external/ibm-public/postfix/dist/src/util/mac_parse.c

   1 /*      $NetBSD$        */
   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, char *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, char *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) \
 100         for (var = start; *var && (cond); var++);
 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
 169 static int mac_parse_print(int type, VSTRING *buf, char *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
 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, (char *) 0);
 193         vstream_fflush(VSTREAM_OUT);
 194     }
 195     vstring_free(buf);
 196     return (0);
 197 }
 198
 199 #endif