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[HB] Add sub-blobs

This commit is contained in:
Behdad Esfahbod 2009-08-03 17:53:29 -04:00
parent b28e21b90c
commit a26442437a
2 changed files with 147 additions and 27 deletions
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162
src/hb-blob.c
View File

@ -28,11 +28,17 @@
#include "hb-blob.h"
#include <unistd.h>
#include <sys/mman.h>
struct _hb_blob_t {
hb_reference_count_t ref_count;
hb_blob_t *parent;
const char *data;
unsigned int len;
unsigned int offset;
unsigned int length;
hb_memory_mode_t mode;
hb_destroy_func_t destroy;
@ -41,8 +47,11 @@ struct _hb_blob_t {
static hb_blob_t _hb_blob_nil = {
HB_REFERENCE_COUNT_INVALID, /* ref_count */
NULL, /* parent */
NULL, /* data */
0, /* len */
0, /* offset */
0, /* length */
HB_MEMORY_MODE_READONLY, /* mode */
NULL, /* destroy */
@ -53,29 +62,71 @@ 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;
}
}
static void
_hb_blob_nullify (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_t *
hb_blob_create (const char *data,
unsigned int len,
unsigned int length,
hb_memory_mode_t mode,
hb_destroy_func_t destroy,
void *user_data)
{
hb_blob_t *blob;
if (!HB_OBJECT_DO_CREATE (blob)) {
if (!length || !HB_OBJECT_DO_CREATE (blob)) {
if (destroy)
destroy (user_data);
return &_hb_blob_nil;
}
blob->data = data;
blob->len = len;
blob->offset = 0;
blob->length = length;
blob->mode = mode;
blob->destroy = destroy;
@ -89,6 +140,37 @@ hb_blob_create (const char *data,
return blob;
}
hb_blob_t *
hb_blob_create_sub_blob (hb_blob_t *parent,
unsigned int offset,
unsigned int length)
{
hb_blob_t *blob;
if (!length || !HB_OBJECT_DO_CREATE (blob))
return &_hb_blob_nil;
blob->parent = parent; /* we keep the ref in user_data */
blob->data = parent->data + 1; /* make sure they're not equal */
blob->offset = offset;
blob->length = length;
blob->mode = parent->mode;
blob->destroy = (hb_destroy_func_t) hb_blob_destroy;
blob->user_data = hb_blob_reference (parent);
_hb_blob_sync_parent_data (blob);
return blob;
}
hb_blob_t *
hb_blob_create_empty (void)
{
return &_hb_blob_nil;
}
hb_blob_t *
hb_blob_reference (hb_blob_t *blob)
{
@ -113,28 +195,50 @@ hb_blob_destroy (hb_blob_t *blob)
const char *
hb_blob_get_data (hb_blob_t *blob,
unsigned int *len)
unsigned int *length)
{
if (len)
*len = blob->len;
_hb_blob_sync_parent_data (blob);
return blob->data;
if (length)
*length = blob->length;
return blob->data + blob->offset;
}
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) {
/* XXX
* mprotect
blob->mode == HB_MEMORY_MODE_WRITEABLE;
*/
_hb_blob_sync_parent_data (blob);
if (blob->length) {
int pagesize;
unsigned int length;
const char *addr;
pagesize = sysconf(_SC_PAGE_SIZE);
if (-1 == pagesize)
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;
@ -144,27 +248,35 @@ hb_blob_try_writeable_inplace (hb_blob_t *blob)
void
hb_blob_make_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_destroy_user_data (blob);
blob->data = NULL;
blob->len = 0;
_hb_blob_nullify (blob);
}
else if (blob->mode == HB_MEMORY_MODE_READONLY)
{
char *new_data;
new_data = malloc (blob->len);
if (new_data)
memcpy (new_data, blob->data, blob->len);
_hb_blob_sync_parent_data (blob);
_hb_blob_destroy_user_data (blob);
if (blob->length) {
new_data = malloc (blob->length);
if (new_data)
memcpy (new_data, blob->data + blob->offset, blob->length);
if (!new_data) {
blob->data = NULL;
blob->len = 0;
} else
blob->data = new_data;
_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;
}

12
src/hb-blob.h
View File

@ -43,11 +43,19 @@ typedef struct _hb_blob_t hb_blob_t;
hb_blob_t *
hb_blob_create (const char *data,
unsigned int len,
unsigned int length,
hb_memory_mode_t mode,
hb_destroy_func_t destroy,
void *user_data);
hb_blob_t *
hb_blob_create_sub_blob (hb_blob_t *parent,
unsigned int offset,
unsigned int length);
hb_blob_t *
hb_blob_create_empty (void);
hb_blob_t *
hb_blob_reference (hb_blob_t *blob);
@ -59,7 +67,7 @@ hb_blob_destroy (hb_blob_t *blob);
const char *
hb_blob_get_data (hb_blob_t *blob,
unsigned int *len);
unsigned int *length);
hb_bool_t
hb_blob_is_writeable (hb_blob_t *blob);