Adding upstream version 3.4.23.upstream/3.4.23upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 123 insertions, 0 deletions

diff --git a/README_FILES/LMDB_README b/README_FILES/LMDB_README
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+PPoossttffiixx OOppeennLLDDAAPP LLMMDDBB HHoowwttoo
+
+-------------------------------------------------------------------------------
+
+IInnttrroodduuccttiioonn
+
+Postfix uses databases of various kinds to store and look up information.
+Postfix databases are specified as "type:name". OpenLDAP LMDB (called "LMDB"
+from here on) implements the Postfix database type "lmdb". The name of a
+Postfix LMDB database is the name of the database file without the ".lmdb"
+suffix.
+
+This document describes:
+
+  * Building Postfix with LMDB support.
+
+  * Configuring LMDB settings.
+
+  * Using LMDB maps with non-Postfix programs.
+
+  * Required minimum LMDB patchlevel.
+
+  * Credits.
+
+BBuuiillddiinngg PPoossttffiixx wwiitthh LLMMDDBB ssuuppppoorrtt
+
+Postfix normally does not enable LMDB support. To build Postfix with LMDB
+support, use something like:
+
+    % make makefiles CCARGS="-DHAS_LMDB -I/usr/local/include" \
+        AUXLIBS_LMDB="-L/usr/local/lib -llmdb"
+    % make
+
+Postfix versions before 3.0 use AUXLIBS instead of AUXLIBS_LMDB. With Postfix
+3.0 and later, the old AUXLIBS variable still supports building a statically-
+loaded LMDB database client, but only the new AUXLIBS_LMDB variable supports
+building a dynamically-loaded or statically-loaded LMDB database client.
+
+    Failure to use the AUXLIBS_LMDB variable will defeat the purpose of dynamic
+    database client loading. Every Postfix executable file will have LMDB
+    database library dependencies. And that was exactly what dynamic database
+    client loading was meant to avoid.
+
+Solaris may need this:
+
+    % make makefiles CCARGS="-DHAS_LMDB -I/usr/local/include" \
+        AUXLIBS_LMDB="-R/usr/local/lib -L/usr/local/lib -llmdb"
+    % make
+
+The exact pathnames depend on how LMDB was installed.
+
+When building Postfix fails with:
+
+    undefined reference to `pthread_mutexattr_destroy'
+    undefined reference to `pthread_mutexattr_init'
+    undefined reference to `pthread_mutex_lock'
+
+Add the "-lpthread" library to the "make makefiles" command.
+
+    % make makefiles .... AUXLIBS_LMDB="... -lpthread"
+
+CCoonnffiigguurriinngg LLMMDDBB sseettttiinnggss
+
+Postfix provides one configuration parameter that controls LMDB database
+behavior.
+
+  * lmdb_map_size (default: 16777216). This setting specifies the initial LMDB
+    database size limit in bytes. Each time a database becomes "full", its size
+    limit is doubled. The maximum size is the largest signed integer value of
+    "long".
+
+UUssiinngg LLMMDDBB mmaappss wwiitthh nnoonn--PPoossttffiixx pprrooggrraammss
+
+Programs that use LMDB's built-in locking protocol will corrupt a Postfix LMDB
+database or will read garbage.
+
+Postfix does not use LMDB's built-in locking protocol, because that would
+require world-writable lockfiles, and would violate Postfix security policy.
+Instead, Postfix uses external locks based on fcntl(2) to prevent writers from
+corrupting the database, and to prevent readers from receiving garbage.
+
+See lmdb_table(5) for a detailed description of the locking protocol that all
+programs must use when they access a Postfix LMDB database.
+
+RReeqquuiirreedd mmiinniimmuumm LLMMDDBB ppaattcchhlleevveell
+
+Currently, Postfix requires LMDB 0.9.11 or later. The required minimum LMDB
+patchlevel has evolved over time, as the result of Postfix deployment
+experience:
+
+  * LMDB 0.9.11 allows Postfix daemons to log an LMDB error message, instead of
+    falling out of the sky without any notification.
+
+  * LMDB 0.9.10 closes an information leak where LMDB was writing up to 4-kbyte
+    chunks of uninitialized heap memory to the database. This would persist
+    information that was not meant to be persisted, or share information that
+    was not meant to be shared.
+
+  * LMDB 0.9.9 allows Postfix to use external (fcntl()-based) locks, instead of
+    having to use world-writable LMDB lock files, violating the Postfix
+    security model in multiple ways.
+
+  * LMDB 0.9.8 allows Postfix to recover from a "database full" error without
+    having to close the database. This version adds support to update the
+    database size limit on-the-fly. This is necessary because Postfix database
+    sizes vary with mail server load.
+
+  * LMDB 0.9.7 allows the postmap(1) and postalias(1) commands to use a bulk-
+    mode transaction larger than the amount of physical memory. This is
+    necessary because LMDB supports databases larger than physical memory.
+
+CCrreeddiittss
+
+  * Howard Chu contributed the initial Postfix dict_lmdb driver.
+
+  * Wietse Venema wrote an abstraction layer (slmdb) that behaves more like
+    Berkeley DB, NDBM, etc. This layer automatically retries an LMDB request
+    when a database needs to be resized, or after a database was resized by a
+    different process.
+
+  * Howard and Wietse went through many iterations with changes to both LMDB
+    and Postfix, with input from Viktor Dukhovni.
+