/* 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 Reutner-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 NOFORK applet. Be very careful! */

/* test_main() is called from shells, and we need to be extra careful here.
 * This is true regardless of PREFER_APPLETS and STANDALONE_SHELL
 * state. */


/* 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>
*/

#define TEST_DEBUG 0

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)

#if TEST_DEBUG
int depth;
#define nest_msg(...) do { \
        depth++; \
        fprintf(stderr, "%*s", depth*2, ""); \
        fprintf(stderr, __VA_ARGS__); \
} while (0)
#define unnest_msg(...) do { \
        fprintf(stderr, "%*s", depth*2, ""); \
        fprintf(stderr, __VA_ARGS__); \
        depth--; \
} while (0)
#define dbg_msg(...) do { \
        fprintf(stderr, "%*s", depth*2, ""); \
        fprintf(stderr, __VA_ARGS__); \
} while (0)
#define unnest_msg_and_return(expr, ...) do { \
        number_t __res = (expr); \
        fprintf(stderr, "%*s", depth*2, ""); \
        fprintf(stderr, __VA_ARGS__, res); \
        depth--; \
        return __res; \
} while (0)
static const char *const TOKSTR[] = {
        "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"
};
#else
#define nest_msg(...)   ((void)0)
#define unnest_msg(...) ((void)0)
#define dbg_msg(...)    ((void)0)
#define unnest_msg_and_return(expr, ...) return expr
#endif

enum token_types {
        UNOP,
        BINOP,
        BUNOP,
        BBINOP,
        PAREN
};

struct operator_t {
        char op_text[4];
        unsigned char op_num, op_type;
};

static const struct operator_t 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 number_t;
#else
typedef int number_t;
#endif


/* We try to minimize both static and stack usage. */
struct test_statics {
        char **args;
        /* set only by check_operator(), either to bogus struct
         * or points to matching operator_t struct. Never NULL. */
        const struct operator_t *last_operator;
        gid_t *group_array;
        int ngroups;
        jmp_buf leaving;
};

/* See test_ptr_hack.c */
extern struct test_statics *const test_ptr_to_statics;

#define S (*test_ptr_to_statics)
#define args            (S.args         )
#define last_operator   (S.last_operator)
#define group_array     (S.group_array  )
#define ngroups         (S.ngroups      )
#define leaving         (S.leaving      )

#define INIT_S() do { \
        (*(struct test_statics**)&test_ptr_to_statics) = xzalloc(sizeof(S)); \
        barrier(); \
} while (0)
#define DEINIT_S() do { \
        free(test_ptr_to_statics); \
} while (0)

static number_t primary(enum token n);

static void syntax(const char *op, const char *msg) 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);
}

/* atoi with error detection */
//XXX: FIXME: duplicate of existing libbb function?
static number_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);
}
*/


static enum token check_operator(char *s)
{
        static const struct operator_t no_op = {
                .op_num = -1,
                .op_type = -1
        };
        const struct operator_t *op;

        last_operator = &no_op;
        if (s == NULL) {
                return EOI;
        }

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

        return OPERAND;
}


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

        opnd1 = *args;
        check_operator(*++args);
        op = last_operator;

        opnd2 = *++args;
        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 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;
}


/* 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 int filstat(char *nm, enum token mode)
{
        struct stat s;
        unsigned 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 number_t nexpr(enum token n)
{
        number_t res;

        nest_msg(">nexpr(%s)\n", TOKSTR[n]);
        if (n == UNOT) {
                res = !nexpr(check_operator(*++args));
                unnest_msg("<nexpr:%lld\n", res);
                return res;
        }
        res = primary(n);
        unnest_msg("<nexpr:%lld\n", res);
        return res;
}


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

        nest_msg(">aexpr(%s)\n", TOKSTR[n]);
        res = nexpr(n);
        dbg_msg("aexpr: nexpr:%lld, next args:%s\n", res, args[1]);
        if (check_operator(*++args) == BAND) {
                dbg_msg("aexpr: arg is AND, next args:%s\n", args[1]);
                res = aexpr(check_operator(*++args)) && res;
                unnest_msg("<aexpr:%lld\n", res);
                return res;
        }
        args--;
        unnest_msg("<aexpr:%lld, args:%s\n", res, args[0]);
        return res;
}


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

        nest_msg(">oexpr(%s)\n", TOKSTR[n]);
        res = aexpr(n);
        dbg_msg("oexpr: aexpr:%lld, next args:%s\n", res, args[1]);
        if (check_operator(*++args) == BOR) {
                dbg_msg("oexpr: next arg is OR, next args:%s\n", args[1]);
                res = oexpr(check_operator(*++args)) || res;
                unnest_msg("<oexpr:%lld\n", res);
                return res;
        }
        args--;
        unnest_msg("<oexpr:%lld, args:%s\n", res, args[0]);
        return res;
}


static number_t primary(enum token n)
{
#if TEST_DEBUG
        number_t res = res; /* for compiler */
#else
        number_t res;
#endif
        const struct operator_t *args0_op;

        nest_msg(">primary(%s)\n", TOKSTR[n]);
        if (n == EOI) {
                syntax(NULL, "argument expected");
        }
        if (n == LPAREN) {
                res = oexpr(check_operator(*++args));
                if (check_operator(*++args) != RPAREN)
                        syntax(NULL, "closing paren expected");
                unnest_msg("<primary:%lld\n", res);
                return res;
        }

        /* coreutils 6.9 checks "is args[1] binop and args[2] exist?" first,
         * do the same */
        args0_op = last_operator;
        /* last_operator = operator at args[1] */
        if (check_operator(args[1]) != EOI) { /* if args[1] != NULL */
                if (args[2]) {
                        // coreutils also does this:
                        // if (args[3] && args[0]="-l" && args[2] is BINOP)
                        //      return binop(1 /* prepended by -l */);
                        if (last_operator->op_type == BINOP)
                                unnest_msg_and_return(binop(), "<primary: binop:%lld\n");
                }
        }
        /* check "is args[0] unop?" second */
        if (args0_op->op_type == UNOP) {
                /* unary expression */
                if (args[1] == NULL)
//                      syntax(args0_op->op_text, "argument expected");
                        goto check_emptiness;
                args++;
                if (n == STREZ)
                        unnest_msg_and_return(args[0][0] == '\0', "<primary:%lld\n");
                if (n == STRNZ)
                        unnest_msg_and_return(args[0][0] != '\0', "<primary:%lld\n");
                if (n == FILTT)
                        unnest_msg_and_return(isatty(getn(*args)), "<primary: isatty(%s)%lld\n", *args);
                unnest_msg_and_return(filstat(*args, n), "<primary: filstat(%s):%lld\n", *args);
        }

        /*check_operator(args[1]); - already done */
        if (last_operator->op_type == BINOP) {
                /* args[2] is known to be NULL, isn't it bound to fail? */
                unnest_msg_and_return(binop(), "<primary:%lld\n");
        }
 check_emptiness:
        unnest_msg_and_return(args[0][0] != '\0', "<primary:%lld\n");
}


int test_main(int argc, char **argv)
{
        int res;
        const char *arg0;
//      bool negate = 0;

        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;
        }

        /* We must do DEINIT_S() prior to returning */
        INIT_S();

        res = setjmp(leaving);
        if (res)
                goto ret;

        /* 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;

        //argc--;
        argv++;

        /* Implement special cases from POSIX.2, section 4.62.4 */
        if (!argv[0]) { /* "test" */
                res = 1;
                goto ret;
        }
#if 0
// Now it's fixed in the parser and should not be needed
        if (LONE_CHAR(argv[0], '!') && argv[1]) {
                negate = 1;
                //argc--;
                argv++;
        }
        if (!argv[1]) { /* "test [!] arg" */
                res = (*argv[0] == '\0');
                goto ret;
        }
        if (argv[2] && !argv[3]) {
                check_operator(argv[1]);
                if (last_operator->op_type == BINOP) {
                        /* "test [!] arg1 <binary_op> arg2" */
                        args = &argv[0];
                        res = (binop() == 0);
                        goto ret;
                }
        }

        /* Some complex expression. Undo '!' removal */
        if (negate) {
                negate = 0;
                //argc++;
                argv--;
        }
#endif
        args = &argv[0];
        res = !oexpr(check_operator(*args));

        if (*args != NULL && *++args != NULL) {
                /* TODO: example when this happens? */
                bb_error_msg("%s: unknown operand", *args);
                res = 2;
        }
 ret:
        DEINIT_S();
//      return negate ? !res : res;
        return res;
}