[flashrom] [PATCH 1/2] layout: Add -i <region>[:<file>] support.

[Stefan Tauner]

On Fri, 20 Sep 2013 03:48:15 +0200
Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net> wrote:

> Am 19.09.2013 01:29 schrieb Stefan Tauner:
> > Add an optional sub-parameter to the -i parameter to allow building the
> > image to be written from multiple files. This will also allow regions to
> > be read from flash and written to separate image files in a later patch.
> > Existing function read_buf_from_file() is refined and reused to read the file.
> >
> > Document the whole layout handling including the new features a bit better
> > and refine wording regarding files, images, layouts and regions as discussed.
> >
> > Also, finally introduce helpers.c: a module containing utility functions to be
> > shared which do not fit elsewhere. The first function to be added is
> > unquote_string() which is used throughout this patch.
> >
> > Abort for non-write operations if a layout file is given.
> >
> > based on chromiumos'
> > d0ea9ed71e7f86bb8e8db2ca7c32a96de25343d8
> > Signed-off-by: David Hendricks <dhendrix at chromium.org>
> > Signed-off-by: Stefan Tauner <stefan.tauner at student.tuwien.ac.at>
> 
> Counter-proposal for helpers.c, addressing all my complaints:
> - The first token must either be completely enclosed in double quotes or
> not quoted at all.
> - There must be end-of-string or delimiter after the closing quote.
> - The first token shall not have stray quotes anywhere.
> 
> Function description is yours.
> 
> Tested with the following inputs (input/output in single quotes):
> 
> # ./unqote ''
> Input ''
> ret=1
> First token '', remaining text ''
> # ./unqote '""'
> Input '""'
> ret=1
> First token '', remaining text ''
> # ./unqote 'foo'
> Input 'foo'
> ret=0
> First token 'foo', remaining text ''
> # ./unqote ' foo '
> Input ' foo '
> ret=0
> First token 'foo', remaining text ''
> # ./unqote '"foo"'
> Input '"foo"'
> ret=0
> First token 'foo', remaining text ''
> # ./unqote ' "foo" '
> Input ' "foo" '
> ret=0
> First token 'foo', remaining text ' '
> # ./unqote ' " foo " '
> Input ' " foo " '
> ret=0
> First token ' foo ', remaining text ' '
> # ./unqote 'foo bar'
> Input 'foo bar'
> ret=0
> First token 'foo', remaining text 'bar'
> # ./unqote ' foo  bar '
> Input ' foo  bar '
> ret=0
> First token 'foo', remaining text ' bar '
> # ./unqote ' "foo"  bar '
> Input ' "foo"  bar '
> ret=0
> First token 'foo', remaining text '  bar '
> # ./unqote ' "foo  bar '
> Input ' "foo  bar '
> ret=-1
> Aborting.
> # ./unqote ' "foo""  bar '
> Input ' "foo""  bar '
> ret=-1
> Aborting.
> # ./unqote ' "foo"""'
> Input ' "foo"""'
> ret=-1
> Aborting.
> # ./unqote ' "foo"bar'
> Input ' "foo"bar'
> ret=-1
> Aborting.
> 
> Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net>
> 
> --- /dev/null	2013-08-19 11:01:03.588011829 +0200
> +++ helpers.c	2013-09-20 03:31:28.000000000 +0200
> @@ -0,0 +1,86 @@
> +/*
> + * This file is part of the flashrom project.
> + *
> + * Copyright (C) 2013 Carl-Daniel Hailfinger
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
> + */
> +
> +#include <string.h>
> +
> +#include <string.h>
> +#include "flash.h"
> +
> +/** Parse a \em possibly quoted string.
> + *
> + * The function expects \a startp to point to the string to be parsed without a prefix. If the
> + * string starts with a quotation mark it looks for the second one and removes both in-place, if not then it
> + * looks for the first character contained in \a delimiters and ends the wanted string there by replacing the
> + * character with '\0'. If \a delimiters is NULL an empty set is assumed, hence the whole start string equals
> + * the wanted string.
> + *
> + * After returning \a startp will point to a string that is either the first quoted part of the
> + * original string with the quotation marks removed, or the first word of that string before any delimiter.
> + * If \a endp is not NULL it will be set to point to the first character after the parsed string, or to the
> + * '\0' at the end of the string pointed to by \a startp if there are no more subsequent characters.
> + *
> + * @param start	Points to the input string.
> + * @param end	Is set to the first char following the input string.
> + * @return	-1 if a quotation mark is not matched,
> + *		0 on success,
> + *		1 if the parsed string is empty.
> + */
> +int unquote_string(char **startp, char **endp, const char *delimiters)
> +{
> +	size_t len;
> +
> +	/* Strip leading delimiters. */
> +	*startp += strspn(*startp, delimiters);

Above explodes for delimiters == NULL. It makes it also completely
useless when the caller needs to track the number of fields (defined by
the delimiters).

> +
> +	/* Check for empty string. */
> +	if (strlen(*startp) == 0) {
> +		*endp = *startp;
> +		return 1;
> +	}
> +
> +	/* Handle unqoted string. */
> +	if (**startp != '"') {
> +		len = strcspn(*startp, delimiters);
> +		/* Check for quotes in the middle. */
> +		if (strcspn(*startp, "\"") < len)
> +			return -1;
> +		/* Check if there is anything after this string. */
> +		if (strlen(*startp + len) > 0)
> +			*endp = *startp + len + 1;

Explodes for endp == NULL

> +		else
> +			*endp = *startp + len;

Likewise.

> +		(*startp)[len] = '\0';
> +		return 0;
> +	}
> +
> +	/* Handle quoted string. */
> +	(*startp)++;
> +	len = strcspn(*startp, "\"");
> +	/* Catch unclosed quotes and closing quotes not followed immediately by delimiter or end-of-string. */
> +	if ((*startp)[len] == '\0' || strcspn(*startp + len + 1, delimiters) > 0)

This will trigger on """ for example (and explode on delimiters ==
NULL).

> +		return -1;
> +	/* Overwrite closing quote. */
> +	(*startp)[len] = '\0';
> +	*endp = *startp + len + 1;
> +	/* Check for empty string. */
> +	if (strlen(*startp) == 0)
> +		return 1;
> +	return 0;
> +}

All in all I think it does way more than a generic unquoting function
to be used in parsers should do.

-- 
Kind regards/Mit freundlichen Grüßen, Stefan Tauner