1 files changed, 64 insertions, 3 deletions

diff --git a/src/fe_utils/string_utils.c b/src/fe_utils/string_utils.c
index 4cf08dbdcaa..f986dbcf39b 100644
--- a/src/fe_utils/string_utils.c
+++ b/src/fe_utils/string_utils.c
@@ -488,10 +488,10 @@ appendConnStrVal(PQExpBuffer buf, const char *str)
 	bool		needquotes;
 
 	/*
-	 * If the string consists entirely of plain ASCII characters, no need to
-	 * quote it. This is quite conservative, but better safe than sorry.
+	 * If the string is one or more plain ASCII characters, no need to quote
+	 * it. This is quite conservative, but better safe than sorry.
 	 */
-	needquotes = false;
+	needquotes = true;
 	for (s = str; *s; s++)
 	{
 		if (!((*s >= 'a' && *s <= 'z') || (*s >= 'A' && *s <= 'Z') ||
@@ -500,6 +500,7 @@ appendConnStrVal(PQExpBuffer buf, const char *str)
 			needquotes = true;
 			break;
 		}
+		needquotes = false;
 	}
 
 	if (needquotes)
@@ -522,6 +523,66 @@ appendConnStrVal(PQExpBuffer buf, const char *str)
 
 
 /*
+ * Append a psql meta-command that connects to the given database with the
+ * then-current connection's user, host and port.
+ */
+void
+appendPsqlMetaConnect(PQExpBuffer buf, const char *dbname)
+{
+	const char *s;
+	bool		complex;
+
+	/*
+	 * If the name is plain ASCII characters, emit a trivial "\connect "foo"".
+	 * For other names, even many not technically requiring it, skip to the
+	 * general case.  No database has a zero-length name.
+	 */
+	complex = false;
+	for (s = dbname; *s; s++)
+	{
+		if (*s == '\n' || *s == '\r')
+		{
+			fprintf(stderr,
+					_("database name contains a newline or carriage return: \"%s\"\n"),
+					dbname);
+			exit(EXIT_FAILURE);
+		}
+
+		if (!((*s >= 'a' && *s <= 'z') || (*s >= 'A' && *s <= 'Z') ||
+			  (*s >= '0' && *s <= '9') || *s == '_' || *s == '.'))
+		{
+			complex = true;
+		}
+	}
+
+	appendPQExpBufferStr(buf, "\\connect ");
+	if (complex)
+	{
+		PQExpBufferData connstr;
+
+		initPQExpBuffer(&connstr);
+		appendPQExpBuffer(&connstr, "dbname=");
+		appendConnStrVal(&connstr, dbname);
+
+		appendPQExpBuffer(buf, "-reuse-previous=on ");
+
+		/*
+		 * As long as the name does not contain a newline, SQL identifier
+		 * quoting satisfies the psql meta-command parser.  Prefer not to
+		 * involve psql-interpreted single quotes, which behaved differently
+		 * before PostgreSQL 9.2.
+		 */
+		appendPQExpBufferStr(buf, fmtId(connstr.data));
+
+		termPQExpBuffer(&connstr);
+	}
+	else
+		appendPQExpBufferStr(buf, fmtId(dbname));
+	appendPQExpBufferChar(buf, '\n');
+}
+
+
+/*
  * Deconstruct the text representation of a 1-dimensional Postgres array
  * into individual items.
  *