aboutsummaryrefslogtreecommitdiff
path: root/sh-i18n--envsubst.c
blob: 6dd03a974ae9a5063c40cd50e0c6e7645afca971 (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
/*
 * sh-i18n--envsubst.c - a stripped-down version of gettext's envsubst(1)
 *
 * Copyright (C) 2010 Ævar Arnfjörð Bjarmason
 *
 * This is a modified version of
 * 67d0871a8c:gettext-runtime/src/envsubst.c from the gettext.git
 * repository. It has been stripped down to only implement the
 * envsubst(1) features that we need in the git-sh-i18n fallbacks.
 *
 * The "Close standard error" part in main() is from
 * 8dac033df0:gnulib-local/lib/closeout.c. The copyright notices for
 * both files are reproduced immediately below.
 */

#include "git-compat-util.h"

/* Substitution of environment variables in shell format strings.
   Copyright (C) 2003-2007 Free Software Foundation, Inc.
   Written by Bruno Haible <bruno@clisp.org>, 2003.

   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, 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, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

/* closeout.c - close standard output and standard error
   Copyright (C) 1998-2007 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 2, 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, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* If true, substitution shall be performed on all variables.  */
static unsigned short int all_variables;

/* Forward declaration of local functions.  */
static void print_variables (const char *string);
static void note_variables (const char *string);
static void subst_from_stdin (void);

int
main (int argc, char *argv[])
{
  /* Default values for command line options.  */
  /* unsigned short int show_variables = 0; */

  switch (argc)
	{
	case 1:
	  error ("we won't substitute all variables on stdin for you");
	  break;
	  /*
	  all_variables = 1;
      subst_from_stdin ();
	  */
	case 2:
	  /* echo '$foo and $bar' | git sh-i18n--envsubst --variables '$foo and $bar' */
	  all_variables = 0;
	  note_variables (argv[1]);
      subst_from_stdin ();
	  break;
	case 3:
	  /* git sh-i18n--envsubst --variables '$foo and $bar' */
	  if (strcmp(argv[1], "--variables"))
		error ("first argument must be --variables when two are given");
	  /* show_variables = 1; */
      print_variables (argv[2]);
	  break;
	default:
	  error ("too many arguments");
	  break;
	}

  /* Close standard error.  This is simpler than fwriteerror_no_ebadf, because
     upon failure we don't need an errno - all we can do at this point is to
     set an exit status.  */
  errno = 0;
  if (ferror (stderr) || fflush (stderr))
    {
      fclose (stderr);
      exit (EXIT_FAILURE);
    }
  if (fclose (stderr) && errno != EBADF)
    exit (EXIT_FAILURE);

  exit (EXIT_SUCCESS);
}

/* Parse the string and invoke the callback each time a $VARIABLE or
   ${VARIABLE} construct is seen, where VARIABLE is a nonempty sequence
   of ASCII alphanumeric/underscore characters, starting with an ASCII
   alphabetic/underscore character.
   We allow only ASCII characters, to avoid dependencies w.r.t. the current
   encoding: While "${\xe0}" looks like a variable access in ISO-8859-1
   encoding, it doesn't look like one in the BIG5, BIG5-HKSCS, GBK, GB18030,
   SHIFT_JIS, JOHAB encodings, because \xe0\x7d is a single character in these
   encodings.  */
static void
find_variables (const char *string,
		void (*callback) (const char *var_ptr, size_t var_len))
{
  for (; *string != '\0';)
    if (*string++ == '$')
      {
	const char *variable_start;
	const char *variable_end;
	unsigned short int valid;
	char c;

	if (*string == '{')
	  string++;

	variable_start = string;
	c = *string;
	if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || c == '_')
	  {
	    do
	      c = *++string;
	    while ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')
		   || (c >= '0' && c <= '9') || c == '_');
	    variable_end = string;

	    if (variable_start[-1] == '{')
	      {
		if (*string == '}')
		  {
		    string++;
		    valid = 1;
		  }
		else
		  valid = 0;
	      }
	    else
	      valid = 1;

	    if (valid)
	      callback (variable_start, variable_end - variable_start);
	  }
      }
}


/* Print a variable to stdout, followed by a newline.  */
static void
print_variable (const char *var_ptr, size_t var_len)
{
  fwrite (var_ptr, var_len, 1, stdout);
  putchar ('\n');
}

/* Print the variables contained in STRING to stdout, each one followed by a
   newline.  */
static void
print_variables (const char *string)
{
  find_variables (string, &print_variable);
}


/* Type describing list of immutable strings,
   implemented using a dynamic array.  */
typedef struct string_list_ty string_list_ty;
struct string_list_ty
{
  const char **item;
  size_t nitems;
  size_t nitems_max;
};

/* Initialize an empty list of strings.  */
static inline void
string_list_init (string_list_ty *slp)
{
  slp->item = NULL;
  slp->nitems = 0;
  slp->nitems_max = 0;
}

/* Append a single string to the end of a list of strings.  */
static inline void
string_list_append (string_list_ty *slp, const char *s)
{
  /* Grow the list.  */
  if (slp->nitems >= slp->nitems_max)
    {
      size_t nbytes;

      slp->nitems_max = slp->nitems_max * 2 + 4;
      nbytes = slp->nitems_max * sizeof (slp->item[0]);
      slp->item = (const char **) xrealloc (slp->item, nbytes);
    }

  /* Add the string to the end of the list.  */
  slp->item[slp->nitems++] = s;
}

/* Compare two strings given by reference.  */
static int
cmp_string (const void *pstr1, const void *pstr2)
{
  const char *str1 = *(const char **)pstr1;
  const char *str2 = *(const char **)pstr2;

  return strcmp (str1, str2);
}

/* Sort a list of strings.  */
static inline void
string_list_sort (string_list_ty *slp)
{
  if (slp->nitems > 0)
    qsort (slp->item, slp->nitems, sizeof (slp->item[0]), cmp_string);
}

/* Test whether a sorted string list contains a given string.  */
static int
sorted_string_list_member (const string_list_ty *slp, const char *s)
{
  size_t j1, j2;

  j1 = 0;
  j2 = slp->nitems;
  if (j2 > 0)
    {
      /* Binary search.  */
      while (j2 - j1 > 1)
	{
	  /* Here we know that if s is in the list, it is at an index j
	     with j1 <= j < j2.  */
	  size_t j = (j1 + j2) >> 1;
	  int result = strcmp (slp->item[j], s);

	  if (result > 0)
	    j2 = j;
	  else if (result == 0)
	    return 1;
	  else
	    j1 = j + 1;
	}
      if (j2 > j1)
	if (strcmp (slp->item[j1], s) == 0)
	  return 1;
    }
  return 0;
}


/* Set of variables on which to perform substitution.
   Used only if !all_variables.  */
static string_list_ty variables_set;

/* Adds a variable to variables_set.  */
static void
note_variable (const char *var_ptr, size_t var_len)
{
  char *string = xmemdupz (var_ptr, var_len);

  string_list_append (&variables_set, string);
}

/* Stores the variables occurring in the string in variables_set.  */
static void
note_variables (const char *string)
{
  string_list_init (&variables_set);
  find_variables (string, &note_variable);
  string_list_sort (&variables_set);
}


static int
do_getc (void)
{
  int c = getc (stdin);

  if (c == EOF)
    {
      if (ferror (stdin))
	error ("error while reading standard input");
    }

  return c;
}

static inline void
do_ungetc (int c)
{
  if (c != EOF)
    ungetc (c, stdin);
}

/* Copies stdin to stdout, performing substitutions.  */
static void
subst_from_stdin (void)
{
  static char *buffer;
  static size_t bufmax;
  static size_t buflen;
  int c;

  for (;;)
    {
      c = do_getc ();
      if (c == EOF)
	break;
      /* Look for $VARIABLE or ${VARIABLE}.  */
      if (c == '$')
	{
	  unsigned short int opening_brace = 0;
	  unsigned short int closing_brace = 0;

	  c = do_getc ();
	  if (c == '{')
	    {
	      opening_brace = 1;
	      c = do_getc ();
	    }
	  if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || c == '_')
	    {
	      unsigned short int valid;

	      /* Accumulate the VARIABLE in buffer.  */
	      buflen = 0;
	      do
		{
		  if (buflen >= bufmax)
		    {
		      bufmax = 2 * bufmax + 10;
		      buffer = xrealloc (buffer, bufmax);
		    }
		  buffer[buflen++] = c;

		  c = do_getc ();
		}
	      while ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')
		     || (c >= '0' && c <= '9') || c == '_');

	      if (opening_brace)
		{
		  if (c == '}')
		    {
		      closing_brace = 1;
		      valid = 1;
		    }
		  else
		    {
		      valid = 0;
		      do_ungetc (c);
		    }
		}
	      else
		{
		  valid = 1;
		  do_ungetc (c);
		}

	      if (valid)
		{
		  /* Terminate the variable in the buffer.  */
		  if (buflen >= bufmax)
		    {
		      bufmax = 2 * bufmax + 10;
		      buffer = xrealloc (buffer, bufmax);
		    }
		  buffer[buflen] = '\0';

		  /* Test whether the variable shall be substituted.  */
		  if (!all_variables
		      && !sorted_string_list_member (&variables_set, buffer))
		    valid = 0;
		}

	      if (valid)
		{
		  /* Substitute the variable's value from the environment.  */
		  const char *env_value = getenv (buffer);

		  if (env_value != NULL)
		    fputs (env_value, stdout);
		}
	      else
		{
		  /* Perform no substitution at all.  Since the buffered input
		     contains no other '$' than at the start, we can just
		     output all the buffered contents.  */
		  putchar ('$');
		  if (opening_brace)
		    putchar ('{');
		  fwrite (buffer, buflen, 1, stdout);
		  if (closing_brace)
		    putchar ('}');
		}
	    }
	  else
	    {
	      do_ungetc (c);
	      putchar ('$');
	      if (opening_brace)
		putchar ('{');
	    }
	}
      else
	putchar (c);
    }
}