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[HB] Simplify sub-blob support

This commit is contained in:
Behdad Esfahbod 2009-08-03 21:27:08 -04:00
parent a26442437a
commit fc6c94002d
2 changed files with 75 additions and 113 deletions
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174
src/hb-blob.c
View File

@ -31,13 +31,14 @@
#include <unistd.h>
#include <sys/mman.h>
/* XXX Not thread-safe */
struct _hb_blob_t {
hb_reference_count_t ref_count;
hb_blob_t *parent;
hb_reference_count_t lock;
const char *data;
unsigned int offset;
unsigned int length;
hb_memory_mode_t mode;
@ -47,12 +48,11 @@ struct _hb_blob_t {
static hb_blob_t _hb_blob_nil = {
HB_REFERENCE_COUNT_INVALID, /* ref_count */
NULL, /* parent */
HB_REFERENCE_COUNT_INVALID, /* lock */
NULL, /* data */
0, /* offset */
0, /* length */
HB_MEMORY_MODE_READONLY, /* mode */
HB_MEMORY_MODE_READONLY_NEVER_DUPLICATE, /* mode */
NULL, /* destroy */
NULL /* user_data */
@ -62,8 +62,6 @@ static void
_hb_blob_destroy_user_data (hb_blob_t *blob)
{
if (blob->destroy) {
if (blob->parent == blob->user_data)
blob->parent = NULL;
blob->destroy (blob->user_data);
blob->destroy = NULL;
blob->user_data = NULL;
@ -71,42 +69,10 @@ _hb_blob_destroy_user_data (hb_blob_t *blob)
}
static void
_hb_blob_nullify (hb_blob_t *blob)
_hb_blob_unlock_and_destroy (hb_blob_t *blob)
{
_hb_blob_destroy_user_data (blob);
blob->data = NULL;
blob->offset = 0;
blob->length = 0;
}
static void
_hb_blob_sync_parent_mode (hb_blob_t *blob)
{
if (blob->parent) {
if (blob->mode != HB_MEMORY_MODE_WRITEABLE && hb_blob_is_writeable (blob->parent))
blob->mode = HB_MEMORY_MODE_WRITEABLE;
}
}
static void
_hb_blob_sync_parent_data (hb_blob_t *blob)
{
if (blob->parent) {
const char *pdata;
unsigned int plength;
pdata = hb_blob_get_data (blob->parent, &plength);
if (pdata != blob->data) {
if (blob->offset >= plength) {
/* nothing left */
_hb_blob_nullify (blob);
} else {
blob->data = pdata;
blob->length = MIN (blob->length, plength - blob->offset);
}
}
}
hb_blob_unlock (blob);
hb_blob_destroy (blob);
}
hb_blob_t *
@ -124,8 +90,9 @@ hb_blob_create (const char *data,
return &_hb_blob_nil;
}
HB_REFERENCE_COUNT_INIT (blob->lock, 0);
blob->data = data;
blob->offset = 0;
blob->length = length;
blob->mode = mode;
@ -134,7 +101,10 @@ hb_blob_create (const char *data,
if (blob->mode == HB_MEMORY_MODE_DUPLICATE) {
blob->mode = HB_MEMORY_MODE_READONLY;
hb_blob_make_writeable (blob);
if (!hb_blob_try_writeable (blob)) {
hb_blob_destroy (blob);
return &_hb_blob_nil;
}
}
return blob;
@ -146,22 +116,20 @@ hb_blob_create_sub_blob (hb_blob_t *parent,
unsigned int length)
{
hb_blob_t *blob;
const char *pdata;
if (!length || !HB_OBJECT_DO_CREATE (blob))
if (!length || offset >= parent->length || !HB_OBJECT_DO_CREATE (blob))
return &_hb_blob_nil;
blob->parent = parent; /* we keep the ref in user_data */
pdata = hb_blob_lock (parent);
blob->data = parent->data + 1; /* make sure they're not equal */
blob->offset = offset;
blob->length = length;
blob->data = pdata + offset;
blob->length = MIN (length, parent->length - offset);
blob->mode = parent->mode;
blob->destroy = (hb_destroy_func_t) hb_blob_destroy;
blob->destroy = (hb_destroy_func_t) _hb_blob_unlock_and_destroy;
blob->user_data = hb_blob_reference (parent);
_hb_blob_sync_parent_data (blob);
return blob;
}
@ -193,93 +161,83 @@ hb_blob_destroy (hb_blob_t *blob)
free (blob);
}
const char *
hb_blob_get_data (hb_blob_t *blob,
unsigned int *length)
unsigned int
hb_blob_get_length (hb_blob_t *blob)
{
_hb_blob_sync_parent_data (blob);
return blob->length;
}
if (length)
*length = blob->length;
const char *
hb_blob_lock (hb_blob_t *blob)
{
if (!HB_OBJECT_IS_INERT (blob))
(void) _hb_reference_count_inc (blob->lock);
return blob->data + blob->offset;
return blob->data;
}
void
hb_blob_unlock (hb_blob_t *blob)
{
if (!HB_OBJECT_IS_INERT (blob)) {
int old_lock = _hb_reference_count_inc (blob->lock);
assert (old_lock > 0);
}
}
hb_bool_t
hb_blob_is_writeable (hb_blob_t *blob)
{
_hb_blob_sync_parent_mode (blob);
return blob->mode == HB_MEMORY_MODE_WRITEABLE;
}
hb_bool_t
hb_blob_try_writeable_inplace (hb_blob_t *blob)
{
if (HB_OBJECT_IS_INERT (blob))
return FALSE;
_hb_blob_sync_parent_mode (blob);
if (blob->mode == HB_MEMORY_MODE_READONLY_MAY_MAKE_WRITEABLE) {
_hb_blob_sync_parent_data (blob);
int pagesize;
unsigned int length;
const char *addr;
if (blob->length) {
int pagesize;
unsigned int length;
const char *addr;
pagesize = sysconf(_SC_PAGE_SIZE);
if (-1 == pagesize)
return FALSE;
pagesize = sysconf(_SC_PAGE_SIZE);
if (-1 == pagesize)
return FALSE;
addr = (const char *) (((size_t) blob->data) & pagesize);
length = (const char *) (((size_t) blob->data + blob->length + pagesize-1) & pagesize) - addr;
if (-1 == mprotect ((void *) addr, length, PROT_READ | PROT_WRITE))
return FALSE;
addr = (const char *) (((size_t) blob->data + blob->offset) & pagesize);
length = (const char *) (((size_t) blob->data + blob->offset + blob->length + pagesize-1) & pagesize) - addr;
if (-1 == mprotect ((void *) addr, length, PROT_READ | PROT_WRITE))
return FALSE;
}
blob->mode = HB_MEMORY_MODE_WRITEABLE;
}
return blob->mode == HB_MEMORY_MODE_WRITEABLE;
}
/* DANGER: May rebase or nullify */
void
hb_blob_make_writeable (hb_blob_t *blob)
hb_bool_t
hb_blob_try_writeable (hb_blob_t *blob)
{
if (HB_OBJECT_IS_INERT (blob))
return;
_hb_blob_sync_parent_mode (blob);
if (blob->mode == HB_MEMORY_MODE_READONLY_NEVER_DUPLICATE)
{
_hb_blob_nullify (blob);
}
else if (blob->mode == HB_MEMORY_MODE_READONLY)
return FALSE;
if (blob->mode == HB_MEMORY_MODE_READONLY)
{
char *new_data;
_hb_blob_sync_parent_data (blob);
if (blob->length) {
new_data = malloc (blob->length);
if (new_data)
memcpy (new_data, blob->data + blob->offset, blob->length);
if (HB_REFERENCE_COUNT_HAS_REFERENCE (blob->lock))
return FALSE;
new_data = malloc (blob->length);
if (new_data) {
memcpy (new_data, blob->data, blob->length);
blob->data = new_data;
blob->mode = HB_MEMORY_MODE_WRITEABLE;
_hb_blob_destroy_user_data (blob);
if (!new_data) {
_hb_blob_nullify (blob);
} else {
blob->data = new_data;
blob->offset = 0;
}
}
blob->mode = HB_MEMORY_MODE_WRITEABLE;
return TRUE;
} else
return FALSE;
}
else
return
hb_blob_try_writeable_inplace (blob);
}

14
src/hb-blob.h
View File

@ -65,9 +65,14 @@ hb_blob_get_reference_count (hb_blob_t *blob);
void
hb_blob_destroy (hb_blob_t *blob);
unsigned int
hb_blob_get_length (hb_blob_t *blob);
const char *
hb_blob_get_data (hb_blob_t *blob,
unsigned int *length);
hb_blob_lock (hb_blob_t *blob);
void
hb_blob_unlock (hb_blob_t *blob);
hb_bool_t
hb_blob_is_writeable (hb_blob_t *blob);
@ -75,9 +80,8 @@ hb_blob_is_writeable (hb_blob_t *blob);
hb_bool_t
hb_blob_try_writeable_inplace (hb_blob_t *blob);
/* DANGER: May rebase or nullify */
void
hb_blob_make_writeable (hb_blob_t *blob);
hb_bool_t
hb_blob_try_writeable (hb_blob_t *blob);
HB_END_DECLS