From: Andre Noll <maan@tuebingen.mpg.de>
Date: Wed, 12 Jul 2017 09:43:25 +0000 (+0200)
Subject: config_file.l: Instruct flex to create a reentrant scanner.
X-Git-Tag: v1.0.1~1
X-Git-Url: http://git.tuebingen.mpg.de/?p=lopsub.git;a=commitdiff_plain;h=427af673591a006e351dcf76e5957ed67d4e0477

config_file.l: Instruct flex to create a reentrant scanner.

This requires some modifications:

* Most functions take an additional yyscan_t argument.
* We must call yylex_init and yylex_destroy().
* Accessor methods must be used to get yytext and yylen.

We used to set the initial start condition in lls_convert_config(),
before the call to yylex(). For reentrant scanners, however,
the BEGIN macro can not be used in the user code section where
lls_convert_config() is located. But pushing a state works and should
be equivalent.

The generated scanner is not reentrant yet because it still has global
variables. This issue will be addressed in a subsequent patch.
---

diff --git a/config_file.l b/config_file.l
index f6fff31..d055599 100644
--- a/config_file.l
+++ b/config_file.l
@@ -7,6 +7,9 @@
  /* We don't want symbols to clash with those of other flex users. */
 %option prefix="lls_yy"
 
+ /* Generate a scanner which is safe to use in multithreaded programs. */
+%option reentrant
+
 %option stack
 %option never-interactive
 %option yylineno
@@ -31,9 +34,9 @@ OPTION [a-zA-Z]+[a-zA-Z0-9_-]*
 	static char **rargv;
 	static const char *subcommand;
 
-	static int add_option(void);
-	static int parse_arg(char **result);
-	static int yywrap(void) {return 1;}
+	static int add_option(yyscan_t yyscanner);
+	static int parse_arg(char **result, yyscan_t yyscanner);
+	static int yywrap(yyscan_t yyscanner) {return 1;}
 %}
 
 %%
@@ -62,10 +65,10 @@ OPTION [a-zA-Z]+[a-zA-Z0-9_-]*
 		BEGIN(SC_SCANNING);
 }
 
-<SC_SCANNING>{OPTION}[[:space:]]*\n add_option();
+<SC_SCANNING>{OPTION}[[:space:]]*\n add_option(yyscanner);
 
 <SC_SCANNING>{OPTION}({EQUALS}|[[:space:]]+) {
-	int ret = add_option();
+	int ret = add_option(yyscanner);
 
 	if (ret < 0)
 		return ret;
@@ -76,7 +79,7 @@ OPTION [a-zA-Z]+[a-zA-Z0-9_-]*
 	const char *opt = rargv[rargc - 1];
 	char *arg, *result;
 	size_t opt_len = strlen(opt), arg_len;
-	int ret = parse_arg(&arg);
+	int ret = parse_arg(&arg, yyscanner);
 
 	if (ret < 0)
 		return ret;
@@ -118,13 +121,15 @@ static int expand_result(void)
 	return 1;
 }
 
-static int add_option(void)
+static int add_option(yyscan_t yyscanner)
 {
 	int ret;
 	unsigned n;
+	int len = yyget_leng(yyscanner);
+	char *text = yyget_text(yyscanner);
 
-	for (n = 0; n < yyleng; n++)
-		if (!isalnum(yytext[n]) && !(yytext[n] == '-'))
+	for (n = 0; n < len; n++)
+		if (!isalnum(text[n]) && !(text[n] == '-'))
 			break;
 	assert(n > 0);
 	ret = expand_result();
@@ -134,22 +139,24 @@ static int add_option(void)
 	if (!rargv[rargc - 1])
 		return -E_LLS_NOMEM;
 	rargv[rargc - 1][0] = rargv[rargc - 1][1] = '-';
-	memcpy(rargv[rargc - 1] + 2, yytext, n);
+	memcpy(rargv[rargc - 1] + 2, text, n);
 	rargv[rargc - 1][n + 2] = '\0';
 	return 1;
 }
 
-static int parse_arg(char **result)
+static int parse_arg(char **result, yyscan_t yyscanner)
 {
 	bool backslash = false, quote = false;
 	const char *in;
 	char *out;
 	int ret;
+	int len = yyget_leng(yyscanner);
+	char *text = yyget_text(yyscanner);
 
-	*result = malloc(yyleng + 1);
+	*result = malloc(len + 1);
 	if (!*result)
 		return -E_LLS_NOMEM;
-	for (in = yytext, out = *result; *in; in++) {
+	for (in = text, out = *result; *in; in++) {
 		if (*in == '\\') {
 			if (!backslash) {
 				backslash = true;
@@ -204,16 +211,16 @@ int lls_convert_config(const char *buf, size_t nbytes, const char *subcmd,
 {
 	int ret;
 	YY_BUFFER_STATE yybs;
+	yyscan_t yyscanner;
 
 	*result = NULL;
 	if (errctx)
 		*errctx = NULL;
+	ret = yylex_init(&yyscanner);
+	assert(ret == 0);
 	subcommand = subcmd;
-	if (!subcmd)
-		BEGIN(SC_SCANNING);
-	else
-		BEGIN(INITIAL);
-	yybs = yy_scan_bytes(buf, nbytes);
+	yy_push_state(subcmd? INITIAL : SC_SCANNING, yyscanner);
+	yybs = yy_scan_bytes(buf, nbytes, yyscanner);
 	if (!yybs)
 		return -E_LLS_YY_SCAN;
 	rargc = 1;
@@ -226,8 +233,9 @@ int lls_convert_config(const char *buf, size_t nbytes, const char *subcmd,
 		return -E_LLS_NOMEM;
 	}
 	rargv[1] = NULL;
-	ret = yylex();
-	yy_delete_buffer(yybs);
+	ret = yylex(yyscanner);
+	yy_delete_buffer(yybs, yyscanner);
+	yylex_destroy(yyscanner);
 	if (ret >= 0) {
 		*result = rargv;
 		return rargc;
@@ -235,7 +243,8 @@ int lls_convert_config(const char *buf, size_t nbytes, const char *subcmd,
 	if (errctx) {
 		*errctx = malloc(100);
 		if (*errctx)
-			sprintf(*errctx, "error at line %d", yyget_lineno());
+			sprintf(*errctx, "error at line %d",
+				yyget_lineno(yyscanner));
 	}
 	for (; rargc >= 0; rargc--)
 		free(rargv[rargc]);