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sysadm |
1.1 |
/* 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@corpit.ru.
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* Public domain.
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*/
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#include "common/setup_before.h"
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#include <stdio.h>
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#ifdef HAVE_SYS_STAT_H
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# include <sys/stat.h>
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#endif
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#include "compat/mmap.h"
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#include "cdb_int.h"
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#include "common/setup_after.h"
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int
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cdb_init(struct cdb *cdbp, FILE *fd)
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{
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unsigned char *mem;
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unsigned fsize, dend;
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/* get file size */
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if (fseek(fd, 0, SEEK_END))
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return -1;
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fsize = (unsigned)(ftell(fd));
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rewind(fd);
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/* trivial sanity check: at least toc should be here */
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if (fsize < 2048)
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return errno = EPROTO, -1;
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/* memory-map file */
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if ((mem = pmmap(NULL, fsize, PROT_READ, MAP_SHARED, fileno(fd), 0)) ==
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(unsigned char *)-1)
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return -1;
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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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pmunmap((void*)cdbp->cdb_mem, cdbp->cdb_fsize);
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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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