[gnuastro-devel] [task #14572] Protect gal_data_t's array and block pointers

[Antonio Diaz Diaz]

Follow-up Comment #5, task #14572 (project gnuastro):

After reading the Gnuastro manual for a while, if I have undertood it
correctly, Gnuastro has two uses for gal_data_t objects; datasets and tiles.
The reason to use the same data type for both is to be able to implement
arbitrary tiling (two-layer tessellation, for example) without special cases
(without the first-level tiles pointing to a dataset, and N-level tiles
pointing to tiles of level N - 1).

My first idea to avoid dangling pointers under these circumstances is to
implement a reference counter in gal_data_t. Every time a new tile is created
(by one of the handling functions), the reference counter of its underlying
gal_data_t is increased. And every time a tile is freed, its own reference
counter is verified to be 0 and then the reference counter of its underlying
gal_data_t is decreased.

Also when a tile is reassigned to another dataset of the same size (as is now
done by changing manually tile->array and tile->block), the reference counter
of its old dataset is decreased, while the reference counter of its new
dataset is increased.


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