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".

diff --git a/src/backend/parser/scansup.c b/src/backend/parser/scansup.c
index efa851ea0baa89abb334922ed5383b045f18fde5..061b68b359f56f0ddfa99c88713f0f2d619516b0 100644 (file)
--- a/src/backend/parser/scansup.c
+++ b/src/backend/parser/scansup.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/parser/scansup.c,v 1.30 2005/10/15 02:49:22 momjian Exp $
+ *       $PostgreSQL: pgsql/src/backend/parser/scansup.c,v 1.30.2.1 2010/05/08 16:40:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -177,10 +177,20 @@ truncate_identifier(char *ident, int len, bool warn)
        {
                len = pg_mbcliplen(ident, len, NAMEDATALEN - 1);
                if (warn)
+               {
+                       /*
+                        * Cannot use %.*s here because some machines interpret %s's
+                        * precision in characters, others in bytes.
+                        */
+                       char    buf[NAMEDATALEN];
+
+                       memcpy(buf, ident, len);
+                       buf[len] = '\0';
                        ereport(NOTICE,
                                        (errcode(ERRCODE_NAME_TOO_LONG),
-                                        errmsg("identifier \"%s\" will be truncated to \"%.*s\"",
-                                                       ident, len, ident)));
+                                        errmsg("identifier \"%s\" will be truncated to \"%s\"",
+                                                       ident, buf)));
+               }
                ident[len] = '\0';
        }
 }

diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
index 77ca1cec33dd97c21ca4db66bdb8818ea136f749..73170457675a431031925fc7195c825b834072e8 100644 (file)
--- a/src/backend/utils/error/elog.c
+++ b/src/backend/utils/error/elog.c
@@ -42,7 +42,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/utils/error/elog.c,v 1.167.2.9 2009/03/03 00:17:29 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/utils/error/elog.c,v 1.167.2.10 2010/05/08 16:40:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1547,7 +1547,7 @@ log_line_prefix(StringInfo buf)
                                        int                     displen;
 
                                        psdisp = get_ps_display(&displen);
-                                       appendStringInfo(buf, "%.*s", displen, psdisp);
+                                       appendBinaryStringInfo(buf, psdisp, displen);
                                }
                                break;
                        case 'r':

diff --git a/src/interfaces/libpq/fe-misc.c b/src/interfaces/libpq/fe-misc.c
index cd9f56fe38b9f771315b2b2738437edc807b0c83..fff8b6e388146a79f64051319e042dc86f2b28a1 100644 (file)
--- 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 1.122.2.1 2005/11/22 18:23:30 momjian Exp $
+ *       $PostgreSQL: pgsql/src/interfaces/libpq/fe-misc.c,v 1.122.2.2 2010/05/08 16:40:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -69,6 +69,20 @@ static int pqSocketCheck(PGconn *conn, int forRead, int forWrite,
 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
  *
@@ -175,8 +189,11 @@ 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;
 }
@@ -192,7 +209,11 @@ 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;
 }