Hi list,So I'm looking at t_gpointer in m_pd.h, and I'm noticing that for arrays it has gp_w which is a union _word pointer. This is the raw data that I was asking about in my previous request for a free lesson. :) However, in the code for [setsize] the data is resized dynamically using realloc. So... Suppose I have a [pointer] in a patch which is pointing to a nested array, and a [setsize] which is pointing to the container array. If I send an enormous float to [setsize], isn't it likely that realloc will move the data and my [pointer] data will silently become stale? After all, gp_w has no idea if realloc moves the data. Seems like it'd be pointing to the wrong place and likely to cause a crash. I don't have access to a running Pd instance atm, otherwise I'd test... Thanks,Jonathan
Looked at this again and I can't seem to induce an error or crash. But I also cannot understand how gp_w can be used to reliably refer to an element in a dynamically allocated byte array. Doesn't this stackoverflow discussion apply here?http://stackoverflow.com/questions/2172127/how-to-update-other-pointers-when... Thanks,Jonathan
On Wednesday, August 19, 2015 11:33 AM, Jonathan Wilkes via Pd-list <pd-list@lists.iem.at> wrote:
Hi list,So I'm looking at t_gpointer in m_pd.h, and I'm noticing that for arrays it has gp_w which is a union _word pointer. This is the raw data that I was asking about in my previous request for a free lesson. :) However, in the code for [setsize] the data is resized dynamically using realloc. So... Suppose I have a [pointer] in a patch which is pointing to a nested array, and a [setsize] which is pointing to the container array. If I send an enormous float to [setsize], isn't it likely that realloc will move the data and my [pointer] data will silently become stale? After all, gp_w has no idea if realloc moves the data. Seems like it'd be pointing to the wrong place and likely to cause a crash. I don't have access to a running Pd instance atm, otherwise I'd test... Thanks,Jonathan
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Jonathan Wilkes