From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mike Frysinger <vapier@gentoo.org>
Date: Thu, 1 Sep 2011 13:47:00 -0400
Subject: [U-Boot] [PATCHv5] new tool mkenvimage: generates an env image
	from an arbitrary config file
In-Reply-To: <1314892629-2002-1-git-send-email-david.wagner@free-electrons.com>
References: <1312555798-29542-1-git-send-email-david.wagner@free-electrons.com>
	<1314892629-2002-1-git-send-email-david.wagner@free-electrons.com>
Message-ID: <201109011347.01447.vapier@gentoo.org>
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To: u-boot@lists.denx.de

On Thursday, September 01, 2011 11:57:09 David Wagner wrote:
> +	txt_filename = argv[optind];
> +	if (strcmp(txt_filename, "-") == 0) {
> +		txt_fd = STDIN_FILENO;
> +	} else {
> +		txt_fd = open(txt_filename, O_RDONLY);
> +		if (txt_fd == -1) {
> +			fprintf(stderr, "Can't open \"%s\": %s\n",
> +					txt_filename, strerror(errno));
> +			return EXIT_FAILURE;
> +		}
> +	}
> +	/* ... and check it */
> +	ret = fstat(txt_fd, &txt_file_stat);
> +	if (ret == -1) {
> +		fprintf(stderr, "Can't stat() on \"%s\": "
> +				"%s\n", txt_filename, strerror(errno));
> +		return EXIT_FAILURE;
> +	}
> +	/*
> +	 * The right test to do is "=>" (not ">") because of the additionnal
> +	 * ending \0. See below.
> +	 */
> +	if (txt_file_stat.st_size >= envsize) {
> +		fprintf(stderr, "The input file is larger than the "
> +				"envrionnment partition size\n");
> +		return EXIT_FAILURE;
> +	}
> +
> +	/* Read the raw input file and transform it */
> +	filebuf = malloc(sizeof(*envptr) * txt_file_stat.st_size);
> +	ret = read(txt_fd, filebuf, sizeof(*envptr) * txt_file_stat.st_size);
> +	if (ret != txt_file_stat.st_size) {
> +		fprintf(stderr, "Can't read the whole input file\n");
> +		return EXIT_FAILURE;
> +	}

i think the stdin logic here is broken.  when you fstat() stdin, you get back 
st_size == 0, and so you end up doing a read() on stdin of 0 bytes, and it 
writes out an empty image.

simple test:
echo foo=var | ./mkenvimage -s 0x1000 -o foo -
hexdump -C foo
<see that the env is empty>

running it through strace shows the bum read(0, "", 0) ...
-mike
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