xref: /titanic_52/usr/src/boot/sys/boot/common/interp_parse.c (revision 4a5d661a82b942b6538acd26209d959ce98b593a)
1 /*-
2  * Redistribution and use in source and binary forms, with or without
3  * modification, are permitted provided that the following conditions
4  * are met:
5  * 1. Redistributions of source code must retain the above copyright
6  *    notice, this list of conditions and the following disclaimer.
7  * 2. Redistributions in binary form must reproduce the above copyright
8  *    notice, this list of conditions and the following disclaimer in the
9  *    documentation and/or other materials provided with the distribution.
10  *
11  * Jordan K. Hubbard
12  * 29 August 1998
13  *
14  * The meat of the simple parser.
15  */
16 
17 #include <sys/cdefs.h>
18 __FBSDID("$FreeBSD$");
19 
20 #include <stand.h>
21 #include <string.h>
22 #include "bootstrap.h"
23 
24 static void	 clean(void);
25 static int	 insert(int *argcp, char *buf);
26 static char	*variable_lookup(char *name);
27 
28 #define PARSE_BUFSIZE	1024	/* maximum size of one element */
29 #define MAXARGS		20	/* maximum number of elements */
30 static char		*args[MAXARGS];
31 
32 /*
33  * parse: accept a string of input and "parse" it for backslash
34  * substitutions and environment variable expansions (${var}),
35  * returning an argc/argv style vector of whitespace separated
36  * arguments.  Returns 0 on success, 1 on failure (ok, ok, so I
37  * wimped-out on the error codes! :).
38  *
39  * Note that the argv array returned must be freed by the caller, but
40  * we own the space allocated for arguments and will free that on next
41  * invocation.  This allows argv consumers to modify the array if
42  * required.
43  *
44  * NB: environment variables that expand to more than one whitespace
45  * separated token will be returned as a single argv[] element, not
46  * split in turn.  Expanded text is also immune to further backslash
47  * elimination or expansion since this is a one-pass, non-recursive
48  * parser.  You didn't specify more than this so if you want more, ask
49  * me. - jkh
50  */
51 
52 #define PARSE_FAIL(expr) \
53 if (expr) { \
54     printf("fail at line %d\n", __LINE__); \
55     clean(); \
56     free(copy); \
57     free(buf); \
58     return 1; \
59 }
60 
61 /* Accept the usual delimiters for a variable, returning counterpart */
62 static char
63 isdelim(int ch)
64 {
65     if (ch == '{')
66 	return '}';
67     else if (ch == '(')
68 	return ')';
69     return '\0';
70 }
71 
72 static int
73 isquote(int ch)
74 {
75     return (ch == '\'');
76 }
77 
78 static int
79 isdquote(int ch)
80 {
81     return (ch == '"');
82 }
83 
84 int
85 parse(int *argc, char ***argv, char *str)
86 {
87     int ac;
88     char *val, *p, *q, *copy = NULL;
89     size_t i = 0;
90     char token, tmp, quote, dquote, *buf;
91     enum { STR, VAR, WHITE } state;
92 
93     ac = *argc = 0;
94     dquote = quote = 0;
95     if (!str || (p = copy = backslash(str)) == NULL)
96 	return 1;
97 
98     /* Initialize vector and state */
99     clean();
100     state = STR;
101     buf = (char *)malloc(PARSE_BUFSIZE);
102     token = 0;
103 
104     /* And awaaaaaaaaay we go! */
105     while (*p) {
106 	switch (state) {
107 	case STR:
108 	    if ((*p == '\\') && p[1]) {
109 		p++;
110 		PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
111 		buf[i++] = *p++;
112 	    } else if (isquote(*p)) {
113 		quote = quote ? 0 : *p;
114 		if (dquote) { /* keep quote */
115 			PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
116 			buf[i++] = *p++;
117 		} else {
118 			++p;
119 		}
120 	    } else if (isdquote(*p)) {
121 		dquote = dquote ? 0 : *p;
122 		if (quote) { /* keep dquote */
123 			PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
124 			buf[i++] = *p++;
125 		} else {
126 			++p;
127 		}
128 	    } else if (isspace(*p) && !quote && !dquote) {
129 		state = WHITE;
130 		if (i) {
131 		    buf[i] = '\0';
132 		    PARSE_FAIL(insert(&ac, buf));
133 		    i = 0;
134 		}
135 		++p;
136 	    } else if (*p == '$' && !quote) {
137 		token = isdelim(*(p + 1));
138 		if (token)
139 		    p += 2;
140 		else
141 		    ++p;
142 		state = VAR;
143 	    } else {
144 		PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
145 		buf[i++] = *p++;
146 	    }
147 	    break;
148 
149 	case WHITE:
150 	    if (isspace(*p))
151 		++p;
152 	    else
153 		state = STR;
154 	    break;
155 
156 	case VAR:
157 	    if (token) {
158 		PARSE_FAIL((q = strchr(p, token)) == NULL);
159 	    } else {
160 		q = p;
161 		while (*q && !isspace(*q))
162 		    ++q;
163 	    }
164 	    tmp = *q;
165 	    *q = '\0';
166 	    if ((val = variable_lookup(p)) != NULL) {
167 		size_t len = strlen(val);
168 
169 		strncpy(buf + i, val, PARSE_BUFSIZE - (i + 1));
170 		i += min(len, PARSE_BUFSIZE - 1);
171 	    }
172 	    *q = tmp;	/* restore value */
173 	    p = q + (token ? 1 : 0);
174 	    state = STR;
175 	    break;
176 	}
177     }
178     /* missing terminating ' or " */
179     PARSE_FAIL(quote || dquote);
180     /* If at end of token, add it */
181     if (i && state == STR) {
182 	buf[i] = '\0';
183 	PARSE_FAIL(insert(&ac, buf));
184     }
185     args[ac] = NULL;
186     *argc = ac;
187     *argv = (char **)malloc((sizeof(char *) * ac + 1));
188     bcopy(args, *argv, sizeof(char *) * ac + 1);
189     free(buf);
190     free(copy);
191     return 0;
192 }
193 
194 #define MAXARGS	20
195 
196 /* Clean vector space */
197 static void
198 clean(void)
199 {
200     int		i;
201 
202     for (i = 0; i < MAXARGS; i++) {
203 	if (args[i] != NULL) {
204 	    free(args[i]);
205 	    args[i] = NULL;
206 	}
207     }
208 }
209 
210 static int
211 insert(int *argcp, char *buf)
212 {
213     if (*argcp >= MAXARGS)
214 	return 1;
215     args[(*argcp)++] = strdup(buf);
216     return 0;
217 }
218 
219 static char *
220 variable_lookup(char *name)
221 {
222     /* XXX search "special variable" space first? */
223     return (char *)getenv(name);
224 }
225