source: MondoRescue/branches/stable/mindi-busybox/coreutils/test.c@ 1770

/* vi: set sw=4 ts=4: */
/*
 * test implementation for busybox
 *
 * Copyright (c) by a whole pile of folks:
 *
 *     test(1); version 7-like  --  author Erik Baalbergen
 *     modified by Eric Gisin to be used as built-in.
 *     modified by Arnold Robbins to add SVR3 compatibility
 *     (-x -c -b -p -u -g -k) plus Korn's -L -nt -ot -ef and new -S (socket).
 *     modified by J.T. Conklin for NetBSD.
 *     modified by Herbert Xu to be used as built-in in ash.
 *     modified by Erik Andersen <andersen@codepoet.org> to be used
 *     in busybox.
 *     modified by Bernhard Fischer to be useable (i.e. a bit less bloaty).
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 *
 * Original copyright notice states:
 *     "This program is in the Public Domain."
 */

#include "libbb.h"
#include <setjmp.h>

/* This is a NOEXEC applet. Be very careful! */


/* test(1) accepts the following grammar:
    oexpr   ::= aexpr | aexpr "-o" oexpr ;
    aexpr   ::= nexpr | nexpr "-a" aexpr ;
    nexpr   ::= primary | "!" primary
    primary ::= unary-operator operand
        | operand binary-operator operand
        | operand
        | "(" oexpr ")"
        ;
    unary-operator ::= "-r"|"-w"|"-x"|"-f"|"-d"|"-c"|"-b"|"-p"|
        "-u"|"-g"|"-k"|"-s"|"-t"|"-z"|"-n"|"-o"|"-O"|"-G"|"-L"|"-S";

    binary-operator ::= "="|"=="|"!="|"-eq"|"-ne"|"-ge"|"-gt"|"-le"|"-lt"|
            "-nt"|"-ot"|"-ef";
    operand ::= <any legal UNIX file name>
*/

enum token {
    EOI,
    FILRD,
    FILWR,
    FILEX,
    FILEXIST,
    FILREG,
    FILDIR,
    FILCDEV,
    FILBDEV,
    FILFIFO,
    FILSOCK,
    FILSYM,
    FILGZ,
    FILTT,
    FILSUID,
    FILSGID,
    FILSTCK,
    FILNT,
    FILOT,
    FILEQ,
    FILUID,
    FILGID,
    STREZ,
    STRNZ,
    STREQ,
    STRNE,
    STRLT,
    STRGT,
    INTEQ,
    INTNE,
    INTGE,
    INTGT,
    INTLE,
    INTLT,
    UNOT,
    BAND,
    BOR,
    LPAREN,
    RPAREN,
    OPERAND
};
#define is_int_op(a) (((unsigned char)((a) - INTEQ)) <= 5)
#define is_str_op(a) (((unsigned char)((a) - STREZ)) <= 5)
#define is_file_op(a) (((unsigned char)((a) - FILNT)) <= 2)
#define is_file_access(a) (((unsigned char)((a) - FILRD)) <= 2)
#define is_file_type(a) (((unsigned char)((a) - FILREG)) <= 5)
#define is_file_bit(a) (((unsigned char)((a) - FILSUID)) <= 2)
enum token_types {
    UNOP,
    BINOP,
    BUNOP,
    BBINOP,
    PAREN
};

static const struct t_op {
    char op_text[4];
    unsigned char op_num, op_type;
} ops[] = {
    { "-r", FILRD   , UNOP   },
    { "-w", FILWR   , UNOP   },
    { "-x", FILEX   , UNOP   },
    { "-e", FILEXIST, UNOP   },
    { "-f", FILREG  , UNOP   },
    { "-d", FILDIR  , UNOP   },
    { "-c", FILCDEV , UNOP   },
    { "-b", FILBDEV , UNOP   },
    { "-p", FILFIFO , UNOP   },
    { "-u", FILSUID , UNOP   },
    { "-g", FILSGID , UNOP   },
    { "-k", FILSTCK , UNOP   },
    { "-s", FILGZ   , UNOP   },
    { "-t", FILTT   , UNOP   },
    { "-z", STREZ   , UNOP   },
    { "-n", STRNZ   , UNOP   },
    { "-h", FILSYM  , UNOP   },    /* for backwards compat */

    { "-O" , FILUID , UNOP   },
    { "-G" , FILGID , UNOP   },
    { "-L" , FILSYM , UNOP   },
    { "-S" , FILSOCK, UNOP   },
    { "="  , STREQ  , BINOP  },
    { "==" , STREQ  , BINOP  },
    { "!=" , STRNE  , BINOP  },
    { "<"  , STRLT  , BINOP  },
    { ">"  , STRGT  , BINOP  },
    { "-eq", INTEQ  , BINOP  },
    { "-ne", INTNE  , BINOP  },
    { "-ge", INTGE  , BINOP  },
    { "-gt", INTGT  , BINOP  },
    { "-le", INTLE  , BINOP  },
    { "-lt", INTLT  , BINOP  },
    { "-nt", FILNT  , BINOP  },
    { "-ot", FILOT  , BINOP  },
    { "-ef", FILEQ  , BINOP  },
    { "!"  , UNOT   , BUNOP  },
    { "-a" , BAND   , BBINOP },
    { "-o" , BOR    , BBINOP },
    { "("  , LPAREN , PAREN  },
    { ")"  , RPAREN , PAREN  },
};


#if ENABLE_FEATURE_TEST_64
typedef int64_t arith_t;
#else
typedef int arith_t;
#endif

/* Cannot eliminate these static data (do the G trick)
 * because of test_main usage from other applets */
static char **t_wp;
static struct t_op const *t_wp_op;
static gid_t *group_array;
static int ngroups;
static jmp_buf leaving;

static enum token t_lex(char *s);
static arith_t oexpr(enum token n);
static arith_t aexpr(enum token n);
static arith_t nexpr(enum token n);
static int binop(void);
static arith_t primary(enum token n);
static int filstat(char *nm, enum token mode);
static arith_t getn(const char *s);
/* UNUSED
static int newerf(const char *f1, const char *f2);
static int olderf(const char *f1, const char *f2);
static int equalf(const char *f1, const char *f2);
*/
static int test_eaccess(char *path, int mode);
static int is_a_group_member(gid_t gid);
static void initialize_group_array(void);

int test_main(int argc, char **argv)
{
    int res;
    const char *arg0;
    bool _off;

    arg0 = bb_basename(argv[0]);
    if (arg0[0] == '[') {
        --argc;
        if (!arg0[1]) { /* "[" ? */
            if (NOT_LONE_CHAR(argv[argc], ']')) {
                bb_error_msg("missing ]");
                return 2;
            }
        } else { /* assuming "[[" */
            if (strcmp(argv[argc], "]]") != 0) {
                bb_error_msg("missing ]]");
                return 2;
            }
        }
        argv[argc] = NULL;
    }

    res = setjmp(leaving);
    if (res)
        return res;

    /* resetting ngroups is probably unnecessary.  it will
     * force a new call to getgroups(), which prevents using
     * group data fetched during a previous call.  but the
     * only way the group data could be stale is if there's
     * been an intervening call to setgroups(), and this
     * isn't likely in the case of a shell.  paranoia
     * prevails...
     */
    ngroups = 0;

    /* Implement special cases from POSIX.2, section 4.62.4 */
    if (argc == 1)
        return 1;
    if (argc == 2)
        return *argv[1] == '\0';
//assert(argc);
    /* remember if we saw argc==4 which wants *no* '!' test */
    _off = argc - 4;
    if (_off ?
        (LONE_CHAR(argv[1], '!'))
        : (argv[1][0] != '!' || argv[1][1] != '\0'))
    {
        if (argc == 3)
            return *argv[2] != '\0';

        t_lex(argv[2 + _off]);
        if (t_wp_op && t_wp_op->op_type == BINOP) {
            t_wp = &argv[1 + _off];
            return binop() == _off;
        }
    }
    t_wp = &argv[1];
    res = !oexpr(t_lex(*t_wp));

    if (*t_wp != NULL && *++t_wp != NULL) {
        bb_error_msg("%s: unknown operand", *t_wp);
        return 2;
    }
    return res;
}

static void syntax(const char *op, const char *msg) ATTRIBUTE_NORETURN;
static void syntax(const char *op, const char *msg)
{
    if (op && *op) {
        bb_error_msg("%s: %s", op, msg);
    } else {
        bb_error_msg("%s: %s"+4, msg);
    }
    longjmp(leaving, 2);
}

static arith_t oexpr(enum token n)
{
    arith_t res;

    res = aexpr(n);
    if (t_lex(*++t_wp) == BOR) {
        return oexpr(t_lex(*++t_wp)) || res;
    }
    t_wp--;
    return res;
}

static arith_t aexpr(enum token n)
{
    arith_t res;

    res = nexpr(n);
    if (t_lex(*++t_wp) == BAND)
        return aexpr(t_lex(*++t_wp)) && res;
    t_wp--;
    return res;
}

static arith_t nexpr(enum token n)
{
    if (n == UNOT)
        return !nexpr(t_lex(*++t_wp));
    return primary(n);
}

static arith_t primary(enum token n)
{
    arith_t res;

    if (n == EOI) {
        syntax(NULL, "argument expected");
    }
    if (n == LPAREN) {
        res = oexpr(t_lex(*++t_wp));
        if (t_lex(*++t_wp) != RPAREN)
            syntax(NULL, "closing paren expected");
        return res;
    }
    if (t_wp_op && t_wp_op->op_type == UNOP) {
        /* unary expression */
        if (*++t_wp == NULL)
            syntax(t_wp_op->op_text, "argument expected");
        if (n == STREZ)
            return t_wp[0][0] == '\0';
        if (n == STRNZ)
            return t_wp[0][0] != '\0';
        if (n == FILTT)
            return isatty(getn(*t_wp));
        return filstat(*t_wp, n);
    }

    t_lex(t_wp[1]);
    if (t_wp_op && t_wp_op->op_type == BINOP) {
        return binop();
    }

    return t_wp[0][0] != '\0';
}

static int binop(void)
{
    const char *opnd1, *opnd2;
    struct t_op const *op;
    arith_t val1, val2;

    opnd1 = *t_wp;
    (void) t_lex(*++t_wp);
    op = t_wp_op;

    opnd2 = *++t_wp;
    if (opnd2 == NULL)
        syntax(op->op_text, "argument expected");

    if (is_int_op(op->op_num)) {
        val1 = getn(opnd1);
        val2 = getn(opnd2);
        if (op->op_num == INTEQ)
            return val1 == val2;
        if (op->op_num == INTNE)
            return val1 != val2;
        if (op->op_num == INTGE)
            return val1 >= val2;
        if (op->op_num == INTGT)
            return val1 >  val2;
        if (op->op_num == INTLE)
            return val1 <= val2;
        if (op->op_num == INTLT)
            return val1 <  val2;
    }
    if (is_str_op(op->op_num)) {
        val1 = strcmp(opnd1, opnd2);
        if (op->op_num == STREQ)
            return val1 == 0;
        if (op->op_num == STRNE)
            return val1 != 0;
        if (op->op_num == STRLT)
            return val1 < 0;
        if (op->op_num == STRGT)
            return val1 > 0;
    }
    /* We are sure that these three are by now the only binops we didn't check
     * yet, so we do not check if the class is correct:
     */
/*  if (is_file_op(op->op_num)) */
    {
        struct stat b1, b2;

        if (stat(opnd1, &b1) || stat(opnd2, &b2))
            return 0; /* false, since at least one stat failed */
        if (op->op_num == FILNT)
            return b1.st_mtime > b2.st_mtime;
        if (op->op_num == FILOT)
            return b1.st_mtime < b2.st_mtime;
        if (op->op_num == FILEQ)
            return b1.st_dev == b2.st_dev && b1.st_ino == b2.st_ino;
    }
    return 1; /* NOTREACHED */
}

static int filstat(char *nm, enum token mode)
{
    struct stat s;
    int i = i; /* gcc 3.x thinks it can be used uninitialized */

    if (mode == FILSYM) {
#ifdef S_IFLNK
        if (lstat(nm, &s) == 0) {
            i = S_IFLNK;
            goto filetype;
        }
#endif
        return 0;
    }

    if (stat(nm, &s) != 0)
        return 0;
    if (mode == FILEXIST)
        return 1;
    if (is_file_access(mode)) {
        if (mode == FILRD)
            i = R_OK;
        if (mode == FILWR)
            i = W_OK;
        if (mode == FILEX)
            i = X_OK;
        return test_eaccess(nm, i) == 0;
    }
    if (is_file_type(mode)) {
        if (mode == FILREG)
            i = S_IFREG;
        if (mode == FILDIR)
            i = S_IFDIR;
        if (mode == FILCDEV)
            i = S_IFCHR;
        if (mode == FILBDEV)
            i = S_IFBLK;
        if (mode == FILFIFO) {
#ifdef S_IFIFO
            i = S_IFIFO;
#else
            return 0;
#endif
        }
        if (mode == FILSOCK) {
#ifdef S_IFSOCK
            i = S_IFSOCK;
#else
            return 0;
#endif
        }
 filetype:
        return ((s.st_mode & S_IFMT) == i);
    }
    if (is_file_bit(mode)) {
        if (mode == FILSUID)
            i = S_ISUID;
        if (mode == FILSGID)
            i = S_ISGID;
        if (mode == FILSTCK)
            i = S_ISVTX;
        return ((s.st_mode & i) != 0);
    }
    if (mode == FILGZ)
        return s.st_size > 0L;
    if (mode == FILUID)
        return s.st_uid == geteuid();
    if (mode == FILGID)
        return s.st_gid == getegid();
    return 1; /* NOTREACHED */
}

static enum token t_lex(char *s)
{
    const struct t_op *op;

    t_wp_op = NULL;
    if (s == NULL) {
        return EOI;
    }

    op = ops;
    do {
        if (strcmp(s, op->op_text) == 0) {
            t_wp_op = op;
            return op->op_num;
        }
        op++;
    } while (op < ops + ARRAY_SIZE(ops));

    return OPERAND;
}

/* atoi with error detection */
//XXX: FIXME: duplicate of existing libbb function?
static arith_t getn(const char *s)
{
    char *p;
#if ENABLE_FEATURE_TEST_64
    long long r;
#else
    long r;
#endif

    errno = 0;
#if ENABLE_FEATURE_TEST_64
    r = strtoll(s, &p, 10);
#else
    r = strtol(s, &p, 10);
#endif

    if (errno != 0)
        syntax(s, "out of range");

    if (*(skip_whitespace(p)))
        syntax(s, "bad number");

    return r;
}

/* UNUSED
static int newerf(const char *f1, const char *f2)
{
    struct stat b1, b2;

    return (stat(f1, &b1) == 0 &&
            stat(f2, &b2) == 0 && b1.st_mtime > b2.st_mtime);
}

static int olderf(const char *f1, const char *f2)
{
    struct stat b1, b2;

    return (stat(f1, &b1) == 0 &&
            stat(f2, &b2) == 0 && b1.st_mtime < b2.st_mtime);
}

static int equalf(const char *f1, const char *f2)
{
    struct stat b1, b2;

    return (stat(f1, &b1) == 0 &&
            stat(f2, &b2) == 0 &&
            b1.st_dev == b2.st_dev && b1.st_ino == b2.st_ino);
}
*/

/* Do the same thing access(2) does, but use the effective uid and gid,
   and don't make the mistake of telling root that any file is
   executable. */
static int test_eaccess(char *path, int mode)
{
    struct stat st;
    unsigned int euid = geteuid();

    if (stat(path, &st) < 0)
        return -1;

    if (euid == 0) {
        /* Root can read or write any file. */
        if (mode != X_OK)
            return 0;

        /* Root can execute any file that has any one of the execute
           bits set. */
        if (st.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))
            return 0;
    }

    if (st.st_uid == euid)  /* owner */
        mode <<= 6;
    else if (is_a_group_member(st.st_gid))
        mode <<= 3;

    if (st.st_mode & mode)
        return 0;

    return -1;
}

static void initialize_group_array(void)
{
    ngroups = getgroups(0, NULL);
    if (ngroups > 0) {
        /* FIXME: ash tries so hard to not die on OOM,
         * and we spoil it with just one xrealloc here */
        /* We realloc, because test_main can be entered repeatedly by shell.
         * Testcase (ash): 'while true; do test -x some_file; done'
         * and watch top. (some_file must have owner != you) */
        group_array = xrealloc(group_array, ngroups * sizeof(gid_t));
        getgroups(ngroups, group_array);
    }
}

/* Return non-zero if GID is one that we have in our groups list. */
//XXX: FIXME: duplicate of existing libbb function?
// see toplevel TODO file:
// possible code duplication ingroup() and is_a_group_member()
static int is_a_group_member(gid_t gid)
{
    int i;

    /* Short-circuit if possible, maybe saving a call to getgroups(). */
    if (gid == getgid() || gid == getegid())
        return 1;

    if (ngroups == 0)
        initialize_group_array();

    /* Search through the list looking for GID. */
    for (i = 0; i < ngroups; i++)
        if (gid == group_array[i])
            return 1;

    return 0;
}