interp_parse.c revision 1.2 
1/*	$NetBSD: interp_parse.c,v 1.2 2006/04/22 07:58:53 cherry Exp $	*/
2
3/*-
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * Jordan K. Hubbard
14 * 29 August 1998
15 *
16 * The meat of the simple parser.
17 */
18
19#include <sys/cdefs.h>
20/* __FBSDID("$FreeBSD: src/sys/boot/common/interp_parse.c,v 1.10 2003/08/25 23:30:41 obrien Exp $"); */
21
22#include <lib/libsa/stand.h>
23#include <lib/libkern/libkern.h>
24
25#include "bootstrap.h"
26
27static void	 clean(void);
28static int	 insert(int *argcp, char *buf);
29static char	*variable_lookup(char *name);
30
31#define PARSE_BUFSIZE	1024	/* maximum size of one element */
32#define MAXARGS		20	/* maximum number of elements */
33static char		*args[MAXARGS];
34
35/*
36 * parse: accept a string of input and "parse" it for backslash
37 * substitutions and environment variable expansions (${var}),
38 * returning an argc/argv style vector of whitespace separated
39 * arguments.  Returns 0 on success, 1 on failure (ok, ok, so I
40 * wimped-out on the error codes! :).
41 *
42 * Note that the argv array returned must be freed by the caller, but
43 * we own the space allocated for arguments and will free that on next
44 * invocation.  This allows argv consumers to modify the array if
45 * required.
46 *
47 * NB: environment variables that expand to more than one whitespace
48 * separated token will be returned as a single argv[] element, not
49 * split in turn.  Expanded text is also immune to further backslash
50 * elimination or expansion since this is a one-pass, non-recursive
51 * parser.  You didn't specify more than this so if you want more, ask
52 * me. - jkh
53 */
54
55#define PARSE_FAIL(expr) \
56if (expr) { \
57    printf("fail at line %d\n", __LINE__); \
58    clean(); \
59    free(copy); \
60    free(buf); \
61    return 1; \
62}
63
64/* Accept the usual delimiters for a variable, returning counterpart */
65static char
66isdelim(int ch)
67{
68    if (ch == '{')
69	return '}';
70    else if (ch == '(')
71	return ')';
72    return '\0';
73}
74
75static int
76isquote(int ch)
77{
78    return (ch == '\'' || ch == '"');
79}
80
81int
82parse(int *argc, char ***argv, char *str)
83{
84    int ac;
85    char *val, *p, *q, *copy = NULL;
86    size_t i = 0;
87    char token, tmp, quote, *buf;
88    enum { STR, VAR, WHITE } state;
89
90    ac = *argc = 0;
91    quote = 0;
92    if (!str || (p = copy = backslash(str)) == NULL)
93	return 1;
94
95    /* Initialize vector and state */
96    clean();
97    state = STR;
98    buf = (char *)alloc(PARSE_BUFSIZE);
99    token = 0;
100
101    /* And awaaaaaaaaay we go! */
102    while (*p) {
103	switch (state) {
104	case STR:
105	    if ((*p == '\\') && p[1]) {
106		p++;
107		PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
108		buf[i++] = *p++;
109	    } else if (isquote(*p)) {
110		quote = quote ? 0 : *p;
111		++p;
112	    }
113	    else if (isspace(*p) && !quote) {
114		state = WHITE;
115		if (i) {
116		    buf[i] = '\0';
117		    PARSE_FAIL(insert(&ac, buf));
118		    i = 0;
119		}
120		++p;
121	    } else if (*p == '$') {
122		token = isdelim(*(p + 1));
123		if (token)
124		    p += 2;
125		else
126		    ++p;
127		state = VAR;
128	    } else {
129		PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
130		buf[i++] = *p++;
131	    }
132	    break;
133
134	case WHITE:
135	    if (isspace(*p))
136		++p;
137	    else
138		state = STR;
139	    break;
140
141	case VAR:
142	    if (token) {
143		PARSE_FAIL((q = strchr(p, token)) == NULL);
144	    } else {
145		q = p;
146		while (*q && !isspace(*q))
147		    ++q;
148	    }
149	    tmp = *q;
150	    *q = '\0';
151	    if ((val = variable_lookup(p)) != NULL) {
152		size_t len = strlen(val);
153
154		strncpy(buf + i, val, PARSE_BUFSIZE - (i + 1));
155		i += min(len, PARSE_BUFSIZE - 1);
156	    }
157	    *q = tmp;	/* restore value */
158	    p = q + (token ? 1 : 0);
159	    state = STR;
160	    break;
161	}
162    }
163    /* If at end of token, add it */
164    if (i && state == STR) {
165	buf[i] = '\0';
166	PARSE_FAIL(insert(&ac, buf));
167    }
168    args[ac] = NULL;
169    *argc = ac;
170    *argv = (char **)alloc((sizeof(char *) * ac + 1));
171    bcopy(args, *argv, sizeof(char *) * ac + 1);
172    free(buf);
173    free(copy);
174    return 0;
175}
176
177#define MAXARGS	20
178
179/* Clean vector space */
180static void
181clean(void)
182{
183    int		i;
184
185    for (i = 0; i < MAXARGS; i++) {
186	if (args[i] != NULL) {
187	    free(args[i]);
188	    args[i] = NULL;
189	}
190    }
191}
192
193static int
194insert(int *argcp, char *buf)
195{
196    if (*argcp >= MAXARGS)
197	return 1;
198    args[(*argcp)++] = strdup(buf);
199    return 0;
200}
201
202static char *
203variable_lookup(char *name)
204{
205    /* XXX search "special variable" space first? */
206    return (char *)getenv(name);
207}
208