/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * 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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <unistd.h>
#include <stdlib.h>
#include <paths.h>

/*
 * Shell variables.
 */

#include <locale.h>
#include <langinfo.h>

#include "shell.h"
#include "output.h"
#include "expand.h"
#include "nodes.h"      /* for other headers */
#include "eval.h"       /* defines cmdenviron */
#include "exec.h"
#include "syntax.h"
#include "options.h"
#include "mail.h"
#include "var.h"
#include "memalloc.h"
#include "error.h"
#include "mystring.h"
#include "parser.h"
#include "builtins.h"
#ifndef NO_HISTORY
#include "myhistedit.h"
#endif


#ifndef VTABSIZE
#define VTABSIZE 39
#endif


struct varinit {
        struct var *var;
        int flags;
        const char *text;
        void (*func)(const char *);
};


#ifndef NO_HISTORY
struct var vhistsize;
struct var vterm;
#endif
struct var vifs;
struct var vmail;
struct var vmpath;
struct var vpath;
struct var vps1;
struct var vps2;
struct var vps4;
static struct var voptind;
struct var vdisvfork;

struct localvar *localvars;
int forcelocal;

static const struct varinit varinit[] = {
#ifndef NO_HISTORY
        { &vhistsize,   VUNSET,                         "HISTSIZE=",
          sethistsize },
#endif
        { &vifs,        0,                              "IFS= \t\n",
          NULL },
        { &vmail,       VUNSET,                         "MAIL=",
          NULL },
        { &vmpath,      VUNSET,                         "MAILPATH=",
          NULL },
        { &vpath,       0,                              "PATH=" _PATH_DEFPATH,
          changepath },
        /*
         * vps1 depends on uid
         */
        { &vps2,        0,                              "PS2=> ",
          NULL },
        { &vps4,        0,                              "PS4=+ ",
          NULL },
#ifndef NO_HISTORY
        { &vterm,       VUNSET,                         "TERM=",
          setterm },
#endif
        { &voptind,     0,                              "OPTIND=1",
          getoptsreset },
        { &vdisvfork,   VUNSET,                         "SH_DISABLE_VFORK=",
          NULL },
        { NULL, 0,                              NULL,
          NULL }
};

static struct var *vartab[VTABSIZE];

static const char *const locale_names[7] = {
        "LC_COLLATE", "LC_CTYPE", "LC_MONETARY",
        "LC_NUMERIC", "LC_TIME", "LC_MESSAGES", NULL
};
static const int locale_categories[7] = {
        LC_COLLATE, LC_CTYPE, LC_MONETARY, LC_NUMERIC, LC_TIME, LC_MESSAGES, 0
};

static int varequal(const char *, const char *);
static struct var *find_var(const char *, struct var ***, int *);
static int localevar(const char *);
static void setvareq_const(const char *s, int flags);

extern char **environ;

/*
 * This routine initializes the builtin variables and imports the environment.
 * It is called when the shell is initialized.
 */

void
initvar(void)
{
        char ppid[20];
        const struct varinit *ip;
        struct var *vp;
        struct var **vpp;
        char **envp;

        for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
                if (find_var(ip->text, &vpp, &vp->name_len) != NULL)
                        continue;
                vp->next = *vpp;
                *vpp = vp;
                vp->text = __DECONST(char *, ip->text);
                vp->flags = ip->flags | VSTRFIXED | VTEXTFIXED;
                vp->func = ip->func;
        }
        /*
         * PS1 depends on uid
         */
        if (find_var("PS1", &vpp, &vps1.name_len) == NULL) {
                vps1.next = *vpp;
                *vpp = &vps1;
                vps1.text = __DECONST(char *, geteuid() ? "PS1=$ " : "PS1=# ");
                vps1.flags = VSTRFIXED|VTEXTFIXED;
        }
        fmtstr(ppid, sizeof(ppid), "%d", (int)getppid());
        setvarsafe("PPID", ppid, 0);
        for (envp = environ ; *envp ; envp++) {
                if (strchr(*envp, '=')) {
                        setvareq(*envp, VEXPORT|VTEXTFIXED);
                }
        }
        setvareq_const("OPTIND=1", 0);
        setvareq_const("IFS= \t\n", 0);
}

/*
 * Safe version of setvar, returns 1 on success 0 on failure.
 */

int
setvarsafe(const char *name, const char *val, int flags)
{
        struct jmploc jmploc;
        struct jmploc *const savehandler = handler;
        int err = 0;
        int inton;

        inton = is_int_on();
        if (setjmp(jmploc.loc))
                err = 1;
        else {
                handler = &jmploc;
                setvar(name, val, flags);
        }
        handler = savehandler;
        SETINTON(inton);
        return err;
}

/*
 * Set the value of a variable.  The flags argument is stored with the
 * flags of the variable.  If val is NULL, the variable is unset.
 */

void
setvar(const char *name, const char *val, int flags)
{
        const char *p;
        size_t len;
        size_t namelen;
        size_t vallen;
        char *nameeq;
        int isbad;

        isbad = 0;
        p = name;
        if (! is_name(*p))
                isbad = 1;
        p++;
        for (;;) {
                if (! is_in_name(*p)) {
                        if (*p == '\0' || *p == '=')
                                break;
                        isbad = 1;
                }
                p++;
        }
        namelen = p - name;
        if (isbad)
                error("%.*s: bad variable name", (int)namelen, name);
        len = namelen + 2;              /* 2 is space for '=' and '\0' */
        if (val == NULL) {
                flags |= VUNSET;
                vallen = 0;
        } else {
                vallen = strlen(val);
                len += vallen;
        }
        INTOFF;
        nameeq = ckmalloc(len);
        memcpy(nameeq, name, namelen);
        nameeq[namelen] = '=';
        if (val)
                memcpy(nameeq + namelen + 1, val, vallen + 1);
        else
                nameeq[namelen + 1] = '\0';
        setvareq(nameeq, flags);
        INTON;
}

static int
localevar(const char *s)
{
        const char *const *ss;

        if (*s != 'L')
                return 0;
        if (varequal(s + 1, "ANG"))
                return 1;
        if (strncmp(s + 1, "C_", 2) != 0)
                return 0;
        if (varequal(s + 3, "ALL"))
                return 1;
        for (ss = locale_names; *ss ; ss++)
                if (varequal(s + 3, *ss + 3))
                        return 1;
        return 0;
}


/*
 * Sets/unsets an environment variable from a pointer that may actually be a
 * pointer into environ where the string should not be manipulated.
 */
static void
change_env(const char *s, int set)
{
        char *eqp;
        char *ss;

        INTOFF;
        ss = savestr(s);
        if ((eqp = strchr(ss, '=')) != NULL)
                *eqp = '\0';
        if (set && eqp != NULL)
                (void) setenv(ss, eqp + 1, 1);
        else
                (void) unsetenv(ss);
        ckfree(ss);
        INTON;

        return;
}


/*
 * Same as setvar except that the variable and value are passed in
 * the first argument as name=value.  Since the first argument will
 * be actually stored in the table, it should not be a string that
 * will go away.
 */

void
setvareq(char *s, int flags)
{
        struct var *vp, **vpp;
        int nlen;

        if (aflag)
                flags |= VEXPORT;
        if (forcelocal && !(flags & (VNOSET | VNOLOCAL)))
                mklocal(s);
        vp = find_var(s, &vpp, &nlen);
        if (vp != NULL) {
                if (vp->flags & VREADONLY) {
                        if ((flags & (VTEXTFIXED|VSTACK)) == 0)
                                ckfree(s);
                        error("%.*s: is read only", vp->name_len, vp->text);
                }
                if (flags & VNOSET) {
                        if ((flags & (VTEXTFIXED|VSTACK)) == 0)
                                ckfree(s);
                        return;
                }
                INTOFF;

                if (vp->func && (flags & VNOFUNC) == 0)
                        (*vp->func)(s + vp->name_len + 1);

                if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
                        ckfree(vp->text);

                vp->flags &= ~(VTEXTFIXED|VSTACK|VUNSET);
                vp->flags |= flags;
                vp->text = s;

                /*
                 * We could roll this to a function, to handle it as
                 * a regular variable function callback, but why bother?
                 *
                 * Note: this assumes iflag is not set to 1 initially.
                 * As part of initvar(), this is called before arguments
                 * are looked at.
                 */
                if ((vp == &vmpath || (vp == &vmail && ! mpathset())) &&
                    iflag == 1)
                        chkmail(1);
                if ((vp->flags & VEXPORT) && localevar(s)) {
                        change_env(s, 1);
                        (void) setlocale(LC_ALL, "");
                        updatecharset();
                }
                INTON;
                return;
        }
        /* not found */
        if (flags & VNOSET) {
                if ((flags & (VTEXTFIXED|VSTACK)) == 0)
                        ckfree(s);
                return;
        }
        INTOFF;
        vp = ckmalloc(sizeof (*vp));
        vp->flags = flags;
        vp->text = s;
        vp->name_len = nlen;
        vp->next = *vpp;
        vp->func = NULL;
        *vpp = vp;
        if ((vp->flags & VEXPORT) && localevar(s)) {
                change_env(s, 1);
                (void) setlocale(LC_ALL, "");
                updatecharset();
        }
        INTON;
}


static void
setvareq_const(const char *s, int flags)
{
        setvareq(__DECONST(char *, s), flags | VTEXTFIXED);
}


/*
 * Process a linked list of variable assignments.
 */

void
listsetvar(struct arglist *list, int flags)
{
        int i;

        INTOFF;
        for (i = 0; i < list->count; i++)
                setvareq(savestr(list->args[i]), flags);
        INTON;
}



/*
 * Find the value of a variable.  Returns NULL if not set.
 */

char *
lookupvar(const char *name)
{
        struct var *v;

        v = find_var(name, NULL, NULL);
        if (v == NULL || v->flags & VUNSET)
                return NULL;
        return v->text + v->name_len + 1;
}



/*
 * Search the environment of a builtin command.  If the second argument
 * is nonzero, return the value of a variable even if it hasn't been
 * exported.
 */

char *
bltinlookup(const char *name, int doall)
{
        struct var *v;
        char *result;
        int i;

        result = NULL;
        if (cmdenviron) for (i = 0; i < cmdenviron->count; i++) {
                if (varequal(cmdenviron->args[i], name))
                        result = strchr(cmdenviron->args[i], '=') + 1;
        }
        if (result != NULL)
                return result;

        v = find_var(name, NULL, NULL);
        if (v == NULL || v->flags & VUNSET ||
            (!doall && (v->flags & VEXPORT) == 0))
                return NULL;
        return v->text + v->name_len + 1;
}


/*
 * Set up locale for a builtin (LANG/LC_* assignments).
 */
void
bltinsetlocale(void)
{
        int act = 0;
        char *loc, *locdef;
        int i;

        if (cmdenviron) for (i = 0; i < cmdenviron->count; i++) {
                if (localevar(cmdenviron->args[i])) {
                        act = 1;
                        break;
                }
        }
        if (!act)
                return;
        loc = bltinlookup("LC_ALL", 0);
        INTOFF;
        if (loc != NULL) {
                setlocale(LC_ALL, loc);
                INTON;
                updatecharset();
                return;
        }
        locdef = bltinlookup("LANG", 0);
        for (i = 0; locale_names[i] != NULL; i++) {
                loc = bltinlookup(locale_names[i], 0);
                if (loc == NULL)
                        loc = locdef;
                if (loc != NULL)
                        setlocale(locale_categories[i], loc);
        }
        INTON;
        updatecharset();
}

/*
 * Undo the effect of bltinlocaleset().
 */
void
bltinunsetlocale(void)
{
        int i;

        INTOFF;
        if (cmdenviron) for (i = 0; i < cmdenviron->count; i++) {
                if (localevar(cmdenviron->args[i])) {
                        setlocale(LC_ALL, "");
                        updatecharset();
                        break;
                }
        }
        INTON;
}

/*
 * Update the localeisutf8 flag.
 */
void
updatecharset(void)
{
        char *charset;

        charset = nl_langinfo(CODESET);
        localeisutf8 = !strcmp(charset, "UTF-8");
}

void
initcharset(void)
{
        updatecharset();
        initial_localeisutf8 = localeisutf8;
}

/*
 * Generate a list of exported variables.  This routine is used to construct
 * the third argument to execve when executing a program.
 */

char **
environment(void)
{
        int nenv;
        struct var **vpp;
        struct var *vp;
        char **env, **ep;

        nenv = 0;
        for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
                for (vp = *vpp ; vp ; vp = vp->next)
                        if ((vp->flags & (VEXPORT|VUNSET)) == VEXPORT)
                                nenv++;
        }
        ep = env = stalloc((nenv + 1) * sizeof *env);
        for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
                for (vp = *vpp ; vp ; vp = vp->next)
                        if ((vp->flags & (VEXPORT|VUNSET)) == VEXPORT)
                                *ep++ = vp->text;
        }
        *ep = NULL;
        return env;
}


static int
var_compare(const void *a, const void *b)
{
        const char *const *sa, *const *sb;

        sa = a;
        sb = b;
        /*
         * This compares two var=value strings which creates a different
         * order from what you would probably expect.  POSIX is somewhat
         * ambiguous on what should be sorted exactly.
         */
        return strcoll(*sa, *sb);
}


/*
 * Command to list all variables which are set.  This is invoked from the
 * set command when it is called without any options or operands.
 */

int
showvarscmd(int argc __unused, char **argv __unused)
{
        struct var **vpp;
        struct var *vp;
        const char *s;
        const char **vars;
        int i, n;

        /*
         * POSIX requires us to sort the variables.
         */
        n = 0;
        for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) {
                for (vp = *vpp; vp; vp = vp->next) {
                        if (!(vp->flags & VUNSET))
                                n++;
                }
        }

        INTOFF;
        vars = ckmalloc(n * sizeof(*vars));
        i = 0;
        for (vpp = vartab; vpp < vartab + VTABSIZE; vpp++) {
                for (vp = *vpp; vp; vp = vp->next) {
                        if (!(vp->flags & VUNSET))
                                vars[i++] = vp->text;
                }
        }

        qsort(vars, n, sizeof(*vars), var_compare);
        for (i = 0; i < n; i++) {
                /*
                 * Skip improper variable names so the output remains usable as
                 * shell input.
                 */
                if (!isassignment(vars[i]))
                        continue;
                s = strchr(vars[i], '=');
                s++;
                outbin(vars[i], s - vars[i], out1);
                out1qstr(s);
                out1c('\n');
        }
        ckfree(vars);
        INTON;

        return 0;
}



/*
 * The export and readonly commands.
 */

int
exportcmd(int argc __unused, char **argv)
{
        struct var **vpp;
        struct var *vp;
        char **ap;
        char *name;
        char *p;
        char *cmdname;
        int ch, values;
        int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;

        cmdname = argv[0];
        values = 0;
        while ((ch = nextopt("p")) != '\0') {
                switch (ch) {
                case 'p':
                        values = 1;
                        break;
                }
        }

        if (values && *argptr != NULL)
                error("-p requires no arguments");
        if (*argptr != NULL) {
                for (ap = argptr; (name = *ap) != NULL; ap++) {
                        if ((p = strchr(name, '=')) != NULL) {
                                p++;
                        } else {
                                vp = find_var(name, NULL, NULL);
                                if (vp != NULL) {
                                        vp->flags |= flag;
                                        if ((vp->flags & VEXPORT) && localevar(vp->text)) {
                                                change_env(vp->text, 1);
                                                (void) setlocale(LC_ALL, "");
                                                updatecharset();
                                        }
                                        continue;
                                }
                        }
                        setvar(name, p, flag);
                }
        } else {
                for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
                        for (vp = *vpp ; vp ; vp = vp->next) {
                                if (vp->flags & flag) {
                                        if (values) {
                                                /*
                                                 * Skip improper variable names
                                                 * so the output remains usable
                                                 * as shell input.
                                                 */
                                                if (!isassignment(vp->text))
                                                        continue;
                                                out1str(cmdname);
                                                out1c(' ');
                                        }
                                        if (values && !(vp->flags & VUNSET)) {
                                                outbin(vp->text,
                                                    vp->name_len + 1, out1);
                                                out1qstr(vp->text +
                                                    vp->name_len + 1);
                                        } else
                                                outbin(vp->text, vp->name_len,
                                                    out1);
                                        out1c('\n');
                                }
                        }
                }
        }
        return 0;
}


/*
 * The "local" command.
 */

int
localcmd(int argc __unused, char **argv __unused)
{
        char *name;

        nextopt("");
        if (! in_function())
                error("Not in a function");
        while ((name = *argptr++) != NULL) {
                mklocal(name);
        }
        return 0;
}


/*
 * Make a variable a local variable.  When a variable is made local, it's
 * value and flags are saved in a localvar structure.  The saved values
 * will be restored when the shell function returns.  We handle the name
 * "-" as a special case.
 */

void
mklocal(char *name)
{
        struct localvar *lvp;
        struct var **vpp;
        struct var *vp;

        INTOFF;
        lvp = ckmalloc(sizeof (struct localvar));
        if (name[0] == '-' && name[1] == '\0') {
                lvp->text = ckmalloc(sizeof optval);
                memcpy(lvp->text, optval, sizeof optval);
                vp = NULL;
        } else {
                vp = find_var(name, &vpp, NULL);
                if (vp == NULL) {
                        if (strchr(name, '='))
                                setvareq(savestr(name), VSTRFIXED | VNOLOCAL);
                        else
                                setvar(name, NULL, VSTRFIXED | VNOLOCAL);
                        vp = *vpp;      /* the new variable */
                        lvp->text = NULL;
                        lvp->flags = VUNSET;
                } else {
                        lvp->text = vp->text;
                        lvp->flags = vp->flags;
                        vp->flags |= VSTRFIXED|VTEXTFIXED;
                        if (name[vp->name_len] == '=')
                                setvareq(savestr(name), VNOLOCAL);
                }
        }
        lvp->vp = vp;
        lvp->next = localvars;
        localvars = lvp;
        INTON;
}


/*
 * Called after a function returns.
 */

void
poplocalvars(void)
{
        struct localvar *lvp;
        struct var *vp;
        int islocalevar;

        INTOFF;
        while ((lvp = localvars) != NULL) {
                localvars = lvp->next;
                vp = lvp->vp;
                if (vp == NULL) {       /* $- saved */
                        memcpy(optval, lvp->text, sizeof optval);
                        ckfree(lvp->text);
                        optschanged();
                } else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
                        vp->flags &= ~VREADONLY;
                        (void)unsetvar(vp->text);
                } else {
                        islocalevar = (vp->flags | lvp->flags) & VEXPORT &&
                            localevar(lvp->text);
                        if ((vp->flags & VTEXTFIXED) == 0)
                                ckfree(vp->text);
                        vp->flags = lvp->flags;
                        vp->text = lvp->text;
                        if (vp->func)
                                (*vp->func)(vp->text + vp->name_len + 1);
                        if (islocalevar) {
                                change_env(vp->text, vp->flags & VEXPORT &&
                                    (vp->flags & VUNSET) == 0);
                                setlocale(LC_ALL, "");
                                updatecharset();
                        }
                }
                ckfree(lvp);
        }
        INTON;
}


int
setvarcmd(int argc, char **argv)
{
        if (argc <= 2)
                return unsetcmd(argc, argv);
        else if (argc == 3)
                setvar(argv[1], argv[2], 0);
        else
                error("too many arguments");
        return 0;
}


/*
 * The unset builtin command.
 */

int
unsetcmd(int argc __unused, char **argv __unused)
{
        char **ap;
        int i;
        int flg_func = 0;
        int flg_var = 0;
        int ret = 0;

        while ((i = nextopt("vf")) != '\0') {
                if (i == 'f')
                        flg_func = 1;
                else
                        flg_var = 1;
        }
        if (flg_func == 0 && flg_var == 0)
                flg_var = 1;

        INTOFF;
        for (ap = argptr; *ap ; ap++) {
                if (flg_func)
                        ret |= unsetfunc(*ap);
                if (flg_var)
                        ret |= unsetvar(*ap);
        }
        INTON;
        return ret;
}


/*
 * Unset the specified variable.
 * Called with interrupts off.
 */

int
unsetvar(const char *s)
{
        struct var **vpp;
        struct var *vp;

        vp = find_var(s, &vpp, NULL);
        if (vp == NULL)
                return (0);
        if (vp->flags & VREADONLY)
                return (1);
        if (vp->text[vp->name_len + 1] != '\0')
                setvar(s, "", 0);
        if ((vp->flags & VEXPORT) && localevar(vp->text)) {
                change_env(s, 0);
                setlocale(LC_ALL, "");
                updatecharset();
        }
        vp->flags &= ~VEXPORT;
        vp->flags |= VUNSET;
        if ((vp->flags & VSTRFIXED) == 0) {
                if ((vp->flags & VTEXTFIXED) == 0)
                        ckfree(vp->text);
                *vpp = vp->next;
                ckfree(vp);
        }
        return (0);
}



/*
 * Returns true if the two strings specify the same variable.  The first
 * variable name is terminated by '='; the second may be terminated by
 * either '=' or '\0'.
 */

static int
varequal(const char *p, const char *q)
{
        while (*p == *q++) {
                if (*p++ == '=')
                        return 1;
        }
        if (*p == '=' && *(q - 1) == '\0')
                return 1;
        return 0;
}

/*
 * Search for a variable.
 * 'name' may be terminated by '=' or a NUL.
 * vppp is set to the pointer to vp, or the list head if vp isn't found
 * lenp is set to the number of characters in 'name'
 */

static struct var *
find_var(const char *name, struct var ***vppp, int *lenp)
{
        unsigned int hashval;
        int len;
        struct var *vp, **vpp;
        const char *p = name;

        hashval = 0;
        while (*p && *p != '=')
                hashval = 2 * hashval + (unsigned char)*p++;
        len = p - name;

        if (lenp)
                *lenp = len;
        vpp = &vartab[hashval % VTABSIZE];
        if (vppp)
                *vppp = vpp;

        for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
                if (vp->name_len != len)
                        continue;
                if (memcmp(vp->text, name, len) != 0)
                        continue;
                if (vppp)
                        *vppp = vpp;
                return vp;
        }
        return NULL;
}