github-mirror/fish-shell
github-mirror/fish-shell
2
0
Fork 0
mirror of https://github.com/fish-shell/fish-shell.git synced 2025-03-24 20:05:13 +08:00
Code Issues Actions Packages Projects Releases Wiki Activity

Be a bit more careful with memory alignemnt in halloc

Browse Source 
darcs-hash:20060930121917-ac50b-6292696663684a38844b4c21360274b365e52969.gz
This commit is contained in:
axel 2006-09-30 22:19:17 +10:00
parent 92df4a6d91
commit 421ebcc2d7
1 changed files with 43 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
halloc.c
View File

@ -24,9 +24,12 @@
#define HALLOC_BLOCK_SIZE 128
/**
Maximum size of trailing halloc space to refuse to discard
Maximum size of trailing halloc space to refuse to discard. This is
set to be larger on 64-bit platforms, since we don't want to get
'stuck' with an unusably small slice of memory, and what is
unusably small often depends on pointer size.
*/
#define HALLOC_SCRAP_SIZE 16
#define HALLOC_SCRAP_SIZE (4*sizeof(void *))
#ifdef HALLOC_DEBUG
/**
@ -71,24 +74,32 @@ typedef struct halloc
/**
Amount of free space in the scratch area
*/
size_t scratch_free;
#if __STDC_VERSION__ < 199901L
/**
The actual data. Made to be of type long long to make sure memory alignment is in order.
*/
long long data[1]; // Waste one byte on non-C99 compilers... :-(
#else
long long data[];
#endif
ssize_t scratch_free;
}
halloc_t;
static void *align_ptr( void *in )
{
unsigned long step = maxi(sizeof(double),sizeof(void *));
unsigned long inc = step-1;
unsigned long long_in = (long)in;
unsigned long long_out = ((long_in+inc)/step)*step;
return (void *)long_out;
}
static size_t align_sz( size_t in )
{
size_t step = maxi(sizeof(double),sizeof(void *));
size_t inc = step-1;
return ((in+inc)/step)*step;
}
/**
Get the offset of the halloc structure before a data block
*/
static halloc_t *halloc_from_data( void *data )
{
return (halloc_t *)(((char *)data) - sizeof( halloc_t ) );
return (halloc_t *)(((char *)data) - align_sz(sizeof( halloc_t ) ));
}
/**
@ -104,7 +115,7 @@ static void late_free( void *data)
statistics, like number of allocations and number of internal calls
to malloc.
*/
static void woot()
static void halloc_report()
{
if( getpid() == pid )
{
@ -115,25 +126,40 @@ static void woot()
}
#endif
void *halloc( void *context, size_t size )
{
halloc_t *me, *parent;
if( context )
{
void *res;
void *aligned;
#ifdef HALLOC_DEBUG
if( !child_count )
{
pid = getpid();
atexit( woot );
atexit( &halloc_report );
}
child_count++;
child_size += size;
#endif
parent = halloc_from_data( context );
/*
Align memory address
*/
aligned = align_ptr( parent->scratch );
parent->scratch_free -= (aligned-parent->scratch);
if( parent->scratch_free < 0 )
parent->scratch_free=0;
parent->scratch = aligned;
if( size <= parent->scratch_free )
{
res = parent->scratch;
@ -169,18 +195,18 @@ void *halloc( void *context, size_t size )
}
else
{
me = (halloc_t *)calloc( 1, sizeof(halloc_t) + size + HALLOC_BLOCK_SIZE );
me = (halloc_t *)calloc( 1, align_sz(sizeof(halloc_t)) + align_sz(size) + HALLOC_BLOCK_SIZE );
if( !me )
return 0;
#ifdef HALLOC_DEBUG
parent_count++;
#endif
me->scratch = ((char *)me) + sizeof(halloc_t) + size;
me->scratch = ((char *)me) + align_sz(sizeof(halloc_t)) + align_sz(size);
me->scratch_free = HALLOC_BLOCK_SIZE;
al_init( &me->children );
return &me->data;
return ((char *)me) + align_sz(sizeof(halloc_t));
}
}