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Subject[PATCH 08/30] kconfig: add built-in function support
Date
This commit adds a new concept 'function' to do more text processing
in Kconfig.

A function call looks like this:

$(function arg1, arg2, arg3, ...)

This commit adds the basic infrastructure to expand functions.
Change the text expansion helpers to take arguments.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

Changes in v3:
- Split base infrastructure and 'shell' function
into separate patches.

Changes in v2:
- Use 'shell' for getting stdout from the comment.
It was 'shell-stdout' in the previous version.
- Symplify the implementation since the expansion has been moved to
lexer.

scripts/kconfig/preprocess.c | 142 +++++++++++++++++++++++++++++++++++++++----
1 file changed, 130 insertions(+), 12 deletions(-)

diff --git a/scripts/kconfig/preprocess.c b/scripts/kconfig/preprocess.c
index fa4abc8..e77cf7c 100644
--- a/scripts/kconfig/preprocess.c
+++ b/scripts/kconfig/preprocess.c
@@ -8,6 +8,10 @@

#include "list.h"

+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+
+static char *expand_string_with_args(const char *in, int argc, char *argv[]);
+
/*
* Environment variables
*/
@@ -74,9 +78,47 @@ void env_write_dep(FILE *f, const char *autoconfig_name)
}
}

-static char *eval_clause(const char *in)
+/*
+ * Built-in Functions
+ */
+struct function {
+ char *name;
+ char *(*func)(int argc, char *argv[]);
+};
+
+static const struct function function_table[] = {
+};
+
+static char *function_call(const char *name, int argc, char *argv[])
{
- char *res, *name;
+ const struct function *f;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(function_table); i++) {
+ f = &function_table[i];
+ if (!strcmp(f->name, name))
+ return f->func(argc, argv);
+ }
+
+ return NULL;
+}
+
+#define FUNCTION_MAX_ARGS 16
+
+/*
+ * Evaluate a clause with arguments. argc/argv are arguments from the upper
+ * function call.
+ *
+ * Returned string must be freed when done
+ */
+static char *eval_clause(const char *in, int argc, char *argv[])
+{
+ char *tmp, *prev, *p, *res, *name;
+ char delim = ' ';
+ int new_argc = 0;
+ char *new_argv[FUNCTION_MAX_ARGS];
+ int nest = 0;
+ int i;

/*
* Returns an empty string because '$()' should be evaluated
@@ -85,10 +127,73 @@ static char *eval_clause(const char *in)
if (!*in)
return xstrdup("");

- name = expand_string(in);
+ tmp = xstrdup(in);
+
+ prev = p = tmp;

- res = env_expand(name);
+ /*
+ * Split into tokens
+ * The function name and the first argument are separated by a space.
+ * Arguments are separated by a comma.
+ * For example, if the function call is like this:
+ * $(foo abc,$(x),$(y))
+ *
+ * The input string for this helper should be:
+ * foo abc,$(x),$(y)
+ *
+ * and split into:
+ * new_argv[0]: foo
+ * new_argv[1]: abc
+ * new_argv[2]: $(x)
+ * new_argv[3]: $(y)
+ */
+ while (*p) {
+ if (nest == 0 && *p == delim) {
+ *p = 0;
+ new_argv[new_argc++] = prev;
+ prev = p + 1;
+ delim = ',';
+ } else if (*p == '(') {
+ nest++;
+ } else if (*p == ')') {
+ nest--;
+ }
+
+ p++;
+ }
+ new_argv[new_argc++] = prev;
+
+ /*
+ * Shift arguments
+ * new_argv[0] represents a function name or a variable name. Put it
+ * into 'name', then shift the rest of the arguments. This simplifies
+ * 'const' handling.
+ */
+ name = expand_string_with_args(new_argv[0], argc, argv);
+ new_argc--;
+ for (i = 0; i < new_argc; i++)
+ new_argv[i] = expand_string_with_args(new_argv[i + 1],
+ argc, argv);
+
+ free(tmp);
+
+ /* Look for built-in functions */
+ res = function_call(name, new_argc, new_argv);
+ if (res)
+ goto out;
+
+ /* Last, try environment variable */
+ if (new_argc == 0) {
+ res = env_expand(name);
+ if (res)
+ goto out;
+ }
+
+ res = xstrdup("");
+out:
free(name);
+ for (i = 0; i < new_argc; i++)
+ free(new_argv[i]);

return res;
}
@@ -115,7 +220,7 @@ static char *eval_clause(const char *in)
* This is because $ABC is equivalent to $(A)BC. (Like Make, you can omit
* parentheses if the variable name consists of a single character.
*/
-char *expand_dollar(const char **str)
+static char *expand_dollar_with_args(const char **str, int argc, char *argv[])
{
const char *p = *str;
const char *q;
@@ -124,6 +229,9 @@ char *expand_dollar(const char **str)

/*
* A standalone '$' at the end of a token is treated as-is.
+ * For example, the '$' before the comma in $(foo $,A) and the '$'
+ * before the closing parenthesis in $(shell echo $) lose the special
+ * meaning. This is the behavior of Make 4.2 or newer.
*/
if (!*p)
return xstrdup("$");
@@ -140,15 +248,15 @@ char *expand_dollar(const char **str)
tmp[0] = *p;
tmp[1] = 0;
*str = p + 1;
- out = eval_clause(tmp);
+ out = eval_clause(tmp, argc, argv);
free(tmp);
return out;
}

/*
- * Variables that consist of multiple letters
+ * Variables that consist of multiple letters, and function calls
* must be surrounded with parentheses.
- * For example, $(FOO)
+ * For example, $(FOO), $(shell echo helloworld)
*/
p++;
q = p;
@@ -163,7 +271,7 @@ char *expand_dollar(const char **str)
memcpy(tmp, p, q - p);
tmp[q - p] = 0;
*str = q + 1;
- out = eval_clause(tmp);
+ out = eval_clause(tmp, argc, argv);
free(tmp);
return out;
}
@@ -179,11 +287,11 @@ char *expand_dollar(const char **str)
}

/*
- * Expand variables in the given string. Undefined variables
+ * Expand variables, functions, etc. 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)
+static char *expand_string_with_args(const char *in, int argc, char *argv[])
{
const char *prev_in, *p;
char *new, *out;
@@ -195,7 +303,7 @@ char *expand_string(const char *in)
while ((p = strchr(in, '$'))) {
prev_in = in;
in = p + 1;
- new = expand_dollar(&in);
+ new = expand_dollar_with_args(&in, argc, argv);
outlen = strlen(out) + (p - prev_in) + strlen(new) + 1;
out = xrealloc(out, outlen);
strncat(out, prev_in, p - prev_in);
@@ -210,6 +318,16 @@ char *expand_string(const char *in)
return out;
}

+char *expand_string(const char *in)
+{
+ return expand_string_with_args(in, 0, NULL);
+}
+
+char *expand_dollar(const char **str)
+{
+ return expand_dollar_with_args(str, 0, NULL);
+}
+
/*
* 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
--
2.7.4
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