This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
[PATCH] malloc: Update heap dumping/undumping comments [BZ #23351]
- From: fweimer at redhat dot com (Florian Weimer)
- To: libc-alpha at sourceware dot org
- Date: Fri, 29 Jun 2018 14:46:33 +0200
- Subject: [PATCH] malloc: Update heap dumping/undumping comments [BZ #23351]
Also remove a few now-unused declarations and definitions.
2018-06-29 Florian Weimer <fweimer@redhat.com>
[BZ #23351]
* malloc/hooks.c: Update comments on restoring of dumped heaps.
(disallow_malloc_check): Remove variable.
(__malloc_check_init): Adjust.
(malloc_set_state): Update comment.
* malloc/malloc.c (__malloc_get_state, __malloc_set_state): Remove
declarations.
diff --git a/malloc/hooks.c b/malloc/hooks.c
index 95aefd0bfc..ae7305b036 100644
--- a/malloc/hooks.c
+++ b/malloc/hooks.c
@@ -52,30 +52,10 @@ memalign_hook_ini (size_t alignment, size_t sz, const void *caller)
/* Whether we are using malloc checking. */
static int using_malloc_checking;
-/* A flag that is set by malloc_set_state, to signal that malloc checking
- must not be enabled on the request from the user (via the MALLOC_CHECK_
- environment variable). It is reset by __malloc_check_init to tell
- malloc_set_state that the user has requested malloc checking.
-
- The purpose of this flag is to make sure that malloc checking is not
- enabled when the heap to be restored was constructed without malloc
- checking, and thus does not contain the required magic bytes.
- Otherwise the heap would be corrupted by calls to free and realloc. If
- it turns out that the heap was created with malloc checking and the
- user has requested it malloc_set_state just calls __malloc_check_init
- again to enable it. On the other hand, reusing such a heap without
- further malloc checking is safe. */
-static int disallow_malloc_check;
-
/* Activate a standard set of debugging hooks. */
void
__malloc_check_init (void)
{
- if (disallow_malloc_check)
- {
- disallow_malloc_check = 0;
- return;
- }
using_malloc_checking = 1;
__malloc_hook = malloc_check;
__free_hook = free_check;
@@ -407,21 +387,11 @@ memalign_check (size_t alignment, size_t bytes, const void *caller)
#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_25)
-/* Get/set state: malloc_get_state() records the current state of all
- malloc variables (_except_ for the actual heap contents and `hook'
- function pointers) in a system dependent, opaque data structure.
- This data structure is dynamically allocated and can be free()d
- after use. malloc_set_state() restores the state of all malloc
- variables to the previously obtained state. This is especially
- useful when using this malloc as part of a shared library, and when
- the heap contents are saved/restored via some other method. The
- primary example for this is GNU Emacs with its `dumping' procedure.
- `Hook' function pointers are never saved or restored by these
- functions, with two exceptions: If malloc checking was in use when
- malloc_get_state() was called, then malloc_set_state() calls
- __malloc_check_init() if possible; if malloc checking was not in
- use in the recorded state but the user requested malloc checking,
- then the hooks are reset to 0. */
+/* Support for restoring dumped heaps contained in historic Emacs
+ executables. The heap saving feature (malloc_get_state) is no
+ longer implemented in this version of glibc, but we have a heap
+ rewriter in malloc_set_state which transforms the heap into a
+ version compatible with current malloc. */
#define MALLOC_STATE_MAGIC 0x444c4541l
#define MALLOC_STATE_VERSION (0 * 0x100l + 5l) /* major*0x100 + minor */
@@ -476,7 +446,7 @@ malloc_set_state (void *msptr)
if ((ms->version & ~0xffl) > (MALLOC_STATE_VERSION & ~0xffl))
return -2;
- /* We do not need to perform locking here because __malloc_set_state
+ /* We do not need to perform locking here because malloc_set_state
must be called before the first call into the malloc subsytem
(usually via __malloc_initialize_hook). pthread_create always
calls calloc and thus must be called only afterwards, so there
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 9614954975..e247c77b7d 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -697,22 +697,6 @@ size_t __malloc_usable_size(void*);
*/
void __malloc_stats(void);
-/*
- malloc_get_state(void);
-
- Returns the state of all malloc variables in an opaque data
- structure.
-*/
-void* __malloc_get_state(void);
-
-/*
- malloc_set_state(void* state);
-
- Restore the state of all malloc variables from data obtained with
- malloc_get_state().
-*/
-int __malloc_set_state(void*);
-
/*
posix_memalign(void **memptr, size_t alignment, size_t size);