kconfig: add a symbol string expansion helper

Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Michal Marek <mmarek@suse.cz>

2 files changed, 50 insertions, 0 deletions

diff --git a/scripts/kconfig/lkc_proto.h b/scripts/kconfig/lkc_proto.h
index 9a948c9ce44e..4531badb3fe1 100644
--- a/scripts/kconfig/lkc_proto.h
+++ b/scripts/kconfig/lkc_proto.h
@@ -28,6 +28,7 @@ P(symbol_hash,struct symbol *,[SYMBOL_HASHSIZE]);
 
 P(sym_lookup,struct symbol *,(const char *name, int flags));
 P(sym_find,struct symbol *,(const char *name));
+P(sym_expand_string_value,const char *,(const char *in));
 P(sym_re_search,struct symbol **,(const char *pattern));
 P(sym_type_name,const char *,(enum symbol_type type));
 P(sym_calc_value,void,(struct symbol *sym));
diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c
index 943712ca6c0a..dc5dcf2189a0 100644
--- a/scripts/kconfig/symbol.c
+++ b/scripts/kconfig/symbol.c
@@ -840,6 +840,55 @@ struct symbol *sym_find(const char *name)
         return symbol;
 }
 
+/*
+ * Expand symbol's names embedded in the string given in argument. Symbols'
+ * name to be expanded shall be prefixed by a '$'. Unknown symbol expands to
+ * the empty string.
+ */
+const char *sym_expand_string_value(const char *in)
+{
+        const char *src;
+        char *res;
+        size_t reslen;
+
+        reslen = strlen(in) + 1;
+        res = malloc(reslen);
+        res[0] = '\0';
+
+        while ((src = strchr(in, '$'))) {
+                char *p, name[SYMBOL_MAXLENGTH];
+                const char *symval = "";
+                struct symbol *sym;
+                size_t newlen;
+
+                strncat(res, in, src - in);
+                src++;
+
+                p = name;
+                while (isalnum(*src) || *src == '_')
+                        *p++ = *src++;
+                *p = '\0';
+
+                sym = sym_find(name);
+                if (sym != NULL) {
+                        sym_calc_value(sym);
+                        symval = sym_get_string_value(sym);
+                }
+
+                newlen = strlen(res) + strlen(symval) + strlen(src);
+                if (newlen > reslen) {
+                        reslen = newlen;
+                        realloc(res, reslen);
+                }
+
+                strcat(res, symval);
+                in = src;
+        }
+        strcat(res, in);
+
+        return res;
+}
+
 struct symbol **sym_re_search(const char *pattern)
 {
         struct symbol *sym, **sym_arr = NULL;