# db_env_set_func_ioinfo

`

###

    #include <db.h>

    int
    db_env_set_func_ioinfo(int (*func_ioinfo)(const char *path,
        int fd, u_int32_t *mbytesp, u_int32_t *bytesp, u_int32_t *iosizep));

# Description

The Berkeley DB library requires the ability to determine the size and I/O characteristics of a file. The func_ioinfo argument must conform to the following interface:

>     int ioinfo(const char *path, int fd,
>     u_int32_t *mbytesp, u_int32_t *bytesp, u_int32_t *iosizep);

The path argument is the pathname of the file to be checked, and the fd argument is an open file descriptor on the file.

If the mbytesp and bytesp arguments are non-NULL, the ioinfo function must return in them the size of the file: the number of megabytes in the file into the memory location referenced by the mbytesp argument, and the number of bytes over and above that number of megabytes into the memory location referenced by the bytesp argument.

In addition, if the iosizep argument is non-NULL, the ioinfo function must return the optimum granularity for I/O operations to the file in the memory location referenced by it.

The func_ioinfo function must return the value of errno on failure and 0 on success.

The db_env_set_func_ioinfo interface affects the entire application, not a single database or database environment.

While the db_env_set_func_ioinfo interface may be used to configure Berkeley DB at any time during the life of the application, it should normally be called before making any calls to the db_env_create or db_create functions.

The db_env_set_func_ioinfo function returns a non-zero error value on failure and 0 on success.

# Errors

EINVAL
  An invalid flag value or parameter was specified.

# See Also

db_env_set_func_close, db_env_set_func_dirfree, db_env_set_func_dirlist, db_env_set_func_exists, db_env_set_func_free, db_env_set_func_fsync, db_env_set_func_ioinfo, db_env_set_func_malloc, db_env_set_func_map, db_env_set_func_open, db_env_set_func_read, db_env_set_func_realloc, db_env_set_func_seek, db_env_set_func_sleep, db_env_set_func_unlink, db_env_set_func_unmap, db_env_set_func_write and db_env_set_func_yield.`

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