libvector: fix -Wformat-overflow warning (#1401)

lib/vector/Vlib/dbcolumns.c

@@ -23,6 +23,8 @@
 #include <grass/vector.h>
 #include <grass/dbmi.h>
 
+#define BUFF_MAX 2000
+
 /*!
    \brief Fetches list of DB column names of vector map attribute table
 
@@ -40,8 +42,8 @@ const char *Vect_get_column_names(const struct Map_info *Map, int field)
     dbHandle handle;
     dbString table_name;
     dbTable *table;
-    char buf[2000];
-
+    const char **col_names;
+    char *list;
 
     num_dblinks = Vect_get_num_dblinks(Map);
     if (num_dblinks <= 0)
@@ -65,21 +67,18 @@ const char *Vect_get_column_names(const struct Map_info *Map, int field)
 	return (NULL);
 
     ncols = db_get_table_number_of_columns(table);
-    sprintf(buf, " ");
-    for (col = 0; col < ncols; col++) {
-	if (col == 0)
-	    sprintf(buf, "%s",
-		    db_get_column_name(db_get_table_column(table, col)));
-	else
-	    sprintf(buf, "%s,%s", buf,
-		    db_get_column_name(db_get_table_column(table, col)));
-    }
-    G_debug(3, "%s", buf);
+    col_names = G_malloc(ncols * sizeof(char *));
+    for (col = 0; col < ncols; col++)
+        col_names[col] = db_get_column_name(db_get_table_column(table, col));
+    if ((list = G_str_concat(col_names, ncols, ",", BUFF_MAX)) == NULL)
+        list = G_store("");
+    G_free(col_names);
+    G_debug(3, "%s", list);
 
     db_close_database(driver);
     db_shutdown_driver(driver);
 
-    return G_store(G_chop(buf));
+    return list;
 }
 
 /*!
@@ -99,8 +98,8 @@ const char *Vect_get_column_types(const struct Map_info *Map, int field)
     dbHandle handle;
     dbString table_name;
     dbTable *table;
-    char buf[2000];
-
+    const char **sqltype_names;
+    char *list;
 
     num_dblinks = Vect_get_num_dblinks(Map);
     if (num_dblinks <= 0)
@@ -124,23 +123,20 @@ const char *Vect_get_column_types(const struct Map_info *Map, int field)
 	return (NULL);
 
     ncols = db_get_table_number_of_columns(table);
-    sprintf(buf, " ");
-    for (col = 0; col < ncols; col++) {
-	if (col == 0)
-	    sprintf(buf, "%s",
-		    db_sqltype_name(db_get_column_sqltype
-				    (db_get_table_column(table, col))));
-	else
-	    sprintf(buf, "%s,%s", buf,
-		    db_sqltype_name(db_get_column_sqltype
-				    (db_get_table_column(table, col))));
-    }
-    G_debug(3, "%s", buf);
+    sqltype_names = G_malloc(ncols * sizeof(char *));
+    for (col = 0; col < ncols; col++)
+        sqltype_names[col] = db_sqltype_name(db_get_column_sqltype
+                                             (db_get_table_column
+                                              (table, col)));
+    if ((list = G_str_concat(sqltype_names, ncols, ",", BUFF_MAX)) == NULL)
+        list = G_store("");
+    G_free(sqltype_names);
+    G_debug(3, "%s", list);
 
     db_close_database(driver);
     db_shutdown_driver(driver);
 
-    return G_store(G_chop(buf));
+    return list;
 }
 
 
@@ -161,8 +157,8 @@ const char *Vect_get_column_names_types(const struct Map_info *Map, int field)
     dbHandle handle;
     dbString table_name;
     dbTable *table;
-    char buf[2000];
-
+    const char **col_type_names;
+    char *list;
 
     num_dblinks = Vect_get_num_dblinks(Map);
     if (num_dblinks <= 0)
@@ -186,23 +182,23 @@ const char *Vect_get_column_names_types(const struct Map_info *Map, int field)
 	return (NULL);
 
     ncols = db_get_table_number_of_columns(table);
-    sprintf(buf, " ");
+    col_type_names = G_malloc(ncols * sizeof(char *));
     for (col = 0; col < ncols; col++) {
-	if (col == 0)
-	    sprintf(buf, "%s(%s)",
-		    db_get_column_name(db_get_table_column(table, col)),
-		    db_sqltype_name(db_get_column_sqltype
-				    (db_get_table_column(table, col))));
-	else
-	    sprintf(buf, "%s,%s(%s)", buf,
-		    db_get_column_name(db_get_table_column(table, col)),
-		    db_sqltype_name(db_get_column_sqltype
-				    (db_get_table_column(table, col))));
+        char buf[256];
+
+        sprintf(buf, "%s(%s)",
+                db_get_column_name(db_get_table_column(table, col)),
+                db_sqltype_name(db_get_column_sqltype
+                                (db_get_table_column(table, col))));
+        col_type_names[col] = buf;
     }
-    G_debug(3, "%s", buf);
+    if ((list = G_str_concat(col_type_names, ncols, ",", BUFF_MAX)) == NULL)
+        list = G_store("");
+    G_free(col_type_names);
+    G_debug(3, "%s", list);
 
     db_close_database(driver);
     db_shutdown_driver(driver);
 
-    return G_store(G_chop(buf));
+    return list;
 }