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authorUlrich Drepper <drepper@redhat.com>2010-02-02 09:55:55 -0800
committerUlrich Drepper <drepper@redhat.com>2010-02-02 09:55:55 -0800
commitc63bfa79941496190b22179cd5a73addff3a7e8b (patch)
tree81e5bad0f46e29916bb0198718a0e5f78de2c067 /stdlib
parentb34e12e22c00d74ee549ae9ac304f64d1d6374d5 (diff)
downloadglibc-c63bfa79941496190b22179cd5a73addff3a7e8b.tar.gz
Avoid alloca in setenv for long strings.
Diffstat (limited to 'stdlib')
-rw-r--r--stdlib/setenv.c94
1 files changed, 64 insertions, 30 deletions
diff --git a/stdlib/setenv.c b/stdlib/setenv.c
index fe591b7db8..89644b4884 100644
--- 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);
}