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

[Carl-Daniel Hailfinger]

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 
> Signed-off-by: Stefan Tauner

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

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