/*
* Copyright (C) 2009 Sourcefire, Inc.
*
* Authors: aCaB <acab@clamav.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
/* an mmap "replacement" which doesn't suck */
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#define _XOPEN_SOURCE 500
#define _BSD_SOURCE
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include "others.h"
#include "cltypes.h"
#define FM_MASK_COUNT 0x3fffffff
#define FM_MASK_PAGED 0x40000000
#define FM_MASK_SEEN 0x80000000
#define FM_MASK_LOCKED FM_MASK_SEEN
/* 2 high bits:
00 - not seen - not paged - N/A
01 - N/A - paged - not locked
10 - seen - not paged - N/A
11 - N/A - paged - locked
*/
/* FIXME: tune this stuff */
#define UNPAGE_THRSHLD_LO 4*1024*1024
#define UNPAGE_THRSHLD_HI 8*1024*1024
#define READAHEAD_PAGES 4
static unsigned int fmap_align_items(unsigned int sz, unsigned int al) {
return sz / al + (sz % al != 0);
}
static unsigned int fmap_align_to(unsigned int sz, unsigned int al) {
return al * fmap_align_items(sz, al);
}
static unsigned int fmap_which_page(struct F_MAP *m, size_t at) {
return at / m->pgsz;
}
struct F_MAP *fmap(int fd, off_t offset, size_t len) {
unsigned int pages, mapsz, hdrsz;
int pgsz = cli_getpagesize();
struct stat st;
struct F_MAP *m;
if(fstat(fd, &st)) {
cli_warnmsg("fmap: fstat failed\n");
return NULL;
}
if(offset < 0 || offset != fmap_align_to(offset, pgsz)) {
cli_warnmsg("fmap: attempted mapping with unaligned offset\n");
return NULL;
}
if(!len) len = st.st_size - offset; /* bound checked later */
if(!len) {
cli_warnmsg("fmap: attempted void mapping\n");
return NULL;
}
if(!CLI_ISCONTAINED(0, st.st_size, offset, len)) {
cli_warnmsg("fmap: attempted oof mapping\n");
return NULL;
}
pages = fmap_align_items(len, pgsz);
hdrsz = fmap_align_to(sizeof(struct F_MAP) + pages * sizeof(uint32_t), pgsz);
mapsz = pages * pgsz + hdrsz;
if ((m = (struct F_MAP *)mmap(NULL, mapsz, PROT_READ | PROT_WRITE, MAP_PRIVATE|ANONYMOUS_MAP, -1, 0)) == MAP_FAILED) {
cli_warnmsg("fmap: mmap() failed\n");
return NULL;
}
m->fd = fd;
m->mtime = st.st_mtime;
m->offset = offset;
m->len = len;
m->pages = pages;
m->hdrsz = hdrsz;
m->pgsz = pgsz;
m->paged = 0;
memset(m->bitmap, 0, sizeof(uint32_t) * pages);
// cli_errmsg("FMAPDBG: created %p - len %u pages %u hdrsz %u\n", m, len, pages, hdrsz);
return m;
}
static void fmap_qsel(struct F_MAP *m, unsigned int *freeme, unsigned int left, unsigned int right) {
unsigned int i = left, j = right;
unsigned int pivot = m->bitmap[freeme[(left + right) / 2]] & FM_MASK_COUNT;
while(i <= j) {
while((m->bitmap[freeme[i]] & FM_MASK_COUNT) > pivot)
i++;
while((m->bitmap[freeme[j]] & FM_MASK_COUNT) < pivot)
j--;
if(i <= j) {
unsigned int temp = freeme[i];
freeme[i] = freeme[j];
freeme[j] = temp;
i++;
j--;
}
}
if(left < j)
fmap_qsel(m, freeme, left, j);
if(i < right)
fmap_qsel(m, freeme, i, right);
}
static void fmap_aging(struct F_MAP *m) {
if(m->paged * m->pgsz > UNPAGE_THRSHLD_LO) { /* we alloc'd too much */
unsigned int i, avail = 0, *freeme;
freeme = cli_malloc(sizeof(unsigned int) * m->pages);
if(!freeme) return;
for(i=0; i<m->pages; i++) {
uint32_t s = m->bitmap[i];
if((s & (FM_MASK_PAGED | FM_MASK_LOCKED)) == FM_MASK_PAGED ) {
/* page is paged and not locked: dec age */
if(s & FM_MASK_COUNT) m->bitmap[i]--;
/* and make it available for unpaging */
freeme[avail] = i;
avail++;
}
}
if(avail) { /* at least one page is paged and not locked */
if(avail * m->pgsz > UNPAGE_THRSHLD_HI ) {
/* if we've got more unpageable pages than we need, we pick the oldest */
fmap_qsel(m, freeme, 0, avail - 1);
avail = UNPAGE_THRSHLD_HI / m->pgsz;
}
for(i=0; i<avail; i++) {
char *pptr = (char *)m + i * m->pgsz + m->hdrsz;
/* we mark the page as seen */
m->bitmap[freeme[i]] = FM_MASK_SEEN;
m->paged--;
/* and we mmap the page over so the kernel knows there's nothing good in there */
if(mmap(pptr, m->pgsz, PROT_READ | PROT_WRITE, MAP_FIXED|MAP_PRIVATE|ANONYMOUS_MAP, -1, 0) == MAP_FAILED)
cli_warnmsg("fmap_aging: kernel hates you\n");
}
}
free(freeme);
}
}
static int fmap_readpage(struct F_MAP *m, unsigned int first_page, unsigned int count, unsigned int lock_count) {
size_t readsz = 0, got;
char *pptr = NULL;
uint32_t s;
unsigned int i, page = first_page, force_read = 0;
for(i=0; i<=count; i++, page++) {
int lock;
if(lock_count) {
lock_count--;
lock = 1;
} else lock = 0;
if(i == count) {
/* we count one page too much to flush pending reads */
if(!pptr) return 0; /* if we have any */
force_read = 1;
} else if((s=m->bitmap[page]) & FM_MASK_PAGED) {
/* page already paged */
if(lock) {
/* we want locking */
if(s & FM_MASK_LOCKED) {
/* page already locked */
s &= FM_MASK_COUNT;
if(s == FM_MASK_COUNT) { /* lock count already at max: fial! */
cli_errmsg("fmap_readpage: lock count exceeded\n");
return 1;
}
/* acceptable lock count: inc lock count */
m->bitmap[page]++;
} else /* page not currently locked: set lock count = 1 */
m->bitmap[page] = 1 | FM_MASK_LOCKED | FM_MASK_PAGED;
} else {
/* we don't want locking */
if(!(s & FM_MASK_LOCKED)) {
/* page is not locked: we reset aging to max */
m->bitmap[page] = FM_MASK_PAGED | FM_MASK_COUNT;
}
}
if(!pptr) continue;
force_read = 1;
}
if(force_read) {
/* we have some pending reads to perform */
unsigned int j;
for(j=first_page; j<page; j++) {
if(m->bitmap[j] & FM_MASK_SEEN) {
/* page we've seen before: check mtime */
struct stat st;
if(fstat(m->fd, &st)) {
cli_warnmsg("fmap_readpage: fstat failed\n");
return 1;
}
if(m->mtime != st.st_mtime) {
cli_warnmsg("fmap_readpage: file changed as we read it\n");
return 1;
}
break;
}
}
if((got=pread(m->fd, pptr, readsz, m->offset + first_page * m->pgsz)) != readsz) {
cli_warnmsg("pread fail: page %u pages %u map-offset %lu - asked for %lu bytes, got %lu\n", first_page, m->pages, (long unsigned int)m->offset, (long unsigned int)readsz, (long unsigned int)got);
return 1;
}
pptr = NULL;
force_read = 0;
readsz = 0;
continue;
}
/* page is not already paged */
if(!pptr) {
/* set a new start for pending reads if we don't have one */
pptr = (char *)m + page * m->pgsz + m->hdrsz;
first_page = page;
}
if((page == m->pages - 1) && (m->len % m->pgsz))
readsz += m->len % m->pgsz;
else
readsz += m->pgsz;
if(lock) /* lock requested: set paged, lock page and set lock count to 1 */
m->bitmap[page] = FM_MASK_PAGED | FM_MASK_LOCKED | 1;
else /* no locking: set paged and set aging to max */
m->bitmap[page] = FM_MASK_PAGED | FM_MASK_COUNT;
m->paged++;
}
return 0;
}
static void *fmap_need(struct F_MAP *m, size_t at, size_t len, int lock) {
unsigned int i, first_page, last_page, lock_count;
char *ret;
if(!len) {
cli_warnmsg("fmap: attempted void need\n");
return NULL;
}
if(!CLI_ISCONTAINED(0, m->len, at, len)) {
cli_warnmsg("fmap: attempted oof need\n");
return NULL;
}
fmap_aging(m);
first_page = fmap_which_page(m, at);
last_page = fmap_which_page(m, at + len - 1);
lock_count = (lock!=0) * (last_page-first_page+1);
#ifdef READAHED_PAGES
last_page += READAHED_PAGES;
if(last_page >= m->pages) last_page = m->pages - 1;
#endif
// cli_errmsg("FMAPDBG: +++ map %p - len %u lock: %d (page %u to %u)\n", m, len, lock, first_page, last_page);
if(fmap_readpage(m, first_page, last_page-first_page+1, lock_count))
return NULL;
ret = (char *)m;
ret += at + m->hdrsz;
return (void *)ret;
}
void *fmap_need_off(struct F_MAP *m, size_t at, size_t len) {
// cli_errmsg("FMAPDBG: need_off map %p at %u len %u\n", m, at, len);
return fmap_need(m, at, len, 1);
}
void *fmap_need_off_once(struct F_MAP *m, size_t at, size_t len) {
// cli_errmsg("FMAPDBG: need_off_once map %p at %u len %u\n", m, at, len);
return fmap_need(m, at, len, 0);
}
void *fmap_need_ptr(struct F_MAP *m, void *ptr, size_t len) {
// cli_errmsg("FMAPDBG: need_ptr map %p at %p len %u\n", m, ptr, len);
return fmap_need_off(m, (char *)ptr - (char *)m - m->hdrsz, len);
}
void *fmap_need_ptr_once(struct F_MAP *m, void *ptr, size_t len) {
// cli_errmsg("FMAPDBG: need_ptr_once map %p at %p len %u\n", m, ptr, len);
return fmap_need_off_once(m, (char *)ptr - (char *)m - m->hdrsz, len);
}
void *fmap_need_str(struct F_MAP *m, void *ptr, size_t len) {
const size_t at = (char *)ptr - (char *)m - m->hdrsz;
unsigned int i, first_page, last_page;
if(!len)
len = m->len - at;
if(!CLI_ISCONTAINED(0, m->len, at, len)) {
cli_warnmsg("fmap: attempted oof need_str\n");
return NULL;
}
fmap_aging(m);
// cli_errmsg("FMAPDBG: need_str map %p at %p len %u\n", m, ptr, len);
first_page = fmap_which_page(m, at);
last_page = fmap_which_page(m, at + len - 1);
for(i=first_page; i<=last_page; i++) {
char *thispage = (char *)m + m->hdrsz + i * m->pgsz;
unsigned int scanat, scansz;
// cli_errmsg("FMAPDBG: +s+ map %p - (page %u)\n", m, i);
if(fmap_readpage(m, i, 1, 1))
return NULL;
if(i == first_page) {
scanat = at % m->pgsz;
scansz = m->pgsz - scanat;
} else {
scanat = 0;
scansz = m->pgsz;
}
if(memchr(&thispage[scanat], 0, scansz))
return ptr;
}
return NULL;
}
static void fmap_unneed_page(struct F_MAP *m, unsigned int page) {
uint32_t s = m->bitmap[page];
// cli_errmsg("FMAPDBG: --- map %p - page %u status %u count %u\n", m, page, s>>30, s & FM_MASK_COUNT);
if((s & (FM_MASK_PAGED | FM_MASK_LOCKED)) == (FM_MASK_PAGED | FM_MASK_LOCKED)) {
/* page is paged and locked: check lock count */
s &= FM_MASK_COUNT;
if(s > 1) /* locked more than once: dec lock count */
m->bitmap[page]--;
else if (s == 1) /* only one lock left: unlock and begin aging */
m->bitmap[page] = FM_MASK_COUNT | FM_MASK_PAGED;
else
cli_errmsg("fmap_unneed: inconsistent map state\n");
return;
}
cli_warnmsg("fmap_unneed: unneed on a unlocked page\n");
return;
}
void fmap_unneed_off(struct F_MAP *m, size_t at, size_t len) {
unsigned int i, first_page, last_page;
if(!len) {
cli_warnmsg("fmap_unneed: attempted void unneed\n");
return;
}
if(!CLI_ISCONTAINED(0, m->len, at, len)) {
cli_warnmsg("fmap: attempted oof need\n");
return;
}
// cli_errmsg("FMAPDBG: unneed_off map %p at %u len %u\n", m, at, len);
first_page = fmap_which_page(m, at);
last_page = fmap_which_page(m, at + len - 1);
for(i=first_page; i<=last_page; i++) {
fmap_unneed_page(m, i);
}
}
void fmap_unneed_ptr(struct F_MAP *m, void *ptr, size_t len) {
// cli_errmsg("FMAPDBG: unneed_ptr map %p at %p len %u\n", m, ptr, len);
return fmap_unneed_off(m, (char *)ptr - (char *)m - m->hdrsz, len);
}
int fmap_readn(struct F_MAP *m, void *dst, size_t at, size_t len) {
char *src;
if(at > m->len)
return -1;
if(len > m->len - at)
len = m->len - at;
src = fmap_need_off_once(m, at, len);
if(!src)
return -1;
memcpy(dst, src, len);
return len;
}
void fmunmap(struct F_MAP *m) {
void *p = (void *)m;
size_t len = m->pages * m->pgsz + m->hdrsz;
munmap(p, len);
}