Start/stop acquisition callbacks: Consistently name the 'void *' parameter
cb_data for now. The per-device-instance device pointer is called
'session_dev_id' everywhere for now, but this should be renamed to
something more clear.
Avoid plain malloc()/free() in sr/srd, especially in the API calls.
Also avoid g_malloc*() in favor of g_try_malloc*().
Use g_strdup() instead of strdup() so that we can use g_free()
consistently everywhere.
Exceptions: Stuff that is allocated via other libs (not using glib),
should also be properly free'd using the respective free-ing function
(instead of g_free()). Examples: Stuff allocated by libusb, libftdi, etc.
Also, use sr_err() instead of sr_warn() for actual errors. sr_warn() is
meant for non-fatal/uncritical warnings.
Use SR_API to mark public API symbols, and SR_PRIV for private symbols.
Variables and functions marked 'static' are private already and don't
need SR_PRIV. However, functions which are not static (because they need
to be used in other libsigrok-internal files) but are also not meant to
be part of the public libsigrok API, must use SR_PRIV.
This uses the 'visibility' feature of gcc (requires gcc >= 4.0).
Details: http://gcc.gnu.org/wiki/Visibility
For now, there's no analog/scope support in sigrok yet (will be added
later), so remove any such items from the public API (sigrok.h).
Having '#if defined(HAVE_LA_ALSA)' in sigrok.h is a bug anyway, the API
must not have anything device-dependent in general, and sigrok.h
specifically must not have any #ifdefs for specific hardware.
In the lib, we should only #include "sigrok.h" or "sigrok-internal.h",
but not the (possibly installed and thus different/older versions) via
<sigrok.h> or <sigrok-internal.h>.
Frontends should of course use <sigrok.h> and <sigrok-internal.h>.
This is useful to allow frontends to react upon close failures in a
way they see fit (e.g. a popup in the GUI, or error message in the CLI).
They can also still ignore the error if they want, of course.
We should use these (internal) functions in libsigrok exclusively from
now on, i.e. no more use of glib's g_debug() etc.
These functions are only for libsigrok, the frontends use whatever
logging mechanism is suitable there.