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 #include <stand.h>
19 #include <string.h>
20 #include "bootstrap.h"
21
22 static void clean(void);
23 static int insert(int *argcp, char *buf);
24 static char *variable_lookup(char *name);
25
26 #define PARSE_BUFSIZE 1024 /* maximum size of one element */
27 #define MAXARGS 20 /* maximum number of elements */
28 static char *args[MAXARGS];
29
30 /*
31 * parse: accept a string of input and "parse" it for backslash
32 * substitutions and environment variable expansions (${var}),
33 * returning an argc/argv style vector of whitespace separated
34 * arguments. Returns 0 on success, 1 on failure (ok, ok, so I
35 * wimped-out on the error codes! :).
36 *
37 * Note that the argv array returned must be freed by the caller, but
38 * we own the space allocated for arguments and will free that on next
39 * invocation. This allows argv consumers to modify the array if
40 * required.
41 *
42 * NB: environment variables that expand to more than one whitespace
43 * separated token will be returned as a single argv[] element, not
44 * split in turn. Expanded text is also immune to further backslash
45 * elimination or expansion since this is a one-pass, non-recursive
46 * parser. You didn't specify more than this so if you want more, ask
47 * me. - jkh
48 */
49
50 #define PARSE_FAIL(expr) \
51 if (expr) { \
52 printf("fail at line %d\n", __LINE__); \
53 clean(); \
54 free(copy); \
55 free(buf); \
56 return 1; \
57 }
58
59 /* Accept the usual delimiters for a variable, returning counterpart */
60 static char
isdelim(int ch)61 isdelim(int ch)
62 {
63
64 if (ch == '{')
65 return '}';
66 else if (ch == '(')
67 return ')';
68 return '\0';
69 }
70
71 static int
isquote(int ch)72 isquote(int ch)
73 {
74
75 return (ch == '\'');
76 }
77
78 static int
isdquote(int ch)79 isdquote(int ch)
80 {
81
82 return (ch == '"');
83 }
84
85 int
parse(int * argc,char *** argv,const char * str)86 parse(int *argc, char ***argv, const char *str)
87 {
88 int ac;
89 char *val, *p, *q, *copy = NULL;
90 size_t i = 0;
91 char token, tmp, quote, dquote, *buf;
92 enum { STR, VAR, WHITE } state;
93
94 ac = *argc = 0;
95 dquote = quote = 0;
96 if (!str || (p = copy = backslash(str)) == NULL)
97 return 1;
98
99 /* Initialize vector and state */
100 clean();
101 state = STR;
102 buf = (char *)malloc(PARSE_BUFSIZE);
103 token = 0;
104
105 /* And awaaaaaaaaay we go! */
106 while (*p) {
107 switch (state) {
108 case STR:
109 if ((*p == '\\') && p[1]) {
110 p++;
111 PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
112 buf[i++] = *p++;
113 } else if (isquote(*p)) {
114 quote = quote ? 0 : *p;
115 if (dquote) { /* keep quote */
116 PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
117 buf[i++] = *p++;
118 } else
119 ++p;
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 } else if (isspace(*p) && !quote && !dquote) {
128 state = WHITE;
129 if (i) {
130 buf[i] = '\0';
131 PARSE_FAIL(insert(&ac, buf));
132 i = 0;
133 }
134 ++p;
135 } else if (*p == '$' && !quote) {
136 token = isdelim(*(p + 1));
137 if (token)
138 p += 2;
139 else
140 ++p;
141 state = VAR;
142 } else {
143 PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
144 buf[i++] = *p++;
145 }
146 break;
147
148 case WHITE:
149 if (isspace(*p))
150 ++p;
151 else
152 state = STR;
153 break;
154
155 case VAR:
156 if (token) {
157 PARSE_FAIL((q = strchr(p, token)) == NULL);
158 } else {
159 q = p;
160 while (*q && !isspace(*q))
161 ++q;
162 }
163 tmp = *q;
164 *q = '\0';
165 if ((val = variable_lookup(p)) != NULL) {
166 size_t len = strlen(val);
167
168 strncpy(buf + i, val, PARSE_BUFSIZE - (i + 1));
169 i += min(len, PARSE_BUFSIZE - 1);
170 }
171 *q = tmp; /* restore value */
172 p = q + (token ? 1 : 0);
173 state = STR;
174 break;
175 }
176 }
177 /* missing terminating ' or " */
178 PARSE_FAIL(quote || dquote);
179 /* If at end of token, add it */
180 if (i && state == STR) {
181 buf[i] = '\0';
182 PARSE_FAIL(insert(&ac, buf));
183 }
184 args[ac] = NULL;
185 *argc = ac;
186 *argv = (char **)malloc((sizeof(char *) * ac + 1));
187 bcopy(args, *argv, sizeof(char *) * ac + 1);
188 free(buf);
189 free(copy);
190 return 0;
191 }
192
193 #define MAXARGS 20
194
195 /* Clean vector space */
196 static void
clean(void)197 clean(void)
198 {
199 int i;
200
201 for (i = 0; i < MAXARGS; i++) {
202 if (args[i] != NULL) {
203 free(args[i]);
204 args[i] = NULL;
205 }
206 }
207 }
208
209 static int
insert(int * argcp,char * buf)210 insert(int *argcp, char *buf)
211 {
212
213 if (*argcp >= MAXARGS)
214 return 1;
215 args[(*argcp)++] = strdup(buf);
216 return 0;
217 }
218
219 static char *
variable_lookup(char * name)220 variable_lookup(char *name)
221 {
222
223 /* XXX search "special variable" space first? */
224 return (char *)getenv(name);
225 }
226