env: Add support for callbacks to environment vars

Add support for per-variable callbacks to the "hashtable" functions.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>

!!!fix comment in callback

1 files changed, 55 insertions, 0 deletions

diff --git a/include/env_attr.h b/include/env_attr.h
new file mode 100644
index 0000000..6ef114f
--- /dev/null
+++ b/include/env_attr.h
@@ -0,0 +1,55 @@
+/*
+ * (C) Copyright 2012
+ * Joe Hershberger, National Instruments, joe.hershberger@ni.com
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#ifndef __ENV_ATTR_H__
+#define __ENV_ATTR_H__
+
+#define ENV_ATTR_LIST_DELIM	','
+#define ENV_ATTR_SEP		':'
+
+/*
+ * env_attr_walk takes as input an "attr_list" that takes the form:
+ *	attributes = [^,:\s]*
+ *	entry = name[:attributes]
+ *	list = entry[,list]
+ * It will call the "callback" function with the "name" and attribute as "value"
+ * The callback may return a non-0 to abort the list walk.
+ * This return value will be passed through to the caller.
+ * 0 is returned on success.
+ */
+extern int env_attr_walk(const char *attr_list,
+	int (*callback)(const char *name, const char *value));
+
+/*
+ * env_attr_lookup takes as input an "attr_list" with the same form as above.
+ * It also takes as input a "name" to look for.
+ * If the name is found in the list, it's value is copied into "attributes".
+ * There is no protection on attributes being too small for the value.
+ * It returns -1 if attributes is NULL, 1 if "name" is not found, 2 if
+ * "attr_list" is NULL.
+ * Returns 0 on success.
+ */
+extern int env_attr_lookup(const char *attr_list, const char *name,
+	char *attributes);
+
+#endif /* __ENV_ATTR_H__ */