external/bsd/ntp/dist/ntpd/ntp_scanner.h

   1 /*      $NetBSD$        */
   2
   3 /* ntp_scanner.h
   4  *
   5  * The header file for a simple lexical analyzer.
   6  *
   7  * Written By:  Sachin Kamboj
   8  *              University of Delaware
   9  *              Newark, DE 19711
  10  * Copyright (c) 2006
  11  */
  12
  13 #ifndef NTP_SCANNER_H
  14 #define NTP_SCANNER_H
  15
  16 /*
  17  * ntp.conf syntax is slightly irregular in that some tokens such as
  18  * hostnames do not require quoting even if they might otherwise be
  19  * recognized as T_ terminal tokens.  This hand-crafted lexical scanner
  20  * uses a "followed by" value associated with each keyword to indicate
  21  * normal scanning of the next token, forced scanning of the next token
  22  * alone as a T_String, or forced scanning of all tokens to the end of
  23  * the command as T_String.
  24  * In the past the identifiers for this functionality ended in _ARG:
  25  *
  26  * NO_ARG       ->      FOLLBY_TOKEN
  27  * SINGLE_ARG   ->      FOLLBY_STRING
  28  * MULTIPLE_ARG ->      FOLLBY_STRINGS_TO_EOC
  29  *
  30  * Note that some tokens use FOLLBY_TOKEN even though they sometimes
  31  * are followed by strings.  FOLLBY_STRING is used only when needed to
  32  * avoid the keyword scanner matching a token where a string is needed.
  33  *
  34  * FOLLBY_NON_ACCEPT is an overloading of this field to distinguish
  35  * non-accepting states (where the state number does not match a T_
  36  * value).
  37  */
  38 typedef enum {
  39         FOLLBY_TOKEN = 0,
  40         FOLLBY_STRING,
  41         FOLLBY_STRINGS_TO_EOC,
  42         FOLLBY_NON_ACCEPTING
  43 } follby;
  44
  45 #define MAXLINE         1024    /* maximum length of line */
  46 #define MAXINCLUDELEVEL 5       /* maximum include file levels */
  47
  48 /* STRUCTURES
  49  * ----------
  50  */
  51
  52 /*
  53  * Define a structure to hold the FSA for the keywords.
  54  * The structure is actually a trie.
  55  *
  56  * To save space, a single u_int32 encodes four fields, and a fifth
  57  * (the token completed for terminal states) is implied by the index of
  58  * the rule within the scan state array, taking advantage of the fact
  59  * there are more scan states than the highest T_ token number.
  60  *
  61  * The lowest 8 bits hold the character the state matches on.
  62  * Bits 8 and 9 hold the followedby value (0 - 3).  For non-accepting
  63  *   states (which do not match a completed token) the followedby
  64  *   value 3 (FOLLBY_NONACCEPTING) denotes that fact.  For accepting
  65  *   states, values 0 - 2 control whether the scanner forces the
  66  *   following token(s) to strings.
  67  * Bits 10 through 20 hold the next state to check not matching
  68  * this state's character.
  69  * Bits 21 through 31 hold the next state to check matching the char.
  70  */
  71
  72 #define S_ST(ch, fb, match_n, other_n) (                        \
  73         (u_char)((ch) & 0xff) |                                 \
  74         ((u_int32)(fb) << 8) |                                  \
  75         ((u_int32)(match_n) << 10) |                            \
  76         ((u_int32)(other_n) << 21)                              \
  77 )
  78
  79 #define SS_CH(ss)       ((char)(u_char)((ss) & 0xff))
  80 #define SS_FB(ss)       (((u_int)(ss) >>  8) & 0x3)
  81 #define SS_MATCH_N(ss)  (((u_int)(ss) >> 10) & 0x7ff)
  82 #define SS_OTHER_N(ss)  (((u_int)(ss) >> 21) & 0x7ff)
  83
  84 typedef u_int32 scan_state;
  85
  86
  87 /* Structure to hold a filename, file pointer and positional info */
  88 struct FILE_INFO {
  89         const char *    fname;                  /* Path to the file */
  90         FILE *          fd;                     /* File Descriptor */
  91         int             line_no;                /* Line Number */
  92         int             col_no;                 /* Column Number */
  93         int             prev_line_col_no;       /* Col No on the
  94                                                    previous line when a
  95                                                    '\n' was seen */
  96         int             prev_token_line_no;     /* Line at start of
  97                                                    token */
  98         int             prev_token_col_no;      /* Col No at start of
  99                                                    token */
 100         int             err_line_no;
 101         int             err_col_no;
 102 };
 103
 104
 105 /* SCANNER GLOBAL VARIABLES
 106  * ------------------------
 107  */
 108 extern struct config_tree cfgt;   /* Parser output stored here */
 109 extern int curr_include_level;    /* The current include level */
 110
 111 extern struct FILE_INFO *ip_file; /* Pointer to the configuration file stream */
 112
 113 /* VARIOUS EXTERNAL DECLARATIONS
 114  * -----------------------------
 115  */
 116 extern short default_ai_family;
 117 extern int old_config_style;
 118 extern int input_from_file;
 119 extern struct FILE_INFO *fp[];
 120
 121 /* VARIOUS SUBROUTINE DECLARATIONS
 122  * -------------------------------
 123  */
 124 extern const char *keyword(int token);
 125 extern char *quote_if_needed(char *str);
 126 int yylex(void);
 127
 128 struct FILE_INFO *F_OPEN(const char *path, const char *mode);
 129 int FGETC(struct FILE_INFO *stream);
 130 int UNGETC(int ch, struct FILE_INFO *stream);
 131 int FCLOSE(struct FILE_INFO *stream);
 132
 133 void push_back_char(int ch);
 134
 135 #endif  /* NTP_SCANNER_H */