usr/src/boot/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
  17 #include <sys/cdefs.h>
  18 __FBSDID("$FreeBSD$");
  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 == '\'');
  76 }
  77
  78 static int
  79 isdquote(int ch)
  80 {
  81     return (ch == '"');
  82 }
  83
  84 int
  85 parse(int *argc, char ***argv, char *str)
  86 {
  87     int ac;
  88     char *val, *p, *q, *copy = NULL;
  89     size_t i = 0;
  90     char token, tmp, quote, dquote, *buf;
  91     enum { STR, VAR, WHITE } state;
  92
  93     ac = *argc = 0;
  94     dquote = quote = 0;
  95     if (!str || (p = copy = backslash(str)) == NULL)
  96         return 1;
  97
  98     /* Initialize vector and state */
  99     clean();
 100     state = STR;
 101     buf = (char *)malloc(PARSE_BUFSIZE);
 102     token = 0;
 103
 104     /* And awaaaaaaaaay we go! */
 105     while (*p) {
 106         switch (state) {
 107         case STR:
 108             if ((*p == '\\') && p[1]) {
 109                 p++;
 110                 PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
 111                 buf[i++] = *p++;
 112             } else if (isquote(*p)) {
 113                 quote = quote ? 0 : *p;
 114                 if (dquote) { /* keep quote */
 115                         PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
 116                         buf[i++] = *p++;
 117                 } else {
 118                         ++p;
 119                 }
 120             } else if (isdquote(*p)) {
 121                 dquote = dquote ? 0 : *p;
 122                 if (quote) { /* keep dquote */
 123                         PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
 124                         buf[i++] = *p++;
 125                 } else {
 126                         ++p;
 127                 }
 128             } else if (isspace(*p) && !quote && !dquote) {
 129                 state = WHITE;
 130                 if (i) {
 131                     buf[i] = '\0';
 132                     PARSE_FAIL(insert(&ac, buf));
 133                     i = 0;
 134                 }
 135                 ++p;
 136             } else if (*p == '$' && !quote) {
 137                 token = isdelim(*(p + 1));
 138                 if (token)
 139                     p += 2;
 140                 else
 141                     ++p;
 142                 state = VAR;
 143             } else {
 144                 PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
 145                 buf[i++] = *p++;
 146             }
 147             break;
 148
 149         case WHITE:
 150             if (isspace(*p))
 151                 ++p;
 152             else
 153                 state = STR;
 154             break;
 155
 156         case VAR:
 157             if (token) {
 158                 PARSE_FAIL((q = strchr(p, token)) == NULL);
 159             } else {
 160                 q = p;
 161                 while (*q && !isspace(*q))
 162                     ++q;
 163             }
 164             tmp = *q;
 165             *q = '\0';
 166             if ((val = variable_lookup(p)) != NULL) {
 167                 size_t len = strlen(val);
 168
 169                 strncpy(buf + i, val, PARSE_BUFSIZE - (i + 1));
 170                 i += min(len, PARSE_BUFSIZE - 1);
 171             }
 172             *q = tmp;   /* restore value */
 173             p = q + (token ? 1 : 0);
 174             state = STR;
 175             break;
 176         }
 177     }
 178     /* missing terminating ' or " */
 179     PARSE_FAIL(quote || dquote);
 180     /* If at end of token, add it */
 181     if (i && state == STR) {
 182         buf[i] = '\0';
 183         PARSE_FAIL(insert(&ac, buf));
 184     }
 185     args[ac] = NULL;
 186     *argc = ac;
 187     *argv = (char **)malloc((sizeof(char *) * ac + 1));
 188     bcopy(args, *argv, sizeof(char *) * ac + 1);
 189     free(buf);
 190     free(copy);
 191     return 0;
 192 }
 193
 194 #define MAXARGS 20
 195
 196 /* Clean vector space */
 197 static void
 198 clean(void)
 199 {
 200     int         i;
 201
 202     for (i = 0; i < MAXARGS; i++) {
 203         if (args[i] != NULL) {
 204             free(args[i]);
 205             args[i] = NULL;
 206         }
 207     }
 208 }
 209
 210 static int
 211 insert(int *argcp, char *buf)
 212 {
 213     if (*argcp >= MAXARGS)
 214         return 1;
 215     args[(*argcp)++] = strdup(buf);
 216     return 0;
 217 }
 218
 219 static char *
 220 variable_lookup(char *name)
 221 {
 222     /* XXX search "special variable" space first? */
 223     return (char *)getenv(name);
 224 }