#11754: Computation of rank-decompositions in Sage
-----------------------------+----------------------------------------------
Reporter: ncohen | Owner: jason, ncohen, rlm
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-4.8
Component: graph theory | Keywords:
Work_issues: | Upstream: N/A
Reviewer: David Coudert | Author: Nathann Cohen
Merged: | Dependencies:
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Comment(by ncohen):
Helloooooo !!!
Patch updated to make the 32 limit clearer `:-)`
About the segfault : the point is that there is nothing I could "check" to
return an exception to avoid the segault unless I know where it comes
from. The function you mention contains a total of 5 lines which can
produce no segfault, and exclusively consist in memory allocations and
checking the memory has been allocated
{{{
int init_rw(uint_fast8_t n)
{
num_vertices = n;
adjacency_matrix = malloc(sizeof(subset_t) * n);
slots = malloc(sizeof(uint_fast8_t) * (1ul << n));
cslots = 0;
return((adjacency_matrix && slots) ? 0 : -1);
}
}}}
If anything goes wrong, the function return -1 instead of 0. And this
function (which is defined in the original C code) is called as you said,
by a "if" that is precisely there to ensure the memory allocation went
smoothly. If it did not, it also returns and error and the function above
(rank_decomposition) raises the exception. I mean, there is no memory
allocation that I could check and that is not checked already `O_o`
Nathann
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11754#comment:9>
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