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* Joe Hershberger, National Instruments, joe.hershberger@ni.com
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* SPDX-License-Identifier: GPL-2.0+
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#ifdef USE_HOSTCC /* Eliminate "ANSI does not permit..." warnings */
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#include <linux/linux_string.h>
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#include <linux/string.h>
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* Iterate through the whole list calling the callback for each found element.
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* "attr_list" takes the form:
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* attributes = [^,:\s]*
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* entry = name[:attributes]
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int env_attr_walk(const char *attr_list,
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int (*callback)(const char *name, const char *attributes))
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const char *entry, *entry_end;
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char *name, *attributes;
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char *entry_cpy = NULL;
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entry_end = strchr(entry, ENV_ATTR_LIST_DELIM);
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/* check if this is the last entry in the list */
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if (entry_end == NULL) {
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int entry_len = strlen(entry);
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* allocate memory to copy the entry into since
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* we will need to inject '\0' chars and squash
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* white-space before calling the callback
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entry_cpy = malloc(entry_len + 1);
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/* copy the rest of the list */
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strcpy(entry_cpy, entry);
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int entry_len = entry_end - entry;
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* allocate memory to copy the entry into since
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* we will need to inject '\0' chars and squash
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* white-space before calling the callback
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entry_cpy = malloc(entry_len + 1);
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/* copy just this entry and null term */
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strncpy(entry_cpy, entry, entry_len);
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entry_cpy[entry_len] = '\0';
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/* check if there is anything to process (e.g. not ",,,") */
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if (entry_cpy != NULL) {
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attributes = strchr(entry_cpy, ENV_ATTR_SEP);
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/* check if there is a ':' */
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if (attributes != NULL) {
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/* replace the ':' with '\0' to term name */
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/* remove white-space from attributes */
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attributes = strim(attributes);
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/* remove white-space from name */
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name = strim(entry_cpy);
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/* only call the callback if there is a name */
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if (strlen(name) != 0) {
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retval = callback(name, attributes);
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entry = entry_end + 1;
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} while (entry_end != NULL);
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* Search for the last matching string in another string with the option to
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* start looking at a certain point (i.e. ignore anything beyond that point).
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static char *reverse_strstr(const char *searched, const char *search_for,
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const char *searched_start)
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if (*search_for == '\0')
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return (char *)searched;
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char *match = strstr(searched, search_for);
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* Stop looking if no new match is found or looking past the
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* searched_start pointer
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if (match == NULL || (searched_start != NULL &&
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match + strlen(search_for) > searched_start))
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searched = match + 1;
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* Retrieve the attributes string associated with a single name in the list
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* There is no protection on attributes being too small for the value
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int env_attr_lookup(const char *attr_list, const char *name, char *attributes)
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const char *entry = NULL;
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entry = reverse_strstr(attr_list, name, NULL);
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while (entry != NULL) {
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const char *prevch = entry - 1;
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const char *nextch = entry + strlen(name);
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while (*prevch == ' ')
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while (*nextch == ' ')
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/* check for an exact match */
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if ((entry == attr_list ||
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*prevch == ENV_ATTR_LIST_DELIM) &&
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(*nextch == ENV_ATTR_SEP ||
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*nextch == ENV_ATTR_LIST_DELIM ||
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entry = reverse_strstr(attr_list, name, entry);
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entry += strlen(name);
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while (*entry == ' ')
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if (*entry != ENV_ATTR_SEP)
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static const char delims[] = {
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ENV_ATTR_LIST_DELIM, ' ', '\0'};
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/* skip the attr sep */
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while (*entry == ' ')
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delim = strpbrk(entry, delims);
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memcpy(attributes, entry, len);
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attributes[len] = '\0';
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/* not found in list */