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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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26
src/bin/psql/print.c
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@ -3,7 +3,7 @@
*
* Copyright (c) 2000-2010, PostgreSQL Global Development Group
*
* $PostgreSQL: pgsql/src/bin/psql/print.c,v 1.124 2010/03/01 21:27:26 heikki Exp $
* $PostgreSQL: pgsql/src/bin/psql/print.c,v 1.125 2010/05/08 16:39:52 tgl Exp $
*/
#include "postgres_fe.h"
@ -252,6 +252,20 @@ format_numeric_locale(const char *my_str)
}
/*
* 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);
}
/*************************/
/* Unaligned text */
/*************************/
@ -913,14 +927,16 @@ print_aligned_text(const printTableContent *cont, FILE *fout)
{
/* spaces first */
fprintf(fout, "%*s", width_wrap[j] - chars_to_output, "");
fprintf(fout, "%.*s", bytes_to_output,
this_line->ptr + bytes_output[j]);
fputnbytes(fout,
this_line->ptr + bytes_output[j],
bytes_to_output);
}
else /* Left aligned cell */
{
/* spaces second */
fprintf(fout, "%.*s", bytes_to_output,
this_line->ptr + bytes_output[j]);
fputnbytes(fout,
this_line->ptr + bytes_output[j],
bytes_to_output);
}
bytes_output[j] += bytes_to_output;