usr/src/lib/libmail/common/xgetenv.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
  28 /*        All Rights Reserved   */
  29
  30 #pragma ident   "%Z%%M% %I%     %E% SMI"
  31
  32 /*
  33  *  NAME
  34  *      xsetenv, xgetenv, Xgetenv - manage an alternate environment space
  35  *
  36  *  SYNOPSIS
  37  *      int ret = xsetenv(file)
  38  *      char *x = xgetenv("FOO");
  39  *      char *x = Xgetenv("FOO");
  40  *
  41  *  DESCRIPTION
  42  *      xsetenv() reads the given file into an internal buffer
  43  *      and sets up an alternate environment.
  44  *
  45  *      Return values:  1 - OKAY
  46  *                      0 - troubles reading the file
  47  *                      -1 - troubles opening the file
  48  *
  49  *      xgetenv() returns the environment value from the
  50  *      alternate environment.
  51  *
  52  *      Return values:  (char *)0 - no value for that variable
  53  *                      pointer  - the value
  54  *
  55  *      Xgetenv() returns the environment value from the
  56  *      alternate environment.
  57  *
  58  *      Return values:  "" - no value for that variable
  59  *                      pointer  - the value
  60  *
  61  *  LIMITATIONS
  62  *      Assumes the environment is < 5120 bytes, as in the UNIX
  63  *      System environment. Assumes < 512 lines in the file.
  64  *      These values may be adjusted below.
  65  */
  66
  67 #include <sys/types.h>
  68 #include "libmail.h"
  69 #include <stdio.h>
  70 #include <string.h>
  71 #include <fcntl.h>
  72 #include <ctype.h>
  73
  74 #include <stdlib.h>
  75 #include <unistd.h>
  76
  77 #define MAXVARS  512
  78 #define MAXENV  5120
  79
  80 static char **xenv = 0;
  81 static char *(xenvptrs[MAXVARS]);
  82 static char xbuf[MAXENV];
  83
  84 static void reduce(char *);
  85
  86 /*
  87  *      set up an environment buffer
  88  *      and the pointers into it
  89  */
  90 int
  91 xsetenv(char *xfile)
  92 {
  93         int envctr, infd;
  94         ssize_t i, nread;
  95
  96         /* Open the file */
  97         infd = open(xfile, O_RDONLY);
  98         if (infd == -1) {
  99                 return (-1);
 100         }
 101
 102         /* Read in the entire file. */
 103         nread = read(infd, xbuf, sizeof (xbuf));
 104         if (nread < 0) {
 105                 (void) close(infd);
 106                 return (0);
 107         }
 108
 109         /*
 110          * Set up pointers into the buffer.
 111          * Replace \n with \0.
 112          * Collapse white space around the = sign and at the
 113          * beginning and end of the line.
 114          */
 115         xenv = xenvptrs;
 116         xenv[0] = &xbuf[0];
 117         for (i = 0, envctr = 0; i < nread; i++) {
 118                 if (xbuf[i] == '\n') {
 119                         xbuf[i] = '\0';
 120                         reduce(xenv[envctr]);
 121                         xenv[++envctr] = &xbuf[i+1];
 122                         if (envctr == MAXVARS) {
 123                                 break;
 124                         }
 125                 }
 126         }
 127
 128         xenv[envctr] = 0;
 129         (void) close(infd);
 130         return (1);
 131 }
 132
 133 /*
 134  *      Let getenv() do the dirty work
 135  *      of looking up the variable. We
 136  *      do this by temporarily resetting
 137  *      environ to point to the local area.
 138  */
 139 char *
 140 xgetenv(char *env)
 141 {
 142         extern char **environ;
 143         char *ret, **svenviron = environ;
 144
 145         environ = xenv;
 146         ret = getenv(env);
 147         environ = svenviron;
 148         return (ret);
 149 }
 150
 151 /*
 152  *      Let xgetenv() do the dirty work
 153  *      of looking up the variable.
 154  */
 155 char *
 156 Xgetenv(char *env)
 157 {
 158         char *ret = xgetenv(env);
 159         return (ret ? ret : "");
 160 }
 161
 162 /*
 163  * Remove the spaces within the environment variable.
 164  * The variable can look like this:
 165  *
 166  * <sp1> variable <sp2> = <sp3> value <sp4> \0
 167  *
 168  * All spaces can be removed, except within
 169  * the variable name and the value.
 170  */
 171
 172 static void
 173 reduce(char *from)
 174 {
 175         char *to = from;
 176         char *svfrom = from;
 177
 178         /* <sp1> */
 179         while (*from &&isspace((int)*from))
 180                 from++;
 181
 182         /* variable */
 183         while (*from && (*from != '=') && !isspace((int)*from))
 184                 *to++ = *from++;
 185
 186         /* <sp2> */
 187         while (*from && isspace((int)*from))
 188                 from++;
 189
 190         /* = */
 191         if (*from == '=')
 192                 *to++ = *from++;
 193
 194         /* <sp3> */
 195         while (*from && isspace((int)*from))
 196                 from++;
 197
 198         /* value */
 199         while (*from)
 200                 *to++ = *from++;
 201
 202         /* <sp4> */
 203         while ((to > svfrom) && isspace((int)to[-1]))
 204                 to--;
 205         *to = '\0';
 206 }