From fba6ed5589616edf70edb83ab7eb8b1945a94b37 Mon Sep 17 00:00:00 2001
From: "houzj.fnst" <63178771+sherlockcpp@users.noreply.github.com>
Date: Fri, 24 Jul 2020 15:41:04 +0800
Subject: [PATCH 1/5] Update pool_relcache.c

---
 src/utils/pool_relcache.c | 154 ++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 142 insertions(+), 12 deletions(-)

diff --git a/src/utils/pool_relcache.c b/src/utils/pool_relcache.c
index c801b94..e4b995f 100644
--- a/src/utils/pool_relcache.c
+++ b/src/utils/pool_relcache.c
@@ -36,6 +36,7 @@
 #include "utils/palloc.h"
 #include "utils/memutils.h"
 #include "utils/elog.h"
+#include "parser/scansup.h"
 
 static void SearchRelCacheErrorCb(void *arg);
 static POOL_SELECT_RESULT *query_cache_to_relation_cache(char *data, size_t size);
@@ -343,25 +344,154 @@ SearchRelCacheErrorCb(void *arg)
 }
 
 
+/*
+ * SplitIdentifierString --- parse a string containing identifiers
+ *
+ * This is the guts of textToQualifiedNameList, and is exported for use in
+ * other situations such as parsing GUC variables.  In the GUC case, it's
+ * important to avoid memory leaks, so the API is designed to minimize the
+ * amount of stuff that needs to be allocated and freed.
+ *
+ * Inputs:
+ *	rawstring: the input string; must be overwritable!	On return, it's
+ *			   been modified to contain the separated identifiers.
+ *	separator: the separator punctuation expected between identifiers
+ *			   (typically '.' or ',').  Whitespace may also appear around
+ *			   identifiers.
+ * Outputs:
+ *	namelist: filled with a palloc'd list of pointers to identifiers within
+ *			  rawstring.  Caller should list_free() this even on error return.
+ *
+ * Returns true if okay, false if there is a syntax error in the string.
+ *
+ * Note that an empty string is considered okay here, though not in
+ * textToQualifiedNameList.
+ */
+bool
+SplitIdentifierString(char *rawstring, char separator,
+					  Node **nlist)
+{
+	char	   *nextp = rawstring;
+	bool		done = false;
+	List	  **namelist = (List **) nlist;
+
+	*namelist = NIL;
+
+	while (scanner_isspace(*nextp))
+		nextp++;				/* skip leading whitespace */
+
+	if (*nextp == '\0')
+		return true;			/* allow empty string */
+
+	/* At the top of the loop, we are at start of a new identifier. */
+	do
+	{
+		char	   *curname;
+		char	   *endp;
+
+		if (*nextp == '"')
+		{
+			/* Quoted name --- collapse quote-quote pairs, no downcasing */
+			curname = nextp + 1;
+			for (;;)
+			{
+				endp = strchr(nextp + 1, '"');
+				if (endp == NULL)
+					return false;	/* mismatched quotes */
+				if (endp[1] != '"')
+					break;		/* found end of quoted name */
+				/* Collapse adjacent quotes into one quote, and look again */
+				memmove(endp, endp + 1, strlen(endp));
+				nextp = endp;
+			}
+			/* endp now points at the terminating quote */
+			nextp = endp + 1;
+		}
+		else
+		{
+			/* Unquoted name --- extends to separator or whitespace */
+			char	   *downname;
+			int			len;
+
+			curname = nextp;
+			while (*nextp && *nextp != separator &&
+				   !scanner_isspace(*nextp))
+				nextp++;
+			endp = nextp;
+			if (curname == nextp)
+				return false;	/* empty unquoted name not allowed */
+
+			/*
+			 * Downcase the identifier, using same code as main lexer does.
+			 *
+			 * XXX because we want to overwrite the input in-place, we cannot
+			 * support a downcasing transformation that increases the string
+			 * length.  This is not a problem given the current implementation
+			 * of downcase_truncate_identifier, but we'll probably have to do
+			 * something about this someday.
+			 */
+			len = endp - curname;
+			downname = downcase_truncate_identifier(curname, len, false);
+			Assert(strlen(downname) <= len);
+			strncpy(curname, downname, len);	/* strncpy is required here */
+			pfree(downname);
+		}
+
+		while (scanner_isspace(*nextp))
+			nextp++;			/* skip trailing whitespace */
+
+		if (*nextp == separator)
+		{
+			nextp++;
+			while (scanner_isspace(*nextp))
+				nextp++;		/* skip leading whitespace for next */
+			/* we expect another name, so done remains false */
+		}
+		else if (*nextp == '\0')
+			done = true;
+		else
+			return false;		/* invalid syntax */
+
+		/* Now safe to overwrite separator with a null */
+		*endp = '\0';
+
+		/* Truncate name if it's overlength */
+		truncate_identifier(curname, strlen(curname), false);
+
+		/*
+		 * Finished isolating current name --- add it to list
+		 */
+		*namelist = lappend(*namelist, curname);
+
+		/* Loop back if we didn't reach end of string */
+	} while (!done);
+
+	return true;
+}
+
 char *
 remove_quotes_and_schema_from_relname(char *table)
 {
 	static char rel[MAX_ITEM_LENGTH];
-	char	   *p;
-	int			i = 0;
+	char	   *rawstring;
+	List	   *names;
 
-	/* get rid of schema name */
-	p = strchr(table, '.');
-	if (p)
-		table = p + 1;
-
-	/* get rid of quotation marks */
-	for (i = 0; *table; table++)
+	rawstring = pstrdup(table);
+	if(SplitIdentifierString(rawstring, '.', (Node **) &names) && names != NIL)
+	{
+		/*
+		 * Since table name is always the last one in the list,
+		 * we use llast() to get table name.
+		 */
+		strlcpy(rel, llast(names), sizeof(rel));
+	}
+	else
 	{
-		if (*table != '"')
-			rel[i++] = *table;
+		rel[0] = '\0';
 	}
-	rel[i] = '\0';
+
+	pfree(rawstring);
+	list_free(names);
 
 	return rel;
 }
-- 
1.8.3.1