summaryrefslogtreecommitdiffstats
path: root/zdiff.cc
blob: 66195178a67d3ab852713f77ea42f464d419c776 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
/* Zdiff - decompress and compare two files line by line
   Copyright (C) 2010-2022 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 2 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 <algorithm>
#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 "rc.h"
#include "zutils.h"


namespace {

std::string fifonames[2];	// names of the two fifos passed to diff

#include "zcmpdiff.cc"

void show_help()
  {
  std::printf( "zdiff compares two files and, if they differ, writes to standard output the\n"
               "differences line by line. A hyphen '-' used as a file argument means standard\n"
               "input. If any file given is compressed, its decompressed content is used.\n"
               "zdiff is a front end to the program diff and has the limitation that messages\n"
               "from diff refer to temporary file names instead of those specified.\n"
               "\n'zdiff -v -V' prints the version of the diff program used.\n"
               "\nThe formats supported are bzip2, gzip, lzip, xz, and zstd.\n"
               "\nUsage: zdiff [options] file1 [file2]\n"
               "\nzdiff compares file1 to file2. The standard input is used only if file1 or\n"
               "file2 refers to standard input. If file2 is omitted zdiff tries the\n"
               "following:\n"
               "\n  - If file1 is compressed, compares its decompressed contents with\n"
               "  the corresponding uncompressed file (the name of file1 with the\n"
               "  extension removed).\n"
               "\n  - If file1 is uncompressed, compares it with the decompressed\n"
               "  contents of file1.[lz|bz2|gz|zst|xz] (the first one that is found).\n"
               "\nExit status is 0 if inputs are identical, 1 if different, 2 if trouble.\n"
               "Some options only work if the diff program used supports them.\n"
               "\nOptions:\n"
               "  -h, --help                        display this help and exit\n"
               "  -V, --version                     output version information and exit\n"
               "  -a, --text                        treat all files as text\n"
               "  -b, --ignore-space-change         ignore changes in the amount of white space\n"
               "  -B, --ignore-blank-lines          ignore changes whose lines are all blank\n"
               "  -c                                use the context output format\n"
               "  -C, --context=<n>                 same as -c but use <n> lines of context\n"
               "  -d, --minimal                     try hard to find a smaller set of changes\n"
               "  -E, --ignore-tab-expansion        ignore changes due to tab expansion\n"
               "  -i, --ignore-case                 ignore case differences in file contents\n"
               "  -M, --format=<list>               process only the formats in <list>\n"
               "  -N, --no-rcfile                   don't read runtime configuration file\n"
               "  -O, --force-format=[<f1>][,<f2>]  force one or both input formats\n"
               "  -p, --show-c-function             show which C function each change is in\n"
               "  -q, --brief                       output only whether files differ\n"
               "  -s, --report-identical-files      report when two files are identical\n"
               "  -t, --expand-tabs                 expand tabs to spaces in output\n"
               "  -T, --initial-tab                 make tabs line up by prepending a tab\n"
               "  -u                                use the unified output format\n"
               "  -U, --unified=<n>                 same as -u but use <n> lines of context\n"
               "  -v, --verbose                     verbose mode (for --version)\n"
               "  -w, --ignore-all-space            ignore all white space\n"
               "  -W, --width=<n>                   output at most <n> print columns (for -y)\n"
               "  -y, --side-by-side                output in two columns\n"
               "      --bz2=<command>               set compressor and options for bzip2 format\n"
               "      --gz=<command>                set compressor and options for gzip format\n"
               "      --lz=<command>                set compressor and options for lzip format\n"
               "      --xz=<command>                set compressor and options for xz format\n"
               "      --zst=<command>               set compressor and options for zstd format\n"
               "\nValid formats for options '-M' and '-O' are 'bz2', 'gz', 'lz', 'xz', 'zst',\n"
               "and 'un' for uncompressed.\n" );
  show_help_addr();
  }


const char * my_basename( const char * filename )
  {
  const char * c = filename;
  while( *c ) { if( *c == '/' ) { filename = c + 1; } ++c; }
  return filename;
  }


extern "C" void remove_fifos()
  {
  if( fifonames[0].size() )
    { std::remove( fifonames[0].c_str() ); fifonames[0].clear(); }
  if( fifonames[1].size() )
    { std::remove( fifonames[1].c_str() ); fifonames[1].clear(); }
  }


/* Set fifonames[i] to "${TMPDIR}/<coded_pid>[_-]<basename(filenames[i])>"
   and create FIFOs. The pid is coded in little endian order.
*/
bool set_fifonames( const std::string filenames[2] )
  {
  enum { num_codes = 36 };
  const char * const codes = "0123456789abcdefghijklmnopqrstuvwxyz";
  const char * p = std::getenv( "TMPDIR" );

  if( p ) { fifonames[0] = p; fifonames[0] += '/'; }
  else fifonames[0] = "/tmp/";
  unsigned n = getpid();
  do fifonames[0] += codes[n % num_codes]; while( n /= num_codes );
  const unsigned pos = fifonames[0].size();
  fifonames[0] += '_';
  fifonames[1] = fifonames[0];
  fifonames[0] += my_basename( filenames[0].c_str() );
  fifonames[1] += my_basename( filenames[1].c_str() );
  if( fifonames[1] == fifonames[0] ) fifonames[1][pos] = '-';

  for( int i = 0; i < 2; ++i )
    if( mkfifo( fifonames[i].c_str(), S_IRUSR | S_IWUSR ) != 0 )
      {
      if( errno == EEXIST )
        {
        std::remove( fifonames[i].c_str() );
        if( mkfifo( fifonames[i].c_str(), S_IRUSR | S_IWUSR ) == 0 )
          continue;
        }
      show_file_error( fifonames[i].c_str(), "Can't create FIFO", errno );
      return false;
      }
  return true;
  }


bool set_data_feeder( const std::string & filename,
                      const std::string & fifoname, const int infd,
                      Children & children, int format_index )
  {
  uint8_t magic_data[magic_buf_size];
  int magic_size = 0;
  if( format_index < 0 )
    format_index = test_format( infd, magic_data, &magic_size );
  children.compressor_name = get_compressor_name( format_index );

  if( children.compressor_name )	// compressed
    {
    int fda[2];				// pipe from feeder to compressor
    if( pipe( fda ) < 0 )
      { show_error( "Can't create pipe", errno ); return false; }
    const pid_t pid = fork();
    if( pid == 0 )			// child 1 (compressor feeder)
      {
      if( close( fda[0] ) != 0 ||
          !feed_data( filename, infd, fda[1], magic_data, magic_size ) )
        _exit( 2 );
      if( close( fda[1] ) != 0 )
        { show_close_error(); _exit( 2 ); }
      _exit( 0 );
      }
    if( pid < 0 )			// parent
      { show_fork_error( "data feeder" ); return false; }

    const pid_t pid2 = fork();
    if( pid2 == 0 )			// child 2 (compressor)
      {
      const int outfd = open( fifoname.c_str(), O_WRONLY | O_BINARY );
      if( outfd < 0 )
        { show_file_error( fifoname.c_str(), "Can't open FIFO for writing",
                           errno ); _exit( 2 ); }
      if( dup2( fda[0], STDIN_FILENO ) >= 0 &&
          dup2( outfd, STDOUT_FILENO ) >= 0 &&
          close( fda[0] ) == 0 && close( fda[1] ) == 0 &&
          close( outfd ) == 0 )
        {
        const std::vector< std::string > & compressor_args =
          get_compressor_args( format_index );
        const int size = compressor_args.size();
        const char ** const argv = new const char *[size+3];
        argv[0] = children.compressor_name;
        for( int i = 0; i < size; ++i )
          argv[i+1] = compressor_args[i].c_str();
        argv[size+1] = ( verbosity >= 0 ) ? "-d" : "-dq";
        argv[size+2] = 0;
        execvp( argv[0], (char **)argv );
        }
      show_exec_error( children.compressor_name );
      _exit( 2 );
      }
    if( pid2 < 0 )			// parent
      { show_fork_error( children.compressor_name ); return false; }

    close( fda[0] ); close( fda[1] );
    children.pid[0] = pid;
    children.pid[1] = pid2;
    }
  else					// uncompressed
    {
    const pid_t pid = fork();
    if( pid == 0 )			// child (feeder)
      {
      const int outfd = open( fifoname.c_str(), O_WRONLY | O_BINARY );
      if( outfd < 0 )
        { show_file_error( fifoname.c_str(), "Can't open FIFO for writing",
                           errno ); _exit( 2 ); }
      if( !feed_data( filename, infd, outfd, magic_data, magic_size ) )
        _exit( 2 );
      if( close( outfd ) != 0 )
        { show_close_error(); _exit( 2 ); }
      _exit( 0 );
      }
    if( pid < 0 )			// parent
      { show_fork_error( "data feeder" ); return false; }
    children.pid[0] = pid;
    children.pid[1] = 0;
    }
  return true;
  }


extern "C" void signal_handler( int sig )
  {
  remove_fifos();
  std::signal( sig, SIG_DFL );
  std::raise( sig );
  }


void set_signals()
  {
  std::signal( SIGHUP, signal_handler );
  std::signal( SIGINT, signal_handler );
  std::signal( SIGTERM, signal_handler );
  }

} // end namespace


int main( const int argc, const char * const argv[] )
  {
  enum { bz2_opt = 256, gz_opt, lz_opt, xz_opt, zst_opt };
  std::vector< const char * > diff_args;	// args to diff, maybe empty
  int format_types[2] = { -1, -1 };		// < 0 means undefined
  program_name = "zdiff";
  invocation_name = ( argc > 0 ) ? argv[0] : program_name;

  const Arg_parser::Option options[] =
    {
    { 'a', "text",                   Arg_parser::no  },
    { 'b', "ignore-space-change",    Arg_parser::no  },
    { 'B', "ignore-blank-lines",     Arg_parser::no  },
    { 'c',  0,                       Arg_parser::no  },
    { 'C', "context",                Arg_parser::yes },
    { 'd', "minimal",                Arg_parser::no  },
    { 'E', "ignore-tab-expansion",   Arg_parser::no  },
    { 'h', "help",                   Arg_parser::no  },
    { 'i', "ignore-case",            Arg_parser::no  },
    { 'M', "format",                 Arg_parser::yes },
    { 'N', "no-rcfile",              Arg_parser::no  },
    { 'O', "force-format",           Arg_parser::yes },
    { 'p', "show-c-function",        Arg_parser::no  },
    { 'q', "brief",                  Arg_parser::no  },
    { 's', "report-identical-files", Arg_parser::no  },
    { 't', "expand-tabs",            Arg_parser::no  },
    { 'T', "initial-tab",            Arg_parser::no  },
    { 'u',  0,                       Arg_parser::no  },
    { 'U', "unified",                Arg_parser::yes },
    { 'v', "verbose",                Arg_parser::no  },
    { 'V', "version",                Arg_parser::no  },
    { 'w', "ignore-all-space",       Arg_parser::no  },
    { 'W', "width",                  Arg_parser::yes },
    { 'y', "side-by-side",           Arg_parser::no  },
    { bz2_opt, "bz2",                Arg_parser::yes },
    { gz_opt,  "gz",                 Arg_parser::yes },
    { lz_opt,  "lz",                 Arg_parser::yes },
    { xz_opt,  "xz",                 Arg_parser::yes },
    { zst_opt, "zst",                Arg_parser::yes },
    {  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; }

  maybe_process_config_file( parser );

  int argind = 0;
  for( ; argind < parser.arguments(); ++argind )
    {
    const int code = parser.code( argind );
    if( !code ) break;					// no more options
    const char * const pn = parser.parsed_name( argind ).c_str();
    const std::string & sarg = parser.argument( argind );
    const char * const arg = sarg.c_str();
    switch( code )
      {
      case 'a': diff_args.push_back( "-a" ); break;
      case 'b': diff_args.push_back( "-b" ); break;
      case 'B': diff_args.push_back( "-B" ); break;
      case 'c': diff_args.push_back( "-c" ); break;
      case 'C': diff_args.push_back( "-C" ); diff_args.push_back( arg ); break;
      case 'd': diff_args.push_back( "-d" ); break;
      case 'E': diff_args.push_back( "-E" ); break;
      case 'h': show_help(); return 0;
      case 'i': diff_args.push_back( "-i" ); break;
      case 'M': parse_format_list( sarg, pn ); break;
      case 'N': break;
      case 'O': parse_format_types2( sarg, pn, format_types ); break;
      case 'p': diff_args.push_back( "-p" ); break;
      case 'q': diff_args.push_back( "-q" ); break;
      case 's': diff_args.push_back( "-s" ); break;
      case 't': diff_args.push_back( "-t" ); break;
      case 'T': diff_args.push_back( "-T" ); break;
      case 'u': diff_args.push_back( "-u" ); break;
      case 'U': diff_args.push_back( "-U" ); diff_args.push_back( arg ); break;
      case 'v': if( verbosity < 4 ) ++verbosity; break;
      case 'V': show_version( DIFF " --version" ); return 0;
      case 'w': diff_args.push_back( "-w" ); break;
      case 'W': diff_args.push_back( "-W" ); diff_args.push_back( arg ); break;
      case 'y': diff_args.push_back( "-y" ); break;
      case bz2_opt: parse_compressor( sarg, pn, fmt_bz2 ); break;
      case gz_opt: parse_compressor( sarg, pn, fmt_gz ); break;
      case lz_opt: parse_compressor( sarg, pn, fmt_lz ); break;
      case xz_opt: parse_compressor( sarg, pn, fmt_xz ); break;
      case zst_opt: parse_compressor( sarg, pn, fmt_zst ); break;
      default : internal_error( "uncaught option." );
      }
    } // end process options

#if defined __MSVCRT__ || defined __OS2__
  setmode( STDIN_FILENO, O_BINARY );
  setmode( STDOUT_FILENO, O_BINARY );
#endif

  const int files = parser.arguments() - argind;
  if( files < 1 ) { show_error( "No files given.", 0, true ); return 2; }
  if( files > 2 ) { show_error( "Too many files.", 0, true ); return 2; }

  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 == 2 )
    {
    if( check_identical( filenames[0].c_str(), filenames[1].c_str() ) )
      return 0;
    infd[1] = ( filenames[1] == "-" ) ?
      STDIN_FILENO : open_instream( filenames[1] );
    if( infd[1] < 0 ) return 2;
    }
  else
    {
    if( filenames[0] == "-" )
      { show_error( "Missing operand after '-'.", 0, true ); return 2; }
    if( format_types[0] >= 0 || format_types[1] >= 0 )
      { show_error( "Two files must be given when format is specified.", 0, true );
        return 2; }
    filenames[1] = filenames[0];
    infd[1] = open_other_instream( filenames[1] );
    if( infd[1] < 0 )
      {
      if( verbosity >= 0 )
        std::fprintf( stderr, "%s: Can't find file to compare with '%s'.\n",
                      program_name, filenames[0].c_str() );
      show_error( 0, 0, true ); return 2;
      }
    }

  std::atexit( remove_fifos );
  set_signals();
  if( !set_fifonames( filenames ) ) return 2;

  Children children[2];
  if( !set_data_feeder( filenames[0], fifonames[0], infd[0], children[0],
                        format_types[0] ) ||
      !set_data_feeder( filenames[1], fifonames[1], infd[1], children[1],
                        format_types[1] ) )
    return 2;

  const pid_t diff_pid = fork();
  if( diff_pid == 0 )			// child (diff)
    {
    const char ** const argv = new const char *[diff_args.size()+5];
    argv[0] = DIFF;
    for( unsigned i = 0; i < diff_args.size(); ++i )
      argv[i+1] = diff_args[i];
    argv[diff_args.size()+1] = "--";
    argv[diff_args.size()+2] = fifonames[0].c_str();
    argv[diff_args.size()+3] = fifonames[1].c_str();
    argv[diff_args.size()+4] = 0;
    execvp( argv[0], (char **)argv );
    show_exec_error( DIFF );
    _exit( 2 );
    }
  if( diff_pid < 0 )			// parent
    { show_fork_error( DIFF ); return 2; }

  int retval = wait_for_child( diff_pid, DIFF );

  for( int i = 0; i < 2; ++i )
    {
    int infd;			// fifo from decompressor
    do infd = open( fifonames[i].c_str(), O_RDONLY | O_NONBLOCK | O_BINARY );
    while( infd < 0 && errno == EINTR );
    bool finished = false;	// set to true if fifo is empty and at EOF
    if( infd >= 0 )
      {
      uint8_t b;
      if( readblock( infd, &b, 1 ) <= 0 && errno == 0 ) finished = true;
      close( infd );
      }
    if( !good_status( children[i], finished ) ) retval = 2;
    }

  for( int i = 0; i < 2; ++i )
    if( filenames[i] != "-" && close( infd[i] ) != 0 )
      {
      show_file_error( filenames[i].c_str(), "Error closing input file", errno );
      retval = 2;
      }

  return retval;
  }