5. Building A Windows DLL does not indicate how to compile SQLITE3.DLL with an extension.

For Windows, how can I compile the DLL with the fileio.c extension?

If you can compile such a DLL from the amalgamation, one possible hacky fix is to create a file like this one:

#define SQLITE_OMIT_AUTOINIT

// Amalgamation
#include "sqlite3.c"
// Extensions
#include "ext/anycollseq.c"
#include "ext/base64.c"
#include "ext/decimal.c"
#include "ext/ieee754.c"
#include "ext/regexp.c"
#include "ext/series.c"
#include "ext/spellfix.c"
#include "ext/uint.c"

__attribute__((constructor)) void init() {
  sqlite3_initialize();
  sqlite3_auto_extension((void (*)(void))sqlite3_base_init);
  sqlite3_auto_extension((void (*)(void))sqlite3_decimal_init);
  sqlite3_auto_extension((void (*)(void))sqlite3_ieee_init);
  sqlite3_auto_extension((void (*)(void))sqlite3_regexp_init);
  sqlite3_auto_extension((void (*)(void))sqlite3_series_init);
  sqlite3_auto_extension((void (*)(void))sqlite3_spellfix_init);
  sqlite3_auto_extension((void (*)(void))sqlite3_uint_init);
}

Place it besides the amalgamation (sqlite3.c), add the desired extensions in an ext folder (and tweak the above - pay attention to the exact _init function's name), then compile it as if you were compiling sqlite3.c. www:/howtocompile.html#building_a_windows_dll

PS: it seems __attribute__((constructor)) doesn't work with MSVC. I'm a bit spoiled by clang/GCC. Does MinGW work for you?

Thanks for the guidelines.

it seems __attribute__((constructor)) doesn't work with MSVC. ... Does MinGW work for you?

I do not have MinGW.

Not knowing C is enough of an affliction without opening pathways to another compiler of which I have no knowledge.

Thanks for your patience.

The amalgamation has just these files:shell.c sqlite3.c sqlite3.h sqlite3ext.h

I am somewhat confused since in this block of your suggestion:

// Amalgamation
#include "sqlite3.c"
// Extensions
#include "ext/anycollseq.c"
#include "ext/base64.c"
#include "ext/decimal.c"
#include "ext/ieee754.c"
#include "ext/regexp.c"
#include "ext/series.c"
#include "ext/spellfix.c"
#include "ext/uint.c"

1. the files listed are NOT in the amalgamation e.g. #include "ext/anycollseq.c" etc.
2. I do not see FILEIO.C

This is an example that includes several extensions I use, none of which are fileio.c.

I understand you don't know C, but I don't have a Windows machine, so I'd rather you tried to learn enough C to understand what I'm trying to explain, rather than just copying something verbatim and building it without much consideration.

So, please try this, if it makes sense:

1. replace those #include lines with the extension(s) you need
2. replace the sqlite3_auto_extension with one that calls the initialization function from the extension(s) you need

To explain a bit what's going on: #include <FILE> is like copy pasting the contents of a file into this new file; #define is like defining a constant.

So what you're actually doing is:

1. telling SQLite there's an additional initialization function it should call (named extra_init), before
2. copy pasting the amalgamation, then
3. appending a copy of all extensions you want, and finally
4. defining the extra_init function, which I initializes all extensions and reports any errors.

Does that make sense?

Does that make sense?

Very very slowly beginning to ... (as always it is easy when you know how and I am not there yet!)

My custom file looks as folows:

#define SQLITE_EXTRA_INIT extra_init

#ifdef _WIN32
#define SQLITE_API __declspec(dllexport)
#endif

// Amalgamation
#include "sqlite3.c"
// Extensions
#include "ext/fileio.c"

int extra_init(const char* dummy) {
  int n = 0;
  n += sqlite3_auto_extension((void (*)(void))sqlite3_fileio_init);
  return n ? SQLITE_ERROR : SQLITE_OK;
}

I got an error relating to test_windirent.h; I downloaded this file.

Then I hit these errors:

error LNK2019: unresolved external symbol _opendir referenced in function _fsdirSetErrmsg
error LNK2019: unresolved external symbol _readdir referenced in function _fsdirSetErrmsg
error LNK2019: unresolved external symbol _closedir referenced in function _fsdirResetCursor

OK, then you should be close(r).

It seems you need test_windirent.c and test_windirent.h too.

Add them to the ext folder, and #include them after the amalgamation:

// Amalgamation
#include "sqlite3.c"
// Needed by extensions
#include "ext/test_windirent.c"
// Extensions
#include "ext/fileio.c"

(you don't need an ext folder, you can organize them however you want, just adjust the paths)

Thank you for your help; much appreciated.

Managed to build the DLL which incorporates fileio.c.

My file is called custom.c and I end up with custom.dll by default (which I renamed sqlite3.DLL).

(Now on to some exhaustive testing.)