ((f = calloc(1, sizeof(struct field))) == NULL) {
@@ -333,11 +329,6 @@ sqlite3_init_db(struct ulogd_pluginstance *pi)
 		snprintf(f->name, sizeof(f->name),
 			 "%s", sqlite3_column_name(schema_stmt, col));
 
-		/* replace all underscores with dots */
-		for (underscore = f->name;
-		     (underscore = strchr(underscore, '_')) != NULL; )
-			*underscore = '.';
-
 		DEBUGP("field '%s' found\n", f->name);
 
 		if ((f->key = ulogd_find_key(pi, f->name)) == NULL) {
-- 
2.33.0