aboutsummaryrefslogtreecommitdiff
path: root/src/lib/memarea
diff options
context:
space:
mode:
authorNick Mathewson <nickm@torproject.org>2018-06-28 09:25:18 -0400
committerNick Mathewson <nickm@torproject.org>2018-06-28 09:25:18 -0400
commiteee86e627b670b153bb5a0f41f9f8dfa4c378884 (patch)
tree0dd2a6db0e84f148d5d5614c336d56742d321c80 /src/lib/memarea
parent9cf335c9a5fe6767e90cc5cfdc1f5c95465edb10 (diff)
downloadtor-eee86e627b670b153bb5a0f41f9f8dfa4c378884.tar.gz
tor-eee86e627b670b153bb5a0f41f9f8dfa4c378884.zip
Extract memarea into its own library
Diffstat (limited to 'src/lib/memarea')
-rw-r--r--src/lib/memarea/.may_include6
-rw-r--r--src/lib/memarea/include.am17
-rw-r--r--src/lib/memarea/memarea.c400
-rw-r--r--src/lib/memarea/memarea.h30
4 files changed, 453 insertions, 0 deletions
diff --git a/src/lib/memarea/.may_include b/src/lib/memarea/.may_include
new file mode 100644
index 0000000000..c55722284f
--- /dev/null
+++ b/src/lib/memarea/.may_include
@@ -0,0 +1,6 @@
+orconfig.h
+lib/arch/*.h
+lib/cc/*.h
+lib/log/*.h
+lib/malloc/*.h
+lib/memarea/*.h
diff --git a/src/lib/memarea/include.am b/src/lib/memarea/include.am
new file mode 100644
index 0000000000..94343dcead
--- /dev/null
+++ b/src/lib/memarea/include.am
@@ -0,0 +1,17 @@
+
+noinst_LIBRARIES += src/lib/libtor-memarea.a
+
+if UNITTESTS_ENABLED
+noinst_LIBRARIES += src/lib/libtor-memarea-testing.a
+endif
+
+src_lib_libtor_memarea_a_SOURCES = \
+ src/lib/memarea/memarea.c
+
+src_lib_libtor_memarea_testing_a_SOURCES = \
+ $(src_lib_libtor_memarea_a_SOURCES)
+src_lib_libtor_memarea_testing_a_CPPFLAGS = $(AM_CPPFLAGS) $(TEST_CPPFLAGS)
+src_lib_libtor_memarea_testing_a_CFLAGS = $(AM_CFLAGS) $(TEST_CFLAGS)
+
+noinst_HEADERS += \
+ src/lib/memarea/memarea.h
diff --git a/src/lib/memarea/memarea.c b/src/lib/memarea/memarea.c
new file mode 100644
index 0000000000..7fe3825723
--- /dev/null
+++ b/src/lib/memarea/memarea.c
@@ -0,0 +1,400 @@
+/* Copyright (c) 2008-2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/** \file memarea.c
+ * \brief Implementation for memarea_t, an allocator for allocating lots of
+ * small objects that will be freed all at once.
+ */
+
+#include "orconfig.h"
+#include "lib/memarea/memarea.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "lib/cc/torint.h"
+#include "lib/arch/bytes.h"
+#include "lib/log/torlog.h"
+#include "lib/log/util_bug.h"
+#include "lib/malloc/util_malloc.h"
+
+#ifndef DISABLE_MEMORY_SENTINELS
+
+/** If true, we try to detect any attempts to write beyond the length of a
+ * memarea. */
+#define USE_SENTINELS
+
+/** All returned pointers should be aligned to the nearest multiple of this
+ * value. */
+#define MEMAREA_ALIGN SIZEOF_VOID_P
+
+/** A value which, when masked out of a pointer, produces a maximally aligned
+ * pointer. */
+#if MEMAREA_ALIGN == 4
+#define MEMAREA_ALIGN_MASK ((uintptr_t)3)
+#elif MEMAREA_ALIGN == 8
+#define MEMAREA_ALIGN_MASK ((uintptr_t)7)
+#else
+#error "void* is neither 4 nor 8 bytes long. I don't know how to align stuff."
+#endif /* MEMAREA_ALIGN == 4 || ... */
+
+#if defined(__GNUC__) && defined(FLEXIBLE_ARRAY_MEMBER)
+#define USE_ALIGNED_ATTRIBUTE
+/** Name for the 'memory' member of a memory chunk. */
+#define U_MEM mem
+#else
+#define U_MEM u.mem
+#endif /* defined(__GNUC__) && defined(FLEXIBLE_ARRAY_MEMBER) */
+
+#ifdef USE_SENTINELS
+/** Magic value that we stick at the end of a memarea so we can make sure
+ * there are no run-off-the-end bugs. */
+#define SENTINEL_VAL 0x90806622u
+/** How many bytes per area do we devote to the sentinel? */
+#define SENTINEL_LEN sizeof(uint32_t)
+/** Given a mem_area_chunk_t with SENTINEL_LEN extra bytes allocated at the
+ * end, set those bytes. */
+#define SET_SENTINEL(chunk) \
+ STMT_BEGIN \
+ set_uint32( &(chunk)->U_MEM[chunk->mem_size], SENTINEL_VAL ); \
+ STMT_END
+/** Assert that the sentinel on a memarea is set correctly. */
+#define CHECK_SENTINEL(chunk) \
+ STMT_BEGIN \
+ uint32_t sent_val = get_uint32(&(chunk)->U_MEM[chunk->mem_size]); \
+ tor_assert(sent_val == SENTINEL_VAL); \
+ STMT_END
+#else /* !(defined(USE_SENTINELS)) */
+#define SENTINEL_LEN 0
+#define SET_SENTINEL(chunk) STMT_NIL
+#define CHECK_SENTINEL(chunk) STMT_NIL
+#endif /* defined(USE_SENTINELS) */
+
+/** Increment <b>ptr</b> until it is aligned to MEMAREA_ALIGN. */
+static inline void *
+realign_pointer(void *ptr)
+{
+ uintptr_t x = (uintptr_t)ptr;
+ x = (x+MEMAREA_ALIGN_MASK) & ~MEMAREA_ALIGN_MASK;
+ /* Reinstate this if bug 930 ever reappears
+ tor_assert(((void*)x) >= ptr);
+ */
+ return (void*)x;
+}
+
+/** Implements part of a memarea. New memory is carved off from chunk->mem in
+ * increasing order until a request is too big, at which point a new chunk is
+ * allocated. */
+typedef struct memarea_chunk_t {
+ /** Next chunk in this area. Only kept around so we can free it. */
+ struct memarea_chunk_t *next_chunk;
+ size_t mem_size; /**< How much RAM is available in mem, total? */
+ char *next_mem; /**< Next position in mem to allocate data at. If it's
+ * equal to mem+mem_size, this chunk is full. */
+#ifdef USE_ALIGNED_ATTRIBUTE
+ /** Actual content of the memory chunk. */
+ char mem[FLEXIBLE_ARRAY_MEMBER] __attribute__((aligned(MEMAREA_ALIGN)));
+#else
+ union {
+ char mem[1]; /**< Memory space in this chunk. */
+ void *void_for_alignment_; /**< Dummy; used to make sure mem is aligned. */
+ } u; /**< Union used to enforce alignment when we don't have support for
+ * doing it right. */
+#endif /* defined(USE_ALIGNED_ATTRIBUTE) */
+} memarea_chunk_t;
+
+/** How many bytes are needed for overhead before we get to the memory part
+ * of a chunk? */
+#define CHUNK_HEADER_SIZE offsetof(memarea_chunk_t, U_MEM)
+
+/** What's the smallest that we'll allocate a chunk? */
+#define CHUNK_SIZE 4096
+
+/** A memarea_t is an allocation region for a set of small memory requests
+ * that will all be freed at once. */
+struct memarea_t {
+ memarea_chunk_t *first; /**< Top of the chunk stack: never NULL. */
+};
+
+/** Helper: allocate a new memarea chunk of around <b>chunk_size</b> bytes. */
+static memarea_chunk_t *
+alloc_chunk(size_t sz)
+{
+ tor_assert(sz < SIZE_T_CEILING);
+
+ size_t chunk_size = sz < CHUNK_SIZE ? CHUNK_SIZE : sz;
+ memarea_chunk_t *res;
+ chunk_size += SENTINEL_LEN;
+ res = tor_malloc(chunk_size);
+ res->next_chunk = NULL;
+ res->mem_size = chunk_size - CHUNK_HEADER_SIZE - SENTINEL_LEN;
+ res->next_mem = res->U_MEM;
+ tor_assert(res->next_mem+res->mem_size+SENTINEL_LEN ==
+ ((char*)res)+chunk_size);
+ tor_assert(realign_pointer(res->next_mem) == res->next_mem);
+ SET_SENTINEL(res);
+ return res;
+}
+
+/** Release <b>chunk</b> from a memarea. */
+static void
+memarea_chunk_free_unchecked(memarea_chunk_t *chunk)
+{
+ CHECK_SENTINEL(chunk);
+ tor_free(chunk);
+}
+
+/** Allocate and return new memarea. */
+memarea_t *
+memarea_new(void)
+{
+ memarea_t *head = tor_malloc(sizeof(memarea_t));
+ head->first = alloc_chunk(CHUNK_SIZE);
+ return head;
+}
+
+/** Free <b>area</b>, invalidating all pointers returned from memarea_alloc()
+ * and friends for this area */
+void
+memarea_drop_all_(memarea_t *area)
+{
+ memarea_chunk_t *chunk, *next;
+ for (chunk = area->first; chunk; chunk = next) {
+ next = chunk->next_chunk;
+ memarea_chunk_free_unchecked(chunk);
+ }
+ area->first = NULL; /*fail fast on */
+ tor_free(area);
+}
+
+/** Forget about having allocated anything in <b>area</b>, and free some of
+ * the backing storage associated with it, as appropriate. Invalidates all
+ * pointers returned from memarea_alloc() for this area. */
+void
+memarea_clear(memarea_t *area)
+{
+ memarea_chunk_t *chunk, *next;
+ if (area->first->next_chunk) {
+ for (chunk = area->first->next_chunk; chunk; chunk = next) {
+ next = chunk->next_chunk;
+ memarea_chunk_free_unchecked(chunk);
+ }
+ area->first->next_chunk = NULL;
+ }
+ area->first->next_mem = area->first->U_MEM;
+}
+
+/** Return true iff <b>p</b> is in a range that has been returned by an
+ * allocation from <b>area</b>. */
+int
+memarea_owns_ptr(const memarea_t *area, const void *p)
+{
+ memarea_chunk_t *chunk;
+ const char *ptr = p;
+ for (chunk = area->first; chunk; chunk = chunk->next_chunk) {
+ if (ptr >= chunk->U_MEM && ptr < chunk->next_mem)
+ return 1;
+ }
+ return 0;
+}
+
+/** Return a pointer to a chunk of memory in <b>area</b> of at least <b>sz</b>
+ * bytes. <b>sz</b> should be significantly smaller than the area's chunk
+ * size, though we can deal if it isn't. */
+void *
+memarea_alloc(memarea_t *area, size_t sz)
+{
+ memarea_chunk_t *chunk = area->first;
+ char *result;
+ tor_assert(chunk);
+ CHECK_SENTINEL(chunk);
+ tor_assert(sz < SIZE_T_CEILING);
+ if (sz == 0)
+ sz = 1;
+ tor_assert(chunk->next_mem <= chunk->U_MEM + chunk->mem_size);
+ const size_t space_remaining =
+ (chunk->U_MEM + chunk->mem_size) - chunk->next_mem;
+ if (sz > space_remaining) {
+ if (sz+CHUNK_HEADER_SIZE >= CHUNK_SIZE) {
+ /* This allocation is too big. Stick it in a special chunk, and put
+ * that chunk second in the list. */
+ memarea_chunk_t *new_chunk = alloc_chunk(sz+CHUNK_HEADER_SIZE);
+ new_chunk->next_chunk = chunk->next_chunk;
+ chunk->next_chunk = new_chunk;
+ chunk = new_chunk;
+ } else {
+ memarea_chunk_t *new_chunk = alloc_chunk(CHUNK_SIZE);
+ new_chunk->next_chunk = chunk;
+ area->first = chunk = new_chunk;
+ }
+ tor_assert(chunk->mem_size >= sz);
+ }
+ result = chunk->next_mem;
+ chunk->next_mem = chunk->next_mem + sz;
+ /* Reinstate these if bug 930 ever comes back
+ tor_assert(chunk->next_mem >= chunk->U_MEM);
+ tor_assert(chunk->next_mem <= chunk->U_MEM+chunk->mem_size);
+ */
+ chunk->next_mem = realign_pointer(chunk->next_mem);
+ return result;
+}
+
+/** As memarea_alloc(), but clears the memory it returns. */
+void *
+memarea_alloc_zero(memarea_t *area, size_t sz)
+{
+ void *result = memarea_alloc(area, sz);
+ memset(result, 0, sz);
+ return result;
+}
+
+/** As memdup, but returns the memory from <b>area</b>. */
+void *
+memarea_memdup(memarea_t *area, const void *s, size_t n)
+{
+ char *result = memarea_alloc(area, n);
+ memcpy(result, s, n);
+ return result;
+}
+
+/** As strdup, but returns the memory from <b>area</b>. */
+char *
+memarea_strdup(memarea_t *area, const char *s)
+{
+ return memarea_memdup(area, s, strlen(s)+1);
+}
+
+/** As strndup, but returns the memory from <b>area</b>. */
+char *
+memarea_strndup(memarea_t *area, const char *s, size_t n)
+{
+ size_t ln = 0;
+ char *result;
+ tor_assert(n < SIZE_T_CEILING);
+ for (ln = 0; ln < n && s[ln]; ++ln)
+ ;
+ result = memarea_alloc(area, ln+1);
+ memcpy(result, s, ln);
+ result[ln]='\0';
+ return result;
+}
+
+/** Set <b>allocated_out</b> to the number of bytes allocated in <b>area</b>,
+ * and <b>used_out</b> to the number of bytes currently used. */
+void
+memarea_get_stats(memarea_t *area, size_t *allocated_out, size_t *used_out)
+{
+ size_t a = 0, u = 0;
+ memarea_chunk_t *chunk;
+ for (chunk = area->first; chunk; chunk = chunk->next_chunk) {
+ CHECK_SENTINEL(chunk);
+ a += CHUNK_HEADER_SIZE + chunk->mem_size;
+ tor_assert(chunk->next_mem >= chunk->U_MEM);
+ u += CHUNK_HEADER_SIZE + (chunk->next_mem - chunk->U_MEM);
+ }
+ *allocated_out = a;
+ *used_out = u;
+}
+
+/** Assert that <b>area</b> is okay. */
+void
+memarea_assert_ok(memarea_t *area)
+{
+ memarea_chunk_t *chunk;
+ tor_assert(area->first);
+
+ for (chunk = area->first; chunk; chunk = chunk->next_chunk) {
+ CHECK_SENTINEL(chunk);
+ tor_assert(chunk->next_mem >= chunk->U_MEM);
+ tor_assert(chunk->next_mem <=
+ (char*) realign_pointer(chunk->U_MEM+chunk->mem_size));
+ }
+}
+
+#else /* !(!defined(DISABLE_MEMORY_SENTINELS)) */
+
+struct memarea_t {
+ smartlist_t *pieces;
+};
+
+memarea_t *
+memarea_new(void)
+{
+ memarea_t *ma = tor_malloc_zero(sizeof(memarea_t));
+ ma->pieces = smartlist_new();
+ return ma;
+}
+void
+memarea_drop_all_(memarea_t *area)
+{
+ memarea_clear(area);
+ smartlist_free(area->pieces);
+ tor_free(area);
+}
+void
+memarea_clear(memarea_t *area)
+{
+ SMARTLIST_FOREACH(area->pieces, void *, p, tor_free_(p));
+ smartlist_clear(area->pieces);
+}
+int
+memarea_owns_ptr(const memarea_t *area, const void *ptr)
+{
+ SMARTLIST_FOREACH(area->pieces, const void *, p, if (ptr == p) return 1;);
+ return 0;
+}
+
+void *
+memarea_alloc(memarea_t *area, size_t sz)
+{
+ void *result = tor_malloc(sz);
+ smartlist_add(area->pieces, result);
+ return result;
+}
+
+void *
+memarea_alloc_zero(memarea_t *area, size_t sz)
+{
+ void *result = tor_malloc_zero(sz);
+ smartlist_add(area->pieces, result);
+ return result;
+}
+void *
+memarea_memdup(memarea_t *area, const void *s, size_t n)
+{
+ void *r = memarea_alloc(area, n);
+ memcpy(r, s, n);
+ return r;
+}
+char *
+memarea_strdup(memarea_t *area, const char *s)
+{
+ size_t n = strlen(s);
+ char *r = memarea_alloc(area, n+1);
+ memcpy(r, s, n);
+ r[n] = 0;
+ return r;
+}
+char *
+memarea_strndup(memarea_t *area, const char *s, size_t n)
+{
+ size_t ln = strnlen(s, n);
+ char *r = memarea_alloc(area, ln+1);
+ memcpy(r, s, ln);
+ r[ln] = 0;
+ return r;
+}
+void
+memarea_get_stats(memarea_t *area,
+ size_t *allocated_out, size_t *used_out)
+{
+ (void)area;
+ *allocated_out = *used_out = 128;
+}
+void
+memarea_assert_ok(memarea_t *area)
+{
+ (void)area;
+}
+
+#endif /* !defined(DISABLE_MEMORY_SENTINELS) */
diff --git a/src/lib/memarea/memarea.h b/src/lib/memarea/memarea.h
new file mode 100644
index 0000000000..e52f5a1be7
--- /dev/null
+++ b/src/lib/memarea/memarea.h
@@ -0,0 +1,30 @@
+/* Copyright (c) 2008-2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+/* Tor dependencies */
+
+#ifndef TOR_MEMAREA_H
+#define TOR_MEMAREA_H
+
+#include <stddef.h>
+
+typedef struct memarea_t memarea_t;
+
+memarea_t *memarea_new(void);
+void memarea_drop_all_(memarea_t *area);
+#define memarea_drop_all(area) \
+ do { \
+ memarea_drop_all_(area); \
+ (area) = NULL; \
+ } while (0)
+void memarea_clear(memarea_t *area);
+int memarea_owns_ptr(const memarea_t *area, const void *ptr);
+void *memarea_alloc(memarea_t *area, size_t sz);
+void *memarea_alloc_zero(memarea_t *area, size_t sz);
+void *memarea_memdup(memarea_t *area, const void *s, size_t n);
+char *memarea_strdup(memarea_t *area, const char *s);
+char *memarea_strndup(memarea_t *area, const char *s, size_t n);
+void memarea_get_stats(memarea_t *area,
+ size_t *allocated_out, size_t *used_out);
+void memarea_assert_ok(memarea_t *area);
+
+#endif /* !defined(TOR_MEMAREA_H) */