From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Kunshchikov Vladimir <Vladimir.Kunshchikov@infotecs.ru>
Cc: pgsql-hackers@postgresql.org <pgsql-hackers@postgresql.org>
Subject: Re: [patch] pg_dump/pg_restore zerror() and strerror() mishap
Date: Fri, 28 Jul 2017 12:25:52 -0400
Message-ID: <20170728162552.fhr5nfj5dvvxjhdh@alvherre.pgsql> (raw)
In-Reply-To: <571149215d3c467dac8b000651507445@infotecs.ru>
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Kunshchikov Vladimir wrote:
> Hello Alvaro,
>
> here goes v4 version: removed unused header.
>
> Compilation of this code snippet with -Wall -Wexter -std=c89 doesn't produce any warnings.
Great, thanks.
+const char *
+get_cfp_error(cfp* fp)
+{
+#ifdef HAVE_LIBZ
+ if(fp->compressedfp){
+ int errnum;
+ static const char fallback[] = "Zlib error";
+ const int maxlen = 255;
+ const char *errmsg = gzerror(fp->compressedfp, &errnum);
+ if(!errmsg || !memchr(errmsg, 0, maxlen))
+ errmsg = fallback;
+
+ return errnum == Z_ERRNO ? strerror(errno) : errmsg;
+ }
#endif
+ return strerror(errno);
+}
This "maxlen" business and the fallback error message are strange. We
have roughly equivalent code in pg_basebackup.c, which has been working
since 2011 (commit 048d148fe631), and it looks like this:
#ifdef HAVE_LIBZ
static const char *
get_gz_error(gzFile gzf)
{
int errnum;
const char *errmsg;
errmsg = gzerror(gzf, &errnum);
if (errnum == Z_ERRNO)
return strerror(errno);
else
return errmsg;
}
#endif
Perhaps you can drop the memchr/fallback tricks and adopt the
pg_basebackup coding? Or is there a specific reason to have the memchr
check?
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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To: pgsql-hackers@postgresql.org
Cc: alvherre@2ndquadrant.com, Vladimir.Kunshchikov@infotecs.ru
Subject: Re: [patch] pg_dump/pg_restore zerror() and strerror() mishap
In-Reply-To: <20170728162552.fhr5nfj5dvvxjhdh@alvherre.pgsql>
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