Date: Sat, 27 Dec 2008 01:40:13 -0800 From: Gary Kline <kline@thought.org> To: Giorgos Keramidas <keramida@ceid.upatras.gr> Cc: FreeBSD Mailing List <freebsd-questions@freebsd.org> Subject: Re: how can i be certain that a file has copied exactly? Message-ID: <20081227094012.GA39306@thought.org> In-Reply-To: <8763l61gbd.fsf@kobe.laptop> References: <20081227011335.GA29354@thought.org> <87ocyy2you.fsf@kobe.laptop> <20081227015634.GB29639@thought.org> <8763l61gbd.fsf@kobe.laptop>
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On Sat, Dec 27, 2008 at 04:51:18AM +0200, Giorgos Keramidas wrote:
> On Fri, 26 Dec 2008 17:56:34 -0800, Gary Kline <kline@thought.org> wrote:
> > On Sat, Dec 27, 2008 at 03:29:05AM +0200, Giorgos Keramidas wrote:
> >> On Fri, 26 Dec 2008 17:13:39 -0800, Gary Kline <kline@thought.org> wrote:
> >> > is there a way i can be sure that my little C program has copied a
> >> > dos/win file named, say, foo.htm\;7 to simply foo.htm?
> >> >
> >> > my program uses fopen/fgets/fputs to copy the markup files. of the
> >> > several i have copied, no problem. unless i hack cmp or diff, i have
> >> > to avoid the shell.
> >> >
> >> > any ideas? in other words, does anybody have a prefab cmp(oldfile,
> >> > newfile) fn?
> >>
> >> You don't need a prefab `cmp' function, because the base system already
> >> includes tools that can help:
> >>
> >> cmp file1 file2 ; echo $?
> >> md5 file1 file2
> >> sha1 file1 file2
> >> sha256 file1 file2
> >
> > the problem is that there are several thousands of these files with
> > dos names and an embedded '\;'7 in the file names. the shell gets in
> > the way. i have tried
> >
> > sprintf(cmdbuf, "/usr/bin/cmp %s %s", orig, new);
> > system(cmdbuf);
> >
> > chokes on the embedded bytes.
> >
> > i'm thinking of using
> >
> > find . -name "*" -print -exec {} \;
> >
> > and let me program select out the file suffix. i unlink the screwy
> > dos-ish filename. that's why i want to be sure the copied/renamed
> > files are right.
>
> Use quoting (and snprintf() because it supports range-checks for the
> buffer you are passing to it):
>
> snprintf(cmdbuf, sizeof(cmdbuf), "cmp \"%s\" \"%s\"", orig, new);
>
howdy,
in a word, YES, /usr/bin/cmp saved the save before i unlinked the
oldfile. here is the strangeness. maybe you know, giorgos, or
somebody else on-list. At first--before i got smart and used your
snprintf to simply /bin/cp and then unlink---yes, or /bin/mv, or
simply rename()--- Before, while i creating via fgets/fputs a new
file, everything went fine until i ran out of buffer space. i
increased to buf[4096] to buf[65535]. more files were
successfully
copied from dos\;5 to .dos/*.htm, actually. suddenly, cmp caught
a mismatch and the program exited. a careful diff showed the err
a something like line 3751. my copy was missing a byte near the
EOF:
</body></html
minus the closing ">"
so i upped the buffer space to 256000; same thing. is there a lim
on the sizeof arrays, or is it [more likely] sloppy hacking? the
size of the last file that wouldn't copy is 202K.
just wondering.
as i said, using snprintf() with quotes works, so i can do the
same with the jpeg and gif files. just cp or mv then to a
cleaner, more rational unix-esque [[ :-) ]] name.
gary
--
Gary Kline kline@thought.org http://www.thought.org Public Service Unix
http://jottings.thought.org http://transfinite.thought.org
The 2.17a release of Jottings: http://jottings.thought.org/index.php
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