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From: peter@Starbase.NeoSoft.COM (Peter da Silva)
Newsgroups: comp.os.386bsd.questions,comp.os.386bsd.development,comp.os.386bsd.misc
Subject: Re: Why does FreeBSD 1.1.5 say gets() is unsafe?
Date: 31 Jul 1994 14:53:05 -0500
Organization: NeoSoft Internet Services +1 713 684 5969
Lines: 32
Message-ID: <31gvf1$h19@Starbase.NeoSoft.COM>
References: <30lrf3$2ii@acmez.gatech.edu> <31cf70$3c@Starbase.NeoSoft.COM> <jmonroyCts1rL.96o@netcom.com> <31f1v8$2lg@mozo.cc.purdue.edu>
NNTP-Posting-Host: starbase.neosoft.com
In article <31f1v8$2lg@mozo.cc.purdue.edu>,
Ben Jackson <bj@staff.cc.purdue.edu> wrote:
>Test what you MEAN, sheesh! That will fail if your buffer is too short
>to hold the line, or if there is no newline in the input stream. If
>you don't want to write on a null pointer, TEST THE POINTER YOU'RE
>WRITING ON. Duh:
> if (fgets(buf, sizeof(buf), stdin) && result = strchr(buf, '\n'))
> *result = '\0';
You're right. My original code was:
> if(result = fgets(buf, sizeof(buf), stdin)) {
char *tmp;
> if(tmp = strchr(buf, '\n'))
> *tmp = '\0';
}
I managed to somehow convince myself that if result was nonzero, I was safe
without the extra temporary.
I can't imagine what I was thinking of.
You *do* need another temporary, though, because otherwise result will be
pointing to the wrong place. Alternatively, you can do this:
> if (fgets(buf, sizeof(buf), stdin) && result = strchr(buf, '\n')) {
> *result = '\0';
result = buf;
}
But I think an explicit temp will be easier to optimise.