1 /*++
2 /* NAME
3 /* mac_parse 3
4 /* SUMMARY
5 /* locate macro references in string
6 /* SYNOPSIS
7 /* #include <mac_parse.h>
8 /*
9 /* int mac_parse(string, action, context)
10 /* const char *string;
11 /* int (*action)(int type, VSTRING *buf, void *context);
12 /* DESCRIPTION
13 /* This module recognizes macro expressions in null-terminated
14 /* strings. Macro expressions have the form $name, $(text) or
15 /* ${text}. A macro name consists of alphanumerics and/or
16 /* underscore. Text other than macro expressions is treated
17 /* as literal text.
18 /*
19 /* mac_parse() breaks up its string argument into macro references
20 /* and other text, and invokes the \fIaction\fR routine for each item
21 /* found. With each action routine call, the \fItype\fR argument
22 /* indicates what was found, \fIbuf\fR contains a copy of the text
23 /* found, and \fIcontext\fR is passed on unmodified from the caller.
24 /* The application is at liberty to clobber \fIbuf\fR.
25 /* .IP MAC_PARSE_LITERAL
26 /* The content of \fIbuf\fR is literal text.
27 /* .IP MAC_PARSE_EXPR
28 /* The content of \fIbuf\fR is a macro expression: either a
29 /* bare macro name without the preceding "$", or all the text
30 /* inside $() or ${}.
31 /* .PP
32 /* The action routine result value is the bit-wise OR of zero or more
33 /* of the following:
34 /* .IP MAC_PARSE_ERROR
35 /* A parsing error was detected.
36 /* .IP MAC_PARSE_UNDEF
37 /* A macro was expanded but not defined.
38 /* .PP
39 /* Use the constant MAC_PARSE_OK when no error was detected.
40 /* SEE ALSO
41 /* dict(3) dictionary interface.
42 /* DIAGNOSTICS
43 /* Fatal errors: out of memory. malformed macro name.
44 /*
45 /* The result value is the bit-wise OR of zero or more of the
46 /* following:
47 /* .IP MAC_PARSE_ERROR
48 /* A parsing error was detected.
49 /* .IP MAC_PARSE_UNDEF
50 /* A macro was expanded but not defined.
51 /* LICENSE
52 /* .ad
53 /* .fi
54 /* The Secure Mailer license must be distributed with this software.
55 /* AUTHOR(S)
56 /* Wietse Venema
57 /* IBM T.J. Watson Research
58 /* P.O. Box 704
59 /* Yorktown Heights, NY 10598, USA
60 /*--*/
61
62 /* System library. */
63
64 #include <sys_defs.h>
65 #include <ctype.h>
66
67 /* Utility library. */
68
69 #include <msg.h>
70 #include <mac_parse.h>
71
72 /*
73 * Helper macro for consistency. Null-terminate the temporary buffer,
74 * execute the action, and reset the temporary buffer for re-use.
75 */
76 #define MAC_PARSE_ACTION(status, type, buf, context) \
77 do { \
78 VSTRING_TERMINATE(buf); \
79 status |= action((type), (buf), (context)); \
80 VSTRING_RESET(buf); \
81 } while(0)
82
83 /* mac_parse - split string into literal text and macro references */
84
mac_parse(const char * value,MAC_PARSE_FN action,void * context)85 int mac_parse(const char *value, MAC_PARSE_FN action, void *context)
86 {
87 const char *myname = "mac_parse";
88 VSTRING *buf = vstring_alloc(1); /* result buffer */
89 const char *vp; /* value pointer */
90 const char *pp; /* open_paren pointer */
91 const char *ep; /* string end pointer */
92 static char open_paren[] = "({";
93 static char close_paren[] = ")}";
94 int level;
95 int status = 0;
96
97 #define SKIP(start, var, cond) do { \
98 for (var = start; *var && (cond); var++) \
99 /* void */; \
100 } while (0)
101
102 if (msg_verbose > 1)
103 msg_info("%s: %s", myname, value);
104
105 for (vp = value; *vp;) {
106 if (*vp != '$') { /* ordinary character */
107 VSTRING_ADDCH(buf, *vp);
108 vp += 1;
109 } else if (vp[1] == '$') { /* $$ becomes $ */
110 VSTRING_ADDCH(buf, *vp);
111 vp += 2;
112 } else { /* found bare $ */
113 if (VSTRING_LEN(buf) > 0)
114 MAC_PARSE_ACTION(status, MAC_PARSE_LITERAL, buf, context);
115 vp += 1;
116 pp = open_paren;
117 if (*vp == *pp || *vp == *++pp) { /* ${x} or $(x) */
118 level = 1;
119 vp += 1;
120 for (ep = vp; level > 0; ep++) {
121 if (*ep == 0) {
122 msg_warn("truncated macro reference: \"%s\"", value);
123 status |= MAC_PARSE_ERROR;
124 break;
125 }
126 if (*ep == *pp)
127 level++;
128 if (*ep == close_paren[pp - open_paren])
129 level--;
130 }
131 if (status & MAC_PARSE_ERROR)
132 break;
133 vstring_strncat(buf, vp, level > 0 ? ep - vp : ep - vp - 1);
134 vp = ep;
135 } else { /* plain $x */
136 SKIP(vp, ep, ISALNUM(*ep) || *ep == '_');
137 vstring_strncat(buf, vp, ep - vp);
138 vp = ep;
139 }
140 if (VSTRING_LEN(buf) == 0) {
141 status |= MAC_PARSE_ERROR;
142 msg_warn("empty macro name: \"%s\"", value);
143 break;
144 }
145 MAC_PARSE_ACTION(status, MAC_PARSE_EXPR, buf, context);
146 }
147 }
148 if (VSTRING_LEN(buf) > 0 && (status & MAC_PARSE_ERROR) == 0)
149 MAC_PARSE_ACTION(status, MAC_PARSE_LITERAL, buf, context);
150
151 /*
152 * Cleanup.
153 */
154 vstring_free(buf);
155
156 return (status);
157 }
158
159 #ifdef TEST
160
161 /*
162 * Proof-of-concept test program. Read strings from stdin, print parsed
163 * result to stdout.
164 */
165 #include <vstring_vstream.h>
166
167 /* mac_parse_print - print parse tree */
168
mac_parse_print(int type,VSTRING * buf,void * unused_context)169 static int mac_parse_print(int type, VSTRING *buf, void *unused_context)
170 {
171 char *type_name;
172
173 switch (type) {
174 case MAC_PARSE_EXPR:
175 type_name = "MAC_PARSE_EXPR";
176 break;
177 case MAC_PARSE_LITERAL:
178 type_name = "MAC_PARSE_LITERAL";
179 break;
180 default:
181 msg_panic("unknown token type %d", type);
182 }
183 vstream_printf("%s \"%s\"\n", type_name, vstring_str(buf));
184 return (0);
185 }
186
main(int unused_argc,char ** unused_argv)187 int main(int unused_argc, char **unused_argv)
188 {
189 VSTRING *buf = vstring_alloc(1);
190
191 while (vstring_fgets_nonl(buf, VSTREAM_IN)) {
192 mac_parse(vstring_str(buf), mac_parse_print, (void *) 0);
193 vstream_fflush(VSTREAM_OUT);
194 }
195 vstring_free(buf);
196 return (0);
197 }
198
199 #endif
200