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 == '\'' || ch == '"');
76 }
77
78 int
79 parse(int *argc, char ***argv, char *str)
80 {
81 int ac;
82 char *val, *p, *q, *copy = NULL;
83 size_t i = 0;
84 char token, tmp, quote, *buf;
85 enum { STR, VAR, WHITE } state;
86
87 ac = *argc = 0;
88 quote = 0;
89 if (!str || (p = copy = backslash(str)) == NULL)
90 return 1;
91
92 /* Initialize vector and state */
93 clean();
94 state = STR;
95 buf = (char *)malloc(PARSE_BUFSIZE);
96 token = 0;
97
98 /* And awaaaaaaaaay we go! */
99 while (*p) {
100 switch (state) {
101 case STR:
102 if ((*p == '\\') && p[1]) {
103 p++;
104 PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
105 buf[i++] = *p++;
106 } else if (isquote(*p)) {
107 quote = quote ? 0 : *p;
108 ++p;
109 }
110 else if (isspace(*p) && !quote) {
111 state = WHITE;
112 if (i) {
113 buf[i] = '\0';
114 PARSE_FAIL(insert(&ac, buf));
115 i = 0;
116 }
117 ++p;
118 } else if (*p == '$') {
119 token = isdelim(*(p + 1));
120 if (token)
121 p += 2;
122 else
123 ++p;
124 state = VAR;
125 } else {
126 PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
127 buf[i++] = *p++;
128 }
129 break;
130
131 case WHITE:
132 if (isspace(*p))
133 ++p;
134 else
135 state = STR;
136 break;
137
138 case VAR:
139 if (token) {
140 PARSE_FAIL((q = index(p, token)) == NULL);
141 } else {
142 q = p;
143 while (*q && !isspace(*q))
144 ++q;
145 }
146 tmp = *q;
147 *q = '\0';
148 if ((val = variable_lookup(p)) != NULL) {
149 size_t len = strlen(val);
150
151 strncpy(buf + i, val, PARSE_BUFSIZE - (i + 1));
152 i += min(len, PARSE_BUFSIZE - 1);
153 }
154 *q = tmp; /* restore value */
155 p = q + (token ? 1 : 0);
156 state = STR;
157 break;
158 }
159 }
160 /* If at end of token, add it */
161 if (i && state == STR) {
162 buf[i] = '\0';
163 PARSE_FAIL(insert(&ac, buf));
164 }
165 args[ac] = NULL;
166 *argc = ac;
167 *argv = (char **)malloc((sizeof(char *) * ac + 1));
168 bcopy(args, *argv, sizeof(char *) * ac + 1);
169 free(buf);
170 free(copy);
171 return 0;
172 }
173
174 #define MAXARGS 20
175
176 /* Clean vector space */
177 static void
178 clean(void)
179 {
180 int i;
181
182 for (i = 0; i < MAXARGS; i++) {
183 if (args[i] != NULL) {
184 free(args[i]);
185 args[i] = NULL;
186 }
187 }
188 }
189
190 static int
191 insert(int *argcp, char *buf)
192 {
193 if (*argcp >= MAXARGS)
194 return 1;
195 args[(*argcp)++] = strdup(buf);
196 return 0;
197 }
198
199 static char *
200 variable_lookup(char *name)
201 {
202 /* XXX search "special variable" space first? */
203 return (char *)getenv(name);
204 }
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