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Differential D4165

index: avoid duplicating capacity-growth expression
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Authored by martinvonz on Aug 9 2018, 3:27 AM.

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Commits
rHG06ff7ea4f440: index: avoid duplicating capacity-growth expression
Summary

We were duplicating the "*2" instead of reusing it. It's overflow-safe
to reuse as long as the growth factor (i.e. currently 2) is not larger
than sizeof(nodetreenode) (currently 64 or 128).

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rHG Mercurial
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Automatic diff as part of commit; lint not applicable.
Unit
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PathPackages
Mmercurial/cext/revlog.c (7 lines)

Diff 10338

mercurial/cext/revlog.c

return -4; return -4;
} }
static int nt_new(nodetree *self) static int nt_new(nodetree *self)
{ {
if (self->length == self->capacity) { if (self->length == self->capacity) {
unsigned newcapacity; unsigned newcapacity;
nodetreenode *newnodes; nodetreenode *newnodes;
if (self->capacity >= INT_MAX / (sizeof(nodetreenode) * 2)) { newcapacity = self->capacity * 2;
PyErr_SetString(PyExc_MemoryError, if (newcapacity >= INT_MAX / sizeof(nodetreenode)) {
"overflow in nt_new"); PyErr_SetString(PyExc_MemoryError, "overflow in nt_new");
return -1; return -1;
} }
newcapacity = self->capacity * 2;
newnodes = realloc(self->nodes, newcapacity * sizeof(nodetreenode)); newnodes = realloc(self->nodes, newcapacity * sizeof(nodetreenode));
if (newnodes == NULL) { if (newnodes == NULL) {
PyErr_SetString(PyExc_MemoryError, "out of memory"); PyErr_SetString(PyExc_MemoryError, "out of memory");
return -1; return -1;
} }
self->capacity = newcapacity; self->capacity = newcapacity;
self->nodes = newnodes; self->nodes = newnodes;
memset(&self->nodes[self->length], 0, memset(&self->nodes[self->length], 0,