sys/boot/common/interp_parse.c

   1 /*-
   2  * Redistribution and use in source and binary forms, with or without
   3  * modification, are permitted provided that the following conditions
   4  * are met:
   5  * 1. Redistributions of source code must retain the above copyright
   6  *    notice, this list of conditions and the following disclaimer.
   7  * 2. Redistributions in binary form must reproduce the above copyright
   8  *    notice, this list of conditions and the following disclaimer in the
   9  *    documentation and/or other materials provided with the distribution.
  10  *
  11  * Jordan K. Hubbard
  12  * 29 August 1998
  13  *
  14  * The meat of the simple parser.
  15  *
  16  * $FreeBSD: src/sys/boot/common/interp_parse.c,v 1.10 2003/08/25 23:30:41 obrien Exp $
  17  * $DragonFly: src/sys/boot/common/interp_parse.c,v 1.3 2003/11/10 06:08:31 dillon Exp $
  18  */
  19
  20 #include <stand.h>
  21 #include <string.h>
  22 #include "bootstrap.h"
  23
  24 static void      clean(void);
  25 static int       insert(int *argcp, char *buf);
  26 static char     *variable_lookup(char *name);
  27
  28 #define PARSE_BUFSIZE   1024    /* maximum size of one element */
  29 #define MAXARGS         20      /* maximum number of elements */
  30 static char             *args[MAXARGS];
  31
  32 /*
  33  * parse: accept a string of input and "parse" it for backslash
  34  * substitutions and environment variable expansions (${var}),
  35  * returning an argc/argv style vector of whitespace separated
  36  * arguments.  Returns 0 on success, 1 on failure (ok, ok, so I
  37  * wimped-out on the error codes! :).
  38  *
  39  * Note that the argv array returned must be freed by the caller, but
  40  * we own the space allocated for arguments and will free that on next
  41  * invocation.  This allows argv consumers to modify the array if
  42  * required.
  43  *
  44  * NB: environment variables that expand to more than one whitespace
  45  * separated token will be returned as a single argv[] element, not
  46  * split in turn.  Expanded text is also immune to further backslash
  47  * elimination or expansion since this is a one-pass, non-recursive
  48  * parser.  You didn't specify more than this so if you want more, ask
  49  * me. - jkh
  50  */
  51
  52 #define PARSE_FAIL(expr) \
  53 if (expr) { \
  54     printf("fail at line %d\n", __LINE__); \
  55     clean(); \
  56     free(copy); \
  57     free(buf); \
  58     return 1; \
  59 }
  60
  61 /* Accept the usual delimiters for a variable, returning counterpart */
  62 static char
  63 isdelim(int ch)
  64 {
  65     if (ch == '{')
  66         return '}';
  67     else if (ch == '(')
  68         return ')';
  69     return '\0';
  70 }
  71
  72 static int
  73 isquote(int ch)
  74 {
  75     return (ch == '\'' || ch == '"');
  76 }
  77
  78 int
  79 parse(int *argc, char ***argv, char *str)
  80 {
  81     int ac;
  82     char *val, *p, *q, *copy = NULL;
  83     size_t i = 0;
  84     char token, tmp, quote, *buf;
  85     enum { STR, VAR, WHITE } state;
  86
  87     ac = *argc = 0;
  88     quote = 0;
  89     if (!str || (p = copy = backslash(str)) == NULL)
  90         return 1;
  91
  92     /* Initialize vector and state */
  93     clean();
  94     state = STR;
  95     buf = (char *)malloc(PARSE_BUFSIZE);
  96     token = 0;
  97
  98     /* And awaaaaaaaaay we go! */
  99     while (*p) {
 100         switch (state) {
 101         case STR:
 102             /*
 103              * Check comment
 104              */
 105             if (*p == '#' && quote == 0) {
 106                 *p = 0;
 107                 break;
 108             }
 109
 110             /*
 111              * Check line continuation
 112              */
 113             if (*p == '\\' && p[1]) {
 114                 p++;
 115                 PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
 116                 buf[i++] = *p++;
 117             } else if (isquote(*p)) {
 118                 quote = quote ? 0 : *p;
 119                 ++p;
 120             }
 121             else if (isspace(*p) && !quote) {
 122                 state = WHITE;
 123                 if (i) {
 124                     buf[i] = '\0';
 125                     PARSE_FAIL(insert(&ac, buf));
 126                     i = 0;
 127                 }
 128                 ++p;
 129             } else if (*p == '$') {
 130                 token = isdelim(*(p + 1));
 131                 if (token)
 132                     p += 2;
 133                 else
 134                     ++p;
 135                 state = VAR;
 136             } else {
 137                 PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
 138                 buf[i++] = *p++;
 139             }
 140             break;
 141
 142         case WHITE:
 143             if (isspace(*p))
 144                 ++p;
 145             else
 146                 state = STR;
 147             break;
 148
 149         case VAR:
 150             if (token) {
 151                 PARSE_FAIL((q = index(p, token)) == NULL);
 152             } else {
 153                 q = p;
 154                 while (*q && !isspace(*q))
 155                     ++q;
 156             }
 157             tmp = *q;
 158             *q = '\0';
 159             if ((val = variable_lookup(p)) != NULL) {
 160                 size_t len = strlen(val);
 161
 162                 strncpy(buf + i, val, PARSE_BUFSIZE - (i + 1));
 163                 i += min(len, PARSE_BUFSIZE - 1);
 164             }
 165             *q = tmp;   /* restore value */
 166             p = q + (token ? 1 : 0);
 167             state = STR;
 168             break;
 169         }
 170     }
 171     /* If at end of token, add it */
 172     if (i && state == STR) {
 173         buf[i] = '\0';
 174         PARSE_FAIL(insert(&ac, buf));
 175     }
 176     args[ac] = NULL;
 177     *argc = ac;
 178     *argv = (char **)malloc(sizeof(char *) * (ac + 1));
 179     bcopy(args, *argv, sizeof(char *) * (ac + 1));
 180     free(buf);
 181     free(copy);
 182     return 0;
 183 }
 184
 185 #define MAXARGS 20
 186
 187 /* Clean vector space */
 188 static void
 189 clean(void)
 190 {
 191     int         i;
 192
 193     for (i = 0; i < MAXARGS; i++) {
 194         if (args[i] != NULL) {
 195             free(args[i]);
 196             args[i] = NULL;
 197         }
 198     }
 199 }
 200
 201 static int
 202 insert(int *argcp, char *buf)
 203 {
 204     if (*argcp >= MAXARGS)
 205         return 1;
 206     args[(*argcp)++] = strdup(buf);
 207     return 0;
 208 }
 209
 210 static char *
 211 variable_lookup(char *name)
 212 {
 213     /* XXX search "special variable" space first? */
 214     return (char *)getenv(name);
 215 }