Avoid alloca in setenv for long strings.

diff --git a/ChangeLog b/ChangeLog
index 713c713..e8aad25 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2010-02-02  Ulrich Drepper  <drepper@redhat.com>
+
+       * stdlib/setenv.c (__add_to_environ): Don't use alloca if
+       __libc_use_alloca tells us not to.  Fix memory leak in an error
+       situation.  Based partially on patch by Jim Meyering.
+
 2010-01-26  Samuel Thibault  <samuel.thibault@ens-lyon.org>
 
        * sysdeps/mach/getsysstats.c (get_nprocs_conf, get_nprocs,

diff --git a/stdlib/setenv.c b/stdlib/setenv.c
index fe591b7..89644b4 100644 (file)
--- a/stdlib/setenv.c
+++ b/stdlib/setenv.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1992,1995-2001,2004, 2008 Free Software Foundation, Inc.
+/* Copyright (C) 1992,1995-2001,2004, 2008, 2010 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -136,6 +136,7 @@ __add_to_environ (name, value, combined, replace)
 
   if (ep == NULL || __builtin_expect (*ep == NULL, 1))
     {
+      const size_t varlen = namelen + 1 + vallen;
       char **new_environ;
 
       /* We allocated this space; we can extend it.  */
@@ -156,11 +157,21 @@ __add_to_environ (name, value, combined, replace)
        {
          /* See whether the value is already known.  */
 #ifdef USE_TSEARCH
-# ifdef __GNUC__
-         char new_value[namelen + 1 + vallen];
-# else
-         char *new_value = (char *) alloca (namelen + 1 + vallen);
-# endif
+         char *new_value;
+         int use_alloca = __libc_use_alloca (varlen);
+         if (__builtin_expect (use_alloca, 1))
+           new_value = (char *) alloca (varlen);
+         else
+           {
+             new_value = malloc (varlen);
+             if (new_value == NULL)
+               {
+                 UNLOCK;
+                 if (last_environ == NULL)
+                   free (new_environ);
+                 return -1;
+               }
+           }
 # ifdef _LIBC
          __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
                     value, vallen);
@@ -174,21 +185,28 @@ __add_to_environ (name, value, combined, replace)
          if (__builtin_expect (new_environ[size] == NULL, 1))
 #endif
            {
-             new_environ[size] = (char *) malloc (namelen + 1 + vallen);
-             if (__builtin_expect (new_environ[size] == NULL, 0))
+#ifdef USE_TSEARCH
+             if (__builtin_expect (! use_alloca, 0))
+               new_environ[size] = new_value;
+             else
+#endif
                {
-                 __set_errno (ENOMEM);
-                 UNLOCK;
-                 return -1;
-               }
+                 new_environ[size] = (char *) malloc (varlen);
+                 if (__builtin_expect (new_environ[size] == NULL, 0))
+                   {
+                     UNLOCK;
+                     return -1;
+                   }
 
 #ifdef USE_TSEARCH
-             memcpy (new_environ[size], new_value, namelen + 1 + vallen);
+                 memcpy (new_environ[size], new_value, varlen);
 #else
-             memcpy (new_environ[size], name, namelen);
-             new_environ[size][namelen] = '=';
-             memcpy (&new_environ[size][namelen + 1], value, vallen);
+                 memcpy (new_environ[size], name, namelen);
+                 new_environ[size][namelen] = '=';
+                 memcpy (&new_environ[size][namelen + 1], value, vallen);
 #endif
+               }
+
              /* And save the value now.  We cannot do this when we remove
                 the string since then we cannot decide whether it is a
                 user string or not.  */
@@ -213,12 +231,21 @@ __add_to_environ (name, value, combined, replace)
        np = (char *) combined;
       else
        {
+         const size_t varlen = namelen + 1 + vallen;
 #ifdef USE_TSEARCH
-# ifdef __GNUC__
-         char new_value[namelen + 1 + vallen];
-# else
-         char *new_value = (char *) alloca (namelen + 1 + vallen);
-# endif
+         char *new_value;
+         int use_alloca = __libc_use_alloca (varlen);
+         if (__builtin_expect (use_alloca, 1))
+           new_value = (char *) alloca (varlen);
+         else
+           {
+             new_value = malloc (varlen);
+             if (new_value == NULL)
+               {
+                 UNLOCK;
+                 return -1;
+               }
+           }
 # ifdef _LIBC
          __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
                     value, vallen);
@@ -232,20 +259,27 @@ __add_to_environ (name, value, combined, replace)
          if (__builtin_expect (np == NULL, 1))
 #endif
            {
-             np = malloc (namelen + 1 + vallen);
-             if (__builtin_expect (np == NULL, 0))
+#ifdef USE_TSEARCH
+             if (__builtin_expect (! use_alloca, 0))
+               np = new_value;
+             else
+#endif
                {
-                 UNLOCK;
-                 return -1;
-               }
+                 np = malloc (varlen);
+                 if (__builtin_expect (np == NULL, 0))
+                   {
+                     UNLOCK;
+                     return -1;
+                   }
 
 #ifdef USE_TSEARCH
-             memcpy (np, new_value, namelen + 1 + vallen);
+                 memcpy (np, new_value, varlen);
 #else
-             memcpy (np, name, namelen);
-             np[namelen] = '=';
-             memcpy (&np[namelen + 1], value, vallen);
+                 memcpy (np, name, namelen);
+                 np[namelen] = '=';
+                 memcpy (&np[namelen + 1], value, vallen);
 #endif
+               }
              /* And remember the value.  */
              STORE_VALUE (np);
            }