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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 16:39:53 +00:00
parent 71a185a24d
commit 54cd4f0457
11 changed files with 111 additions and 31 deletions
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29
src/interfaces/libpq/fe-misc.c
View File

@ -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 $
*
*-------------------------------------------------------------------------
*/
@ -67,6 +67,20 @@ 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
*
@ -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;
}