/*      $OpenBSD: env.c,v 1.34 2022/05/21 01:21:29 deraadt Exp $        */

/* Copyright 1988,1990,1993,1994 by Paul Vixie
 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
 * Copyright (c) 1997,2000 by Internet Software Consortium, Inc.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>

#include <bitstring.h>          /* for structs.h */
#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>               /* for structs.h */

#include "macros.h"
#include "structs.h"
#include "funcs.h"
#include "globals.h"

char **
env_init(void)
{
        char **p = malloc(sizeof(char *));

        if (p != NULL)
                p[0] = NULL;
        return (p);
}

void
env_free(char **envp)
{
        char **p;

        for (p = envp; *p != NULL; p++)
                free(*p);
        free(envp);
}

char **
env_copy(char **envp)
{
        int count, i, save_errno;
        char **p;

        for (count = 0; envp[count] != NULL; count++)
                continue;
        p = reallocarray(NULL, count+1, sizeof(char *));  /* 1 for the NULL */
        if (p != NULL) {
                for (i = 0; i < count; i++)
                        if ((p[i] = strdup(envp[i])) == NULL) {
                                save_errno = errno;
                                while (--i >= 0)
                                        free(p[i]);
                                free(p);
                                errno = save_errno;
                                return (NULL);
                        }
                p[count] = NULL;
        }
        return (p);
}

static char *
env_find(char *name, char **envp, size_t *count)
{
        char **ep, *p, *q;
        size_t len;

        /*
         * Find name in envp and return its value along with the
         * index it was found at or the length of envp if not found.
         * We treat a '=' in name as end of string for env_set().
         */
        for (p = name; *p && *p != '='; p++)
                continue;
        len = (size_t)(p - name);
        for (ep = envp; (p = *ep) != NULL; ep++) {
                if ((q = strchr(p, '=')) == NULL)
                        continue;
                if ((size_t)(q - p) == len && strncmp(p, name, len) == 0) {
                        p = q + 1;
                        break;
                }
        }
        *count = (size_t)(ep - envp);
        return (p);
}

char *
env_get(char *name, char **envp)
{
        size_t count;

        return (env_find(name, envp, &count));
}

char **
env_set(char **envp, char *envstr)
{
        size_t count;
        char **p, *envcopy;

        if ((envcopy = strdup(envstr)) == NULL)
                return (NULL);

        /* Replace existing name if found. */
        if (env_find(envstr, envp, &count) != NULL) {
                free(envp[count]);
                envp[count] = envcopy;
                return (envp);
        }

        /* Realloc envp and append new variable. */
        p = reallocarray(envp, count + 2, sizeof(char **));
        if (p == NULL) {
                free(envcopy);
                return (NULL);
        }
        p[count++] = envcopy;
        p[count] = NULL;
        return (p);
}

/* The following states are used by load_env(), traversed in order: */
enum env_state {
        NAMEI,          /* First char of NAME, may be quote */
        NAME,           /* Subsequent chars of NAME */
        EQ1,            /* After end of name, looking for '=' sign */
        EQ2,            /* After '=', skipping whitespace */
        VALUEI,         /* First char of VALUE, may be quote */
        VALUE,          /* Subsequent chars of VALUE */
        FINI,           /* All done, skipping trailing whitespace */
        ERROR           /* Error */
};

/* return       -1 = end of file
 *              FALSE = not an env setting (file was repositioned)
 *              TRUE = was an env setting
 */
int
load_env(char *envstr, FILE *f)
{
        long filepos;
        int fileline;
        enum env_state state;
        char name[MAX_ENVSTR], val[MAX_ENVSTR];
        char quotechar, *c, *str;

        filepos = ftell(f);
        fileline = LineNumber;
        skip_comments(f);
        if (get_string(envstr, MAX_ENVSTR, f, "\n") == EOF)
                return (-1);

        bzero(name, sizeof name);
        bzero(val, sizeof val);
        str = name;
        state = NAMEI;
        quotechar = '\0';
        c = envstr;
        while (state != ERROR && *c) {
                switch (state) {
                case NAMEI:
                case VALUEI:
                        if (*c == '\'' || *c == '"')
                                quotechar = *c++;
                        state++;
                        /* FALLTHROUGH */
                case NAME:
                case VALUE:
                        if (quotechar) {
                                if (*c == quotechar) {
                                        state++;
                                        c++;
                                        break;
                                }
                                if (state == NAME && *c == '=') {
                                        state = ERROR;
                                        break;
                                }
                        } else {
                                if (state == NAME) {
                                        if (isspace((unsigned char)*c)) {
                                                c++;
                                                state++;
                                                break;
                                        }
                                        if (*c == '=') {
                                                state++;
                                                break;
                                        }
                                }
                        }
                        *str++ = *c++;
                        break;
                case EQ1:
                        if (*c == '=') {
                                state++;
                                str = val;
                                quotechar = '\0';
                        } else {
                                if (!isspace((unsigned char)*c))
                                        state = ERROR;
                        }
                        c++;
                        break;
                case EQ2:
                case FINI:
                        if (isspace((unsigned char)*c))
                                c++;
                        else
                                state++;
                        break;
                case ERROR:
                        /* handled below */
                        break;
                }
        }
        if (state != FINI && !(state == VALUE && !quotechar))
                goto not_env;
        if (state == VALUE) {
                /* End of unquoted value: trim trailing whitespace */
                c = val + strlen(val);
                while (c > val && isspace((unsigned char)c[-1]))
                        *(--c) = '\0';
        }

        /* 2 fields from parser; looks like an env setting */

        /*
         * This can't overflow because get_string() limited the size of the
         * name and val fields.  Still, it doesn't hurt to be careful...
         */
        if (snprintf(envstr, MAX_ENVSTR, "%s=%s", name, val) >= MAX_ENVSTR)
                goto not_env;
        return (TRUE);
 not_env:
        fseek(f, filepos, SEEK_SET);
        Set_LineNum(fileline);
        return (FALSE);
}