setenv_r.c

俄罗斯高人Mamaich的Pocket gcc编译器（运行在PocketPC上）的全部源代码。

/* This file may have been modified by DJ Delorie (Jan 1991).  If so,
** these modifications are Copyright (C) 1991 DJ Delorie.
*/

/*
 * Copyright (c) 1987 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that: (1) source distributions retain this entire copyright
 * notice and comment, and (2) distributions including binaries display
 * the following acknowledgement:  ``This product includes software
 * developed by the University of California, Berkeley and its contributors''
 * in the documentation or other materials provided with the distribution
 * and in all advertising materials mentioning features or use of this
 * software. 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include <reent.h>

#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include "envlock.h"

extern char **environ;

/* Only deal with a pointer to environ, to work around subtle bugs with shared
   libraries and/or small data systems where the user declares his own
   'environ'.  */
static char ***p_environ = &environ;

/* _findenv_r is defined in getenv_r.c.  */
extern char *_findenv_r _PARAMS((struct _reent *, const char *, int *));

/*
 * _setenv_r --
 *      Set the value of the environmental variable "name" to be
 *      "value".  If rewrite is set, replace any current value.
 */

int
_DEFUN(_setenv_r, (reent_ptr, name, value, rewrite),
       struct _reent *reent_ptr _AND
       _CONST char *name _AND _CONST char *value _AND int rewrite)
{
  static int alloced;           /* if allocated space before */
  register char *C;
  int l_value, offset;

  ENV_LOCK;

  if (*value == '=')            /* no `=' in value */
    ++value;
  l_value = strlen(value);
  if ((C = _findenv_r(reent_ptr, name, &offset))) {     /* find if already exists */
    if (!rewrite) {
      ENV_UNLOCK;
      return 0;
    }
    if (strlen(C) >= l_value) { /* old larger; copy over */
      while ((*C++ = *value++) != 0);
      ENV_UNLOCK;
      /* if we are changing the TZ environment variable, update timezone info */
      if (strcmp(name, "TZ") == 0)
        tzset();
      return 0;
    }
  } else {                      /* create new slot */
    register int cnt;
    register char **P;

    for (P = *p_environ, cnt = 0; *P; ++P, ++cnt);
    if (alloced) {              /* just increase size */
      *p_environ = (char **) _realloc_r(reent_ptr, (char *) environ,
                                        (size_t) (sizeof(char *) *
                                                  (cnt + 2)));
      if (!*p_environ) {
        ENV_UNLOCK;
        return -1;
      }
    } else {                    /* get new space */
      alloced = 1;              /* copy old entries into it */
      P =
        (char **) _malloc_r(reent_ptr, (size_t) (sizeof(char *) * (cnt + 2)));
      if (!P) {
        ENV_UNLOCK;
        return (-1);
      }
      bcopy((char *) *p_environ, (char *) P, cnt * sizeof(char *));
      *p_environ = P;
    }
    (*p_environ)[cnt + 1] = NULL;
    offset = cnt;
  }
  for (C = (char *) name; *C && *C != '='; ++C);        /* no `=' in name */
  if (!((*p_environ)[offset] = /* name + `=' + value */
        _malloc_r(reent_ptr, (size_t) ((int) (C - name) + l_value + 2)))) {
    ENV_UNLOCK;
    return -1;
  }
  for (C = (*p_environ)[offset]; (*C = *name++) && *C != '='; ++C);
  for (*C++ = '='; (*C++ = *value++) != 0;);

  ENV_UNLOCK;

  /* if we are setting the TZ environment variable, update timezone info */
  if (strcmp(name, "TZ") == 0)
    tzset();

  return 0;
}

/*
 * _unsetenv_r(name) --
 *      Delete environmental variable "name".
 */
void
_DEFUN(_unsetenv_r, (reent_ptr, name),
       struct _reent *reent_ptr _AND _CONST char *name)
{
  register char **P;
  int offset;

  ENV_LOCK;

  while (_findenv_r(reent_ptr, name, &offset))  /* if set multiple times */
    for (P = &(*p_environ)[offset];; ++P)
      if (!(*P = *(P + 1)))
        break;

  ENV_UNLOCK;
}