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