boot/common/interp_parse.c

	interp_parse.c revision 199767f8919635c4928607450d9e0abb932109ce
/*-
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * Jordan K. Hubbard
 * 29 August 1998
 *
 * The meat of the simple parser.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <stand.h>
#include <string.h>
#include "bootstrap.h"

static void  clean(void);
static int   insert(int *argcp, char *buf);
static char *variable_lookup(char *name);

#define PARSE_BUFSIZE   1024    /* maximum size of one element */
#define MAXARGS     20  /* maximum number of elements */
static char     *args[MAXARGS];

/*
 * parse: accept a string of input and "parse" it for backslash
 * substitutions and environment variable expansions (${var}),
 * returning an argc/argv style vector of whitespace separated
 * arguments.  Returns 0 on success, 1 on failure (ok, ok, so I
 * wimped-out on the error codes! :).
 *
 * Note that the argv array returned must be freed by the caller, but
 * we own the space allocated for arguments and will free that on next
 * invocation.  This allows argv consumers to modify the array if
 * required.
 *
 * NB: environment variables that expand to more than one whitespace
 * separated token will be returned as a single argv[] element, not
 * split in turn.  Expanded text is also immune to further backslash
 * elimination or expansion since this is a one-pass, non-recursive
 * parser.  You didn't specify more than this so if you want more, ask
 * me. - jkh
 */

#define PARSE_FAIL(expr) \
if (expr) { \
    printf("fail at line %d\n", __LINE__); \
    clean(); \
    free(copy); \
    free(buf); \
    return 1; \
}

/* Accept the usual delimiters for a variable, returning counterpart */
static char
isdelim(int ch)
{
    if (ch == '{')
    return '}';
    else if (ch == '(')
    return ')';
    return '\0';
}

static int
isquote(int ch)
{
    return (ch == '\'');
}

static int
isdquote(int ch)
{
    return (ch == '"');
}

int
parse(int *argc, char ***argv, char *str)
{
    int ac;
    char *val, *p, *q, *copy = NULL;
    size_t i = 0;
    char token, tmp, quote, dquote, *buf;
    enum { STR, VAR, WHITE } state;

    ac = *argc = 0;
    dquote = quote = 0;
    if (!str || (p = copy = backslash(str)) == NULL)
    return 1;

    /* Initialize vector and state */
    clean();
    state = STR;
    buf = (char *)malloc(PARSE_BUFSIZE);
    token = 0;

    /* And awaaaaaaaaay we go! */
    while (*p) {
    switch (state) {
    case STR:
        if ((*p == '\\') && p[1]) {
        p++;
        PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
        buf[i++] = *p++;
        } else if (isquote(*p)) {
        quote = quote ? 0 : *p;
        if (dquote) { /* keep quote */
            PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
            buf[i++] = *p++;
        } else {
            ++p;
        }
        } else if (isdquote(*p)) {
        dquote = dquote ? 0 : *p;
        if (quote) { /* keep dquote */
            PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
            buf[i++] = *p++;
        } else {
            ++p;
        }
        } else if (isspace(*p) && !quote && !dquote) {
        state = WHITE;
        if (i) {
            buf[i] = '\0';
            PARSE_FAIL(insert(&ac, buf));
            i = 0;
        }
        ++p;
        } else if (*p == '$' && !quote) {
        token = isdelim(*(p + 1));
        if (token)
            p += 2;
        else
            ++p;
        state = VAR;
        } else {
        PARSE_FAIL(i == (PARSE_BUFSIZE - 1));
        buf[i++] = *p++;
        }
        break;

    case WHITE:
        if (isspace(*p))
        ++p;
        else
        state = STR;
        break;

    case VAR:
        if (token) {
        PARSE_FAIL((q = strchr(p, token)) == NULL);
        } else {
        q = p;
        while (*q && !isspace(*q))
            ++q;
        }
        tmp = *q;
        *q = '\0';
        if ((val = variable_lookup(p)) != NULL) {
        size_t len = strlen(val);

        strncpy(buf + i, val, PARSE_BUFSIZE - (i + 1));
        i += min(len, PARSE_BUFSIZE - 1);
        }
        *q = tmp;   /* restore value */
        p = q + (token ? 1 : 0);
        state = STR;
        break;
    }
    }
    /* missing terminating ' or " */
    PARSE_FAIL(quote || dquote);
    /* If at end of token, add it */
    if (i && state == STR) {
    buf[i] = '\0';
    PARSE_FAIL(insert(&ac, buf));
    }
    args[ac] = NULL;
    *argc = ac;
    *argv = (char **)malloc((sizeof(char *) * ac + 1));
    bcopy(args, *argv, sizeof(char *) * ac + 1);
    free(buf);
    free(copy);
    return 0;
}

#define MAXARGS 20

/* Clean vector space */
static void
clean(void)
{
    int     i;

    for (i = 0; i < MAXARGS; i++) {
    if (args[i] != NULL) {
        free(args[i]);
        args[i] = NULL;
    }
    }
}

static int
insert(int *argcp, char *buf)
{
    if (*argcp >= MAXARGS)
    return 1;
    args[(*argcp)++] = strdup(buf);
    return 0;
}

static char *
variable_lookup(char *name)
{
    /* XXX search "special variable" space first? */
    return (char *)getenv(name);
}