3 * $Id: sw_env.c,v 1.3 2004/04/08 01:52:19 mdw Exp $
5 * Mangling of environment variables
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of sw-tools.
14 * sw-tools is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License as published by
16 * the Free Software Foundation; either version 2 of the License, or
17 * (at your option) any later version.
19 * sw-tools is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU General Public License for more details.
24 * You should have received a copy of the GNU General Public License
25 * along with sw-tools; if not, write to the Free Software Foundation,
26 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
29 /*----- Header files ------------------------------------------------------*/
43 extern char **environ
;
46 #include <mLib/alloc.h>
47 #include <mLib/dstr.h>
49 #include <mLib/report.h>
54 /*----- Main code ---------------------------------------------------------*/
56 /* --- @env_error@ --- *
58 * Arguments: @int e@ = error code
60 * Returns: String representation of error.
62 * Use: Transforms an error into something a user can understand.
65 const char *env_error(int e
)
69 "Unexpected end-of-file",
70 "Bad character in variable name",
71 "Bad parameter substitution",
73 "Missing or spurious `}'",
78 return (strerror(errno
));
85 * Arguments: @FILE *fp@ = stream to read from
87 * Returns: Next nonwhitespace character.
89 * Use: Advances the file position past whitespace characters, and
90 * returns the following nonwhitespace character. The character
94 static int peek(FILE *fp
)
102 } while (isspace((unsigned char)ch
));
107 /* --- @env_var@ --- *
109 * Arguments: @sym_table *t@ = pointer to symbol table
110 * @FILE *fp@ = pointer to stream to read from
111 * @dstr *d@ = pointer to output variable
113 * Returns: One of the @ENV_@ constants.
115 * Use: Scans a variable name from the input stream.
118 int env_var(sym_table
*t
, FILE *fp
, dstr
*d
)
124 if (ch
!= '_' && !isalpha((unsigned char)ch
))
129 if (ch
== EOF
|| (ch
!= '_' && !isalnum((unsigned char)ch
)))
137 /* --- @cmdsubst@ --- *
139 * Arguments: @sym_table *t@ = pointer to symbol table
140 * @FILE *fp@ = pointer to stream to read from
141 * @dstr *d@ = pointer to output variable
142 * @unsigned f@ = interesting flags
144 * Returns: An @ENV_@ magic code.
146 * Use: Rips a command line out of the input stream and writes the
147 * output of the command to the variable. The parsing has some
148 * bizarre artifacts, but it's fairly serviceable.
151 static int cmdsubst(sym_table
*t
, FILE *fp
, dstr
*d
, unsigned f
)
153 int term
= (f
& EVF_BACKTICK
) ?
'`' : ')';
161 /* --- Snarfle the arguments --- */
164 while (peek(fp
) != term
) {
165 if ((e
= env_value(t
, fp
, d
, f
)) != ENV_OK
)
176 /* --- Make the @argv@ array --- */
179 char *p
= d
->buf
+ l
;
180 char *lim
= d
->buf
+ d
->len
;
183 v
= argv
= xmalloc(argc
* sizeof(char *));
197 /* --- Do the fork/exec thing --- */
201 if ((kid
= fork()) < 0)
210 environ
= env_export(t
);
211 execvp(argv
[0], argv
);
219 ssize_t n
= read(fd
[0], buf
, sizeof(buf
));
227 while (l
> 0 && d
->buf
[l
- 1] == '\n')
241 /* --- @env_value@ --- *
243 * Arguments: @sym_table *t@ = pointer to symbol table
244 * @FILE *fp@ = pointer to stream to read from
245 * @dstr *d@ = pointer to output variable
246 * @unsigned f@ = various interesting flags
248 * Returns: 0 if OK, @EOF@ if end-of-file encountered, or >0 on error.
250 * Use: Scans a value from the input stream. The value read may be
251 * quoted in a Bourne-shell sort of a way, and contain Bourne-
252 * shell-like parameter substitutions. Some substitutions
253 * aren't available because they're too awkward to implement.
256 int env_value(sym_table
*t
, FILE *fp
, dstr
*d
, unsigned f
)
258 enum { Q_NONE
, Q_SINGLE
, Q_DOUBLE
, Q_BACK
} qt
= Q_NONE
;
265 } while ((f
& EVF_INITSPC
) && isspace((unsigned char)ch
));
267 for (;; ch
= getc(fp
)) {
269 /* --- Sort out the current character --- */
271 if (ch
== EOF
) break;
273 /* --- A backslash escapes the next character --- */
276 if ((ch
= getc(fp
)) == EOF
) break;
282 /* --- A single quote starts single-quoting, unless quoted --- *
284 * Do the single-quoted snarf here rather than fiddling with anything
288 if (ch
== '\'' && qt
== Q_NONE
) {
291 if ((ch
= getc(fp
)) == EOF
) goto done
;
292 if (ch
== '\'') break;
299 /* --- A backtick does the obvious thing --- */
301 if (ch
== '`' && !(f
& EVF_BACKTICK
)) {
303 if ((e
= cmdsubst(t
, fp
, d
, f
| EVF_BACKTICK
)) != ENV_OK
)
308 /* --- Handle double-quoted text --- */
313 else if (qt
== Q_NONE
)
316 return (ENV_INTERNAL
);
320 /* --- Handle variable references and similar magic --- */
328 /* --- Read one character ahead --- */
330 if ((ch
= getc(fp
)) == EOF
) goto done
;
332 /* --- An alphabetic means this is a direct reference --- */
334 if (ch
== '_' || isalpha(ch
)) {
336 if ((e
= env_var(t
, fp
, d
)) != ENV_OK
) return (e
);
338 if ((v
= env_get(t
, d
->buf
+ l
)) != 0)
342 /* --- A brace means this is a more complex substitution --- */
344 else if (ch
== '{') {
345 if ((e
= env_var(t
, fp
, d
)) != ENV_OK
)
348 v
= env_get(t
, d
->buf
+ l
);
366 goto again
; /* `::' and `:}' should be errors */
373 /* Drop through hackily */
380 if ((e
= env_value(t
, fp
, d
, EVF_INCSPC
)) != ENV_OK
)
390 if ((e
= env_value(t
, fp
, d
, EVF_INCSPC
)) != ENV_OK
)
394 vn
= xstrdup(d
->buf
+ l
);
395 if ((e
= env_value(t
, fp
, d
, EVF_INCSPC
)) != ENV_OK
)
398 env_put(t
, vn
, d
->buf
+ l
);
410 /* --- Handle `$(...)'-style command substitution --- */
412 else if (ch
== '(') {
413 if ((e
= cmdsubst(t
, fp
, d
, f
& ~EVF_BACKTICK
)) != ENV_OK
)
417 /* --- No other `$...' tricks implemented yet --- *
419 * Other ideas: `$((...))' arithmetic.
427 /* --- At this point, anything else double-quoted is munched --- */
429 if (qt
== Q_DOUBLE
) {
434 /* --- Some characters just aren't allowed unquoted --- *
436 * They're not an error; they just mean I should stop parsing. They're
437 * probably interesting to the next level up.
447 if (f
& EVF_BACKTICK
) {
454 /* --- Whitespace characters --- *
456 * I might snarf them myself anyway, according to flags. Or I might
457 * stop, and skip any following whitespace
460 if (isspace((unsigned char)ch
) && (f
& EVF_INCSPC
) == 0) {
463 while (ch
!= EOF
&& isspace((unsigned char)ch
));
468 /* --- Get a new character and go around again --- */
473 /* --- Tidying --- */
477 return (qt
== Q_NONE ? ENV_OK
: ENV_QUOTE
);
480 /* --- @env_read@ --- *
482 * Arguments: @sym_table *t@ = pointer to symbol table
483 * @FILE *fp@ = file handle to read
484 * @unsigned f@ = various flags
486 * Returns: Zero if OK, @EOF@ for end-of-file, or error code.
488 * Use: Reads the environment assignment statements in the file.
491 int env_read(sym_table
*t
, FILE *fp
, unsigned f
)
493 dstr n
= DSTR_INIT
, v
= DSTR_INIT
;
502 if ((e
= env_value(t
, fp
, &v
, f
)) != ENV_OK
)
507 do ch
= getc(fp
); while (ch
!= EOF
&& ch
!= '\n');
509 else if (peek(fp
) == '}' ||
510 (e
= env_var(t
, fp
, &n
)) != ENV_OK
)
513 else if (strcmp(n
.buf
, "include") == 0) {
515 if ((e
= env_value(t
, fp
, &v
, f
)) != ENV_OK
)
521 else if (strcmp(n
.buf
, "arch") == 0) {
523 if ((e
= env_value(t
, fp
, &v
, f
)) != ENV_OK
)
525 if (peek(fp
) != '{') {
530 e
= env_read(t
, fp
, strcmp(v
.buf
, ARCH
) ? f
| EVF_SKIP
: f
);
533 if (getc(fp
) != '}') {
539 else if (strcmp(n
.buf
, "unset") == 0) {
541 if ((e
= env_var(t
, fp
, &v
)) != ENV_OK
)
543 env_put(t
, v
.buf
, 0);
547 if (strcmp(n
.buf
, "set") == 0) {
550 if ((e
= env_var(t
, fp
, &n
)) != ENV_OK
)
553 if (peek(fp
) == '=') {
557 if ((e
= env_value(t
, fp
, &v
, f
)) != ENV_OK
)
561 env_put(t
, n
.buf
, v
.buf
);
576 /* --- @env_file@ --- *
578 * Arguments: @sym_table *t@ = pointer to symbol table
579 * @const char *name@ = pointer to filename
581 * Returns: Zero if OK, or an error code.
583 * Use: Reads a named file of environment assignments.
586 int env_file(sym_table
*t
, const char *name
)
591 if ((fp
= fopen(name
, "r")) == 0)
593 e
= env_read(t
, fp
, 0);
597 else if (e
== ENV_OK
)
602 /*----- That's all, folks -------------------------------------------------*/