Support mkdir -p behavior when DB file does not exist

Currently, if you supply a DB path that includes directories which
do not exist, sqlite3 will not attempt to create them and the open
will crash.

This adds a quick attempt to `mkdir` on the db path to ensure all intermediary
directories exist before attempting to create the DB file for cases that
`SQLITE_OPEN_CREATE` flag is enabled and would expect the file to be
created when non-existant

Author: jjcarstens

c_src/sqlite3.c

@@ -17,6 +17,7 @@
 ** language. The code for the "sqlite3" command-line shell is also in a
 ** separate file. This file contains only code for the core SQLite library.
 */
+#include <libgen.h>     /* Needed for dirname() */
 #define SQLITE_CORE 1
 #define SQLITE_AMALGAMATION 1
 #ifndef SQLITE_PRIVATE
@@ -34781,6 +34782,9 @@ static struct unix_syscall {
   { "ioctl",         (sqlite3_syscall_ptr)0,              0 },
 #endif
 
+  { "dirname",        (sqlite3_syscall_ptr)dirname,       0 },
+#define osDirname     ((char*(*)(const char*))aSyscall[29].pCurrent)
+
 }; /* End of the overrideable system calls */
 
 
@@ -67971,6 +67975,14 @@ SQLITE_PRIVATE int sqlite3BtreeOpen(
   if( isMemdb ){
     flags |= BTREE_MEMORY;
   }
+  if( !isMemdb ){
+    /* SQLITE_OPEN_CREATE will create the DB file if not existing, but
+    ** will not create intermediary directories if they are missing.
+    ** So let's preemptively create the intermediate directories here
+    ** before trying to open the DB file.
+    */
+    osMkdir(osDirname(zFilename), 0777);
+  }
   if( (vfsFlags & SQLITE_OPEN_MAIN_DB)!=0 && (isMemdb || isTempDb) ){
     vfsFlags = (vfsFlags & ~SQLITE_OPEN_MAIN_DB) | SQLITE_OPEN_TEMP_DB;
   }

test/exqlite/sqlite3_test.exs

@@ -18,6 +18,15 @@ defmodule Exqlite.Sqlite3Test do
 
       File.rm(path)
     end
+
+    test "creates database path on disk when non-existant" do
+      {:ok, path} = Temp.path()
+      {:ok, conn} = Sqlite3.open(path <> "/non_exist")
+
+      assert conn
+
+      File.rm(path)
+    end
   end
 
   describe ".close/2" do