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
diff --git a/common/env_attr.c b/common/env_attr.c
new file mode 100644
index 0000000..7d330a5
--- /dev/null
+++ b/common/env_attr.c
@@ -0,0 +1,222 @@
+/*
+ * (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
+ */
+
+#include <common.h>
+#include <env_attr.h>
+#include <errno.h>
+#include <linux/string.h>
+#include <malloc.h>
+
+/*
+ * Iterate through the whole list calling the callback for each found element.
+ * "attr_list" takes the form:
+ * attributes = [^,:\s]*
+ * entry = name[:attributes]
+ * list = entry[,list]
+ */
+int env_attr_walk(const char *attr_list,
+ int (*callback)(const char *name, const char *attributes))
+{
+ const char *entry, *entry_end;
+ char *name, *attributes;
+
+ if (!attr_list)
+ /* list not found */
+ return 1;
+
+ entry = attr_list;
+ do {
+ char *entry_cpy = NULL;
+
+ entry_end = strchr(entry, ENV_ATTR_LIST_DELIM);
+ /* check if this is the last entry in the list */
+ if (entry_end == NULL) {
+ int entry_len = strlen(entry);
+
+ if (entry_len) {
+ /*
+ * allocate memory to copy the entry into since
+ * we will need to inject '\0' chars and squash
+ * white-space before calling the callback
+ */
+ entry_cpy = malloc(entry_len + 1);
+ if (entry_cpy)
+ /* copy the rest of the list */
+ strcpy(entry_cpy, entry);
+ else
+ return -ENOMEM;
+ }
+ } else {
+ int entry_len = entry_end - entry;
+
+ if (entry_len) {
+ /*
+ * allocate memory to copy the entry into since
+ * we will need to inject '\0' chars and squash
+ * white-space before calling the callback
+ */
+ entry_cpy = malloc(entry_len + 1);
+ if (entry_cpy) {
+ /* copy just this entry and null term */
+ strncpy(entry_cpy, entry, entry_len);
+ entry_cpy[entry_len] = '\0';
+ } else
+ return -ENOMEM;
+ }
+ }
+
+ /* check if there is anything to process (e.g. not ",,,") */
+ if (entry_cpy != NULL) {
+ attributes = strchr(entry_cpy, ENV_ATTR_SEP);
+ /* check if there is a ':' */
+ if (attributes != NULL) {
+ /* replace the ':' with '\0' to term name */
+ *attributes++ = '\0';
+ /* remove white-space from attributes */
+ attributes = strim(attributes);
+ }
+ /* remove white-space from name */
+ name = strim(entry_cpy);
+
+ /* only call the callback if there is a name */
+ if (strlen(name) != 0) {
+ int retval = 0;
+
+ retval = callback(name, attributes);
+ if (retval) {
+ free(entry_cpy);
+ return retval;
+ }
+ }
+ }
+
+ free(entry_cpy);
+ entry = entry_end + 1;
+ } while (entry_end != NULL);
+
+ return 0;
+}
+
+/*
+ * Search for the last matching string in another string with the option to
+ * start looking at a certain point (i.e. ignore anything beyond that point).
+ */
+static char *reverse_strstr(const char *searched, const char *search_for,
+ const char *searched_start)
+{
+ char *result = NULL;
+
+ if (*search_for == '\0')
+ return (char *)searched;
+
+ for (;;) {
+ char *match = strstr(searched, search_for);
+
+ /*
+ * Stop looking if no new match is found or looking past the
+ * searched_start pointer
+ */
+ if (match == NULL || (searched_start != NULL &&
+ match + strlen(search_for) > searched_start))
+ break;
+
+ result = match;
+ searched = match + 1;
+ }
+
+ return result;
+}
+
+/*
+ * Retrieve the attributes string associated with a single name in the list
+ * There is no protection on attributes being too small for the value
+ */
+int env_attr_lookup(const char *attr_list, const char *name, char *attributes)
+{
+ const char *entry = NULL;
+
+ if (!attributes)
+ /* bad parameter */
+ return -1;
+ if (!attr_list)
+ /* list not found */
+ return 1;
+
+ entry = reverse_strstr(attr_list, name, NULL);
+ while (entry != NULL) {
+ const char *prevch = entry - 1;
+ const char *nextch = entry + strlen(name);
+
+ /* Skip spaces */
+ while (*prevch == ' ')
+ prevch--;
+ while (*nextch == ' ')
+ nextch++;
+
+ /* check for an exact match */
+ if ((entry == attr_list ||
+ *prevch == ENV_ATTR_LIST_DELIM) &&
+ (*nextch == ENV_ATTR_SEP ||
+ *nextch == ENV_ATTR_LIST_DELIM ||
+ *nextch == '\0'))
+ break;
+
+ entry = reverse_strstr(attr_list, name, entry);
+ }
+ if (entry != NULL) {
+ int len;
+
+ /* skip the name */
+ entry += strlen(name);
+ /* skip spaces */
+ while (*entry == ' ')
+ entry++;
+ if (*entry != ENV_ATTR_SEP)
+ len = 0;
+ else {
+ const char *delim;
+ static const char delims[] = {
+ ENV_ATTR_LIST_DELIM, ' ', '\0'};
+
+ /* skip the attr sep */
+ entry += 1;
+ /* skip spaces */
+ while (*entry == ' ')
+ entry++;
+
+ delim = strpbrk(entry, delims);
+ if (delim == NULL)
+ len = strlen(entry);
+ else
+ len = delim - entry;
+ memcpy(attributes, entry, len);
+ }
+ attributes[len] = '\0';
+
+ /* success */
+ return 0;
+ }
+
+ /* not found in list */
+ return 2;
+}