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/* $Id: cdb_init.c,v 1.11 2006/09/03 10:17:45 mjt Exp $
* cdb_init, cdb_free and cdb_read routines
*
* This file is a part of tinycdb package by Michael Tokarev, mjt@corpit.ru.
* Public domain.
*/
#include <sys/types.h>
#ifdef _WIN32
# include <windows.h>
#else
# include <sys/mman.h>
# ifndef MAP_FAILED
# define MAP_FAILED ((void*)-1)
# endif
#endif
#include <sys/stat.h>
#include "cdb_int.h"
int
cdb_init(struct cdb *cdbp, int fd)
{
struct stat st;
unsigned char *mem;
unsigned fsize, dend;
#ifdef _WIN32
HANDLE hFile, hMapping;
#endif
/* get file size */
if (fstat(fd, &st) < 0)
return -1;
/* trivial sanity check: at least toc should be here */
if (st.st_size < 2048)
return errno = EPROTO, -1;
fsize = (unsigned)(st.st_size & 0xffffffffu);
/* memory-map file */
#ifdef _WIN32
hFile = (HANDLE) _get_osfhandle(fd);
if (hFile == (HANDLE) -1)
return -1;
hMapping = CreateFileMapping(hFile, NULL, PAGE_READONLY, 0, 0, NULL);
if (!hMapping)
return -1;
mem = (unsigned char *)MapViewOfFile(hMapping, FILE_MAP_READ, 0, 0, 0);
if (!mem)
return -1;
#else
mem = (unsigned char*)mmap(NULL, fsize, PROT_READ, MAP_SHARED, fd, 0);
if (mem == MAP_FAILED)
return -1;
#endif /* _WIN32 */
cdbp->cdb_fd = fd;
cdbp->cdb_fsize = fsize;
cdbp->cdb_mem = mem;
#if 0
/* XXX don't know well about madvise syscall -- is it legal
to set different options for parts of one mmap() region?
There is also posix_madvise() exist, with POSIX_MADV_RANDOM etc...
*/
#ifdef MADV_RANDOM
/* set madvise() parameters. Ignore errors for now if system
doesn't support it */
madvise(mem, 2048, MADV_WILLNEED);
madvise(mem + 2048, cdbp->cdb_fsize - 2048, MADV_RANDOM);
#endif
#endif
cdbp->cdb_vpos = cdbp->cdb_vlen = 0;
cdbp->cdb_kpos = cdbp->cdb_klen = 0;
dend = cdb_unpack(mem);
if (dend < 2048) dend = 2048;
else if (dend >= fsize) dend = fsize;
cdbp->cdb_dend = dend;
return 0;
}
void
cdb_free(struct cdb *cdbp)
{
if (cdbp->cdb_mem) {
#ifdef _WIN32
HANDLE hFile, hMapping;
#endif
#ifdef _WIN32
hFile = (HANDLE) _get_osfhandle(cdbp->cdb_fd);
hMapping = CreateFileMapping(hFile, NULL, PAGE_READONLY, 0, 0, NULL);
UnmapViewOfFile((void*) cdbp->cdb_mem);
CloseHandle(hMapping);
#else
munmap((void*)cdbp->cdb_mem, cdbp->cdb_fsize);
#endif /* _WIN32 */
cdbp->cdb_mem = NULL;
}
cdbp->cdb_fsize = 0;
}
const void *
cdb_get(const struct cdb *cdbp, unsigned len, unsigned pos)
{
if (pos > cdbp->cdb_fsize || cdbp->cdb_fsize - pos < len) {
errno = EPROTO;
return NULL;
}
return cdbp->cdb_mem + pos;
}
int
cdb_read(const struct cdb *cdbp, void *buf, unsigned len, unsigned pos)
{
const void *data = cdb_get(cdbp, len, pos);
if (!data) return -1;
memcpy(buf, data, len);
return 0;
}
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