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      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 #ifdef HAS_STDLIB_H
     15 #include <stdlib.h>
     16 #endif
     17 #include <string.h>
     18 #ifdef HAVE_ERRNO_H
     19 #include <errno.h>
     20 #endif
     21 
     22 #include "ss_internal.h"
     23 
     24 enum parse_mode { WHITESPACE, TOKEN, QUOTED_STRING };
     25 
     26 /*
     27  * parse(line_ptr, argc_ptr)
     28  *
     29  * Function:
     30  *      Parses line, dividing at whitespace, into tokens, returns
     31  *      the "argc" and "argv" values.
     32  * Arguments:
     33  *      line_ptr (char *)
     34  *              Pointer to text string to be parsed.
     35  *      argc_ptr (int *)
     36  *              Where to put the "argc" (number of tokens) value.
     37  * Returns:
     38  *      argv (char **)
     39  *              Series of pointers to parsed tokens.
     40  */
     41 
     42 #define NEW_ARGV(old,n) (char **)realloc((char *)old,\
     43 					 (unsigned)(n+2)*sizeof(char*))
     44 
     45 char **ss_parse(int sci_idx, register char *line_ptr, int *argc_ptr)
     46 {
     47     register char **argv, *cp;
     48     register int argc;
     49     register enum parse_mode parse_mode;
     50 
     51     argv = (char **) malloc (sizeof(char *));
     52     if (argv == (char **)NULL) {
     53 	ss_error(sci_idx, errno, "Can't allocate storage");
     54 	*argc_ptr = 0;
     55 	return(argv);
     56     }
     57     *argv = (char *)NULL;
     58 
     59     argc = 0;
     60 
     61     parse_mode = WHITESPACE;	/* flushing whitespace */
     62     cp = line_ptr;		/* cp is for output */
     63     while (1) {
     64 #ifdef DEBUG
     65 	{
     66 	    printf ("character `%c', mode %d\n", *line_ptr, parse_mode);
     67 	}
     68 #endif
     69 	while (parse_mode == WHITESPACE) {
     70 	    if (*line_ptr == '\0')
     71 		goto end_of_line;
     72 	    if (*line_ptr == ' ' || *line_ptr == '\t') {
     73 		line_ptr++;
     74 		continue;
     75 	    }
     76 	    if (*line_ptr == '"') {
     77 		/* go to quoted-string mode */
     78 		parse_mode = QUOTED_STRING;
     79 		cp = line_ptr++;
     80 		argv = NEW_ARGV (argv, argc);
     81 		argv[argc++] = cp;
     82 		argv[argc] = NULL;
     83 	    }
     84 	    else {
     85 		/* random-token mode */
     86 		parse_mode = TOKEN;
     87 		cp = line_ptr;
     88 		argv = NEW_ARGV (argv, argc);
     89 		if (argv == NULL) {
     90 			*argc_ptr = errno;
     91 			return argv;
     92 		}
     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 }
    150