1 files changed, 238 insertions, 0 deletions

diff --git a/scripts/kconfig/preprocess.c b/scripts/kconfig/preprocess.c
new file mode 100644
index 000000000000..a2eb2eb02929
--- /dev/null
+++ b/scripts/kconfig/preprocess.c
@@ -0,0 +1,238 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (C) 2018 Masahiro Yamada <yamada.masahiro@socionext.com>
+
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "list.h"
+
+static void __attribute__((noreturn)) pperror(const char *format, ...)
+{
+        va_list ap;
+
+        fprintf(stderr, "%s:%d: ", current_file->name, yylineno);
+        va_start(ap, format);
+        vfprintf(stderr, format, ap);
+        va_end(ap);
+        fprintf(stderr, "\n");
+
+        exit(1);
+}
+
+/*
+ * Environment variables
+ */
+static LIST_HEAD(env_list);
+
+struct env {
+        char *name;
+        char *value;
+        struct list_head node;
+};
+
+static void env_add(const char *name, const char *value)
+{
+        struct env *e;
+
+        e = xmalloc(sizeof(*e));
+        e->name = xstrdup(name);
+        e->value = xstrdup(value);
+
+        list_add_tail(&e->node, &env_list);
+}
+
+static void env_del(struct env *e)
+{
+        list_del(&e->node);
+        free(e->name);
+        free(e->value);
+        free(e);
+}
+
+/* The returned pointer must be freed when done */
+static char *env_expand(const char *name)
+{
+        struct env *e;
+        const char *value;
+
+        if (!*name)
+                return NULL;
+
+        list_for_each_entry(e, &env_list, node) {
+                if (!strcmp(name, e->name))
+                        return xstrdup(e->value);
+        }
+
+        value = getenv(name);
+        if (!value)
+                return NULL;
+
+        /*
+         * We need to remember all referenced environment variables.
+         * They will be written out to include/config/auto.conf.cmd
+         */
+        env_add(name, value);
+
+        return xstrdup(value);
+}
+
+void env_write_dep(FILE *f, const char *autoconfig_name)
+{
+        struct env *e, *tmp;
+
+        list_for_each_entry_safe(e, tmp, &env_list, node) {
+                fprintf(f, "ifneq \"$(%s)\" \"%s\"\n", e->name, e->value);
+                fprintf(f, "%s: FORCE\n", autoconfig_name);
+                fprintf(f, "endif\n");
+                env_del(e);
+        }
+}
+
+static char *eval_clause(const char *str, size_t len)
+{
+        char *tmp, *name, *res;
+
+        tmp = xstrndup(str, len);
+
+        name = expand_string(tmp);
+
+        res = env_expand(name);
+        if (res)
+                goto free;
+
+        res = xstrdup("");
+free:
+        free(name);
+        free(tmp);
+
+        return res;
+}
+
+/*
+ * Expand a string that follows '$'
+ *
+ * For example, if the input string is
+ *     ($(FOO)$($(BAR)))$(BAZ)
+ * this helper evaluates
+ *     $($(FOO)$($(BAR)))
+ * and returns a new string containing the expansion (note that the string is
+ * recursively expanded), also advancing 'str' to point to the next character
+ * after the corresponding closing parenthesis, in this case, *str will be
+ *     $(BAR)
+ */
+char *expand_dollar(const char **str)
+{
+        const char *p = *str;
+        const char *q;
+        int nest = 0;
+
+        /*
+         * In Kconfig, variable references always start with "$(".
+         * Neither single-letter variables as in $A nor curly braces as in ${CC}
+         * are supported.  '$' not followed by '(' loses its special meaning.
+         */
+        if (*p != '(') {
+                *str = p;
+                return xstrdup("$");
+        }
+
+        p++;
+        q = p;
+        while (*q) {
+                if (*q == '(') {
+                        nest++;
+                } else if (*q == ')') {
+                        if (nest-- == 0)
+                                break;
+                }
+                q++;
+        }
+
+        if (!*q)
+                pperror("unterminated reference to '%s': missing ')'", p);
+
+        /* Advance 'str' to after the expanded initial portion of the string */
+        *str = q + 1;
+
+        return eval_clause(p, q - p);
+}
+
+static char *__expand_string(const char **str, bool (*is_end)(char c))
+{
+        const char *in, *p;
+        char *expansion, *out;
+        size_t in_len, out_len;
+
+        out = xmalloc(1);
+        *out = 0;
+        out_len = 1;
+
+        p = in = *str;
+
+        while (1) {
+                if (*p == '$') {
+                        in_len = p - in;
+                        p++;
+                        expansion = expand_dollar(&p);
+                        out_len += in_len + strlen(expansion);
+                        out = xrealloc(out, out_len);
+                        strncat(out, in, in_len);
+                        strcat(out, expansion);
+                        free(expansion);
+                        in = p;
+                        continue;
+                }
+
+                if (is_end(*p))
+                        break;
+
+                p++;
+        }
+
+        in_len = p - in;
+        out_len += in_len;
+        out = xrealloc(out, out_len);
+        strncat(out, in, in_len);
+
+        /* Advance 'str' to the end character */
+        *str = p;
+
+        return out;
+}
+
+static bool is_end_of_str(char c)
+{
+        return !c;
+}
+
+/*
+ * Expand variables in the given string.  Undefined variables
+ * expand to an empty string.
+ * The returned string must be freed when done.
+ */
+char *expand_string(const char *in)
+{
+        return __expand_string(&in, is_end_of_str);
+}
+
+static bool is_end_of_token(char c)
+{
+        /* Why are '.' and '/' valid characters for symbols? */
+        return !(isalnum(c) || c == '_' || c == '-' || c == '.' || c == '/');
+}
+
+/*
+ * Expand variables in a token.  The parsing stops when a token separater
+ * (in most cases, it is a whitespace) is encountered.  'str' is updated to
+ * point to the next character.
+ *
+ * The returned string must be freed when done.
+ */
+char *expand_one_token(const char **str)
+{
+        return __expand_string(str, is_end_of_token);
+}