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