Fix pg_isblank()

There was a pg_isblank() function that claimed to be a replacement for
the standard isblank() function, which was thought to be "not very
portable yet".  We can now assume that it's portable (it's in C99).

But pg_isblank() actually diverged from the standard isblank() by also
accepting '\r', while the standard one only accepts space and tab.
This was added to support parsing pg_hba.conf under Windows.  But the
hba parsing code now works completely differently and already handles
line endings before we get to pg_isblank().  The other user of
pg_isblank() is for ident protocol message parsing, which also handles
'\r' separately.  So this behavior is now obsolete and confusing.

To improve clarity, I separated those concerns.  The ident parsing now
gets its own function that hardcodes the whitespace characters
mentioned by the relevant RFC.  pg_isblank() is now static in hba.c
and is a wrapper around the standard isblank(), with some extra logic
to ensure robust treatment of non-ASCII characters.

Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/170308e6-a7a3-4484-87b2-f960bb564afa%40eisentraut.org

1 files changed, 3 insertions, 6 deletions

diff --git a/src/backend/libpq/hba.c b/src/backend/libpq/hba.c
index 97a3586000b..6cb25399c26 100644
--- a/src/backend/libpq/hba.c
+++ b/src/backend/libpq/hba.c
@@ -138,14 +138,11 @@ static int	regexec_auth_token(const char *match, AuthToken *token,
 static void tokenize_error_callback(void *arg);
 
 
-/*
- * isblank() exists in the ISO C99 spec, but it's not very portable yet,
- * so provide our own version.
- */
-bool
+static bool
 pg_isblank(const char c)
 {
-	return c == ' ' || c == '\t' || c == '\r';
+	/* don't accept non-ASCII data */
+	return (!IS_HIGHBIT_SET(c) && isblank(c));
 }