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Date:   Sun, 18 Feb 2018 12:15:13 +0100
From:   Ulf Magnusson <ulfalizer@gmail.com>
To:     Masahiro Yamada <yamada.masahiro@socionext.com>
Cc:     linux-kbuild@vger.kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Kees Cook <keescook@chromium.org>,
        Randy Dunlap <rdunlap@infradead.org>,
        Sam Ravnborg <sam@ravnborg.org>,
        Michal Marek <michal.lkml@markovi.net>,
        "H. Peter Anvin" <hpa@zytor.com>,
        "David S. Miller" <davem@davemloft.net>,
        Yoshinori Sato <ysato@users.sourceforge.jp>, x86@kernel.org,
        linux-doc@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org,
        linux-sh@vger.kernel.org, Richard Weinberger <richard@nod.at>,
        user-mode-linux-user@lists.sourceforge.net,
        user-mode-linux-devel@lists.sourceforge.net,
        Rich Felker <dalias@libc.org>, Ingo Molnar <mingo@redhat.com>,
        Jeff Dike <jdike@addtoit.com>
Subject: Re: [PATCH 06/23] kconfig: reference environments directly and
 remove 'option env=' syntax
Message-ID: <20180218111513.6ffkj4isjkdc4wvd@huvuddator>
References: <1518806331-7101-1-git-send-email-yamada.masahiro@socionext.com>
 <1518806331-7101-7-git-send-email-yamada.masahiro@socionext.com>
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On Sat, Feb 17, 2018 at 03:38:34AM +0900, Masahiro Yamada wrote:
> To get an environment value, Kconfig needs to define a symbol using
> "option env=" syntax.  It is tedious to add a config entry for each
> environment given that we need more environments such as 'CC', 'AS',
> 'srctree' etc. to evaluate the compiler capability in Kconfig.
> 
> Adding '$' to symbols is weird.  Kconfig can reference symbols directly
> like this:
> 
>   config FOO
>           string
>           default BAR
> 
> So, I want to use the following syntax to get environment 'BAR' from
> the system:
> 
>   config FOO
>           string
>           default $BAR

I like this idea. These bounce symbols always seemed kinda pointless to
me too (and I've seen some other Kconfig dialects that got rid of them).

Getting rid of those symbols also gets rid of the only case where
Kconfig would previously evaluate Kconfig symbols during parsing (for
'source "$ENV"'), so it makes the parsing/evaluation separation a bit
cleaner.


I wonder if we could just make the quotes mandatory though, and treat
$BAR simply as string interpolation, similar to the idea in
https://lkml.org/lkml/2018/2/17/175.

That would make the behavior clearer I think, and you wouldn't have to
do special parsing for symbols starting with $ (but see the note at the
end).

> 
> Looking at the code, the symbols prefixed with 'S' are expanded by:
>  - conf_expand_value()
>    This is used to expand 'arch/$ARCH/defconfig' and 'defconfig_list'
>  - expand_string_value()
>    This is used to expand strings in 'source' and 'mainmenu'
> 
> All of them are independent of user configuration, i.e. fixed values.
> So, this kind of syntax should be moved to simply take the environment.
> 
> This change makes the code much cleaner.  The bounce symbols 'SRCARCH',
> 'ARCH', 'SUBARCH', 'KERNELVERSION' are gone.
> 
> sym_init() hard-coding 'UNAME_RELEASE' is also gone.  'UNAME_RELEASE'
> should be be given from the environment.
> 
> ARCH_DEFCONFIG is a normal symbol, so it should be simply referenced
> by 'default ARCH_DEFCONFIG'.
> 
> An environment can appear anywhere a symbol reference can appear.
> (It is expanded by sym_lookup().)  If an expression (which is derived
> from symbols) is a string, environments in the string are also expanded.
> 
> For example, the following code works.
> 
> Example code:
> 
>   config TOOLCHAIN_LIST
>           string
>           default "My tools: CC=$CC, AS=$AS, CPP=$CPP"
> 
> Result:
> 
>   $ make -s alldefconfig && tail -n 1 .config
>   CONFIG_TOOLCHAIN_LIST="My tools: CC=gcc, AS=as, CPP=gcc -E"
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---
> 
> I tested all 'make *config' for arch architectures.
> I confirmed this commit still produced the same result.
> 
> 
>  Documentation/kbuild/kconfig-language.txt |   8 --
>  Kconfig                                   |   4 -
>  Makefile                                  |   3 +-
>  arch/sh/Kconfig                           |   4 +-
>  arch/sparc/Kconfig                        |   4 +-
>  arch/tile/Kconfig                         |   2 +-
>  arch/um/Kconfig.common                    |   4 -
>  arch/x86/Kconfig                          |   4 +-
>  arch/x86/um/Kconfig                       |   4 +-
>  init/Kconfig                              |  10 +-
>  scripts/kconfig/confdata.c                |  31 +-----
>  scripts/kconfig/kconf_id.c                |   1 -
>  scripts/kconfig/lkc.h                     |   4 -
>  scripts/kconfig/menu.c                    |   3 -
>  scripts/kconfig/symbol.c                  |  84 ++++------------
>  scripts/kconfig/util.c                    | 156 +++++++++++++++++++++---------
>  scripts/kconfig/zconf.l                   |   2 +-
>  scripts/kconfig/zconf.y                   |   1 -
>  18 files changed, 144 insertions(+), 185 deletions(-)
> 
> diff --git a/Documentation/kbuild/kconfig-language.txt b/Documentation/kbuild/kconfig-language.txt
> index f5b9493..0e966e8 100644
> --- a/Documentation/kbuild/kconfig-language.txt
> +++ b/Documentation/kbuild/kconfig-language.txt
> @@ -198,14 +198,6 @@ applicable everywhere (see syntax).
>      enables the third modular state for all config symbols.
>      At most one symbol may have the "modules" option set.
>  
> -  - "env"=<value>
> -    This imports the environment variable into Kconfig. It behaves like
> -    a default, except that the value comes from the environment, this
> -    also means that the behaviour when mixing it with normal defaults is
> -    undefined at this point. The symbol is currently not exported back
> -    to the build environment (if this is desired, it can be done via
> -    another symbol).
> -
>    - "allnoconfig_y"
>      This declares the symbol as one that should have the value y when
>      using "allnoconfig". Used for symbols that hide other symbols.
> diff --git a/Kconfig b/Kconfig
> index 8c4c1cb..e6ece5b 100644
> --- a/Kconfig
> +++ b/Kconfig
> @@ -5,8 +5,4 @@
>  #
>  mainmenu "Linux/$ARCH $KERNELVERSION Kernel Configuration"
>  
> -config SRCARCH
> -	string
> -	option env="SRCARCH"
> -
>  source "arch/$SRCARCH/Kconfig"
> diff --git a/Makefile b/Makefile
> index 94a957e..9a8c689 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -275,7 +275,8 @@ include scripts/Kbuild.include
>  # Read KERNELRELEASE from include/config/kernel.release (if it exists)
>  KERNELRELEASE = $(shell cat include/config/kernel.release 2> /dev/null)
>  KERNELVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(SUBLEVEL)))$(EXTRAVERSION)
> -export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION
> +UNAME_RELEASE := $(shell uname --release)
> +export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION UNAME_RELEASE
>  
>  # SUBARCH tells the usermode build what the underlying arch is.  That is set
>  # first, and if a usermode build is happening, the "ARCH=um" on the command
> diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
> index 97fe293..89fc2f6 100644
> --- a/arch/sh/Kconfig
> +++ b/arch/sh/Kconfig
> @@ -57,7 +57,7 @@ config SUPERH
>  	  <http://www.linux-sh.org/>.
>  
>  config SUPERH32
> -	def_bool ARCH = "sh"
> +	def_bool $ARCH = "sh"

With the idea above, this would just be

	def_bool "$ARCH" = "sh"

instead.

>  	select HAVE_KPROBES
>  	select HAVE_KRETPROBES
>  	select HAVE_IOREMAP_PROT if MMU && !X2TLB
> @@ -76,7 +76,7 @@ config SUPERH32
>  	select HAVE_CC_STACKPROTECTOR
>  
>  config SUPERH64
> -	def_bool ARCH = "sh64"
> +	def_bool $ARCH = "sh64"
>  	select HAVE_EXIT_THREAD
>  	select KALLSYMS
>  
> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
> index 6bf594a..fed3d82 100644
> --- a/arch/sparc/Kconfig
> +++ b/arch/sparc/Kconfig
> @@ -1,6 +1,6 @@
>  config 64BIT
> -	bool "64-bit kernel" if ARCH = "sparc"
> -	default ARCH = "sparc64"
> +	bool "64-bit kernel" if $ARCH = "sparc"
> +	default $ARCH = "sparc64"
>  	help
>  	  SPARC is a family of RISC microprocessors designed and marketed by
>  	  Sun Microsystems, incorporated.  They are very widely found in Sun
> diff --git a/arch/tile/Kconfig b/arch/tile/Kconfig
> index ef9d403..fed372e 100644
> --- a/arch/tile/Kconfig
> +++ b/arch/tile/Kconfig
> @@ -119,7 +119,7 @@ config HVC_TILE
>  # Building with ARCH=tilegx (or ARCH=tile) implies using the
>  # 64-bit TILE-Gx toolchain, so force CONFIG_TILEGX on.
>  config TILEGX
> -	def_bool ARCH != "tilepro"
> +	def_bool $ARCH != "tilepro"
>  	select ARCH_SUPPORTS_ATOMIC_RMW
>  	select GENERIC_IRQ_LEGACY_ALLOC_HWIRQ
>  	select HAVE_ARCH_JUMP_LABEL
> diff --git a/arch/um/Kconfig.common b/arch/um/Kconfig.common
> index c68add8..07f84c8 100644
> --- a/arch/um/Kconfig.common
> +++ b/arch/um/Kconfig.common
> @@ -54,10 +54,6 @@ config HZ
>  	int
>  	default 100
>  
> -config SUBARCH
> -	string
> -	option env="SUBARCH"
> -
>  config NR_CPUS
>  	int
>  	range 1 1
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index a528c14..54d943a 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1,8 +1,8 @@
>  # SPDX-License-Identifier: GPL-2.0
>  # Select 32 or 64 bit
>  config 64BIT
> -	bool "64-bit kernel" if ARCH = "x86"
> -	default ARCH != "i386"
> +	bool "64-bit kernel" if $ARCH = "x86"
> +	default $ARCH != "i386"
>  	---help---
>  	  Say yes to build a 64-bit kernel - formerly known as x86_64
>  	  Say no to build a 32-bit kernel - formerly known as i386
> diff --git a/arch/x86/um/Kconfig b/arch/x86/um/Kconfig
> index 13ed827..d355413 100644
> --- a/arch/x86/um/Kconfig
> +++ b/arch/x86/um/Kconfig
> @@ -16,8 +16,8 @@ config UML_X86
>  	select GENERIC_FIND_FIRST_BIT
>  
>  config 64BIT
> -	bool "64-bit kernel" if SUBARCH = "x86"
> -	default SUBARCH != "i386"
> +	bool "64-bit kernel" if $SUBARCH = "x86"
> +	default $SUBARCH != "i386"
>  
>  config X86_32
>  	def_bool !64BIT
> diff --git a/init/Kconfig b/init/Kconfig
> index df18492..b4814e6 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1,11 +1,3 @@
> -config ARCH
> -	string
> -	option env="ARCH"
> -
> -config KERNELVERSION
> -	string
> -	option env="KERNELVERSION"
> -
>  config DEFCONFIG_LIST
>  	string
>  	depends on !UML
> @@ -13,7 +5,7 @@ config DEFCONFIG_LIST
>  	default "/lib/modules/$UNAME_RELEASE/.config"
>  	default "/etc/kernel-config"
>  	default "/boot/config-$UNAME_RELEASE"
> -	default "$ARCH_DEFCONFIG"
> +	default ARCH_DEFCONFIG
>  	default "arch/$ARCH/defconfig"
>  
>  config CONSTRUCTORS
> diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
> index df26c7b..98c2014 100644
> --- a/scripts/kconfig/confdata.c
> +++ b/scripts/kconfig/confdata.c
> @@ -81,39 +81,13 @@ const char *conf_get_autoconfig_name(void)
>  	return name ? name : "include/config/auto.conf";
>  }
>  
> -static char *conf_expand_value(const char *in)
> -{
> -	struct symbol *sym;
> -	const char *src;
> -	static char res_value[SYMBOL_MAXLENGTH];
> -	char *dst, name[SYMBOL_MAXLENGTH];
> -
> -	res_value[0] = 0;
> -	dst = name;
> -	while ((src = strchr(in, '$'))) {
> -		strncat(res_value, in, src - in);
> -		src++;
> -		dst = name;
> -		while (isalnum(*src) || *src == '_')
> -			*dst++ = *src++;
> -		*dst = 0;
> -		sym = sym_lookup(name, 0);
> -		sym_calc_value(sym);
> -		strcat(res_value, sym_get_string_value(sym));
> -		in = src;
> -	}
> -	strcat(res_value, in);
> -
> -	return res_value;
> -}
> -
>  char *conf_get_default_confname(void)
>  {
>  	struct stat buf;
>  	static char fullname[PATH_MAX+1];
>  	char *env, *name;
>  
> -	name = conf_expand_value(conf_defname);
> +	name = expand_string_value(conf_defname);
>  	env = getenv(SRCTREE);
>  	if (env) {
>  		sprintf(fullname, "%s/%s", env, name);
> @@ -274,7 +248,8 @@ int conf_read_simple(const char *name, int def)
>  			if (expr_calc_value(prop->visible.expr) == no ||
>  			    prop->expr->type != E_SYMBOL)
>  				continue;
> -			name = conf_expand_value(prop->expr->left.sym->name);
> +			sym_calc_value(prop->expr->left.sym);
> +			name = sym_get_string_value(prop->expr->left.sym);
>  			in = zconf_fopen(name);
>  			if (in) {
>  				conf_message(_("using defaults found in %s"),
> diff --git a/scripts/kconfig/kconf_id.c b/scripts/kconfig/kconf_id.c
> index 3ea9c5f..b3e0ea0 100644
> --- a/scripts/kconfig/kconf_id.c
> +++ b/scripts/kconfig/kconf_id.c
> @@ -32,7 +32,6 @@ static struct kconf_id kconf_id_array[] = {
>  	{ "on",			T_ON,			TF_PARAM },
>  	{ "modules",		T_OPT_MODULES,		TF_OPTION },
>  	{ "defconfig_list",	T_OPT_DEFCONFIG_LIST,	TF_OPTION },
> -	{ "env",		T_OPT_ENV,		TF_OPTION },
>  	{ "allnoconfig_y",	T_OPT_ALLNOCONFIG_Y,	TF_OPTION },
>  };
>  
> diff --git a/scripts/kconfig/lkc.h b/scripts/kconfig/lkc.h
> index fb2503a..0ff3256 100644
> --- a/scripts/kconfig/lkc.h
> +++ b/scripts/kconfig/lkc.h
> @@ -58,7 +58,6 @@ enum conf_def_mode {
>  
>  #define T_OPT_MODULES		1
>  #define T_OPT_DEFCONFIG_LIST	2
> -#define T_OPT_ENV		3
>  #define T_OPT_ALLNOCONFIG_Y	4

Decrease T_OPT_ALLNOCONFIG_Y to 3 as well? Looks like a bitmask to me
otherwise.

>  
>  struct kconf_id {
> @@ -134,9 +133,6 @@ void str_printf(struct gstr *gs, const char *fmt, ...);
>  const char *str_get(struct gstr *gs);
>  
>  /* symbol.c */
> -extern struct expr *sym_env_list;
> -
> -void sym_init(void);
>  void sym_clear_all_valid(void);
>  struct symbol *sym_choice_default(struct symbol *sym);
>  const char *sym_get_string_default(struct symbol *sym);
> diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
> index 36cd3e1..a9d0ccc 100644
> --- a/scripts/kconfig/menu.c
> +++ b/scripts/kconfig/menu.c
> @@ -214,9 +214,6 @@ void menu_add_option(int token, char *arg)
>  			zconf_error("trying to redefine defconfig symbol");
>  		sym_defconfig_list->flags |= SYMBOL_AUTO;
>  		break;
> -	case T_OPT_ENV:
> -		prop_add_env(arg);
> -		break;
>  	case T_OPT_ALLNOCONFIG_Y:
>  		current_entry->sym->flags |= SYMBOL_ALLNOCONFIG_Y;
>  		break;
> diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c
> index e4ccf56..96ea8a9 100644
> --- a/scripts/kconfig/symbol.c
> +++ b/scripts/kconfig/symbol.c
> @@ -33,33 +33,6 @@ struct symbol *sym_defconfig_list;
>  struct symbol *modules_sym;
>  tristate modules_val;
>  
> -struct expr *sym_env_list;
> -
> -static void sym_add_default(struct symbol *sym, const char *def)
> -{
> -	struct property *prop = prop_alloc(P_DEFAULT, sym);
> -
> -	prop->expr = expr_alloc_symbol(sym_lookup(def, SYMBOL_CONST));
> -}
> -
> -void sym_init(void)
> -{
> -	struct symbol *sym;
> -	struct utsname uts;
> -	static bool inited = false;
> -
> -	if (inited)
> -		return;
> -	inited = true;
> -
> -	uname(&uts);
> -
> -	sym = sym_lookup("UNAME_RELEASE", 0);
> -	sym->type = S_STRING;
> -	sym->flags |= SYMBOL_AUTO;
> -	sym_add_default(sym, uts.release);
> -}
> -
>  enum symbol_type sym_get_type(struct symbol *sym)
>  {
>  	enum symbol_type type = sym->type;
> @@ -828,28 +801,38 @@ static unsigned strhash(const char *s)
>  
>  struct symbol *sym_lookup(const char *name, int flags)
>  {
> -	struct symbol *symbol;
> +	struct symbol *symbol = NULL;
>  	char *new_name;
>  	int hash;
>  
>  	if (name) {
> -		if (name[0] && !name[1]) {
> -			switch (name[0]) {
> -			case 'y': return &symbol_yes;
> -			case 'm': return &symbol_mod;
> -			case 'n': return &symbol_no;
> +		new_name = expand_string_value(name);
> +		if (new_name[0] && !new_name[1]) {
> +			switch (new_name[0]) {
> +			case 'y':
> +				symbol = &symbol_yes;
> +				break;
> +			case 'm':
> +				symbol = &symbol_mod;
> +				break;
> +			case 'n':
> +				symbol = &symbol_no;
> +				break;
> +			}
> +			if (symbol) {
> +				free(new_name);
> +				return symbol;
>  			}
>  		}
> -		hash = strhash(name) % SYMBOL_HASHSIZE;
> +		hash = strhash(new_name) % SYMBOL_HASHSIZE;
>  
>  		for (symbol = symbol_hash[hash]; symbol; symbol = symbol->next) {
>  			if (symbol->name &&
> -			    !strcmp(symbol->name, name) &&
> +			    !strcmp(symbol->name, new_name) &&
>  			    (flags ? symbol->flags & flags
>  				   : !(symbol->flags & (SYMBOL_CONST|SYMBOL_CHOICE))))
>  				return symbol;
>  		}
> -		new_name = xstrdup(name);
>  	} else {
>  		new_name = NULL;
>  		hash = 0;
> @@ -1336,32 +1319,3 @@ const char *prop_get_type_name(enum prop_type type)
>  	}
>  	return "unknown";
>  }
> -
> -static void prop_add_env(const char *env)
> -{
> -	struct symbol *sym, *sym2;
> -	struct property *prop;
> -	char *p;
> -
> -	sym = current_entry->sym;
> -	sym->flags |= SYMBOL_AUTO;
> -	for_all_properties(sym, prop, P_ENV) {
> -		sym2 = prop_get_symbol(prop);
> -		if (strcmp(sym2->name, env))
> -			menu_warn(current_entry, "redefining environment symbol from %s",
> -				  sym2->name);
> -		return;
> -	}
> -
> -	prop = prop_alloc(P_ENV, sym);
> -	prop->expr = expr_alloc_symbol(sym_lookup(env, SYMBOL_CONST));
> -
> -	sym_env_list = expr_alloc_one(E_LIST, sym_env_list);
> -	sym_env_list->right.sym = sym;
> -
> -	p = getenv(env);
> -	if (p)
> -		sym_add_default(sym, p);
> -	else
> -		menu_warn(current_entry, "environment variable %s undefined", env);
> -}
> diff --git a/scripts/kconfig/util.c b/scripts/kconfig/util.c
> index 22201a4..dddf85b 100644
> --- a/scripts/kconfig/util.c
> +++ b/scripts/kconfig/util.c
> @@ -8,16 +8,98 @@
>  #include <stdarg.h>
>  #include <stdlib.h>
>  #include <string.h>
> +
> +#include "list.h"
>  #include "lkc.h"
>  
> +static LIST_HEAD(env_list);
> +
> +struct env {
> +	char *name;
> +	char *value;
> +	struct list_head node;
> +};
> +
> +static struct env *env_list_lookup(const char *name)
> +{
> +	struct env *e;
> +
> +	list_for_each_entry(e, &env_list, node) {
> +		if (!strcmp(name, e->name))
> +			return e;
> +	}
> +
> +	return NULL;
> +}
> +
> +static void env_list_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_list_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;
> +
> +	e = env_list_lookup(name);
> +	if (e)
> +		return xstrdup(e->value);
> +
> +	value = getenv(name);
> +	if (!value) {
> +		fprintf(stderr, "environment variable \"%s\" undefined\n", name);
> +		value = "";
> +	}
> +
> +	/*
> +	 * we need to remember all referenced environments.
> +	 * They will be written out to include/config/auto.conf.cmd
> +	 */
> +	env_list_add(name, value);
> +
> +	return xstrdup(value);
> +}
> +
> +/* works like env_expand, but 'name' does not need to be null-terminated */
> +static char *env_expand_n(const char *name, size_t n)
> +{
> +	char *tmp, *res;
> +
> +	tmp = xmalloc(n + 1);
> +	memcpy(tmp, name, n);
> +	*(tmp + n) = '\0';
> +
> +	res = env_expand(tmp);
> +
> +	free(tmp);
> +
> +	return res;
> +}
> +
>  /*
> - * Expand symbol's names embedded in the string given in argument. Symbols'
> - * name to be expanded shall be prefixed by a '$'. Unknown symbol expands to
> + * Expand environments embedded in the string given in argument. Environments
> + * to be expanded shall be prefixed by a '$'. Unknown environment expands to
>   * the empty string.
>   */
>  char *expand_string_value(const char *in)
>  {
> -	const char *src;
> +	const char *p, *q;
>  	char *res;
>  	size_t reslen;
>  
> @@ -25,39 +107,28 @@ char *expand_string_value(const char *in)
>  	 * Note: 'in' might come from a token that's about to be
>  	 * freed, so make sure to always allocate a new string
>  	 */
> -	reslen = strlen(in) + 1;
> -	res = xmalloc(reslen);
> -	res[0] = '\0';
> -
> -	while ((src = strchr(in, '$'))) {
> -		char *p, name[SYMBOL_MAXLENGTH];
> -		const char *symval = "";
> -		struct symbol *sym;
> -		size_t newlen;
> -
> -		strncat(res, in, src - in);
> -		src++;
> -
> -		p = name;
> -		while (isalnum(*src) || *src == '_')
> -			*p++ = *src++;
> -		*p = '\0';
> -
> -		sym = sym_find(name);
> -		if (sym != NULL) {
> -			sym_calc_value(sym);
> -			symval = sym_get_string_value(sym);
> -		}
> +	res = xmalloc(1);
> +	*res = '\0';
>  
> -		newlen = strlen(res) + strlen(symval) + strlen(src) + 1;
> -		if (newlen > reslen) {
> -			reslen = newlen;
> -			res = xrealloc(res, reslen);
> -		}
> +	while ((p = strchr(in, '$'))) {
> +		char *new;
> +
> +		q = p + 1;
> +		while (isalnum(*q) || *q == '_')
> +			q++;
>  
> -		strcat(res, symval);
> -		in = src;
> +		new = env_expand_n(p + 1, q - p - 1);
> +
> +		reslen = strlen(res) + (p - in) + strlen(new) + 1;
> +		res = xrealloc(res, reslen);
> +		strncat(res, in, p - in);
> +		strcat(res, new);
> +		free(new);
> +		in = q;
>  	}
> +
> +	reslen = strlen(res) + strlen(in) + 1;
> +	res = xrealloc(res, reslen);
>  	strcat(res, in);
>  
>  	return res;
> @@ -87,8 +158,7 @@ struct file *file_lookup(const char *name)
>  /* write a dependency file as used by kbuild to track dependencies */
>  int file_write_dep(const char *name)
>  {
> -	struct symbol *sym, *env_sym;
> -	struct expr *e;
> +	struct env *env, *tmp;
>  	struct file *file;
>  	FILE *out;
>  
> @@ -107,20 +177,12 @@ int file_write_dep(const char *name)
>  	fprintf(out, "\n%s: \\\n"
>  		     "\t$(deps_config)\n\n", conf_get_autoconfig_name());
>  
> -	expr_list_for_each_sym(sym_env_list, e, sym) {
> -		struct property *prop;
> -		const char *value;
> -
> -		prop = sym_get_env_prop(sym);
> -		env_sym = prop_get_symbol(prop);
> -		if (!env_sym)
> -			continue;
> -		value = getenv(env_sym->name);
> -		if (!value)
> -			value = "";
> -		fprintf(out, "ifneq \"$(%s)\" \"%s\"\n", env_sym->name, value);
> +	list_for_each_entry_safe(env, tmp, &env_list, node) {
> +		fprintf(out, "ifneq \"$(%s)\" \"%s\"\n",
> +			env->name, getenv(env->name) ?: "");
>  		fprintf(out, "%s: FORCE\n", conf_get_autoconfig_name());
>  		fprintf(out, "endif\n");
> +		env_list_del(env);
>  	}
>  
>  	fprintf(out, "\n$(deps_config): ;\n");
> diff --git a/scripts/kconfig/zconf.l b/scripts/kconfig/zconf.l
> index 02de6fe..0d89ea6 100644
> --- a/scripts/kconfig/zconf.l
> +++ b/scripts/kconfig/zconf.l
> @@ -75,7 +75,7 @@ static void warn_ignored_character(char chr)
>  }
>  %}
>  
> -n	[A-Za-z0-9_-]
> +n	[$A-Za-z0-9_-]
>  
>  %%
>  	int str = 0;
> diff --git a/scripts/kconfig/zconf.y b/scripts/kconfig/zconf.y
> index 262c464..784083d 100644
> --- a/scripts/kconfig/zconf.y
> +++ b/scripts/kconfig/zconf.y
> @@ -534,7 +534,6 @@ void conf_parse(const char *name)
>  
>  	zconf_initscan(name);
>  
> -	sym_init();
>  	_menu_init();
>  
>  	if (getenv("ZCONF_DEBUG"))
> -- 
> 2.7.4
> 

Another option if we want to allow $ENV outside of quotes (even though I
prefer mandatory quotes) would be to transform it early into "$ENV" by
returning a T_WORD_QUOTE token for it.

I think you could then get expand_string_value() to handle both the
quoted and unquoted cases.

Cheers,
Ulf