summaryrefslogtreecommitdiff
path: root/src/echo.c
blob: 8c3da597c308bea7b9f765bfb323497ca9cf9fc4 (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
/* echo.c, derived from code echo.c in Bash.
   Copyright (C) 1987-2012 Free Software Foundation, Inc.

   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/>.  */

#include <config.h>
#include <stdio.h>
#include <sys/types.h>
#include "system.h"

/* The official name of this program (e.g., no 'g' prefix).  */
#define PROGRAM_NAME "echo"

#define AUTHORS \
  proper_name ("Brian Fox"), \
  proper_name ("Chet Ramey")

/* If true, interpret backslash escapes by default.  */
#ifndef DEFAULT_ECHO_TO_XPG
enum { DEFAULT_ECHO_TO_XPG = false };
#endif

void
usage (int status)
{
  if (status != EXIT_SUCCESS)
    emit_try_help ();
  else
    {
      printf (_("\
Usage: %s [SHORT-OPTION]... [STRING]...\n\
  or:  %s LONG-OPTION\n\
"), program_name, program_name);
      fputs (_("\
Echo the STRING(s) to standard output.\n\
\n\
  -n             do not output the trailing newline\n\
"), stdout);
      fputs (_(DEFAULT_ECHO_TO_XPG
               ? N_("\
  -e             enable interpretation of backslash escapes (default)\n\
  -E             disable interpretation of backslash escapes\n")
               : N_("\
  -e             enable interpretation of backslash escapes\n\
  -E             disable interpretation of backslash escapes (default)\n")),
             stdout);
      fputs (HELP_OPTION_DESCRIPTION, stdout);
      fputs (VERSION_OPTION_DESCRIPTION, stdout);
      fputs (_("\
\n\
If -e is in effect, the following sequences are recognized:\n\
\n\
"), stdout);
      fputs (_("\
  \\\\      backslash\n\
  \\a      alert (BEL)\n\
  \\b      backspace\n\
  \\c      produce no further output\n\
  \\e      escape\n\
  \\f      form feed\n\
  \\n      new line\n\
  \\r      carriage return\n\
  \\t      horizontal tab\n\
  \\v      vertical tab\n\
"), stdout);
      fputs (_("\
  \\0NNN   byte with octal value NNN (1 to 3 digits)\n\
  \\xHH    byte with hexadecimal value HH (1 to 2 digits)\n\
"), stdout);
      printf (USAGE_BUILTIN_WARNING, PROGRAM_NAME);
      emit_ancillary_info ();
    }
  exit (status);
}

/* Convert C from hexadecimal character to integer.  */
static int
hextobin (unsigned char c)
{
  switch (c)
    {
    default: return c - '0';
    case 'a': case 'A': return 10;
    case 'b': case 'B': return 11;
    case 'c': case 'C': return 12;
    case 'd': case 'D': return 13;
    case 'e': case 'E': return 14;
    case 'f': case 'F': return 15;
    }
}

/* Print the words in LIST to standard output.  If the first word is
   '-n', then don't print a trailing newline.  We also support the
   echo syntax from Version 9 unix systems. */

int
main (int argc, char **argv)
{
  bool display_return = true;
  bool allow_options =
    (! getenv ("POSIXLY_CORRECT")
     || (! DEFAULT_ECHO_TO_XPG && 1 < argc && STREQ (argv[1], "-n")));

  /* System V machines already have a /bin/sh with a v9 behavior.
     Use the identical behavior for these machines so that the
     existing system shell scripts won't barf.  */
  bool do_v9 = DEFAULT_ECHO_TO_XPG;

  initialize_main (&argc, &argv);
  set_program_name (argv[0]);
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);

  atexit (close_stdout);

  /* We directly parse options, rather than use parse_long_options, in
     order to avoid accepting abbreviations.  */
  if (allow_options && argc == 2)
    {
      if (STREQ (argv[1], "--help"))
        usage (EXIT_SUCCESS);

      if (STREQ (argv[1], "--version"))
        {
          version_etc (stdout, PROGRAM_NAME, PACKAGE_NAME, Version, AUTHORS,
                       (char *) NULL);
          exit (EXIT_SUCCESS);
        }
    }

  --argc;
  ++argv;

  if (allow_options)
    while (argc > 0 && *argv[0] == '-')
      {
        char const *temp = argv[0] + 1;
        size_t i;

        /* If it appears that we are handling options, then make sure that
           all of the options specified are actually valid.  Otherwise, the
           string should just be echoed.  */

        for (i = 0; temp[i]; i++)
          switch (temp[i])
            {
            case 'e': case 'E': case 'n':
              break;
            default:
              goto just_echo;
            }

        if (i == 0)
          goto just_echo;

        /* All of the options in TEMP are valid options to ECHO.
           Handle them. */
        while (*temp)
          switch (*temp++)
            {
            case 'e':
              do_v9 = true;
              break;

            case 'E':
              do_v9 = false;
              break;

            case 'n':
              display_return = false;
              break;
            }

        argc--;
        argv++;
      }

just_echo:

  if (do_v9)
    {
      while (argc > 0)
        {
          char const *s = argv[0];
          unsigned char c;

          while ((c = *s++))
            {
              if (c == '\\' && *s)
                {
                  switch (c = *s++)
                    {
                    case 'a': c = '\a'; break;
                    case 'b': c = '\b'; break;
                    case 'c': exit (EXIT_SUCCESS);
                    case 'e': c = '\x1B'; break;
                    case 'f': c = '\f'; break;
                    case 'n': c = '\n'; break;
                    case 'r': c = '\r'; break;
                    case 't': c = '\t'; break;
                    case 'v': c = '\v'; break;
                    case 'x':
                      {
                        unsigned char ch = *s;
                        if (! isxdigit (ch))
                          goto not_an_escape;
                        s++;
                        c = hextobin (ch);
                        ch = *s;
                        if (isxdigit (ch))
                          {
                            s++;
                            c = c * 16 + hextobin (ch);
                          }
                      }
                      break;
                    case '0':
                      c = 0;
                      if (! ('0' <= *s && *s <= '7'))
                        break;
                      c = *s++;
                      /* Fall through.  */
                    case '1': case '2': case '3':
                    case '4': case '5': case '6': case '7':
                      c -= '0';
                      if ('0' <= *s && *s <= '7')
                        c = c * 8 + (*s++ - '0');
                      if ('0' <= *s && *s <= '7')
                        c = c * 8 + (*s++ - '0');
                      break;
                    case '\\': break;

                    not_an_escape:
                    default:  putchar ('\\'); break;
                    }
                }
              putchar (c);
            }
          argc--;
          argv++;
          if (argc > 0)
            putchar (' ');
        }
    }
  else
    {
      while (argc > 0)
        {
          fputs (argv[0], stdout);
          argc--;
          argv++;
          if (argc > 0)
            putchar (' ');
        }
    }

  if (display_return)
    putchar ('\n');
  exit (EXIT_SUCCESS);
}