Improve detection for noexec for default extraction location

[maloewe-ona]

Is your feature request related to a problem? Please describe.
When /tmp is mounted as noexec on Linux, sqlite-jdbc fails to load the native library with an error similar to the following:

java.lang.UnsatisfiedLinkError: /tmp/sqlite-...-libsqlitejdbc.so: /tmp/sqlite-...-libsqlitejdbc.so: failed to map segment from shared object

Users can fix this by not mounting /temp as noexec, or by specifying a custom java.io.tmpdir or org.sqlite.tmpdir system property value pointing to an (existing) directory with execution permission.
But just based on the UnsatisfiedLinkError above, it might not obvious to users what the cause is, or how to fix it.

See related issues:

• java.lang.UnsatisfiedLinkError: org.sqlite.core.NativeDB._open(Ljava/lang/String;I)V #97 (some of the comments there)
• java.lang.UnsatisfiedLinkError CentOS 7  #571

Describe the solution you'd like
sqlite-jdbc should try to detect noexec or other permission errors and report them properly before trying to load the native library and causing an UnsatisfiedLinkError,
or better (?) trigger an UnsatisfiedLinkError but attach additional information, such as whether permissions are correct.

Additionally it could suggest to set the java.io.tmpdir or org.sqlite.tmpdir system property value to an (existing) directory with execution permission.

Additional context
Maybe the checks in SQLiteJDBCLoader.extractAndLoadLibraryFile should be improved:

sqlite-jdbc/src/main/java/org/sqlite/SQLiteJDBCLoader.java

Lines 207 to 209 in 2e336d9

	extractedLibFile.toFile().setReadable(true);
	extractedLibFile.toFile().setWritable(true, true);
	extractedLibFile.toFile().setExecutable(true);

Issues with the current implementation:

• It does not check the return value of the setReadable, ... calls
• After the setExecutable call it should call file.canExecute()
  It seems for noexec file.setExecutable(true) succeeds but file.canExecute() is still false afterwards, so it could be detected like this.

However, I am not that familiar with Linux and the implementation details of java.io.File, so maybe there are cases where for example setReadable, ... fails but the library can still be loaded.
So maybe these checks should only be performed if an UnsatisfiedLinkError occurs, to provide additional troubleshooting information.

Potentially useful: netty/netty#6707, but I am not sure if using PosixFilePermission is really needed or if using the java.io.File API suffices.

[michael-o]

See also:

• Improve error reporting when the tmp dir has the noexec flag fusesource/jansi#193
• JANSI Not Executable In '/tmp' on CENTOS fusesource/jansi#241

[jdev-2020]

use this system property to set another extraction location https://github.com/xerial/sqlite-jdbc/blob/master/src/main/java/org/sqlite/SQLiteJDBCLoader.java#L81