sys/share/posixregex.c

   1 /* aNetHack 0.0.1  posixregex.c $ANH-Date: 1434446947 2015/06/16 09:29:07 $  $ANH-Branch: master $:$ANH-Revision: 1.5 $ */
   2 /* Copyright (c) Sean Hunt  2015.                                 */
   3 /* aNetHack may be freely redistributed.  See license for details. */
   4
   5 #include "hack.h"
   6
   7 #include <regex.h>
   8
   9 /* The nhregex interface is implemented by several source files. The
  10  * file to be used can be linked in by the build.
  11  *
  12  * The regex standard implemented should be POSIX extended regular
  13  * expressions, see:
  14  *   http://pubs.opengroup.org/onlinepubs/009696899/basedefs/xbd_chap09.html
  15  * If an implementation uses an alternate expression format, this should
  16  * be clearly noted; this will result in incompatibility of config files
  17  * when aNetHack is compiled with that implementation.
  18  *
  19  * struct nhregex
  20  * The nhregex structure is an opaque structure type containing the
  21  * information about a compiled regular expression.
  22  *
  23  * struct nhregex *regex_init(void)
  24  * Used to create a new instance of the nhregex structure. It is
  25  * uninitialized and can only safely be passed to regex_compile.
  26  *
  27  * boolean regex_compile(const char *s, struct nhregex *re)
  28  * Used to compile s into a regex and store it in re. Returns TRUE if
  29  * successful and FALSE otherwise. re is invalidated regardless of
  30  * success.
  31  *
  32  * const char *regex_error_desc(struct nhregex *re)
  33  * Used to retrieve an error description from an error created involving
  34  * re. Returns NULL if no description can be retrieved. The returned
  35  * string may be a static buffer and so is only valid until the next
  36  * call to regex_error_desc.
  37  *
  38  * boolean regex_match(const char *s, struct nhregex *re)
  39  * Used to determine if s (or any substring) matches the regex compiled
  40  * into re. Only valid if the most recent call to regex_compile on re
  41  * succeeded.
  42  *
  43  * void regex_free(struct nhregex *re)
  44  * Deallocate a regex object.
  45  */
  46
  47 const char regex_id[] = "posixregex";
  48
  49 struct nhregex {
  50     regex_t re;
  51     int err;
  52 };
  53
  54 struct nhregex *
  55 regex_init()
  56 {
  57     return (struct nhregex *) alloc(sizeof(struct nhregex));
  58 }
  59
  60 boolean
  61 regex_compile(const char *s, struct nhregex *re)
  62 {
  63     if (!re)
  64         return FALSE;
  65     if ((re->err = regcomp(&re->re, s, REG_EXTENDED | REG_NOSUB)))
  66         return FALSE;
  67     return TRUE;
  68 }
  69
  70 const char *
  71 regex_error_desc(struct nhregex *re)
  72 {
  73     static char buf[BUFSZ];
  74
  75     if (!re || !re->err)
  76         return (const char *) 0;
  77
  78     /* FIXME: Using a static buffer here is not ideal, but avoids memory
  79      * leaks. Consider the allocation more carefully. */
  80     regerror(re->err, &re->re, buf, BUFSZ);
  81
  82     return buf;
  83 }
  84
  85 boolean
  86 regex_match(const char *s, struct nhregex *re)
  87 {
  88     int result;
  89
  90     if (!re || !s)
  91         return FALSE;
  92
  93     if ((result = regexec(&re->re, s, 0, (genericptr_t) 0, 0))) {
  94         if (result != REG_NOMATCH)
  95             re->err = result;
  96         return FALSE;
  97     }
  98     return TRUE;
  99 }
 100
 101 void
 102 regex_free(struct nhregex *re)
 103 {
 104     regfree(&re->re);
 105     free(re);
 106 }