From 6ec6cc599678c0ac76f4559039ff3399f843b9b1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Josef=20=C5=A0im=C3=A1nek?= <josef.simanek@gmail.com>
Date: Fri, 15 Dec 2023 13:00:23 +0100
Subject: [PATCH] Add --syntax option to postgres.

- it validates SQL on STDIN and reports back if valid/invalid
---
 src/backend/main/main.c | 45 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/src/backend/main/main.c b/src/backend/main/main.c
index ed11e8be7fab..eb7266f9d5d3 100644
--- a/src/backend/main/main.c
+++ b/src/backend/main/main.c
@@ -40,6 +40,7 @@
 #include "utils/memutils.h"
 #include "utils/pg_locale.h"
 #include "utils/ps_status.h"
+#include "parser/parser.h"
 
 
 const char *progname;
@@ -50,6 +51,7 @@ static void startup_hacks(const char *progname);
 static void init_locale(const char *categoryname, int category, const char *locale);
 static void help(const char *progname);
 static void check_root(const char *progname);
+static void check_syntax(void);
 
 
 /*
@@ -153,6 +155,10 @@ main(int argc, char *argv[])
 			fputs(PG_BACKEND_VERSIONSTR, stdout);
 			exit(0);
 		}
+		if (strcmp(argv[1], "--syntax") == 0)
+		{
+			check_syntax();
+		}
 
 		/*
 		 * In addition to the above, we allow "--describe-config" and "-C var"
@@ -347,6 +353,7 @@ help(const char *progname)
 	printf(_("  -s                 show statistics after each query\n"));
 	printf(_("  -S WORK-MEM        set amount of memory for sorts (in kB)\n"));
 	printf(_("  -V, --version      output version information, then exit\n"));
+	printf(_("  --syntax           checks SQL on STDIN is valid, then exit\n"));
 	printf(_("  --NAME=VALUE       set run-time parameter\n"));
 	printf(_("  --describe-config  describe configuration parameters, then exit\n"));
 	printf(_("  -?, --help         show this help, then exit\n"));
@@ -422,6 +429,44 @@ check_root(const char *progname)
 #endif							/* WIN32 */
 }
 
+static void
+check_syntax() {
+	List *parsetree_list;
+	bool valid = false;
+	char buffer[1024 * 1024];
+	char ch;
+	int i = 0;
+
+	// TODO: check for buffer overflow
+	while ((ch = getchar()) != EOF)
+	{
+		buffer[i] = ch;
+		i++;
+	}
+
+	PG_TRY();
+	{
+		parsetree_list = raw_parser(buffer, RAW_PARSE_DEFAULT);
+		valid = true;
+	}
+	PG_CATCH();
+	{
+		EmitErrorReport();
+		FlushErrorState();
+		valid = false;
+	}
+	PG_END_TRY();
+
+	// TODO: translate output
+	if (valid && parsetree_list) {
+		printf("Valid SQL\n");
+		exit(0);
+	} else {
+		printf("Invalid SQL\n");
+		exit(1);
+	}
+}
+
 /*
  * At least on linux, set_ps_display() breaks /proc/$pid/environ. The
  * sanitizer library uses /proc/$pid/environ to implement getenv() as it wants