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Make zero size allocation result consistent

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The zero size allocations had no consistent behaviour in RTEMS.  For
example, malloc( 0 ) returned NULL and posix_memalign( &p, align, 0 )
returned in p a unique pointer (or NULL if no memory is available).  In
POSIX, zero size memory allocations are implementation-defined
behaviour.  The implementation has two options:

https://pubs.opengroup.org/onlinepubs/9699919799/functions/malloc.html

https://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_memalign.html

Linux and FreeBSD return a unique pointer for zero size memory
allocations.   Use this approach for RTEMS as well throughout the memory
allocation directives

Close #4390.
This commit is contained in:
Sebastian Huber
2021-05-04 09:37:06 +02:00
parent eb7c33add0
commit d692c62dfb
4 changed files with 100 additions and 24 deletions
Download Patch File Download Diff File Expand all files Collapse all files
cpukit/libcsupport/src/malloc.c
-6
View File
@@ -30,12 +30,6 @@ void *malloc(
{
void *return_this;
/*
* Validate the parameters
*/
if ( !size )
return (void *) 0;
return_this = rtems_heap_allocate_aligned_with_boundary( size, 0, 0 );
if ( !return_this ) {
errno = ENOMEM;
cpukit/libcsupport/src/malloc_deferred.c
-4
View File
@@ -106,10 +106,6 @@ void *rtems_heap_allocate_aligned_with_boundary(
void *rtems_malloc( size_t size )
{
if ( size == 0 ) {
return NULL;
}
return rtems_heap_allocate_aligned_with_boundary( size, 0, 0 );
}
#endif
cpukit/libcsupport/src/realloc.c
+4 -4
View File
@@ -53,15 +53,15 @@ void *realloc( void *ptr, size_t size )
uintptr_t old_size;
uintptr_t avail_size;
if ( ptr == NULL ) {
return malloc( size );
}
if ( size == 0 ) {
free( ptr );
return NULL;
}
if ( ptr == NULL ) {
return malloc( size );
}
heap = RTEMS_Malloc_Heap;
switch ( _Malloc_System_state() ) {
testsuites/libtests/malloctest/init.c
+96 -10
View File
@@ -1153,7 +1153,10 @@ static void test_rtems_malloc(void)
void *p;
p = rtems_malloc(0);
rtems_test_assert(p == NULL);
rtems_test_assert(p != NULL);
RTEMS_OBFUSCATE_VARIABLE(p);
free(p);
errno = 0;
p = rtems_malloc(SIZE_MAX / 2);
@@ -1163,6 +1166,7 @@ static void test_rtems_malloc(void)
p = rtems_malloc(1);
rtems_test_assert(p != NULL);
RTEMS_OBFUSCATE_VARIABLE(p);
free(p);
}
@@ -1172,13 +1176,22 @@ static void test_rtems_calloc(void)
int *i;
p = rtems_calloc(0, 0);
rtems_test_assert(p == NULL);
rtems_test_assert(p != NULL);
RTEMS_OBFUSCATE_VARIABLE(p);
free(p);
p = rtems_calloc(0, 1);
rtems_test_assert(p == NULL);
rtems_test_assert(p != NULL);
RTEMS_OBFUSCATE_VARIABLE(p);
free(p);
p = rtems_calloc(1, 0);
rtems_test_assert(p == NULL);
rtems_test_assert(p != NULL);
RTEMS_OBFUSCATE_VARIABLE(p);
free(p);
errno = 0;
p = rtems_calloc(1, SIZE_MAX / 2);
@@ -1202,6 +1215,8 @@ static void test_rtems_calloc(void)
rtems_test_assert(i != NULL);
rtems_test_assert(*i == 0);
RTEMS_OBFUSCATE_VARIABLE(p);
free(i);
}
@@ -1301,6 +1316,82 @@ static void test_greedy_allocate(void)
rtems_test_assert( p == NULL );
}
static void test_alloc_zero_size(void)
{
size_t size;
void *p;
int eno;
size = 0;
RTEMS_OBFUSCATE_VARIABLE( size );
p = malloc( size );
rtems_test_assert( p != NULL );
RTEMS_OBFUSCATE_VARIABLE( p );
free( p );
RTEMS_OBFUSCATE_VARIABLE( size );
p = calloc( 1, size );
rtems_test_assert( p != NULL );
RTEMS_OBFUSCATE_VARIABLE( p );
free( p );
RTEMS_OBFUSCATE_VARIABLE( size );
p = rtems_malloc( size );
rtems_test_assert( p != NULL );
RTEMS_OBFUSCATE_VARIABLE( p );
free( p );
RTEMS_OBFUSCATE_VARIABLE( size );
p = rtems_calloc( 1, size );
rtems_test_assert( p != NULL );
RTEMS_OBFUSCATE_VARIABLE( p );
free( p );
RTEMS_OBFUSCATE_VARIABLE( size );
p = NULL;
eno = posix_memalign( &p, 32, size );
rtems_test_assert( eno == 0 );
rtems_test_assert( p != NULL );
RTEMS_OBFUSCATE_VARIABLE( p );
free( p );
RTEMS_OBFUSCATE_VARIABLE( size );
p = NULL;
eno = rtems_memalign( &p, 32, size );
rtems_test_assert( eno == 0 );
rtems_test_assert( p != NULL );
RTEMS_OBFUSCATE_VARIABLE( p );
free( p );
RTEMS_OBFUSCATE_VARIABLE( size );
p = aligned_alloc( 32, size );
rtems_test_assert( p != NULL );
RTEMS_OBFUSCATE_VARIABLE( p );
free( p );
RTEMS_OBFUSCATE_VARIABLE( size );
p = realloc( NULL, size );
rtems_test_assert( p != NULL );
RTEMS_OBFUSCATE_VARIABLE( p );
free( p );
RTEMS_OBFUSCATE_VARIABLE( size );
p = reallocarray( NULL, 1, size );
rtems_test_assert( p != NULL );
RTEMS_OBFUSCATE_VARIABLE( p );
free( p );
}
rtems_task Init(
rtems_task_argument argument
)
@@ -1327,12 +1418,6 @@ rtems_task Init(
rtems_test_assert( p1 == NULL );
#pragma GCC diagnostic pop
/*
* Verify error case where malloc of size 0.
*/
p1 = malloc( 0 );
rtems_test_assert( p1 == NULL );
test_heap_initialize();
test_heap_block_allocate();
test_heap_allocate();
@@ -1351,6 +1436,7 @@ rtems_task Init(
test_rtems_malloc();
test_rtems_calloc();
test_greedy_allocate();
test_alloc_zero_size();
test_posix_memalign();