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Rewrite image cache so that all reads are block-aligned. #86

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Rewrite image cache so that all reads are block-aligned. #86

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d40b43e
Modified caching in image reading to ensure all reads go through
Aug 6, 2012
13ab34e
Improved comments and platform independence of image cache.
Aug 7, 2012
00a9d8d
Further image cache commentary, etc.
Aug 7, 2012
5de465b
Got rid of exit() in cache alloc.
Aug 7, 2012
a9c6443
Oops -- Windows needs MIN(x,y) defined.
Aug 8, 2012
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Improved comments and platform independence of image cache.
  • Loading branch information
Judson Powers committed Aug 7, 2012
commit 13ab34e32105c1f593b2bf3087978526905eea72
2 changes: 2 additions & 0 deletions configure.ac
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Expand Up @@ -79,6 +79,8 @@ AX_PTHREAD( [
CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
LDFLAGS="$LDFLAGS $PTHREAD_CFLAGS"
CC="$PTHREAD_CC"],[])
AC_CHECK_FUNCS(posix_memalign, [AC_DEFINE(HAVE_POSIX_MEMALIGN, 1, [Define to 1 if you have the posix_memalign() function.])])

# Not all compilers include /usr/local in the include and link path
if test -d /usr/local/include; then
CFLAGS="$CFLAGS -I/usr/local/include"
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18 changes: 9 additions & 9 deletions tsk3/img/img_io.c
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Expand Up @@ -13,14 +13,14 @@
#include "tsk_img_i.h"

/**
* \ingroup imglib
* \internal
* XXX
* @param a_img_info Disk image to read from
* @param ent XXX
* @returns XXX
*/
static int
cache_promote(TSK_IMG_INFO * a_img_info, int ent)
static inline int
tsk_cache_promote(TSK_IMG_INFO * a_img_info, int ent)
{
if (ent == 0)
return 0;
Expand All @@ -34,15 +34,15 @@ cache_promote(TSK_IMG_INFO * a_img_info, int ent)
}

/**
* \ingroup imglib
* \internal
* XXX
* @param a_img_info Disk image to read from
* @param a_off XXX
* @param a_entry XXX
* @returns 0 on error or 1 on success
*/
static int
get_cache_block(TSK_IMG_INFO * a_img_info,
static inline int
tsk_get_cache_block(TSK_IMG_INFO * a_img_info,
TSK_OFF_T a_off, struct TSK_IMG_INFO_CACHE_ENTRY ** a_entry)
{
// we require that we're called with a page-aligned offset
Expand All @@ -56,7 +56,7 @@ get_cache_block(TSK_IMG_INFO * a_img_info,
// find existing cache page
for (ent = 0; ent < a_img_info->cache_used; ent++) {
if (a_img_info->cache_info[ent].offset == a_off) {
ent = cache_promote(a_img_info, ent);
ent = tsk_cache_promote(a_img_info, ent);
*a_entry = &(a_img_info->cache_info[ent]);
return 1;
}
Expand Down Expand Up @@ -85,7 +85,7 @@ get_cache_block(TSK_IMG_INFO * a_img_info,
return 0;
}

ent = cache_promote(a_img_info, ent);
ent = tsk_cache_promote(a_img_info, ent);
*a_entry = &(a_img_info->cache_info[ent]);
return 1;
}
Expand Down Expand Up @@ -152,7 +152,7 @@ tsk_img_read(TSK_IMG_INFO * a_img_info, TSK_OFF_T a_off,

while (rlen > 0) {
// get the current block from cache (possibly reading from disk)
if (! get_cache_block(a_img_info, block_addr, & cache_entry)) {
if (! tsk_get_cache_block(a_img_info, block_addr, & cache_entry)) {
tsk_release_lock(&(a_img_info->cache_lock));
return len2 - rlen;
}
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29 changes: 27 additions & 2 deletions tsk3/img/raw.c
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Expand Up @@ -721,8 +721,33 @@ tsk_img_malloc(size_t a_len)
tsk_init_lock(&(imgInfo->cache_lock));
imgInfo->tag = TSK_IMG_INFO_TAG;

// alloc cache
imgInfo->cache = valloc(TSK_IMG_INFO_CACHE_NUM * TSK_IMG_INFO_CACHE_LEN);
long cachesz = TSK_IMG_INFO_CACHE_NUM * TSK_IMG_INFO_CACHE_LEN;

#ifdef TSK_WIN32
#else

// unistd.h

#ifdef _SC_PAGESIZE
long pagesz = sysconf(_SC_PAGESIZE);
#else
#ifdef _SC_PAGE_SIZE
long pagesz = sysconf(_SC_PAGE_SIZE);
#else
long pagesz = TSK_IMG_INFO_CACHE_LEN;
#endif
#endif // PAGESIZE

#ifdef HAVE_POSIX_MEMALIGN
int retval;
if ((retval = posix_memalign(&imgInfo->cache, pagesz, cachesz)) != 0) {
tsk_fprintf("tsk_img_malloc: unable to allocate cache (%d)\n", retval);
exit(-1); // XXX fix
}
#else // HAVE_POSIX_MEMALIGN
imgInfo->cache = malloc(TSK_IMG_INFO_CACHE_NUM * TSK_IMG_INFO_CACHE_LEN);
#endif // HAVE_POSIX_MEMALIGN
#endif

return (void *) imgInfo;
}
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2 changes: 1 addition & 1 deletion tsk3/img/tsk_img.h
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Expand Up @@ -69,7 +69,7 @@ extern "C" {
TSK_IMG_TYPE_UNSUPP = 0xffff, ///< Unsupported disk image type
} TSK_IMG_TYPE_ENUM;

#define TSK_IMG_INFO_CACHE_NUM 256
#define TSK_IMG_INFO_CACHE_NUM 32
#define TSK_IMG_INFO_CACHE_LEN 32768

typedef struct TSK_IMG_INFO TSK_IMG_INFO;
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