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

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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".
This commit is contained in:
Tom Lane 2010-05-08 16:40:52 +00:00
parent 79c712aae8
commit 47bdd80dc1
2 changed files with 38 additions and 6 deletions
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16
src/backend/parser/scansup.c
View File

@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/scansup.c,v 1.24.4.1 2004/02/21 00:35:13 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/parser/scansup.c,v 1.24.4.2 2010/05/08 16:40:52 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -176,10 +176,20 @@ 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';
}
}

28
src/interfaces/libpq/fe-misc.c
View File

@ -23,7 +23,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-misc.c,v 1.103.2.1 2005/07/08 15:25:19 tgl Exp $
* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-misc.c,v 1.103.2.2 2010/05/08 16:40:52 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
*
@ -175,7 +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;
}
@ -191,7 +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;
}