xlat.c: handle NULL xlat in lookup routines as incremental search

This is going to be used later in IFLA_AF_SPEC decoding.

* xlat.c (xlookup): Add static variable pos, store xlat there when it is
non-NULL, use pos for lookup.
(xlat_search, xlat_idx): Add static variables pos and memb_left, store
xlat and nmemb there when xlat is non-NULL, use them for lookup.
(printxvals_ex): Store the last non-NULL xlat in static variable "last".
If the first xlat argument is NULL, use "last" instead.

Co-Authored-by: Dmitry V. Levin <ldv@altlinux.org>

diff --git a/xlat.c b/xlat.c
index ff249464fa48923cc3333afdfb068b812066f4a7..4614cef7b968411c25c3b23f939683d40649ca04 100644 (file)
--- a/xlat.c
+++ b/xlat.c
@@ -73,9 +73,14 @@ print_xlat_val(uint64_t val, enum xlat_style style)
 const char *
 xlookup(const struct xlat *xlat, const uint64_t val)
 {
-       for (; xlat->str != NULL; xlat++)
-               if (xlat->val == val)
-                       return xlat->str;
+       static const struct xlat *pos;
+
+       if (xlat)
+               pos = xlat;
+
+       for (; pos->str != NULL; pos++)
+               if (pos->val == val)
+                       return pos->str;
        return NULL;
 }
 
@@ -90,11 +95,24 @@ xlat_bsearch_compare(const void *a, const void *b)
 const char *
 xlat_search(const struct xlat *xlat, const size_t nmemb, const uint64_t val)
 {
+       static const struct xlat *pos;
+       static size_t memb_left;
+
+       if (xlat) {
+               pos = xlat;
+               memb_left = nmemb;
+       }
+
        const struct xlat *e =
                bsearch((const void *) &val,
-                       xlat, nmemb, sizeof(*xlat), xlat_bsearch_compare);
+                       pos, memb_left, sizeof(*pos), xlat_bsearch_compare);
 
-       return e ? e->str : NULL;
+       if (e) {
+               memb_left -= e - pos;
+               return e->str;
+       } else {
+               return NULL;
+       }
 }
 
 /**
@@ -112,6 +130,8 @@ int
 printxvals_ex(const uint64_t val, const char *dflt, enum xlat_style style,
              const struct xlat *xlat, ...)
 {
+       static const struct xlat *last;
+
        style = get_xlat_style(style);
 
        if (xlat_verbose(style) == XLAT_STYLE_RAW) {
@@ -123,7 +143,13 @@ printxvals_ex(const uint64_t val, const char *dflt, enum xlat_style style,
        va_list args;
 
        va_start(args, xlat);
+
+       if (!xlat)
+               xlat = last;
+
        for (; xlat; xlat = va_arg(args, const struct xlat *)) {
+               last = xlat;
+
                str = xlookup(xlat, val);
 
                if (str) {
@@ -231,17 +257,25 @@ printxval_searchn_ex(const struct xlat *xlat, size_t xlat_size, uint64_t val,
 const char *
 xlat_idx(const struct xlat *xlat, size_t nmemb, uint64_t val)
 {
-       if (val >= nmemb)
+       static const struct xlat *pos;
+       static size_t memb_left;
+
+       if (xlat) {
+               pos = xlat;
+               memb_left = nmemb;
+       }
+
+       if (val >= memb_left)
                return NULL;
 
-       if (val != xlat[val].val) {
+       if (val != pos[val].val) {
                error_func_msg("Unexpected xlat value %" PRIu64
                               " at index %" PRIu64,
-                              xlat[val].val, val);
+                              pos[val].val, val);
                return NULL;
        }
 
-       return xlat[val].str;
+       return pos[val].str;
 }
 
 int