newsGNU dbm - News: Version 1.13 released

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Version 1.13 released

Item posted by Sergey Poznyakoff <gray> on Sat 11 Mar 2017 05:19:51 PM UTC.

GDBM version 1.13 is available for download.

New in this version:

gdbm_fetch, gdbm_firstkey, and gdbm_nextkey behavior

If the requested key was not found, these functions return datum with dptr pointing to NULL and set gdbm_errno to GDBM_ITEM_NOT_FOUND (in prior releases, gdbm_errno was set to GDBM_NO_ERROR).

If an error occurred, dptr is set to NULL, and gdbm_errno to the error code.

In any case gdbm_errno is guaranteed to have meaningful value upon return.

Error handling

In previous versions of GDBM, fatal errors (such as write error while storing the key/data pair or bucket) caused immediate termination of the program via call to exit(3).  This is no longer the case.

Starting from this version, if a fatal error occurrs while modifying the database file, that database is marked as needing recovery and gdbm_errno is set to GDBM_NEED_RECOVERY.  Calls to any GDBM functions, except gdbm_recover, will then return immediately with the same error code.

The function gdbm_recover examines the database file and fixes eventual inconsistencies.  Upon successful return it clears the error state and makes the database operational again.

For backward compatibility, the fatal_func argument to gdbm_open is retained and its functionality is not changed.  If it is not NULL, the new error handling procedures are disabled, the function it points to will be called upon fatal errors.  When it returns, exit(1) will be called.

Per-database error codes

In addition to gdbm_error global variable, the most recent error state is saved in the GDBM_FILE structure.  This facilitates error handling when operating multiple GDBM databases simultaneously.

The following new functions are implemented for manipulating error states:

gdbm_error gdbm_last_errno (GDBM_FILE dbf)

Returns the code of the most recent error that occurred in the given database.

int gdbm_last_syserr (GDBM_FILE dbf)

Returns the value the system errno variable had when the most recent error occurred.  This provides additional information for such error codes as GDBM_FILE_SEEK_ERROR, GDBM_FILE_WRITE_ERROR and the like.

void gdbm_clear_error (GDBM_FILE dbf)

Clears the error state associated with the database file.

char const *gdbm_db_strerror (GDBM_FILE dbf)

Returns textual description of the error.

int gdbm_needs_recovery (GDBM_FILE dbf)

Returns true if the database file needs recovery.

New gdbm_open flag: GDBM_BSEXACT

When creating a new database, the gdbm_open function will adjust the requested block size so that the block can hold integer number of directory entries.  Thus, the resulting block size can be bigger than the requested one.  If the GDBM_BSEXACT flag is set, this behavior is suppressed and gdbm_open will try to force exactly the requested block size.  If unable to do so, it will set the gdbm_errno variable to GDBM_BLOCK_SIZE_ERROR and return NULL.

New gdbm_setopt option: GDBM_GETBLOCKSIZE

Returns the block size in bytes.  E.g.

 int size;
 if (gdbm_setopt (dbf, GDBM_GETBLOCKSIZE, &size, sizeof size))
   abort ();

New functions

GDBM_FILE gdbm_fd_open (int fd, const char *file_name, int block_size, int flags, void (*fatal_func) (const char *))

Alternative function for opening a GDBM database.  The fd argument is
the file descriptor of the database file obtained by a call to
open(2), creat(2) or similar functions.  The descriptor is not dup'ed, and
will be closed when the returned GDBM_FILE is closed.  Use dup(2) if
that is not desirable.

int gdbm_copy_meta (GDBM_FILE dst, GDBM_FILE src)

Copy meta-information (ownership and file permissions) from src to dst.


Line editing in gdbmtool

The gdbmtool utility now offers the usual line-editing facilities (if the package has been compiled with GNU Readline.

Keyboard shortcuts

If the last entered command was "next", hitting the "Enter" key repeats it without arguments.

Magic file included

The magic file suitable for use with the file(1) command is distributed with the package.  Its name is src/gdbm.magic.

It is not installed by default, as its installation location differs considerably between various distributions.


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