lib/ss/parse.c

   1 /*
   2  * Copyright 1987, 1988 by MIT Student Information Processing Board
   3  *
   4  * Permission to use, copy, modify, and distribute this software and
   5  * its documentation for any purpose is hereby granted, provided that
   6  * the names of M.I.T. and the M.I.T. S.I.P.B. not be used in
   7  * advertising or publicity pertaining to distribution of the software
   8  * without specific, written prior permission.  M.I.T. and the
   9  * M.I.T. S.I.P.B. make no representations about the suitability of
  10  * this software for any purpose.  It is provided "as is" without
  11  * express or implied warranty.
  12  */
  13
  14 #include "config.h"
  15 #ifdef HAS_STDLIB_H
  16 #include <stdlib.h>
  17 #endif
  18 #include <string.h>
  19 #ifdef HAVE_ERRNO_H
  20 #include <errno.h>
  21 #endif
  22
  23 #include "ss_internal.h"
  24
  25 enum parse_mode { WHITESPACE, TOKEN, QUOTED_STRING };
  26
  27 /*
  28  * parse(line_ptr, argc_ptr)
  29  *
  30  * Function:
  31  *      Parses line, dividing at whitespace, into tokens, returns
  32  *      the "argc" and "argv" values.
  33  * Arguments:
  34  *      line_ptr (char *)
  35  *              Pointer to text string to be parsed.
  36  *      argc_ptr (int *)
  37  *              Where to put the "argc" (number of tokens) value.
  38  * Returns:
  39  *      argv (char **)
  40  *              Series of pointers to parsed tokens.
  41  */
  42
  43 #define NEW_ARGV(old,n) (char **)realloc((char *)old,\
  44                                          (unsigned)(n+2)*sizeof(char*))
  45
  46 char **ss_parse (sci_idx, line_ptr, argc_ptr)
  47     int sci_idx;
  48     register char *line_ptr;
  49     int *argc_ptr;
  50 {
  51     register char **argv, *cp;
  52     register int argc;
  53     register enum parse_mode parse_mode;
  54
  55     argv = (char **) malloc (sizeof(char *));
  56     if (argv == (char **)NULL) {
  57         ss_error(sci_idx, errno, "Can't allocate storage");
  58         *argc_ptr = 0;
  59         return(argv);
  60     }
  61     *argv = (char *)NULL;
  62
  63     argc = 0;
  64
  65     parse_mode = WHITESPACE;    /* flushing whitespace */
  66     cp = line_ptr;              /* cp is for output */
  67     while (1) {
  68 #ifdef DEBUG
  69         {
  70             printf ("character `%c', mode %d\n", *line_ptr, parse_mode);
  71         }
  72 #endif
  73         while (parse_mode == WHITESPACE) {
  74             if (*line_ptr == '\0')
  75                 goto end_of_line;
  76             if (*line_ptr == ' ' || *line_ptr == '\t') {
  77                 line_ptr++;
  78                 continue;
  79             }
  80             if (*line_ptr == '"') {
  81                 /* go to quoted-string mode */
  82                 parse_mode = QUOTED_STRING;
  83                 cp = line_ptr++;
  84                 argv = NEW_ARGV (argv, argc);
  85                 argv[argc++] = cp;
  86                 argv[argc] = NULL;
  87             }
  88             else {
  89                 /* random-token mode */
  90                 parse_mode = TOKEN;
  91                 cp = line_ptr;
  92                 argv = NEW_ARGV (argv, argc);
  93                 argv[argc++] = line_ptr;
  94                 argv[argc] = NULL;
  95             }
  96         }
  97         while (parse_mode == TOKEN) {
  98             if (*line_ptr == '\0') {
  99                 *cp++ = '\0';
 100                 goto end_of_line;
 101             }
 102             else if (*line_ptr == ' ' || *line_ptr == '\t') {
 103                 *cp++ = '\0';
 104                 line_ptr++;
 105                 parse_mode = WHITESPACE;
 106             }
 107             else if (*line_ptr == '"') {
 108                 line_ptr++;
 109                 parse_mode = QUOTED_STRING;
 110             }
 111             else {
 112                 *cp++ = *line_ptr++;
 113             }
 114         }
 115         while (parse_mode == QUOTED_STRING) {
 116             if (*line_ptr == '\0') {
 117                 ss_error (sci_idx, 0,
 118                           "Unbalanced quotes in command line");
 119                 free (argv);
 120                 *argc_ptr = 0;
 121                 return NULL;
 122             }
 123             else if (*line_ptr == '"') {
 124                 if (*++line_ptr == '"') {
 125                     *cp++ = '"';
 126                     line_ptr++;
 127                 }
 128                 else {
 129                     parse_mode = TOKEN;
 130                 }
 131             }
 132             else {
 133                 *cp++ = *line_ptr++;
 134             }
 135         }
 136     }
 137 end_of_line:
 138     *argc_ptr = argc;
 139 #ifdef DEBUG
 140     {
 141         int i;
 142         printf ("argc = %d\n", argc);
 143         for (i = 0; i <= argc; i++)
 144             printf ("\targv[%2d] = `%s'\n", i,
 145                     argv[i] ? argv[i] : "<NULL>");
 146     }
 147 #endif
 148     return(argv);
 149 }