Only reference environ indirectly through a pointer

4 files changed, 37 insertions, 23 deletions

diff --git a/newlib/libc/stdlib/getenv.c b/newlib/libc/stdlib/getenv.c
index c9f1ecd96..267f67aac 100644
--- a/newlib/libc/stdlib/getenv.c
+++ b/newlib/libc/stdlib/getenv.c
@@ -18,7 +18,7 @@ TRAD_SYNOPSIS
 
 DESCRIPTION
 <<getenv>> searches the list of environment variable names and values
-(using the global pointer `<<char **environ>>') for a variable whose
+(using the global pointer ``<<char **environ>>'') for a variable whose
 name matches the string at <[name]>.  If a variable name matches,
 <<getenv>> returns a pointer to the associated value.
 
@@ -39,7 +39,7 @@ variables vary from one system to another.
 */
 
 /*
- * Copyright (c) 1987 Regents of the University of California.
+ * Copyright (c) 1987, 2000 Regents of the University of California.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms are permitted
@@ -63,8 +63,6 @@ variables vary from one system to another.
 #include <stddef.h>
 #include <string.h>
 
-extern char **environ;
-
 /*
  * _findenv --
  *	Returns pointer to value associated with name, if any, else NULL.
diff --git a/newlib/libc/stdlib/getenv_r.c b/newlib/libc/stdlib/getenv_r.c
index 2ccb89a17..dbfcdf54b 100644
--- a/newlib/libc/stdlib/getenv_r.c
+++ b/newlib/libc/stdlib/getenv_r.c
@@ -19,7 +19,7 @@ TRAD_SYNOPSIS
 
 DESCRIPTION
 <<_getenv_r>> searches the list of environment variable names and values
-(using the global pointer `<<char **environ>>') for a variable whose
+(using the global pointer ``<<char **environ>>'') for a variable whose
 name matches the string at <[name]>.  If a variable name matches,
 <<_getenv_r>> returns a pointer to the associated value.
 
@@ -65,6 +65,11 @@ variables vary from one system to another.
 
 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 --
  *	Returns pointer to value associated with name, if any, else NULL.
@@ -89,7 +94,7 @@ _DEFUN (_findenv_r, (reent_ptr, name, offset),
 
   /* In some embedded systems, this does not get set.  This protects
      newlib from dereferencing a bad pointer.  */
-  if (!environ)
+  if (!*p_environ)
     return NULL;
 
   c = name;
@@ -100,11 +105,11 @@ _DEFUN (_findenv_r, (reent_ptr, name, offset),
       len++;
     }
 
-  for (p = environ; *p; ++p)
+  for (p = *p_environ; *p; ++p)
     if (!strncmp (*p, name, len))
       if (*(c = *p + len) == '=')
 	{
-	  *offset = p - environ;
+	  *offset = p - *p_environ;
           ENV_UNLOCK;
 	  return (char *) (++c);
 	}
diff --git a/newlib/libc/stdlib/setenv_r.c b/newlib/libc/stdlib/setenv_r.c
index c012e22a3..2fe34e275 100644
--- a/newlib/libc/stdlib/setenv_r.c
+++ b/newlib/libc/stdlib/setenv_r.c
@@ -29,6 +29,13 @@
 #include <string.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 *));
 
@@ -45,7 +52,6 @@ _DEFUN (_setenv_r, (reent_ptr, name, value, rewrite),
 	_CONST char *value _AND
 	int rewrite)
 {
-  extern char **environ;
   static int alloced;		/* if allocated space before */
   register char *C;
   int l_value, offset;
@@ -74,12 +80,12 @@ _DEFUN (_setenv_r, (reent_ptr, name, value, rewrite),
       register int cnt;
       register char **P;
 
-      for (P = environ, cnt = 0; *P; ++P, ++cnt);
+      for (P = *p_environ, cnt = 0; *P; ++P, ++cnt);
       if (alloced)
 	{			/* just increase size */
-	  environ = (char **) _realloc_r (reent_ptr, (char *) environ,
-				       (size_t) (sizeof (char *) * (cnt + 2)));
-	  if (!environ)
+	  *p_environ = (char **) _realloc_r (reent_ptr, (char *) environ,
+					     (size_t) (sizeof (char *) * (cnt + 2)));
+	  if (!*p_environ)
             {
               ENV_UNLOCK;
 	      return -1;
@@ -94,20 +100,20 @@ _DEFUN (_setenv_r, (reent_ptr, name, value, rewrite),
               ENV_UNLOCK;
 	      return (-1);
             }
-	  bcopy ((char *) environ, (char *) P, cnt * sizeof (char *));
-	  environ = P;
+	  bcopy ((char *) *p_environ, (char *) P, cnt * sizeof (char *));
+	  *p_environ = P;
 	}
-      environ[cnt + 1] = NULL;
+      (*p_environ)[cnt + 1] = NULL;
       offset = cnt;
     }
   for (C = (char *) name; *C && *C != '='; ++C);	/* no `=' in name */
-  if (!(environ[offset] =	/* name + `=' + value */
+  if (!((*p_environ)[offset] =	/* name + `=' + value */
 	_malloc_r (reent_ptr, (size_t) ((int) (C - name) + l_value + 2))))
     {
       ENV_UNLOCK;
       return -1;
     }
-  for (C = environ[offset]; (*C = *name++) && *C != '='; ++C);
+  for (C = (*p_environ)[offset]; (*C = *name++) && *C != '='; ++C);
   for (*C++ = '='; (*C++ = *value++) != 0;);
 
   ENV_UNLOCK;
@@ -124,14 +130,13 @@ _DEFUN (_unsetenv_r, (reent_ptr, name),
         struct _reent *reent_ptr _AND
         _CONST char *name)
 {
-  extern char **environ;
   register char **P;
   int offset;
 
   ENV_LOCK;
 
   while (_findenv_r (reent_ptr, name, &offset))	/* if set multiple times */
-    for (P = &environ[offset];; ++P)
+    for (P = &(*p_environ)[offset];; ++P)
       if (!(*P = *(P + 1)))
 	break;
 
diff --git a/newlib/libc/stdlib/system.c b/newlib/libc/stdlib/system.c
index 6a4a33c0b..770996e57 100644
--- a/newlib/libc/stdlib/system.c
+++ b/newlib/libc/stdlib/system.c
@@ -27,7 +27,7 @@ DESCRIPTION
 Use <<system>> to pass a command string <<*<[s]>>> to <</bin/sh>> on
 your system, and wait for it to finish executing.
 
-Use `<<system(NULL)>>' to test whether your system has <</bin/sh>>
+Use ``<<system(NULL)>>'' to test whether your system has <</bin/sh>>
 available.
 
 The alternate function <<_system_r>> is a reentrant version.  The
@@ -107,6 +107,13 @@ system (s)
 #endif
 
 #if defined (unix) && !defined (__CYGWIN__)
+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;
+
 static int
 do_system (ptr, s)
      struct _reent *ptr;
@@ -114,7 +121,6 @@ do_system (ptr, s)
 {
   char *argv[4];
   int pid, status;
-  extern char **environ;
 
   argv[0] = "sh";
   argv[1] = "-c";
@@ -123,7 +129,7 @@ do_system (ptr, s)
 
   if ((pid = _fork_r (ptr)) == 0)
     {
-      _execve ("/bin/sh", argv, environ);
+      _execve ("/bin/sh", argv, *p_environ);
       exit (100);
     }
   else if (pid == -1)