获取crc32的程序

获取crc32的程序
  源程序稍作了修改(chjianash)
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crc32.c
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/*******************************************************************************
  crc32.c by elektron
  Compile:
    # gcc -lz -o crc32 crc32.c
  Usage:
    # ./crc32 -h
    crc32 by elektron
      crc32 [-h] file1 [fileN...]
  Notes:
    This is a hack from someone elses code :
    

    Find the most current version of this application at:
        
*******************************************************************************/

#define VERSION "v.0.1.1"

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include


#define _GNU_SOURCE
#include

int usage( char *progname )
{
  printf( "\n%s %s by elektron\n", progname, VERSION);
  printf( "  %s [-h] file1 [fileN...]\n\n", progname );
}

int getFileSize( char *filename, unsigned long *size )
{
  FILE *input_file;
  unsigned long file_size;

  input_file = fopen( filename, "r" );
  if( input_file == NULL ) {
    printf( "Could not open %s for reading.\n", filename );
    return -1;
  }        
  fseek( input_file, 0, SEEK_END );
  file_size = ftell( input_file );
  rewind( input_file);
  fclose( input_file );
  memcpy(size, &file_size, sizeof(file_size));
  return 0;
}

int computeCRC32( char *filename, unsigned long *crcaddr )
{
  int input_fd;
  char *file_buffer;
  unsigned long file_size;
  unsigned long chunk_size=1024;
  unsigned long bytes_read;
  unsigned long crc=0L;

  if ( getFileSize( filename, &file_size ) != 0) {
    printf( "error determining file size\n" );
    return -1;
  }

  if( file_size == 0 ) {
    printf( "File size is calculated to be 0. Cannot calculate CRC\n" );
    return -1;
  }
  //printf( "size:0x%08X\n", file_size );

  file_buffer = (char *)malloc( chunk_size );
  if( file_buffer == NULL ) {
    printf( "Unable to reserve enough memory for file buffer.\n" );
    return -2;
  }
  crc = crc32( 0L, Z_NULL, 0 );
  input_fd = open( filename, O_RDONLY );
  if( input_fd == -1 ) {
    printf( "Could not open %s for reading.\n", filename );
    free( file_buffer );
    return -3;
  }
  while ( 1 ) {
    bytes_read = read( input_fd, file_buffer, chunk_size );
    if (bytes_read == 0 ) {
         break;
    }
    if (bytes_read == -1 ) {
        perror("read");
        free( file_buffer );
        return -4;
    }
    crc = crc32( crc, file_buffer, bytes_read );
  }
  free( file_buffer );
  close( input_fd );
  memcpy(crcaddr, &crc, sizeof(crc));
  return 0;
}

int main( int argc, char *argv[] )
{
  unsigned long crc=0L;
  extern char *optarg;
  extern int optind, opterr, optopt;
  int i,e=0;

  while ( getopt( argc, argv, "h" ) != -1 ) {
  //    printf("optarg = %s, optind = %d, opterr = %d, optopt = %d\n",
  //        optarg, optind, opterr, optopt);
      if ( strncmp( argv[optind-1], "-h", 2 ) == 0 ) {
          usage( basename(argv[0]) );
          return 0;
      }
  }
 //printf("optarg = %s, optind = %d, opterr = %d, optopt = %d, argc = %d\n",
 //    optarg, optind, opterr, optopt, argc);
  if( argc < optind+1 ) { 
    usage( basename(argv[0]) );
    return 2;
  }          
  for ( i=optind; i    if ( computeCRC32(argv[i], &crc ) != 0 ) {
      e=1;
    } else {
      printf("0x%08X %s\n", crc, argv[i] );
    }
  }
  return e;
}
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===============================================================================
Makefile
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####
# DYNAMIC
LIBS=-lz
STATIC=
#
####
# STATIC
#LIBS=/usr/lib/libz.a
#STATIC=-static
####


crc32: crc32.o
    gcc ${STATIC} -o crc32 crc32.o ${LIBS}

all: crc32

install: crc32
    strip crc32
    install -d ${DESTDIR}/usr/local/bin
    install crc32 ${DESTDIR}/usr/local/bin

clean:
    rm -f crc32.o crc32
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其他程序:

CalcChecksum is a tool for calculating MD5, MD4, CRC32, SHA1 (SHA160), SHA256, RIPE-MD-160, TIGER, HAVAL (128, 160, 192, 224, 256 with 3, 4 or 5 passes) on files, text-strings or hash-lists generated by md5sum or sha1sum.
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