parse.c revision f404167dda29a59d2be2882328aeb074b9899669 
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
25enum 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
46char **ss_parse(int sci_idx, register char *line_ptr, int *argc_ptr)
47{
48    register char **argv, *cp;
49    register int argc;
50    register enum parse_mode parse_mode;
51
52    argv = (char **) malloc (sizeof(char *));
53    if (argv == (char **)NULL) {
54	ss_error(sci_idx, errno, "Can't allocate storage");
55	*argc_ptr = 0;
56	return(argv);
57    }
58    *argv = (char *)NULL;
59
60    argc = 0;
61
62    parse_mode = WHITESPACE;	/* flushing whitespace */
63    cp = line_ptr;		/* cp is for output */
64    while (1) {
65#ifdef DEBUG
66	{
67	    printf ("character `%c', mode %d\n", *line_ptr, parse_mode);
68	}
69#endif
70	while (parse_mode == WHITESPACE) {
71	    if (*line_ptr == '\0')
72		goto end_of_line;
73	    if (*line_ptr == ' ' || *line_ptr == '\t') {
74		line_ptr++;
75		continue;
76	    }
77	    if (*line_ptr == '"') {
78		/* go to quoted-string mode */
79		parse_mode = QUOTED_STRING;
80		cp = line_ptr++;
81		argv = NEW_ARGV (argv, argc);
82		argv[argc++] = cp;
83		argv[argc] = NULL;
84	    }
85	    else {
86		/* random-token mode */
87		parse_mode = TOKEN;
88		cp = line_ptr;
89		argv = NEW_ARGV (argv, argc);
90		if (argv == NULL) {
91			*argc_ptr = errno;
92			return argv;
93		}
94		argv[argc++] = line_ptr;
95		argv[argc] = NULL;
96	    }
97	}
98	while (parse_mode == TOKEN) {
99	    if (*line_ptr == '\0') {
100		*cp++ = '\0';
101		goto end_of_line;
102	    }
103	    else if (*line_ptr == ' ' || *line_ptr == '\t') {
104		*cp++ = '\0';
105		line_ptr++;
106		parse_mode = WHITESPACE;
107	    }
108	    else if (*line_ptr == '"') {
109		line_ptr++;
110		parse_mode = QUOTED_STRING;
111	    }
112	    else {
113		*cp++ = *line_ptr++;
114	    }
115	}
116	while (parse_mode == QUOTED_STRING) {
117	    if (*line_ptr == '\0') {
118		ss_error (sci_idx, 0,
119			  "Unbalanced quotes in command line");
120		free (argv);
121		*argc_ptr = 0;
122		return NULL;
123	    }
124	    else if (*line_ptr == '"') {
125		if (*++line_ptr == '"') {
126		    *cp++ = '"';
127		    line_ptr++;
128		}
129		else {
130		    parse_mode = TOKEN;
131		}
132	    }
133	    else {
134		*cp++ = *line_ptr++;
135	    }
136	}
137    }
138end_of_line:
139    *argc_ptr = argc;
140#ifdef DEBUG
141    {
142	int i;
143	printf ("argc = %d\n", argc);
144	for (i = 0; i <= argc; i++)
145	    printf ("\targv[%2d] = `%s'\n", i,
146		    argv[i] ? argv[i] : "<NULL>");
147    }
148#endif
149    return(argv);
150}
151