1 /* $NetBSD: mac_parse.c,v 1.2 2017/02/14 01:16:49 christos Exp $ */ 2 3 /*++ 4 /* NAME 5 /* mac_parse 3 6 /* SUMMARY 7 /* locate macro references in string 8 /* SYNOPSIS 9 /* #include <mac_parse.h> 10 /* 11 /* int mac_parse(string, action, context) 12 /* const char *string; 13 /* int (*action)(int type, VSTRING *buf, void *context); 14 /* DESCRIPTION 15 /* This module recognizes macro expressions in null-terminated 16 /* strings. Macro expressions have the form $name, $(text) or 17 /* ${text}. A macro name consists of alphanumerics and/or 18 /* underscore. Text other than macro expressions is treated 19 /* as literal text. 20 /* 21 /* mac_parse() breaks up its string argument into macro references 22 /* and other text, and invokes the \fIaction\fR routine for each item 23 /* found. With each action routine call, the \fItype\fR argument 24 /* indicates what was found, \fIbuf\fR contains a copy of the text 25 /* found, and \fIcontext\fR is passed on unmodified from the caller. 26 /* The application is at liberty to clobber \fIbuf\fR. 27 /* .IP MAC_PARSE_LITERAL 28 /* The content of \fIbuf\fR is literal text. 29 /* .IP MAC_PARSE_EXPR 30 /* The content of \fIbuf\fR is a macro expression: either a 31 /* bare macro name without the preceding "$", or all the text 32 /* inside $() or ${}. 33 /* .PP 34 /* The action routine result value is the bit-wise OR of zero or more 35 /* of the following: 36 /* .IP MAC_PARSE_ERROR 37 /* A parsing error was detected. 38 /* .IP MAC_PARSE_UNDEF 39 /* A macro was expanded but not defined. 40 /* .PP 41 /* Use the constant MAC_PARSE_OK when no error was detected. 42 /* SEE ALSO 43 /* dict(3) dictionary interface. 44 /* DIAGNOSTICS 45 /* Fatal errors: out of memory. malformed macro name. 46 /* 47 /* The result value is the bit-wise OR of zero or more of the 48 /* following: 49 /* .IP MAC_PARSE_ERROR 50 /* A parsing error was detected. 51 /* .IP MAC_PARSE_UNDEF 52 /* A macro was expanded but not defined. 53 /* LICENSE 54 /* .ad 55 /* .fi 56 /* The Secure Mailer license must be distributed with this software. 57 /* AUTHOR(S) 58 /* Wietse Venema 59 /* IBM T.J. Watson Research 60 /* P.O. Box 704 61 /* Yorktown Heights, NY 10598, USA 62 /*--*/ 63 64 /* System library. */ 65 66 #include <sys_defs.h> 67 #include <ctype.h> 68 69 /* Utility library. */ 70 71 #include <msg.h> 72 #include <mac_parse.h> 73 74 /* 75 * Helper macro for consistency. Null-terminate the temporary buffer, 76 * execute the action, and reset the temporary buffer for re-use. 77 */ 78 #define MAC_PARSE_ACTION(status, type, buf, context) \ 79 do { \ 80 VSTRING_TERMINATE(buf); \ 81 status |= action((type), (buf), (context)); \ 82 VSTRING_RESET(buf); \ 83 } while(0) 84 85 /* mac_parse - split string into literal text and macro references */ 86 87 int mac_parse(const char *value, MAC_PARSE_FN action, void *context) 88 { 89 const char *myname = "mac_parse"; 90 VSTRING *buf = vstring_alloc(1); /* result buffer */ 91 const char *vp; /* value pointer */ 92 const char *pp; /* open_paren pointer */ 93 const char *ep; /* string end pointer */ 94 static char open_paren[] = "({"; 95 static char close_paren[] = ")}"; 96 int level; 97 int status = 0; 98 99 #define SKIP(start, var, cond) do { \ 100 for (var = start; *var && (cond); var++) \ 101 /* void */; \ 102 } while (0) 103 104 if (msg_verbose > 1) 105 msg_info("%s: %s", myname, value); 106 107 for (vp = value; *vp;) { 108 if (*vp != '$') { /* ordinary character */ 109 VSTRING_ADDCH(buf, *vp); 110 vp += 1; 111 } else if (vp[1] == '$') { /* $$ becomes $ */ 112 VSTRING_ADDCH(buf, *vp); 113 vp += 2; 114 } else { /* found bare $ */ 115 if (VSTRING_LEN(buf) > 0) 116 MAC_PARSE_ACTION(status, MAC_PARSE_LITERAL, buf, context); 117 vp += 1; 118 pp = open_paren; 119 if (*vp == *pp || *vp == *++pp) { /* ${x} or $(x) */ 120 level = 1; 121 vp += 1; 122 for (ep = vp; level > 0; ep++) { 123 if (*ep == 0) { 124 msg_warn("truncated macro reference: \"%s\"", value); 125 status |= MAC_PARSE_ERROR; 126 break; 127 } 128 if (*ep == *pp) 129 level++; 130 if (*ep == close_paren[pp - open_paren]) 131 level--; 132 } 133 if (status & MAC_PARSE_ERROR) 134 break; 135 vstring_strncat(buf, vp, level > 0 ? ep - vp : ep - vp - 1); 136 vp = ep; 137 } else { /* plain $x */ 138 SKIP(vp, ep, ISALNUM(*ep) || *ep == '_'); 139 vstring_strncat(buf, vp, ep - vp); 140 vp = ep; 141 } 142 if (VSTRING_LEN(buf) == 0) { 143 status |= MAC_PARSE_ERROR; 144 msg_warn("empty macro name: \"%s\"", value); 145 break; 146 } 147 MAC_PARSE_ACTION(status, MAC_PARSE_EXPR, buf, context); 148 } 149 } 150 if (VSTRING_LEN(buf) > 0 && (status & MAC_PARSE_ERROR) == 0) 151 MAC_PARSE_ACTION(status, MAC_PARSE_LITERAL, buf, context); 152 153 /* 154 * Cleanup. 155 */ 156 vstring_free(buf); 157 158 return (status); 159 } 160 161 #ifdef TEST 162 163 /* 164 * Proof-of-concept test program. Read strings from stdin, print parsed 165 * result to stdout. 166 */ 167 #include <vstring_vstream.h> 168 169 /* mac_parse_print - print parse tree */ 170 171 static int mac_parse_print(int type, VSTRING *buf, void *unused_context) 172 { 173 char *type_name; 174 175 switch (type) { 176 case MAC_PARSE_EXPR: 177 type_name = "MAC_PARSE_EXPR"; 178 break; 179 case MAC_PARSE_LITERAL: 180 type_name = "MAC_PARSE_LITERAL"; 181 break; 182 default: 183 msg_panic("unknown token type %d", type); 184 } 185 vstream_printf("%s \"%s\"\n", type_name, vstring_str(buf)); 186 return (0); 187 } 188 189 int main(int unused_argc, char **unused_argv) 190 { 191 VSTRING *buf = vstring_alloc(1); 192 193 while (vstring_fgets_nonl(buf, VSTREAM_IN)) { 194 mac_parse(vstring_str(buf), mac_parse_print, (void *) 0); 195 vstream_fflush(VSTREAM_OUT); 196 } 197 vstring_free(buf); 198 return (0); 199 } 200 201 #endif 202