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[git.git] / sh-i18n--envsubst.c
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1 /*
2 * sh-i18n--envsubst.c - a stripped-down version of gettext's envsubst(1)
4 * Copyright (C) 2010 Ævar Arnfjörð Bjarmason
6 * This is a modified version of
7 * 67d0871a8c:gettext-runtime/src/envsubst.c from the gettext.git
8 * repository. It has been stripped down to only implement the
9 * envsubst(1) features that we need in the git-sh-i18n fallbacks.
11 * The "Close standard error" part in main() is from
12 * 8dac033df0:gnulib-local/lib/closeout.c. The copyright notices for
13 * both files are reproduced immediately below.
16 #include "git-compat-util.h"
18 /* Substitution of environment variables in shell format strings.
19 Copyright (C) 2003-2007 Free Software Foundation, Inc.
20 Written by Bruno Haible <bruno@clisp.org>, 2003.
22 This program is free software; you can redistribute it and/or modify
23 it under the terms of the GNU General Public License as published by
24 the Free Software Foundation; either version 2, or (at your option)
25 any later version.
27 This program is distributed in the hope that it will be useful,
28 but WITHOUT ANY WARRANTY; without even the implied warranty of
29 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
30 GNU General Public License for more details.
32 You should have received a copy of the GNU General Public License
33 along with this program; if not, write to the Free Software Foundation,
34 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
36 /* closeout.c - close standard output and standard error
37 Copyright (C) 1998-2007 Free Software Foundation, Inc.
39 This program is free software; you can redistribute it and/or modify
40 it under the terms of the GNU General Public License as published by
41 the Free Software Foundation; either version 2, or (at your option)
42 any later version.
44 This program is distributed in the hope that it will be useful,
45 but WITHOUT ANY WARRANTY; without even the implied warranty of
46 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
47 GNU General Public License for more details.
49 You should have received a copy of the GNU General Public License
50 along with this program; if not, write to the Free Software Foundation,
51 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
53 #include <errno.h>
54 #include <stdio.h>
55 #include <stdlib.h>
56 #include <string.h>
58 /* If true, substitution shall be performed on all variables. */
59 static unsigned short int all_variables;
61 /* Forward declaration of local functions. */
62 static void print_variables (const char *string);
63 static void note_variables (const char *string);
64 static void subst_from_stdin (void);
66 int
67 main (int argc, char *argv[])
69 /* Default values for command line options. */
70 /* unsigned short int show_variables = 0; */
72 switch (argc)
74 case 1:
75 error ("we won't substitute all variables on stdin for you");
76 break;
78 all_variables = 1;
79 subst_from_stdin ();
81 case 2:
82 /* echo '$foo and $bar' | git sh-i18n--envsubst --variables '$foo and $bar' */
83 all_variables = 0;
84 note_variables (argv[1]);
85 subst_from_stdin ();
86 break;
87 case 3:
88 /* git sh-i18n--envsubst --variables '$foo and $bar' */
89 if (strcmp(argv[1], "--variables"))
90 error ("first argument must be --variables when two are given");
91 /* show_variables = 1; */
92 print_variables (argv[2]);
93 break;
94 default:
95 error ("too many arguments");
96 break;
99 /* Close standard error. This is simpler than fwriteerror_no_ebadf, because
100 upon failure we don't need an errno - all we can do at this point is to
101 set an exit status. */
102 errno = 0;
103 if (ferror (stderr) || fflush (stderr))
105 fclose (stderr);
106 exit (EXIT_FAILURE);
108 if (fclose (stderr) && errno != EBADF)
109 exit (EXIT_FAILURE);
111 exit (EXIT_SUCCESS);
114 /* Parse the string and invoke the callback each time a $VARIABLE or
115 ${VARIABLE} construct is seen, where VARIABLE is a nonempty sequence
116 of ASCII alphanumeric/underscore characters, starting with an ASCII
117 alphabetic/underscore character.
118 We allow only ASCII characters, to avoid dependencies w.r.t. the current
119 encoding: While "${\xe0}" looks like a variable access in ISO-8859-1
120 encoding, it doesn't look like one in the BIG5, BIG5-HKSCS, GBK, GB18030,
121 SHIFT_JIS, JOHAB encodings, because \xe0\x7d is a single character in these
122 encodings. */
123 static void
124 find_variables (const char *string,
125 void (*callback) (const char *var_ptr, size_t var_len))
127 for (; *string != '\0';)
128 if (*string++ == '$')
130 const char *variable_start;
131 const char *variable_end;
132 unsigned short int valid;
133 char c;
135 if (*string == '{')
136 string++;
138 variable_start = string;
139 c = *string;
140 if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || c == '_')
143 c = *++string;
144 while ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')
145 || (c >= '0' && c <= '9') || c == '_');
146 variable_end = string;
148 if (variable_start[-1] == '{')
150 if (*string == '}')
152 string++;
153 valid = 1;
155 else
156 valid = 0;
158 else
159 valid = 1;
161 if (valid)
162 callback (variable_start, variable_end - variable_start);
168 /* Print a variable to stdout, followed by a newline. */
169 static void
170 print_variable (const char *var_ptr, size_t var_len)
172 fwrite (var_ptr, var_len, 1, stdout);
173 putchar ('\n');
176 /* Print the variables contained in STRING to stdout, each one followed by a
177 newline. */
178 static void
179 print_variables (const char *string)
181 find_variables (string, &print_variable);
185 /* Type describing list of immutable strings,
186 implemented using a dynamic array. */
187 typedef struct string_list_ty string_list_ty;
188 struct string_list_ty
190 const char **item;
191 size_t nitems;
192 size_t nitems_max;
195 /* Initialize an empty list of strings. */
196 static inline void
197 string_list_init (string_list_ty *slp)
199 slp->item = NULL;
200 slp->nitems = 0;
201 slp->nitems_max = 0;
204 /* Append a single string to the end of a list of strings. */
205 static inline void
206 string_list_append (string_list_ty *slp, const char *s)
208 /* Grow the list. */
209 if (slp->nitems >= slp->nitems_max)
211 size_t nbytes;
213 slp->nitems_max = slp->nitems_max * 2 + 4;
214 nbytes = slp->nitems_max * sizeof (slp->item[0]);
215 slp->item = (const char **) xrealloc (slp->item, nbytes);
218 /* Add the string to the end of the list. */
219 slp->item[slp->nitems++] = s;
222 /* Compare two strings given by reference. */
223 static int
224 cmp_string (const void *pstr1, const void *pstr2)
226 const char *str1 = *(const char **)pstr1;
227 const char *str2 = *(const char **)pstr2;
229 return strcmp (str1, str2);
232 /* Sort a list of strings. */
233 static inline void
234 string_list_sort (string_list_ty *slp)
236 if (slp->nitems > 0)
237 qsort (slp->item, slp->nitems, sizeof (slp->item[0]), cmp_string);
240 /* Test whether a sorted string list contains a given string. */
241 static int
242 sorted_string_list_member (const string_list_ty *slp, const char *s)
244 size_t j1, j2;
246 j1 = 0;
247 j2 = slp->nitems;
248 if (j2 > 0)
250 /* Binary search. */
251 while (j2 - j1 > 1)
253 /* Here we know that if s is in the list, it is at an index j
254 with j1 <= j < j2. */
255 size_t j = (j1 + j2) >> 1;
256 int result = strcmp (slp->item[j], s);
258 if (result > 0)
259 j2 = j;
260 else if (result == 0)
261 return 1;
262 else
263 j1 = j + 1;
265 if (j2 > j1)
266 if (strcmp (slp->item[j1], s) == 0)
267 return 1;
269 return 0;
273 /* Set of variables on which to perform substitution.
274 Used only if !all_variables. */
275 static string_list_ty variables_set;
277 /* Adds a variable to variables_set. */
278 static void
279 note_variable (const char *var_ptr, size_t var_len)
281 char *string = xmemdupz (var_ptr, var_len);
283 string_list_append (&variables_set, string);
286 /* Stores the variables occurring in the string in variables_set. */
287 static void
288 note_variables (const char *string)
290 string_list_init (&variables_set);
291 find_variables (string, &note_variable);
292 string_list_sort (&variables_set);
296 static int
297 do_getc (void)
299 int c = getc (stdin);
301 if (c == EOF)
303 if (ferror (stdin))
304 error ("error while reading standard input");
307 return c;
310 static inline void
311 do_ungetc (int c)
313 if (c != EOF)
314 ungetc (c, stdin);
317 /* Copies stdin to stdout, performing substitutions. */
318 static void
319 subst_from_stdin (void)
321 static char *buffer;
322 static size_t bufmax;
323 static size_t buflen;
324 int c;
326 for (;;)
328 c = do_getc ();
329 if (c == EOF)
330 break;
331 /* Look for $VARIABLE or ${VARIABLE}. */
332 if (c == '$')
334 unsigned short int opening_brace = 0;
335 unsigned short int closing_brace = 0;
337 c = do_getc ();
338 if (c == '{')
340 opening_brace = 1;
341 c = do_getc ();
343 if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || c == '_')
345 unsigned short int valid;
347 /* Accumulate the VARIABLE in buffer. */
348 buflen = 0;
351 if (buflen >= bufmax)
353 bufmax = 2 * bufmax + 10;
354 buffer = xrealloc (buffer, bufmax);
356 buffer[buflen++] = c;
358 c = do_getc ();
360 while ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')
361 || (c >= '0' && c <= '9') || c == '_');
363 if (opening_brace)
365 if (c == '}')
367 closing_brace = 1;
368 valid = 1;
370 else
372 valid = 0;
373 do_ungetc (c);
376 else
378 valid = 1;
379 do_ungetc (c);
382 if (valid)
384 /* Terminate the variable in the buffer. */
385 if (buflen >= bufmax)
387 bufmax = 2 * bufmax + 10;
388 buffer = xrealloc (buffer, bufmax);
390 buffer[buflen] = '\0';
392 /* Test whether the variable shall be substituted. */
393 if (!all_variables
394 && !sorted_string_list_member (&variables_set, buffer))
395 valid = 0;
398 if (valid)
400 /* Substitute the variable's value from the environment. */
401 const char *env_value = getenv (buffer);
403 if (env_value != NULL)
404 fputs (env_value, stdout);
406 else
408 /* Perform no substitution at all. Since the buffered input
409 contains no other '$' than at the start, we can just
410 output all the buffered contents. */
411 putchar ('$');
412 if (opening_brace)
413 putchar ('{');
414 fwrite (buffer, buflen, 1, stdout);
415 if (closing_brace)
416 putchar ('}');
419 else
421 do_ungetc (c);
422 putchar ('$');
423 if (opening_brace)
424 putchar ('{');
427 else
428 putchar (c);