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