annotate audioDB-internals.h @ 411:ad2206c24986 api-inversion

Fix a memory corruption bug.

When allocating the adb_t in audiodb_open(), zero the memory; then we're
not going to try to free() or delete some arbitrary uninitialized thing
if the thing that we're opening turns out not to be an audiodb database.

typedef struct adb_datum_internal {
  uint32_t nvectors;
  uint32_t dim;
  const char *key;
  void *data;
  void *times;
  void *power;
} adb_datum_internal_t;

struct adb {
  char *path;
  int fd;
  int flags;
  adb_header_t *header;
  std::set<std::string> *keys;
};

/* We could go gcc-specific here and use typeof() instead of passing
 * in an explicit type.  Answers on a postcard as to whether that's a
 * good plan or not. */
#define mmap_or_goto_error(type, var, start, length) \
  { void *tmp = mmap(0, length, PROT_READ, MAP_SHARED, adb->fd, (start)); \
    if(tmp == (void *) -1) { \
      goto error; \
    } \
    var = (type) tmp; \
  }

#define maybe_munmap(table, length) \
  { if(table) { \
      munmap(table, length); \
    } \
  }

#define write_or_goto_error(fd, buffer, size) \
  { ssize_t tmp = size; \
    if(write(fd, buffer, size) != tmp) { \
      goto error; \
    } \
  }

#define read_or_goto_error(fd, buffer, size) \
  { ssize_t tmp = size; \
    if(read(fd, buffer, size) != tmp) { \
      goto error; \
    } \
  }

static inline int audiodb_sync_header(adb_t *adb) {
  off_t pos;
  pos = lseek(adb->fd, (off_t) 0, SEEK_CUR);
  if(pos == (off_t) -1) {
    goto error;
  }
  if(lseek(adb->fd, (off_t) 0, SEEK_SET) == (off_t) -1) {
    goto error;
  }
  if(write(adb->fd, adb->header, O2_HEADERSIZE) != O2_HEADERSIZE) {
    goto error;
  }

  /* can be fsync() if fdatasync() is racily exciting and new */
  fdatasync(adb->fd);
  if(lseek(adb->fd, pos, SEEK_SET) == (off_t) -1) {
    goto error;
  }
  return 0;

 error:
  return 1;
}