Go to the first, previous, next, last section, table of contents.


_djstat_fail_bits

Syntax

#include <sys/stat.h>

extern unsigned short   _djstat_fail_bits;

As proper operation of section stat and section fstat depend on undocumented DOS features, they could fail in some incompatible environment or a future DOS version. If they do, the _djstat_fail_bits variable will have some of its bits set. Each bit describes a single feature which was used and failed. The function section _djstat_describe_lossage may be called to print a human-readable description of the bits which were set by the last call to f?stat(). This should make debugging f?stat() failures in an unanticipated environment a lot easier.

The following bits are currently defined:

_STFAIL_SDA
Indicates that Get SDA call failed.
_STFAIL_OSVER
Indicates an unsupported DOS version (less than 3.10 for stat() or less than 2.0 for fstat()).
_STFAIL_BADSDA
The pointer to SDA was found to be bogus.
_STFAIL_TRUENAME
Indicates that section _truename function call failed.
_STFAIL_HASH
Indicates that the starting cluster of the file is unavailable, and inode number was computed by hashing its name.
_STFAIL_LABEL
The application requested the time stamp of a root dir, but no volume label was found.
_STFAIL_DCOUNT
The number of SDA reported is ridiculously large (probbaly an unsupported DOS clone).
_STFAIL_WRITEBIT
fstat() was asked to get write access bit of a file, but couldn't.
_STFAIL_DEVNO
fstat() failed to get device number.
_STFAIL_BADSFT
An SFT entry for this file was found by fstat(), but its contents can't be trusted because it didn't match file size and time stamp as reported by DOS.
_STFAIL_SFTIDX
The SFT index in Job File Table in program's PSP is negative.
_STFAIL_SFTNF
The file entry was not found in the SFT array.

Below are some explanations of terminology and abbreviations used by the printed messages, which will further clarify the meaning of the above bits and their descriptions printed by section _djstat_describe_lossage.

SDA (Swappable Data Area) -- this is an internal DOS structure. stat() uses it to get the full directory entry (including the starting cluster number) of a file. The pointer to SDA found by stat() is trusted only if we find the pathname of our file at a specific offset in that SDA.

SFT (System File Table) -- another internal DOS structure, used in file operations. fstat() uses it to get full information on a file given its handle. An SFT entry which is found by fstat() is only trusted if it contains files size and time stamp like those returned by DOS functions 57h and 42h. Novell NetWare 3.x traps DOS file operations in such a way they never get to SFT, so some failure messages refer specifically to Novell.

Hashing -- the fall-back method of returning a unique inode number for each file. It is used whenever the starting cluster of a file couldn't be reliably determined. The full pathname of the file is looked up in a table of files seen earlier (hashing is used to speed the lookup process). If found, the inode from the table is returned; this ensures that a given file will get the same inode number. Otherwise a new inode number is invented, recorded in the table and returned to caller.

Portability

not ANSI, not POSIX


Go to the first, previous, next, last section, table of contents.