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Date: Sun, 1 Apr 2018 08:05:35 +0200
From: Ulf Magnusson <ulfalizer@...il.com>
To: Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc: Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
Sam Ravnborg <sam@...nborg.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Arnd Bergmann <arnd@...db.de>,
Kees Cook <keescook@...omium.org>,
Thomas Gleixner <tglx@...utronix.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Randy Dunlap <rdunlap@...radead.org>,
"Luis R . Rodriguez" <mcgrof@...nel.org>,
Nicolas Pitre <nico@...aro.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 09/21] kconfig: add 'macro' keyword to support
user-defined function
On Tue, Mar 27, 2018 at 7:29 AM, Masahiro Yamada
<yamada.masahiro@...ionext.com> wrote:
> Now, we got a basic ability to test compiler capability in Kconfig.
>
> config CC_HAS_STACKPROTECTOR
> def_bool $(shell (($CC -Werror -fstack-protector -c -x c /dev/null -o /dev/null) && echo y) || echo n)
>
> This works, but it is ugly to repeat this long boilerplate.
>
> We want to describe like this:
>
> config CC_HAS_STACKPROTECTOR
> bool
> default $(cc-option -fstack-protector)
>
> It is straight-forward to add a new function, but I do not like to
> hard-code specialized functions like this. Hence, here is another
> feature to add functions from Kconfig files.
>
> A user-defined function is defined with a special keyword 'macro'.
> It can be referenced in the same way as built-in functions. This
> feature was also inspired by Makefile where user-defined functions
> are referenced by $(call func-name, args...), but I omitted the 'call'
> to makes it shorter.
>
> The macro definition can contain $(1), $(2), ... which will be replaced
> with arguments from the caller. The macro works just as a textual
> shorthand, which is also expanded in the lexer phase.
>
> [Example Code]
>
> macro success $(shell ($(1) && echo y) || echo n)
>
> config TRUE
> bool "true"
> default $(success true)
>
> config FALSE
> bool "false"
> default $(success false)
>
> [Result]
>
> $ make -s alldefconfig
> $ tail -n 2 .config
> CONFIG_TRUE=y
> # CONFIG_FALSE is not set
>
> [Example Code]
>
> macro success $(shell ($(1) && echo y) || echo n)
>
> macro cc-option $(success $CC -Werror $(1) -c -x c /dev/null -o /dev/null)
>
> config CC_HAS_STACKPROTECTOR
> def_bool $(cc-option -fstack-protector)
>
> [Result]
> $ make -s alldefconfig
> $ tail -n 1 .config
> CONFIG_CC_HAS_STACKPROTECTOR=y
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
> ---
>
> Reminder for myself:
> Update Documentation/kbuild/kconfig-language.txt
>
> Changes in v2:
> - Use 'macro' directly instead of inside the string type symbol.
>
> scripts/kconfig/function.c | 59 +++++++++++++++++++++++++++++++++++++++++++--
> scripts/kconfig/lkc_proto.h | 1 +
> scripts/kconfig/zconf.l | 31 ++++++++++++++++++++++++
> 3 files changed, 89 insertions(+), 2 deletions(-)
>
> diff --git a/scripts/kconfig/function.c b/scripts/kconfig/function.c
> index 913685f..389bb44 100644
> --- a/scripts/kconfig/function.c
> +++ b/scripts/kconfig/function.c
> @@ -15,6 +15,7 @@ static LIST_HEAD(function_list);
> struct function {
> char *name;
> char *(*func)(struct function *f, int argc, char *argv[]);
> + char *macro;
> struct list_head node;
> };
>
> @@ -31,7 +32,8 @@ static struct function *func_lookup(const char *name)
> }
>
> static void func_add(const char *name,
> - char *(*func)(struct function *f, int argc, char *argv[]))
> + char *(*func)(struct function *f, int argc, char *argv[]),
> + const char *macro)
> {
> struct function *f;
>
> @@ -44,6 +46,7 @@ static void func_add(const char *name,
> f = xmalloc(sizeof(*f));
> f->name = xstrdup(name);
> f->func = func;
> + f->macro = macro ? xstrdup(macro) : NULL;
>
> list_add_tail(&f->node, &function_list);
> }
> @@ -51,6 +54,7 @@ static void func_add(const char *name,
> static void func_del(struct function *f)
> {
> list_del(&f->node);
> + free(f->macro);
> free(f->name);
> free(f);
> }
> @@ -108,6 +112,57 @@ char *func_eval_n(const char *func, size_t n)
> return res;
> }
>
> +/* run user-defined function */
> +static char *do_macro(struct function *f, int argc, char *argv[])
> +{
> + char *new;
> + char *src, *p, *res;
> + size_t newlen;
> + int n;
> +
> + new = xmalloc(1);
> + *new = 0;
new = '\0' would be consistent with the rest of the code.
> +
> + /*
> + * This is a format string. $(1), $(2), ... must be replaced with
> + * function arguments.
> + */
> + src = f->macro;
> + p = src;
> +
> + while ((p = strstr(p, "$("))) {
> + if (isdigit(p[2]) && p[3] == ')') {
> + n = p[2] - '0';
> + if (n < argc) {
> + newlen = strlen(new) + (p - src) +
> + strlen(argv[n]) + 1;
> + new = xrealloc(new, newlen);
> + strncat(new, src, p - src);
> + strcat(new, argv[n]);
> + src = p + 4;
> + }
Might be nice to warn when a macro call has missing arguments.
> + p += 2;
> + }
> + p += 2;
> + }
I had to stare at this for a while to see how it worked. What do you
think of this tweak?
while ((p = strstr(p, "$("))) {
if (isdigit(p[2]) && p[3] == ')') {
n = p[2] - '0';
if (n < argc) {
newlen = strlen(new) + (p - src) +
strlen(argv[n]) + 1;
new = xrealloc(new, newlen);
strncat(new, src, p - src);
strcat(new, argv[n]);
/*
* Jump past macro parameter ("$(n)") and remember the
* position
*/
p += 4;
src = p;
continue;
}
}
/* Jump past "$(" that isn't from a macro parameter */
p += 2;
}
> +
> + newlen = strlen(new) + strlen(src) + 1;
> + new = xrealloc(new, newlen);
> + strcat(new, src);
> +
> + res = expand_string_value(new);
> +
> + free(new);
> +
> + return res;
> +}
> +
> +/* add user-defined function (macro) */
> +void func_add_macro(const char *name, const char *macro)
> +{
> + func_add(name, do_macro, macro);
> +}
> +
> /* built-in functions */
> static char *do_shell(struct function *f, int argc, char *argv[])
> {
> @@ -157,7 +212,7 @@ static char *do_shell(struct function *f, int argc, char *argv[])
> void func_init(void)
> {
> /* register built-in functions */
> - func_add("shell", do_shell);
> + func_add("shell", do_shell, NULL);
> }
>
> void func_exit(void)
> diff --git a/scripts/kconfig/lkc_proto.h b/scripts/kconfig/lkc_proto.h
> index 09a4f53..48699c0 100644
> --- a/scripts/kconfig/lkc_proto.h
> +++ b/scripts/kconfig/lkc_proto.h
> @@ -50,6 +50,7 @@ const char * prop_get_type_name(enum prop_type type);
>
> /* function.c */
> char *func_eval_n(const char *func, size_t n);
> +void func_add_macro(const char *name, const char *macro);
> void func_init(void);
> void func_exit(void);
>
> diff --git a/scripts/kconfig/zconf.l b/scripts/kconfig/zconf.l
> index 551ca47..6a18c68 100644
> --- a/scripts/kconfig/zconf.l
> +++ b/scripts/kconfig/zconf.l
> @@ -74,6 +74,36 @@ static void warn_ignored_character(char chr)
> "%s:%d:warning: ignoring unsupported character '%c'\n",
> zconf_curname(), zconf_lineno(), chr);
> }
> +
> +static void handle_macro(const char *text)
> +{
> + char *p, *q;
> +
> + while (isspace(*text))
> + text++;
> +
> + p = xstrdup(text);
> +
> + q = p;
> + while (isalnum(*q) || *q == '_' || *q == '-')
> + q++;
> +
> + if (q == p || !*q) {
> + yyerror("invalid\n");
> + goto free;
> + }
> +
> + *q = '\0';
> +
> + q++;
> + while (isspace(*q))
> + q++;
> +
> + func_add_macro(p, q);
> +free:
> + free(p);
> +}
> +
> %}
>
> n [A-Za-z0-9_-]
> @@ -82,6 +112,7 @@ n [A-Za-z0-9_-]
> int str = 0;
> int ts, i;
>
> +"macro"[ \t].* handle_macro(yytext + 6);
> [ \t]*#.*\n |
> [ \t]*\n {
> return T_EOL;
> --
> 2.7.4
>
Cheers,
Ulf
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