| @node stat-size |
| @section stat-size |
| |
| The @code{stat-size} module provides a small number of macros |
| intended for interpreting the file size information in an instance of |
| @code{struct stat}. |
| |
| @c We deliberately don't document DEV_BSIZE (it looks to James |
| @c Youngman as if the ST_NBLOCKSIZE macro should be used instead). |
| |
| @findex ST_NBLOCKS |
| @findex ST_NBLOCKSIZE |
| @cindex block size |
| On POSIX systems, the @code{st_blocks} member of @code{struct stat} |
| contains the number of disk blocks occupied by a file. The |
| @code{ST_NBLOCKS} macro is used to estimate this quantity on systems |
| which don't actually have @code{st_blocks}. Each of these blocks |
| contains @code{ST_NBLOCKSIZE} bytes. |
| |
| @findex ST_BLKSIZE |
| The value of @code{ST_NBLOCKSIZE} is often quite small, small enough |
| that performing I/O in chunks that size would be inefficient. |
| @code{ST_BLKSIZE} is the I/O block size recommended for I/O to this |
| file. This is not guaranteed to give optimum performance, but it |
| should be reasonably efficient. |
