annotate audioDB-internals.h @ 410:d7e590d58c85 api-inversion

Pavlovian response to compiler warnings...

... attempt to squash them.  For now we can get most of the way by
writing a simple write_or_goto_error() macro for write(), and the
equivalent for read().

One of the warnings, for the return value of chdir(), is silly, because
we're already in an error case, and we really can't do anything sensible
if the chdir fails.  Try to deal with it anyway.

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;
}