* refactor: safe sql access
* Clean up the worst rebase mistakes
* Some more progress on the rebase fallout and this branch
* upgrade and compile again
* cleanup from rebase
* example of how to prepare now
* rebase fixes
* add sql.query_map
* less preparation
* more improvements in sql code
* fix string truncation
* more prepare conversions
* most prep done
* fix tests
* fix ffi
* fix last prepares
* fix segfaults and some queries
* use r2d2 pool
* fix dc_job sql call, to reduce contention
* try newer rust
* No more vararg printing (drop dc_log_)
* ignore expected errors
* fix: uses exists instead of execute where needed
* fix: get_contacts logic was broken
* fix: contact creation
* test on 32bit linux
* ci: try running 32bit without cross
* undo 32bit tests
* refactor: rename dc_sqlite3 to sql
* fix: safer string conversions
* more string fixes
* try fixing appveyor build to 64bit
* chore(ci): hardcode target
* chore(ci): appveyor
* some cleanup work
* try fix darwin
* fix and improve sql escaping
* fix various bugs
* fix chat deletion
* refactor: cleanup config values and move to their own file
* refactor: move more methods onto the sql struct
* dont panic on failed state loading
* first round of cr
* one more cr fix
* stop using strange defaults
* remove unused escapes
The C API allows passing a NULL pointer is for the callback function.
However when calling the callback nothing checks for this null pointer
and thus things fail badly. Even worse since the C API is defined
using an "fn pointer" rather than a "*-ptr" or raw pointer to the
function rust does not realise this can be invalid and therefore the
typechecker does not catch this even though there are no unsafe casts.
Fix this by making the callback an Option in rust, this can be easily
checked when calling. Also add a Context.call_cb() function which
simplifies calling the callback, hides the weird syntax due to the
function pointer and makes the call a little easier. Finally it also
means the option checking is only needed in one place.
For the C API this needs to check if this is a NULL pointer or not,
this is implicitly done by rust using the "nullable pointer
optimisation":
https://doc.rust-lang.org/nomicon/ffi.html#the-nullable-pointer-optimization
The function does a cast and does not create a new objects. The
stdlib convention is to use to_*() for functions which return new
objects and as_*() for functions which keep referring to the same data
but using a different type. Follow that convention.
