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Differential D4154

index: remove side-effect from failed nt_new()
ClosedPublic

Authored by martinvonz on Aug 7 2018, 2:26 AM.

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rHGdcd395dc98d8: index: remove side-effect from failed nt_new()
Summary

As pointed out by Yuya in the review of D4108, if realloc() fails, we
would end up with an invalid nodetree instance (with nt->nodes set to
NULL), which means that if it was later accessed again it would likely
segfault. It's probably unlikely that much else happens in the process
if it ran out memory, but we should of course do our best to handle
it. This patch makes it so we don't update the nodetree in this case.

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rHG Mercurial
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Event Timeline

martinvonz created this revision.Aug 7 2018, 2:26 AM
Closed by commit rHGdcd395dc98d8: index: remove side-effect from failed nt_new() (authored by martinvonz). · Explain WhyAug 7 2018, 8:52 AM
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

PathPackages
Mmercurial/cext/revlog.c (11 lines)

Diff 10049

mercurial/cext/revlog.c

} }
/* multiple matches against an ambiguous prefix */ /* multiple matches against an ambiguous prefix */
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;
nodetreenode *newnodes;
if (self->capacity >= INT_MAX / (sizeof(nodetreenode) * 2)) { if (self->capacity >= INT_MAX / (sizeof(nodetreenode) * 2)) {
PyErr_SetString(PyExc_MemoryError, PyErr_SetString(PyExc_MemoryError,
"overflow in nt_new"); "overflow in nt_new");
return -1; return -1;
} }
self->capacity *= 2; newcapacity = self->capacity * 2;
self->nodes = realloc(self->nodes, newnodes = realloc(self->nodes, newcapacity * sizeof(nodetreenode));
self->capacity * sizeof(nodetreenode)); if (newnodes == NULL) {
if (self->nodes == NULL) {
PyErr_SetString(PyExc_MemoryError, "out of memory"); PyErr_SetString(PyExc_MemoryError, "out of memory");
return -1; return -1;
} }
self->capacity = newcapacity;
self->nodes = newnodes;
memset(&self->nodes[self->length], 0, memset(&self->nodes[self->length], 0,
sizeof(nodetreenode) * (self->capacity - self->length)); sizeof(nodetreenode) * (self->capacity - self->length));
} }
return self->length++; return self->length++;
} }
static int nt_insert(indexObject *self, const char *node, int rev) static int nt_insert(indexObject *self, const char *node, int rev)
{ {