Work around a subtle portability problem in use of printf %s format.

Depending on which spec you read, field widths and precisions in %s may be
counted either in bytes or characters.  Our code was assuming bytes, which
is wrong at least for glibc's implementation, and in any case libc might
have a different idea of the prevailing encoding than we do.  Hence, for
portable results we must avoid using anything more complex than just "%s"
unless the string to be printed is known to be all-ASCII.

This patch fixes the cases I could find, including the psql formatting
failure reported by Hernan Gonzalez.  In HEAD only, I also added comments
to some places where it appears safe to continue using "%.*s".

3 files changed, 36 insertions, 6 deletions

diff --git a/src/interfaces/ecpg/ecpglib/error.c b/src/interfaces/ecpg/ecpglib/error.c
index ea48f082dc..5451fd2981 100644
--- a/src/interfaces/ecpg/ecpglib/error.c
+++ b/src/interfaces/ecpg/ecpglib/error.c
@@ -1,4 +1,4 @@
-/* $PostgreSQL: pgsql/src/interfaces/ecpg/ecpglib/error.c,v 1.25 2010/03/08 12:15:24 meskes Exp $ */
+/* $PostgreSQL: pgsql/src/interfaces/ecpg/ecpglib/error.c,v 1.26 2010/05/08 16:39:52 tgl Exp $ */
 
 #define POSTGRES_ECPG_INTERNAL
 #include "postgres_fe.h"
@@ -332,6 +332,7 @@ ecpg_raise_backend(int line, PGresult *result, PGconn *conn, int compat)
 	else
 		sqlca->sqlcode = ECPG_PGSQL;
 
+	/* %.*s is safe here as long as sqlstate is all-ASCII */
 	ecpg_log("raising sqlstate %.*s (sqlcode %d): %s\n",
 			 sizeof(sqlca->sqlstate), sqlca->sqlstate, sqlca->sqlcode, sqlca->sqlerrm.sqlerrmc);
 
diff --git a/src/interfaces/ecpg/pgtypeslib/dt_common.c b/src/interfaces/ecpg/pgtypeslib/dt_common.c
index 9fb6357dda..dc5fbe7fd9 100644
--- a/src/interfaces/ecpg/pgtypeslib/dt_common.c
+++ b/src/interfaces/ecpg/pgtypeslib/dt_common.c
@@ -1,4 +1,4 @@
-/* $PostgreSQL: pgsql/src/interfaces/ecpg/pgtypeslib/dt_common.c,v 1.51 2009/06/11 14:49:13 momjian Exp $ */
+/* $PostgreSQL: pgsql/src/interfaces/ecpg/pgtypeslib/dt_common.c,v 1.52 2010/05/08 16:39:52 tgl Exp $ */
 
 #include "postgres_fe.h"
 
@@ -855,6 +855,14 @@ EncodeDateTime(struct tm * tm, fsec_t fsec, int *tzp, char **tzn, int style, cha
 			if (tm->tm_year <= 0)
 				sprintf(str + strlen(str), " BC");
 
+			/*
+			 * Note: the uses of %.*s in this function would be unportable
+			 * if the timezone names ever contain non-ASCII characters,
+			 * since some platforms think the string length is measured
+			 * in characters not bytes.  However, all TZ abbreviations in
+			 * the Olson database are plain ASCII.
+			 */
+
 			if (tzp != NULL && tm->tm_isdst >= 0)
 			{
 				if (*tzn != NULL)
diff --git a/src/interfaces/libpq/fe-misc.c b/src/interfaces/libpq/fe-misc.c
index 5176cf5625..096e0d84a7 100644
--- a/src/interfaces/libpq/fe-misc.c
+++ b/src/interfaces/libpq/fe-misc.c
@@ -23,7 +23,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-misc.c,v 1.141 2010/01/02 16:58:12 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-misc.c,v 1.142 2010/05/08 16:39:53 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -68,6 +68,20 @@ static int	pqSocketPoll(int sock, int forRead, int forWrite, time_t end_time);
 
 
 /*
+ * fputnbytes: print exactly N bytes to a file
+ *
+ * Think not to use fprintf with a %.*s format for this.  Some machines
+ * believe %s's precision is measured in characters, others in bytes.
+ */
+static void
+fputnbytes(FILE *f, const char *str, size_t n)
+{
+	while (n-- > 0)
+		fputc(*str++, f);
+}
+
+
+/*
  * pqGetc: get 1 character from the connection
  *
  *	All these routines return 0 on success, EOF on error.
@@ -187,8 +201,11 @@ pqGetnchar(char *s, size_t len, PGconn *conn)
 	conn->inCursor += len;
 
 	if (conn->Pfdebug)
-		fprintf(conn->Pfdebug, "From backend (%lu)> %.*s\n",
-				(unsigned long) len, (int) len, s);
+	{
+		fprintf(conn->Pfdebug, "From backend (%lu)> ", (unsigned long) len);
+		fputnbytes(conn->Pfdebug, s, len);
+		fprintf(conn->Pfdebug, "\n");
+	}
 
 	return 0;
 }
@@ -204,7 +221,11 @@ pqPutnchar(const char *s, size_t len, PGconn *conn)
 		return EOF;
 
 	if (conn->Pfdebug)
-		fprintf(conn->Pfdebug, "To backend> %.*s\n", (int) len, s);
+	{
+		fprintf(conn->Pfdebug, "To backend> ");
+		fputnbytes(conn->Pfdebug, s, len);
+		fprintf(conn->Pfdebug, "\n");
+	}
 
 	return 0;
 }