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-rw-r--r--zcmp.cc502
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+/* Zcmp - decompress and compare two files byte by byte
+ Copyright (C) 2010 Antonio Diaz Diaz.
+
+ 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 3 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, see <http://www.gnu.org/licenses/>.
+*/
+
+#define _FILE_OFFSET_BITS 64
+
+#include <cctype>
+#include <cerrno>
+#include <climits>
+#include <csignal>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <string>
+#include <vector>
+#include <fcntl.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#if defined(__MSVCRT__) || defined(__OS2__)
+#include <io.h>
+#endif
+
+#include "arg_parser.h"
+#include "zutils.h"
+
+#if CHAR_BIT != 8
+#error "Environments where CHAR_BIT != 8 are not supported."
+#endif
+
+#ifndef LLONG_MAX
+#define LLONG_MAX 0x7FFFFFFFFFFFFFFFLL
+#endif
+#ifndef LLONG_MIN
+#define LLONG_MIN (-LLONG_MAX - 1LL)
+#endif
+#ifndef ULLONG_MAX
+#define ULLONG_MAX 0xFFFFFFFFFFFFFFFFULL
+#endif
+
+
+namespace {
+
+#ifdef O_BINARY
+const int o_binary = O_BINARY;
+#else
+const int o_binary = 0;
+#endif
+
+struct { const char * from; const char * to; } const known_extensions[] = {
+ { ".bz2", "" },
+ { ".tbz", ".tar" },
+ { ".tbz2", ".tar" },
+ { ".gz", "" },
+ { ".tgz", ".tar" },
+ { ".lz", "" },
+ { ".tlz", ".tar" },
+ { ".xz", "" },
+ { ".txz", ".tar" },
+ { 0, 0 } };
+
+
+void show_help() throw()
+ {
+ std::printf( "Zcmp compares two files (\"-\" means standard input), and if they\n" );
+ std::printf( "differ, tells the first byte and line number where they differ. Bytes\n" );
+ std::printf( "and lines are numbered starting with 1. If any given file is compressed,\n" );
+ std::printf( "its uncompressed content is used. Compressed files are uncompressed on\n" );
+ std::printf( "the fly; no temporary files are created.\n" );
+ std::printf( "The supported compressors are bzip2, gzip, lzip and xz.\n" );
+ std::printf( "\nUsage: zcmp [options] file1 [file2]\n" );
+ std::printf( "\nCompares <file1> to <file2>. If <file2> is omitted zcmp tries the\n" );
+ std::printf( "following:\n" );
+ std::printf( "If <file1> is compressed, compares <file1> to the file with the\n" );
+ std::printf( "corresponding decompressed file name (removes the extension from\n" );
+ std::printf( "<file1>).\n" );
+ std::printf( "If <file1> is not compressed, compares <file1> to the uncompressed\n" );
+ std::printf( "contents of <file1>.[bz2|gz|lz|xz] (the first one that is found).\n" );
+ std::printf( "If no suitable file is found, compares <file1> to data read from\n" );
+ std::printf( "standard input.\n" );
+ std::printf( "\nExit status is 0 if inputs are identical, 1 if different, 2 if trouble.\n" );
+ std::printf( "\nOptions:\n" );
+ std::printf( " -h, --help display this help and exit\n" );
+ std::printf( " -V, --version output version information and exit\n" );
+ std::printf( " -b, --print-bytes print differing bytes\n" );
+ std::printf( " -i, --ignore-initial=<n>[,<n2>] ignore differences in the first <n> bytes\n" );
+ std::printf( " -l, --list list position, value of all differing bytes\n" );
+ std::printf( " -n, --bytes=<n> compare at most <n> bytes\n" );
+ std::printf( " -q, --quiet suppress all messages\n" );
+ std::printf( " -s, --silent (same as --quiet)\n" );
+ std::printf( " -v, --verbose verbose mode (same as --list)\n" );
+ std::printf( "Numbers may be followed by a multiplier: k = kB = 10^3 = 1000,\n" );
+ std::printf( "Ki = KiB = 2^10 = 1024, M = 10^6, Mi = 2^20, G = 10^9, Gi = 2^30, etc...\n" );
+ show_help_addr();
+ }
+
+
+long long getnum( const char * const ptr, const char ** const tailp = 0,
+ const long long llimit = LLONG_MIN + 1,
+ const long long ulimit = LLONG_MAX ) throw()
+ {
+ errno = 0;
+ char * tail;
+ long long result = strtoll( ptr, &tail, 0 );
+ if( tail == ptr )
+ {
+ show_error( "Bad or missing numerical argument.", 0, true );
+ std::exit( 2 );
+ }
+
+ if( !errno && tail[0] && std::isalpha( tail[0] ) )
+ {
+ int factor = ( tail[1] == 'i' ) ? 1024 : 1000;
+ int exponent = 0;
+ bool bad_multiplier = false;
+ switch( tail[0] )
+ {
+ case 'Y': exponent = 8; break;
+ case 'Z': exponent = 7; break;
+ case 'E': exponent = 6; break;
+ case 'P': exponent = 5; break;
+ case 'T': exponent = 4; break;
+ case 'G': exponent = 3; break;
+ case 'M': exponent = 2; break;
+ case 'K': if( factor == 1024 ) exponent = 1; else bad_multiplier = true;
+ break;
+ case 'k': if( factor == 1000 ) exponent = 1; else bad_multiplier = true;
+ break;
+ default : bad_multiplier = true;
+ }
+ if( bad_multiplier )
+ {
+ show_error( "Bad multiplier in numerical argument.", 0, true );
+ std::exit( 2 );
+ }
+ for( int i = 0; i < exponent; ++i )
+ {
+ if( LLONG_MAX / factor >= llabs( result ) ) result *= factor;
+ else { errno = ERANGE; break; }
+ }
+ }
+ if( !errno && ( result < llimit || result > ulimit ) ) errno = ERANGE;
+ if( errno )
+ {
+ show_error( "Numerical argument out of limits." );
+ std::exit( 2 );
+ }
+ if( tailp ) *tailp = tail;
+ return result;
+ }
+
+
+int open_instream( const std::string & input_filename ) throw()
+ {
+ int infd = open( input_filename.c_str(), O_RDONLY | o_binary );
+ if( infd < 0 && verbosity >= 0 )
+ std::fprintf( stderr, "%s: Can't open input file `%s': %s.\n",
+ util_name, input_filename.c_str(), std::strerror( errno ) );
+ return infd;
+ }
+
+
+int open_other_instream( std::string & name ) throw()
+ {
+ for( int i = 0; known_extensions[i].from; ++i )
+ { // search uncompressed version
+ const std::string from( known_extensions[i].from );
+ if( name.size() > from.size() &&
+ name.compare( name.size() - from.size(), from.size(), from ) == 0 )
+ {
+ name.resize( name.size() - from.size() );
+ name += known_extensions[i].to;
+ return open( name.c_str(), O_RDONLY | o_binary );
+ }
+ }
+ for( int i = 0; simple_extensions[i]; ++i )
+ { // search compressed version
+ const std::string s( name + simple_extensions[i] );
+ const int infd = open( s.c_str(), O_RDONLY | o_binary );
+ if( infd >= 0 ) { name = s; return infd; }
+ }
+ return -1;
+ }
+
+
+bool check_identical( const char * const name1, const char * const name2 ) throw()
+ {
+ if( !std::strcmp( name1, name2 ) ) return true;
+ struct stat stat1, stat2;
+ if( stat( name1, &stat1 ) || stat( name2, &stat2 ) ) return false;
+ return ( stat1.st_ino == stat2.st_ino && stat1.st_dev == stat2.st_dev );
+ }
+
+
+void parse_ignore_initial( const char * const arg, long long ignore_initial[2] )
+ {
+ const char * tail;
+ ignore_initial[0] = getnum( arg, &tail, 0 );
+ if( *tail == ',' || *tail == ':' )
+ ignore_initial[1] = getnum( ++tail, 0, 0 );
+ else ignore_initial[1] = ignore_initial[0];
+ }
+
+
+bool skip_ignore_initial( const long long ignore_initial, const int infd )
+ {
+ if( ignore_initial > 0 )
+ {
+ enum { buffer_size = 4096 };
+ long long rest = ignore_initial;
+ uint8_t buffer[buffer_size];
+ while( rest > 0 )
+ {
+ const int size = std::min( rest, (long long)buffer_size );
+ const int rd = readblock( infd, buffer, size );
+ if( rd != size && errno ) return false;
+ if( rd < size ) break;
+ rest -= rd;
+ }
+ }
+ return true;
+ }
+
+
+// Put into buf the unsigned char c, making unprintable bytes
+// visible by quoting like cat -t does.
+void sprintc( char * const buf, unsigned char c )
+ {
+ int i = 0;
+
+ if( c < 32 || c >= 127 )
+ {
+ if( c >= 128 ) { c -= 128; buf[i++] = 'M'; buf[i++] = '-'; }
+ if( c < 32 ) { c += 64; buf[i++] = '^'; }
+ else if( c == 127 ) { c = '?'; buf[i++] = '^'; }
+ }
+ buf[i++] = c;
+ buf[i++] = 0;
+ }
+
+
+int block_compare( const uint8_t * const buffer0,
+ const uint8_t * const buffer1,
+ long long * line_numberp )
+ {
+ const uint8_t * p0 = buffer0;
+ const uint8_t * p1 = buffer1;
+ if( verbosity == 0 )
+ {
+ int nl_count = 0;
+ while( *p0 == *p1 )
+ { if( *p0 == '\n' ) { ++nl_count; } ++p0; ++p1; }
+ *line_numberp += nl_count;
+ }
+ else while( *p0 == *p1 ) { ++p0; ++p1; }
+ return p0 - buffer0;
+ }
+
+
+int cmp( const long long max_size, const int infd[2],
+ const std::string filenames[2], const bool print_bytes )
+ {
+ enum { buffer_size = 4096 };
+ long long byte_number = 1;
+ long long line_number = 1;
+ long long rest = max_size; // remaining number of bytes to compare
+ // buffers with space for sentinels at the end
+ uint8_t * const buffer0 = new uint8_t[2*(buffer_size+1)];
+ uint8_t * const buffer1 = buffer0 + buffer_size + 1;
+ uint8_t * buffer[2];
+ buffer[0] = buffer0; buffer[1] = buffer1;
+ int different = 0;
+
+ while( rest > 0 )
+ {
+ const int size = std::min( rest, (long long)buffer_size );
+ int rd[2]; // number of bytes read from each file
+ for( int i = 0; i < 2; ++i )
+ {
+ rd[i] = readblock( infd[i], buffer[i], size );
+ if( rd[i] != size && errno )
+ {
+ if( verbosity >= 0 )
+ std::fprintf( stderr, "%s: Error reading file `%s': %s.\n",
+ util_name, filenames[i].c_str(), std::strerror( errno ) );
+ return 2;
+ }
+ }
+ rest -= size;
+
+ buffer0[rd[0]] = ~buffer1[rd[0]]; // sentinels for the block compare
+ buffer1[rd[1]] = ~buffer0[rd[1]];
+
+ int first_diff = block_compare( buffer0, buffer1, &line_number );
+ byte_number += first_diff;
+ const int min_rd = std::min( rd[0], rd[1] );
+
+ if( first_diff < min_rd )
+ {
+ if( verbosity < 0 ) return 1; // return status only
+ if( verbosity == 0 ) // show first difference
+ {
+ if( !print_bytes )
+ std::printf( "%s %s differ: byte %lld, line %lld\n",
+ filenames[0].c_str(), filenames[1].c_str(),
+ byte_number, line_number );
+ else
+ {
+ const unsigned char c0 = buffer0[first_diff];
+ const unsigned char c1 = buffer1[first_diff];
+ char buf0[5], buf1[5];
+ sprintc( buf0, c0 ); sprintc( buf1, c1 );
+ std::printf( "%s %s differ: byte %lld, line %lld is %3o %s %3o %s\n",
+ filenames[0].c_str(), filenames[1].c_str(),
+ byte_number, line_number, c0, buf0, c1, buf1 );
+ }
+ return 1;
+ }
+ else // verbosity > 0 ; show all differences
+ {
+ different = 1;
+ for( ; first_diff < min_rd; ++byte_number, ++first_diff )
+ {
+ const unsigned char c0 = buffer0[first_diff];
+ const unsigned char c1 = buffer1[first_diff];
+ if( c0 != c1 )
+ {
+ if( !print_bytes )
+ std::printf( "%lld %3o %3o\n", byte_number, c0, c1 );
+ else
+ {
+ char buf0[5], buf1[5];
+ sprintc( buf0, c0 ); sprintc( buf1, c1 );
+ std::printf( "%lld %3o %-4s %3o %s\n",
+ byte_number, c0, buf0, c1, buf1 );
+ }
+ }
+ }
+ }
+ }
+
+ if( rd[0] != rd[1] )
+ {
+ if( verbosity >= 0 )
+ std::fprintf( stderr, "%s: EOF on %s\n",
+ util_name, filenames[rd[1]<rd[0]].c_str() );
+ return 1;
+ }
+ if( min_rd != buffer_size ) break;
+ }
+
+ delete[] buffer0;
+ return different;
+ }
+
+} // end namespace
+
+
+int main( const int argc, const char * const argv[] )
+ {
+ // number of initial bytes ignored for each file
+ long long ignore_initial[2] = { 0, 0 };
+ long long max_size = LLONG_MAX;
+ bool print_bytes = false;
+ invocation_name = argv[0];
+ util_name = "zcmp";
+
+ const Arg_parser::Option options[] =
+ {
+ { 'b', "print-bytes", Arg_parser::no },
+ { 'h', "help", Arg_parser::no },
+ { 'i', "ignore-initial", Arg_parser::yes },
+ { 'l', "list", Arg_parser::no },
+ { 'n', "bytes", Arg_parser::yes },
+ { 'q', "quiet", Arg_parser::no },
+ { 's', "silent", Arg_parser::no },
+ { 'v', "verbose", Arg_parser::no },
+ { 'V', "version", Arg_parser::no },
+ { 0 , 0, Arg_parser::no } };
+
+ const Arg_parser parser( argc, argv, options );
+ if( parser.error().size() ) // bad option
+ { show_error( parser.error().c_str(), 0, true ); return 2; }
+
+ int argind = 0;
+ for( ; argind < parser.arguments(); ++argind )
+ {
+ const int code = parser.code( argind );
+ if( !code ) break; // no more options
+ const char * const arg = parser.argument( argind ).c_str();
+ switch( code )
+ {
+ case 'b': print_bytes = true; break;
+ case 'h': show_help(); return 0;
+ case 'i': parse_ignore_initial( arg, ignore_initial ); break;
+ case 'l': verbosity = 1; break;
+ case 'n': max_size = getnum( arg, 0, 0 ); break;
+ case 'q':
+ case 's': verbosity = -1; break;
+ case 'v': verbosity = 1; break;
+ case 'V': show_version( "Zcmp" ); return 0;
+ default : internal_error( "uncaught option" );
+ }
+ } // end process options
+
+#if defined(__MSVCRT__) || defined(__OS2__)
+ _setmode( STDIN_FILENO, O_BINARY );
+ _setmode( STDOUT_FILENO, O_BINARY );
+#endif
+
+ if( argind >= parser.arguments() )
+ { show_error( "No files given.", 0, true ); return 2; }
+ if( argind + 2 < parser.arguments() )
+ { show_error( "Too many files.", 0, true ); return 2; }
+
+ const int files = parser.arguments() - argind;
+ std::string filenames[2]; // file names of the two input files
+ filenames[0] = parser.argument( argind );
+ if( files == 2 ) filenames[1] = parser.argument( argind + 1 );
+
+ int infd[2]; // file descriptors of the two files
+ infd[0] = ( filenames[0] == "-" ) ?
+ STDIN_FILENO : open_instream( filenames[0] );
+ if( infd[0] < 0 ) return 2;
+
+ if( ( files == 1 && filenames[0] == "-" ) ||
+ ( files == 2 && check_identical( filenames[0].c_str(),
+ filenames[1].c_str() ) ) )
+ {
+ if( ignore_initial[0] == ignore_initial[1] ) return 0;
+ else { show_error( "Can't compare parts of same file." ); return 2; }
+ }
+
+ if( files == 2 )
+ {
+ infd[1] = ( filenames[1] == "-" ) ?
+ STDIN_FILENO : open_instream( filenames[1] );
+ if( infd[1] < 0 ) return 2;
+ }
+ else
+ {
+ filenames[1] = filenames[0];
+ infd[1] = open_other_instream( filenames[1] );
+ if( infd[1] < 0 ) { infd[1] = STDIN_FILENO; filenames[1] = "-"; }
+ }
+
+ int old_infd[2]; // copy of file descriptors of the two files
+ old_infd[0] = infd[0]; old_infd[1] = infd[1];
+ pid_t pid[2];
+ if( !set_data_feeder( &infd[0], &pid[0] ) ||
+ !set_data_feeder( &infd[1], &pid[1] ) )
+ return 2;
+
+ for( int i = 0; i < 2; ++i )
+ if( !skip_ignore_initial( ignore_initial[i], infd[i] ) )
+ {
+ if( verbosity >= 0 )
+ std::fprintf( stderr, "%s: Can't skip initial bytes from file `%s': %s.\n",
+ util_name, filenames[i].c_str(), std::strerror( errno ) );
+ return 2;
+ }
+
+ int retval = cmp( max_size, infd, filenames, print_bytes );
+
+ if( ( ( pid[0] && wait_for_child( pid[0], "data feeder" ) != 0 ) ||
+ ( pid[1] && wait_for_child( pid[1], "data feeder" ) != 0 ) ) &&
+ retval == 0 )
+ retval = 2;
+
+ for( int i = 0; i < 2; ++i )
+ {
+ if( close( infd[i] ) != 0 )
+ { show_error( "Can't close output of data feeder", errno ); retval = 2; }
+ if( filenames[i] != "-" && close( old_infd[i] ) != 0 )
+ {
+ if( verbosity >= 0 )
+ std::fprintf( stderr, "%s: Can't close input file `%s': %s.\n",
+ util_name, filenames[i].c_str(), std::strerror( errno ) );
+ retval = 2;
+ }
+ }
+ if( std::fclose( stdout ) != 0 )
+ {
+ show_error( "Can't close stdout", errno );
+ retval = 2;
+ }
+
+ return retval;
+ }