platform_external_dtc/dtc-lexer.l
Ahmad Fatoum ec7986e682 dtc: introduce label relative path references
Reference via label allows extending nodes with compile-time checking of
whether the node being extended exists. This is useful to catch
renamed/removed nodes after an update of the device trees to be extended.

In absence of labels in the original device trees, new style path
references can be used:

  /* upstream device tree */
  / {
	leds: some-non-standard-led-controller-name {
		led-0 {
			default-state = "off";
		};
	};
  };

  /* downstream device tree */
  &{/some-non-standard-led-controller-name/led-0} {
	default-state = "on";
  };

This is a common theme within the barebox bootloader[0], which extends the
upstream (Linux) device trees in that manner. The downside is that,
especially for deep nodes, these references can get quite long and tend to
break often due to upstream rework (e.g. rename to adhere to bindings).

Often there is a label a level or two higher that could be used. This
patch allows combining both a label and a new style path reference to
get a compile-time-checked reference, which allows rewriting the
previous downstream device tree snippet to:

  &{leds/led-0} {
	default-state = "on";
  };

This won't be broken when /some-non-standard-led-controller-name is
renamed or moved while keeping the label. And if led-0 is renamed, we
will get the expected compile-time error.

Overlay support is skipped for now as they require special support: The
label and relative path parts need to be resolved at overlay apply-time,
not at compile-time.

[0]: https://www.barebox.org/doc/latest/devicetree/index.html

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
2022-01-25 17:10:47 +11:00

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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* (C) Copyright David Gibson <dwg@au1.ibm.com>, IBM Corporation. 2005.
*/
%option noyywrap nounput noinput never-interactive
%x BYTESTRING
%x PROPNODENAME
%s V1
PROPNODECHAR [a-zA-Z0-9,._+*#?@-]
PATHCHAR ({PROPNODECHAR}|[/])
LABEL [a-zA-Z_][a-zA-Z0-9_]*
STRING \"([^\\"]|\\.)*\"
CHAR_LITERAL '([^']|\\')*'
WS [[:space:]]
COMMENT "/*"([^*]|\*+[^*/])*\*+"/"
LINECOMMENT "//".*\n
%{
#include "dtc.h"
#include "srcpos.h"
#include "dtc-parser.tab.h"
extern bool treesource_error;
/* CAUTION: this will stop working if we ever use yyless() or yyunput() */
#define YY_USER_ACTION \
{ \
srcpos_update(&yylloc, yytext, yyleng); \
}
/*#define LEXDEBUG 1*/
#ifdef LEXDEBUG
#define DPRINT(fmt, ...) fprintf(stderr, fmt, ##__VA_ARGS__)
#else
#define DPRINT(fmt, ...) do { } while (0)
#endif
static int dts_version = 1;
#define BEGIN_DEFAULT() DPRINT("<V1>\n"); \
BEGIN(V1); \
static void push_input_file(const char *filename);
static bool pop_input_file(void);
static void PRINTF(1, 2) lexical_error(const char *fmt, ...);
%}
%%
<*>"/include/"{WS}*{STRING} {
char *name = strchr(yytext, '\"') + 1;
yytext[yyleng-1] = '\0';
push_input_file(name);
}
<*>^"#"(line)?[ \t]+[0-9]+[ \t]+{STRING}([ \t]+[0-9]+)* {
char *line, *fnstart, *fnend;
struct data fn;
/* skip text before line # */
line = yytext;
while (!isdigit((unsigned char)*line))
line++;
/* regexp ensures that first and list "
* in the whole yytext are those at
* beginning and end of the filename string */
fnstart = memchr(yytext, '"', yyleng);
for (fnend = yytext + yyleng - 1;
*fnend != '"'; fnend--)
;
assert(fnstart && fnend && (fnend > fnstart));
fn = data_copy_escape_string(fnstart + 1,
fnend - fnstart - 1);
/* Don't allow nuls in filenames */
if (memchr(fn.val, '\0', fn.len - 1))
lexical_error("nul in line number directive");
/* -1 since #line is the number of the next line */
srcpos_set_line(xstrdup(fn.val), atoi(line) - 1);
data_free(fn);
}
<*><<EOF>> {
if (!pop_input_file()) {
yyterminate();
}
}
<*>{STRING} {
DPRINT("String: %s\n", yytext);
yylval.data = data_copy_escape_string(yytext+1,
yyleng-2);
return DT_STRING;
}
<*>"/dts-v1/" {
DPRINT("Keyword: /dts-v1/\n");
dts_version = 1;
BEGIN_DEFAULT();
return DT_V1;
}
<*>"/plugin/" {
DPRINT("Keyword: /plugin/\n");
return DT_PLUGIN;
}
<*>"/memreserve/" {
DPRINT("Keyword: /memreserve/\n");
BEGIN_DEFAULT();
return DT_MEMRESERVE;
}
<*>"/bits/" {
DPRINT("Keyword: /bits/\n");
BEGIN_DEFAULT();
return DT_BITS;
}
<*>"/delete-property/" {
DPRINT("Keyword: /delete-property/\n");
DPRINT("<PROPNODENAME>\n");
BEGIN(PROPNODENAME);
return DT_DEL_PROP;
}
<*>"/delete-node/" {
DPRINT("Keyword: /delete-node/\n");
DPRINT("<PROPNODENAME>\n");
BEGIN(PROPNODENAME);
return DT_DEL_NODE;
}
<*>"/omit-if-no-ref/" {
DPRINT("Keyword: /omit-if-no-ref/\n");
DPRINT("<PROPNODENAME>\n");
BEGIN(PROPNODENAME);
return DT_OMIT_NO_REF;
}
<*>{LABEL}: {
DPRINT("Label: %s\n", yytext);
yylval.labelref = xstrdup(yytext);
yylval.labelref[yyleng-1] = '\0';
return DT_LABEL;
}
<V1>([0-9]+|0[xX][0-9a-fA-F]+)(U|L|UL|LL|ULL)? {
char *e;
DPRINT("Integer Literal: '%s'\n", yytext);
errno = 0;
yylval.integer = strtoull(yytext, &e, 0);
if (*e && e[strspn(e, "UL")]) {
lexical_error("Bad integer literal '%s'",
yytext);
}
if (errno == ERANGE)
lexical_error("Integer literal '%s' out of range",
yytext);
else
/* ERANGE is the only strtoull error triggerable
* by strings matching the pattern */
assert(errno == 0);
return DT_LITERAL;
}
<*>{CHAR_LITERAL} {
struct data d;
DPRINT("Character literal: %s\n", yytext);
d = data_copy_escape_string(yytext+1, yyleng-2);
if (d.len == 1) {
lexical_error("Empty character literal");
yylval.integer = 0;
} else {
yylval.integer = (unsigned char)d.val[0];
if (d.len > 2)
lexical_error("Character literal has %d"
" characters instead of 1",
d.len - 1);
}
data_free(d);
return DT_CHAR_LITERAL;
}
<*>\&{LABEL} { /* label reference */
DPRINT("Ref: %s\n", yytext+1);
yylval.labelref = xstrdup(yytext+1);
return DT_LABEL_REF;
}
<*>"&{"{PATHCHAR}*\} { /* new-style path reference */
yytext[yyleng-1] = '\0';
DPRINT("Ref: %s\n", yytext+2);
yylval.labelref = xstrdup(yytext+2);
return DT_PATH_REF;
}
<BYTESTRING>[0-9a-fA-F]{2} {
yylval.byte = strtol(yytext, NULL, 16);
DPRINT("Byte: %02x\n", (int)yylval.byte);
return DT_BYTE;
}
<BYTESTRING>"]" {
DPRINT("/BYTESTRING\n");
BEGIN_DEFAULT();
return ']';
}
<PROPNODENAME>\\?{PROPNODECHAR}+ {
DPRINT("PropNodeName: %s\n", yytext);
yylval.propnodename = xstrdup((yytext[0] == '\\') ?
yytext + 1 : yytext);
BEGIN_DEFAULT();
return DT_PROPNODENAME;
}
"/incbin/" {
DPRINT("Binary Include\n");
return DT_INCBIN;
}
<*>{WS}+ /* eat whitespace */
<*>{COMMENT}+ /* eat C-style comments */
<*>{LINECOMMENT}+ /* eat C++-style comments */
<*>"<<" { return DT_LSHIFT; };
<*>">>" { return DT_RSHIFT; };
<*>"<=" { return DT_LE; };
<*>">=" { return DT_GE; };
<*>"==" { return DT_EQ; };
<*>"!=" { return DT_NE; };
<*>"&&" { return DT_AND; };
<*>"||" { return DT_OR; };
<*>. {
DPRINT("Char: %c (\\x%02x)\n", yytext[0],
(unsigned)yytext[0]);
if (yytext[0] == '[') {
DPRINT("<BYTESTRING>\n");
BEGIN(BYTESTRING);
}
if ((yytext[0] == '{')
|| (yytext[0] == ';')) {
DPRINT("<PROPNODENAME>\n");
BEGIN(PROPNODENAME);
}
return yytext[0];
}
%%
static void push_input_file(const char *filename)
{
assert(filename);
srcfile_push(filename);
yyin = current_srcfile->f;
yypush_buffer_state(yy_create_buffer(yyin, YY_BUF_SIZE));
}
static bool pop_input_file(void)
{
if (srcfile_pop() == 0)
return false;
yypop_buffer_state();
yyin = current_srcfile->f;
return true;
}
static void lexical_error(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
srcpos_verror(&yylloc, "Lexical error", fmt, ap);
va_end(ap);
treesource_error = true;
}