guc: reentrant scanner

Use the flex %option reentrant to make the generated scanner
reentrant, and perhaps eventually thread-safe, but that will require
additional work.

Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-by: Andreas Karlsson <andreas@proxel.se>
Discussion: https://www.postgresql.org/message-id/flat/eb6faeac-2a8a-4b69-9189-c33c520e5b7b@eisentraut.org

diff --git a/src/backend/utils/misc/guc-file.l b/src/backend/utils/misc/guc-file.l
index 73be80076da7390b50deb6ef0471e21fcbdc7024..6c7b8fdec20a0aa3881791083ae5432231c32667 100644 (file)
--- a/src/backend/utils/misc/guc-file.l
+++ b/src/backend/utils/misc/guc-file.l
@@ -57,6 +57,7 @@ static int    GUC_flex_fatal(const char *msg);
 
 %}
 
+%option reentrant
 %option 8bit
 %option never-interactive
 %option nodefault
@@ -353,6 +354,8 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
    unsigned int save_ConfigFileLineno = ConfigFileLineno;
    sigjmp_buf *save_GUC_flex_fatal_jmp = GUC_flex_fatal_jmp;
    sigjmp_buf  flex_fatal_jmp;
+   yyscan_t    scanner;
+   struct yyguts_t *yyg;       /* needed for yytext macro */
    volatile YY_BUFFER_STATE lex_buffer = NULL;
    int         errorcount;
    int         token;
@@ -381,11 +384,15 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
    ConfigFileLineno = 1;
    errorcount = 0;
 
-   lex_buffer = yy_create_buffer(fp, YY_BUF_SIZE);
-   yy_switch_to_buffer(lex_buffer);
+   if (yylex_init(&scanner) != 0)
+       elog(elevel, "yylex_init() failed: %m");
+   yyg = (struct yyguts_t *) scanner;
+
+   lex_buffer = yy_create_buffer(fp, YY_BUF_SIZE, scanner);
+   yy_switch_to_buffer(lex_buffer, scanner);
 
    /* This loop iterates once per logical line */
-   while ((token = yylex()))
+   while ((token = yylex(scanner)))
    {
        char       *opt_name = NULL;
        char       *opt_value = NULL;
@@ -400,9 +407,9 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
        opt_name = pstrdup(yytext);
 
        /* next we have an optional equal sign; discard if present */
-       token = yylex();
+       token = yylex(scanner);
        if (token == GUC_EQUALS)
-           token = yylex();
+           token = yylex(scanner);
 
        /* now we must have the option value */
        if (token != GUC_ID &&
@@ -417,7 +424,7 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
            opt_value = pstrdup(yytext);
 
        /* now we'd like an end of line, or possibly EOF */
-       token = yylex();
+       token = yylex(scanner);
        if (token != GUC_EOL)
        {
            if (token != 0)
@@ -438,7 +445,7 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
                                      depth + 1, elevel,
                                      head_p, tail_p))
                OK = false;
-           yy_switch_to_buffer(lex_buffer);
+           yy_switch_to_buffer(lex_buffer, scanner);
            pfree(opt_name);
            pfree(opt_value);
        }
@@ -453,7 +460,7 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
                                 depth + 1, elevel,
                                 head_p, tail_p))
                OK = false;
-           yy_switch_to_buffer(lex_buffer);
+           yy_switch_to_buffer(lex_buffer, scanner);
            pfree(opt_name);
            pfree(opt_value);
        }
@@ -468,7 +475,7 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
                                 depth + 1, elevel,
                                 head_p, tail_p))
                OK = false;
-           yy_switch_to_buffer(lex_buffer);
+           yy_switch_to_buffer(lex_buffer, scanner);
            pfree(opt_name);
            pfree(opt_value);
        }
@@ -545,14 +552,15 @@ parse_error:
 
        /* resync to next end-of-line or EOF */
        while (token != GUC_EOL && token != 0)
-           token = yylex();
+           token = yylex(scanner);
        /* break out of loop on EOF */
        if (token == 0)
            break;
    }
 
 cleanup:
-   yy_delete_buffer(lex_buffer);
+   yy_delete_buffer(lex_buffer, scanner);
+   yylex_destroy(scanner);
    /* Each recursion level must save and restore these static variables. */
    ConfigFileLineno = save_ConfigFileLineno;
    GUC_flex_fatal_jmp = save_GUC_flex_fatal_jmp;