Re: [U-Boot] [PATCHv5] new tool mkenvimage: generates an env image from an arbitrary config file

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