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Store a size field inside the DSF type.

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This permits bounds-checking of all inputs to dsf_canonify and
dsf_merge, so that any out-of-range values will provoke assertion
failure instead of undefined behaviour.
This commit is contained in:
Simon Tatham
2023-04-20 14:25:22 +01:00
parent 095224d571
commit dad2f35502
1 changed files with 6 additions and 1 deletions
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7
dsf.c
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@ -10,6 +10,7 @@
#include "puzzles.h" #include "puzzles.h"
struct DSF { struct DSF {
int size;
int *p; int *p;
}; };
@ -86,6 +87,7 @@ void dsf_copy(DSF *to, DSF *from, int size)
DSF *snew_dsf(int size) DSF *snew_dsf(int size)
{ {
DSF *ret = snew(DSF); DSF *ret = snew(DSF);
ret->size = size;
ret->p = snewn(size, int); ret->p = snewn(size, int);
dsf_init(ret, size); dsf_init(ret, size);
@ -125,7 +127,7 @@ int edsf_canonify(DSF *dsf, int index, bool *inverse_return)
/* fprintf(stderr, "dsf = %p\n", dsf); */ /* fprintf(stderr, "dsf = %p\n", dsf); */
/* fprintf(stderr, "Canonify %2d\n", index); */ /* fprintf(stderr, "Canonify %2d\n", index); */
assert(index >= 0); assert(0 <= index && index < dsf->size && "Overrun in edsf_canonify");
/* Find the index of the canonical element of the 'equivalence class' of /* Find the index of the canonical element of the 'equivalence class' of
* which start_index is a member, and figure out whether start_index is the * which start_index is a member, and figure out whether start_index is the
@ -163,6 +165,9 @@ void edsf_merge(DSF *dsf, int v1, int v2, bool inverse)
{ {
bool i1, i2; bool i1, i2;
assert(0 <= v1 && v1 < dsf->size && "Overrun in edsf_merge");
assert(0 <= v2 && v2 < dsf->size && "Overrun in edsf_merge");
/* fprintf(stderr, "dsf = %p\n", dsf); */ /* fprintf(stderr, "dsf = %p\n", dsf); */
/* fprintf(stderr, "Merge [%2d,%2d], %d\n", v1, v2, inverse); */ /* fprintf(stderr, "Merge [%2d,%2d], %d\n", v1, v2, inverse); */