Date: Tue, 8 May 2018 15:43:20 -0500 From: Kyle Evans <kevans@freebsd.org> To: Ronald Klop <ronald-lists@klop.ws> Cc: Alexey Dokuchaev <danfe@freebsd.org>, svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers <src-committers@freebsd.org> Subject: Re: svn commit: r333351 - head/usr.bin/grep Message-ID: <CACNAnaH4EZm7kW7K7YSi=8oO7RO37B1mT7QZigqXmnKXxuk97w@mail.gmail.com> In-Reply-To: <op.zipp7obvkndu52@klop.ws> References: <201805080353.w483rlde033542@repo.freebsd.org> <20180508105815.GB7299@FreeBSD.org> <CACNAnaEiV7kC%2BUNy6GwiEtLzOqwA%2BkPuunDNBtb1dQUQeb3uzQ@mail.gmail.com> <20180508144912.GA3581@FreeBSD.org> <op.zipp7obvkndu52@klop.ws>
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On Tue, May 8, 2018 at 3:36 PM, Ronald Klop <ronald-lists@klop.ws> wrote: > On Tue, 08 May 2018 16:49:12 +0200, Alexey Dokuchaev <danfe@freebsd.org> > wrote: > >> On Tue, May 08, 2018 at 09:36:21AM -0500, Kyle Evans wrote: >>> >>> On Tue, May 8, 2018 at 5:58 AM, Alexey Dokuchaev <danfe@freebsd.org> >>> wrote: >>> >> >>> >> - if ((f = fopen(fn, "r")) == NULL) >>> >> + if (strcmp(fn, "-") == 0) >>> >> + f = stdin; >>> > >>> > This makes sense: when `fn' is "-", `f' is stdin. >>> > >>> >> - fclose(f); >>> >> + if (strcmp(fn, "-") != 0) >>> >> + fclose(f); >>> > >>> > But not this one: why are you checking `fn' again? Shouldn't you >>> > fclose(f) if it's not stdin? >>> > >>> > if (f != stdin) >>> > fclose(f); >>> > >>> >>> You say potato, I say potato. =) In this case, it's low overhead in a >>> not particularly performance critical bit and drawing a connection >>> between this and the opening of 'f' above in an extremely obvious way. >> >> >> Well, I'm not worried about the overhead or performance issues, they are >> negligible. I just find second strcmp(fn, "-") to be semantically wrong >> (and that's why you need implicit "there's only one way to get stdin here" >> assert). You assign `f' to stdin based on `fn' being "-", but you >> fclose(f) when it's not stdin; the value of `fn' is irrelevant this time. >> As a nice bonus, you only spell strcmp(fn, "-") once and do not need to >> implicitly assert that there's only one way to get stdin here. >> >>> This also might get ripped out soon -- we'll see how things go. >> >> >> I see, understood. >> >> ./danfe > > > What is the result of "-f /dev/stdin"? Of does that fopen return a different > filedesc? > Indeed- /dev/stdin will force it to open another filedesc and read from stdin all the same. Thanks, Kyle Evans
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