Adding upstream version 3.40.1.upstream/3.40.1upstream

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

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+<h1 align="center">SQLite Source Repository</h1>
+
+This repository contains the complete source code for the
+[SQLite database engine](https://sqlite.org/).  Some test scripts
+are also included.  However, many other test scripts
+and most of the documentation are managed separately.
+
+## Version Control
+
+SQLite sources are managed using the
+[Fossil](https://www.fossil-scm.org/), a distributed version control system
+that was specifically designed and written to support SQLite development.
+The [Fossil repository](https://sqlite.org/src/timeline) contains the urtext.
+
+If you are reading this on GitHub or some other Git repository or service,
+then you are looking at a mirror.  The names of check-ins and
+other artifacts in a Git mirror are different from the official
+names for those objects.  The official names for check-ins are
+found in a footer on the check-in comment for authorized mirrors.
+The official check-in name can also be seen in the `manifest.uuid` file
+in the root of the tree.  Always use the official name, not  the
+Git-name, when communicating about an SQLite check-in.
+
+If you pulled your SQLite source code from a secondary source and want to
+verify its integrity, there are hints on how to do that in the
+[Verifying Code Authenticity](#vauth) section below.
+
+## Obtaining The Code
+
+If you do not want to use Fossil, you can download tarballs or ZIP
+archives or [SQLite archives](https://sqlite.org/cli.html#sqlar) as follows:
+
+  *  Latest trunk check-in as
+     [Tarball](https://www.sqlite.org/src/tarball/sqlite.tar.gz),
+     [ZIP-archive](https://www.sqlite.org/src/zip/sqlite.zip), or
+     [SQLite-archive](https://www.sqlite.org/src/sqlar/sqlite.sqlar).
+
+  *  Latest release as
+     [Tarball](https://www.sqlite.org/src/tarball/sqlite.tar.gz?r=release),
+     [ZIP-archive](https://www.sqlite.org/src/zip/sqlite.zip?r=release), or
+     [SQLite-archive](https://www.sqlite.org/src/sqlar/sqlite.sqlar?r=release).
+
+  *  For other check-ins, substitute an appropriate branch name or
+     tag or hash prefix in place of "release" in the URLs of the previous
+     bullet.  Or browse the [timeline](https://www.sqlite.org/src/timeline)
+     to locate the check-in desired, click on its information page link,
+     then click on the "Tarball" or "ZIP Archive" links on the information
+     page.
+
+If you do want to use Fossil to check out the source tree,
+first install Fossil version 2.0 or later.
+(Source tarballs and precompiled binaries available
+[here](https://www.fossil-scm.org/fossil/uv/download.html).  Fossil is
+a stand-alone program.  To install, simply download or build the single
+executable file and put that file someplace on your $PATH.)
+Then run commands like this:
+
+        mkdir -p ~/sqlite ~/Fossils
+        cd ~/sqlite
+        fossil clone https://www.sqlite.org/src ~/Fossils/sqlite.fossil
+        fossil open ~/Fossils/sqlite.fossil
+
+After setting up a repository using the steps above, you can always
+update to the latest version using:
+
+        fossil update trunk   ;# latest trunk check-in
+        fossil update release ;# latest official release
+
+Or type "fossil ui" to get a web-based user interface.
+
+## Compiling for Unix-like systems
+
+First create a directory in which to place
+the build products.  It is recommended, but not required, that the
+build directory be separate from the source directory.  Cd into the
+build directory and then from the build directory run the configure
+script found at the root of the source tree.  Then run "make".
+
+For example:
+
+        tar xzf sqlite.tar.gz    ;#  Unpack the source tree into "sqlite"
+        mkdir bld                ;#  Build will occur in a sibling directory
+        cd bld                   ;#  Change to the build directory
+        ../sqlite/configure      ;#  Run the configure script
+        make                     ;#  Run the makefile.
+        make sqlite3.c           ;#  Build the "amalgamation" source file
+        make test                ;#  Run some tests (requires Tcl)
+
+See the makefile for additional targets.
+
+The configure script uses autoconf 2.61 and libtool.  If the configure
+script does not work out for you, there is a generic makefile named
+"Makefile.linux-gcc" in the top directory of the source tree that you
+can copy and edit to suit your needs.  Comments on the generic makefile
+show what changes are needed.
+
+## Using MSVC for Windows systems
+
+On Windows, all applicable build products can be compiled with MSVC.
+First open the command prompt window associated with the desired compiler
+version (e.g. "Developer Command Prompt for VS2013").  Next, use NMAKE
+with the provided "Makefile.msc" to build one of the supported targets.
+
+For example, from the parent directory of the source subtree named "sqlite":
+
+        mkdir bld
+        cd bld
+        nmake /f ..\sqlite\Makefile.msc TOP=..\sqlite
+        nmake /f ..\sqlite\Makefile.msc sqlite3.c TOP=..\sqlite
+        nmake /f ..\sqlite\Makefile.msc sqlite3.dll TOP=..\sqlite
+        nmake /f ..\sqlite\Makefile.msc sqlite3.exe TOP=..\sqlite
+        nmake /f ..\sqlite\Makefile.msc test TOP=..\sqlite
+
+There are several build options that can be set via the NMAKE command
+line.  For example, to build for WinRT, simply add "FOR_WINRT=1" argument
+to the "sqlite3.dll" command line above.  When debugging into the SQLite
+code, adding the "DEBUG=1" argument to one of the above command lines is
+recommended.
+
+SQLite does not require [Tcl](http://www.tcl.tk/) to run, but a Tcl installation
+is required by the makefiles (including those for MSVC).  SQLite contains
+a lot of generated code and Tcl is used to do much of that code generation.
+
+## Source Code Tour
+
+Most of the core source files are in the **src/** subdirectory.  The
+**src/** folder also contains files used to build the "testfixture" test
+harness. The names of the source files used by "testfixture" all begin
+with "test".
+The **src/** also contains the "shell.c" file
+which is the main program for the "sqlite3.exe"
+[command-line shell](https://sqlite.org/cli.html) and
+the "tclsqlite.c" file which implements the
+[Tcl bindings](https://sqlite.org/tclsqlite.html) for SQLite.
+(Historical note:  SQLite began as a Tcl
+extension and only later escaped to the wild as an independent library.)
+
+Test scripts and programs are found in the **test/** subdirectory.
+Additional test code is found in other source repositories.
+See [How SQLite Is Tested](http://www.sqlite.org/testing.html) for
+additional information.
+
+The **ext/** subdirectory contains code for extensions.  The
+Full-text search engine is in **ext/fts3**.  The R-Tree engine is in
+**ext/rtree**.  The **ext/misc** subdirectory contains a number of
+smaller, single-file extensions, such as a REGEXP operator.
+
+The **tool/** subdirectory contains various scripts and programs used
+for building generated source code files or for testing or for generating
+accessory programs such as "sqlite3_analyzer(.exe)".
+
+### Generated Source Code Files
+
+Several of the C-language source files used by SQLite are generated from
+other sources rather than being typed in manually by a programmer.  This
+section will summarize those automatically-generated files.  To create all
+of the automatically-generated files, simply run "make target&#95;source".
+The "target&#95;source" make target will create a subdirectory "tsrc/" and
+fill it with all the source files needed to build SQLite, both
+manually-edited files and automatically-generated files.
+
+The SQLite interface is defined by the **sqlite3.h** header file, which is
+generated from src/sqlite.h.in, ./manifest.uuid, and ./VERSION.  The
+[Tcl script](http://www.tcl.tk) at tool/mksqlite3h.tcl does the conversion.
+The manifest.uuid file contains the SHA3 hash of the particular check-in
+and is used to generate the SQLITE\_SOURCE\_ID macro.  The VERSION file
+contains the current SQLite version number.  The sqlite3.h header is really
+just a copy of src/sqlite.h.in with the source-id and version number inserted
+at just the right spots. Note that comment text in the sqlite3.h file is
+used to generate much of the SQLite API documentation.  The Tcl scripts
+used to generate that documentation are in a separate source repository.
+
+The SQL language parser is **parse.c** which is generated from a grammar in
+the src/parse.y file.  The conversion of "parse.y" into "parse.c" is done
+by the [lemon](./doc/lemon.html) LALR(1) parser generator.  The source code
+for lemon is at tool/lemon.c.  Lemon uses the tool/lempar.c file as a
+template for generating its parser.
+Lemon also generates the **parse.h** header file, at the same time it
+generates parse.c.
+
+The **opcodes.h** header file contains macros that define the numbers
+corresponding to opcodes in the "VDBE" virtual machine.  The opcodes.h
+file is generated by scanning the src/vdbe.c source file.  The
+Tcl script at ./mkopcodeh.tcl does this scan and generates opcodes.h.
+A second Tcl script, ./mkopcodec.tcl, then scans opcodes.h to generate
+the **opcodes.c** source file, which contains a reverse mapping from
+opcode-number to opcode-name that is used for EXPLAIN output.
+
+The **keywordhash.h** header file contains the definition of a hash table
+that maps SQL language keywords (ex: "CREATE", "SELECT", "INDEX", etc.) into
+the numeric codes used by the parse.c parser.  The keywordhash.h file is
+generated by a C-language program at tool mkkeywordhash.c.
+
+The **pragma.h** header file contains various definitions used to parse
+and implement the PRAGMA statements.  The header is generated by a
+script **tool/mkpragmatab.tcl**. If you want to add a new PRAGMA, edit
+the **tool/mkpragmatab.tcl** file to insert the information needed by the
+parser for your new PRAGMA, then run the script to regenerate the
+**pragma.h** header file.
+
+### The Amalgamation
+
+All of the individual C source code and header files (both manually-edited
+and automatically-generated) can be combined into a single big source file
+**sqlite3.c** called "the amalgamation".  The amalgamation is the recommended
+way of using SQLite in a larger application.  Combining all individual
+source code files into a single big source code file allows the C compiler
+to perform more cross-procedure analysis and generate better code.  SQLite
+runs about 5% faster when compiled from the amalgamation versus when compiled
+from individual source files.
+
+The amalgamation is generated from the tool/mksqlite3c.tcl Tcl script.
+First, all of the individual source files must be gathered into the tsrc/
+subdirectory (using the equivalent of "make target_source") then the
+tool/mksqlite3c.tcl script is run to copy them all together in just the
+right order while resolving internal "#include" references.
+
+The amalgamation source file is more than 200K lines long.  Some symbolic
+debuggers (most notably MSVC) are unable to deal with files longer than 64K
+lines.  To work around this, a separate Tcl script, tool/split-sqlite3c.tcl,
+can be run on the amalgamation to break it up into a single small C file
+called **sqlite3-all.c** that does #include on about seven other files
+named **sqlite3-1.c**, **sqlite3-2.c**, ..., **sqlite3-7.c**.  In this way,
+all of the source code is contained within a single translation unit so
+that the compiler can do extra cross-procedure optimization, but no
+individual source file exceeds 32K lines in length.
+
+## How It All Fits Together
+
+SQLite is modular in design.
+See the [architectural description](http://www.sqlite.org/arch.html)
+for details. Other documents that are useful in
+(helping to understand how SQLite works include the
+[file format](http://www.sqlite.org/fileformat2.html) description,
+the [virtual machine](http://www.sqlite.org/opcode.html) that runs
+prepared statements, the description of
+[how transactions work](http://www.sqlite.org/atomiccommit.html), and
+the [overview of the query planner](http://www.sqlite.org/optoverview.html).
+
+Years of effort have gone into optimizing SQLite, both
+for small size and high performance.  And optimizations tend to result in
+complex code.  So there is a lot of complexity in the current SQLite
+implementation.  It will not be the easiest library in the world to hack.
+
+Key files:
+
+  *  **sqlite.h.in** - This file defines the public interface to the SQLite
+     library.  Readers will need to be familiar with this interface before
+     trying to understand how the library works internally.
+
+  *  **sqliteInt.h** - this header file defines many of the data objects
+     used internally by SQLite.  In addition to "sqliteInt.h", some
+     subsystems have their own header files.
+
+  *  **parse.y** - This file describes the LALR(1) grammar that SQLite uses
+     to parse SQL statements, and the actions that are taken at each step
+     in the parsing process.
+
+  *  **vdbe.c** - This file implements the virtual machine that runs
+     prepared statements.  There are various helper files whose names
+     begin with "vdbe".  The VDBE has access to the vdbeInt.h header file
+     which defines internal data objects.  The rest of SQLite interacts
+     with the VDBE through an interface defined by vdbe.h.
+
+  *  **where.c** - This file (together with its helper files named
+     by "where*.c") analyzes the WHERE clause and generates
+     virtual machine code to run queries efficiently.  This file is
+     sometimes called the "query optimizer".  It has its own private
+     header file, whereInt.h, that defines data objects used internally.
+
+  *  **btree.c** - This file contains the implementation of the B-Tree
+     storage engine used by SQLite.  The interface to the rest of the system
+     is defined by "btree.h".  The "btreeInt.h" header defines objects
+     used internally by btree.c and not published to the rest of the system.
+
+  *  **pager.c** - This file contains the "pager" implementation, the
+     module that implements transactions.  The "pager.h" header file
+     defines the interface between pager.c and the rest of the system.
+
+  *  **os_unix.c** and **os_win.c** - These two files implement the interface
+     between SQLite and the underlying operating system using the run-time
+     pluggable VFS interface.
+
+  *  **shell.c.in** - This file is not part of the core SQLite library.  This
+     is the file that, when linked against sqlite3.a, generates the
+     "sqlite3.exe" command-line shell.  The "shell.c.in" file is transformed
+     into "shell.c" as part of the build process.
+
+  *  **tclsqlite.c** - This file implements the Tcl bindings for SQLite.  It
+     is not part of the core SQLite library.  But as most of the tests in this
+     repository are written in Tcl, the Tcl language bindings are important.
+
+  *  **test*.c** - Files in the src/ folder that begin with "test" go into
+     building the "testfixture.exe" program.  The testfixture.exe program is
+     an enhanced Tcl shell.  The testfixture.exe program runs scripts in the
+     test/ folder to validate the core SQLite code.  The testfixture program
+     (and some other test programs too) is built and run when you type
+     "make test".
+
+  *  **ext/misc/json1.c** - This file implements the various JSON functions
+     that are built into SQLite.
+
+There are many other source files.  Each has a succinct header comment that
+describes its purpose and role within the larger system.
+
+<a name="vauth"></a>
+## Verifying Code Authenticity
+
+The `manifest` file at the root directory of the source tree
+contains either a SHA3-256 hash (for newer files) or a SHA1 hash (for
+older files) for every source file in the repository.
+The name of the version of the entire source tree is just the
+SHA3-256 hash of the `manifest` file itself, possibly with the
+last line of that file omitted if the last line begins with
+"`# Remove this line`".
+The `manifest.uuid` file should contain the SHA3-256 hash of the
+`manifest` file. If all of the above hash comparisons are correct, then
+you can be confident that your source tree is authentic and unadulterated.
+
+The format of the `manifest` file should be mostly self-explanatory, but
+if you want details, they are available
+[here](https://fossil-scm.org/fossil/doc/trunk/www/fileformat.wiki#manifest).
+
+## Contacts
+
+The main SQLite website is [http://www.sqlite.org/](http://www.sqlite.org/)
+with geographically distributed backups at
+[http://www2.sqlite.org/](http://www2.sqlite.org) and
+[http://www3.sqlite.org/](http://www3.sqlite.org).