coreutils/cksum.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * cksum - calculate the CRC32 checksum of a file
   4  *
   5  * Copyright (C) 2006 by Rob Sullivan, with ideas from code by Walter Harms
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8  */
   9 //config:config CKSUM
  10 //config:       bool "cksum (4.1 kb)"
  11 //config:       default y
  12 //config:       help
  13 //config:       cksum is used to calculate the CRC32 checksum of a file.
  14
  15 //applet:IF_CKSUM(APPLET_NOEXEC(cksum, cksum, BB_DIR_USR_BIN, BB_SUID_DROP, cksum))
  16 /* bb_common_bufsiz1 usage here is safe wrt NOEXEC: not expecting it to be zeroed. */
  17
  18 //kbuild:lib-$(CONFIG_CKSUM) += cksum.o
  19
  20 //usage:#define cksum_trivial_usage
  21 //usage:       "FILE..."
  22 //usage:#define cksum_full_usage "\n\n"
  23 //usage:       "Calculate the CRC32 checksums of FILEs"
  24
  25 #include "libbb.h"
  26 #include "common_bufsiz.h"
  27
  28 /* This is a NOEXEC applet. Be very careful! */
  29
  30 int cksum_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  31 int cksum_main(int argc UNUSED_PARAM, char **argv)
  32 {
  33         uint32_t *crc32_table = crc32_filltable(NULL, 1);
  34         int exit_code = EXIT_SUCCESS;
  35
  36 #if ENABLE_DESKTOP
  37         getopt32(argv, ""); /* coreutils 6.9 compat */
  38         argv += optind;
  39 #else
  40         argv++;
  41 #endif
  42
  43         setup_common_bufsiz();
  44         do {
  45                 uint32_t crc;
  46                 off_t filesize;
  47                 int fd = open_or_warn_stdin(*argv ? *argv : bb_msg_standard_input);
  48
  49                 if (fd < 0) {
  50                         exit_code = EXIT_FAILURE;
  51                         continue;
  52                 }
  53
  54                 crc = 0;
  55                 filesize = 0;
  56 #define read_buf bb_common_bufsiz1
  57                 for (;;) {
  58                         uoff_t t;
  59                         int bytes_read = safe_read(fd, read_buf, COMMON_BUFSIZE);
  60                         if (bytes_read > 0) {
  61                                 filesize += bytes_read;
  62                         } else {
  63                                 /* Checksum filesize bytes, LSB first, and exit */
  64                                 close(fd);
  65                                 fd = -1; /* break flag */
  66                                 t = filesize;
  67                                 bytes_read = 0;
  68                                 while (t != 0) {
  69                                         read_buf[bytes_read++] = (uint8_t)t;
  70                                         t >>= 8;
  71                                 }
  72                         }
  73                         crc = crc32_block_endian1(crc, read_buf, bytes_read, crc32_table);
  74                         if (fd < 0)
  75                                 break;
  76                 }
  77
  78                 crc = ~crc;
  79                 printf((*argv ? "%u %"OFF_FMT"u %s\n" : "%u %"OFF_FMT"u\n"),
  80                                 (unsigned)crc, filesize, *argv);
  81         } while (*argv && *++argv);
  82
  83         fflush_stdout_and_exit(exit_code);
  84 }