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gdataset: handle up to G_MAXUINT32 entries

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GData is a thread safe container. For that reason, it probably is anyway
not suitable to add 4 billion entries. That is even with the new index,
where we now scale with O(1).

Still, the code should not just break down at half of what we
theoretically could add.

Handle overflow and huge sizes correctly.
This commit is contained in:
Thomas Haller 2024-02-06 09:03:39 +01:00
parent 9abc4d9be6
commit af4a43b064
1 changed files with 10 additions and 12 deletions
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22
glib/gdataset.c
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@ -318,15 +318,12 @@ datalist_append (GData **data, GQuark key_id, gpointer new_data, GDestroyNotify
{
guint32 alloc = d->alloc * 2u;
#if G_ENABLE_DEBUG
/* d->alloc is always a power of two. It thus overflows the first time
* when going to (G_MAXUINT32+1), or when requesting 2^31+1 elements.
*
* This is not handled, and we just crash. That's because we track the GData
* in a linear list, which horribly degrades long before we add 2 billion entries.
* Don't ever try to do that. */
g_assert (alloc > d->len);
#endif
if (G_UNLIKELY (alloc < d->alloc))
{
if (d->alloc == G_MAXUINT32)
g_error ("GData cannot contain more than 4294967295 entries");
alloc = G_MAXUINT32;
}
d = datalist_realloc (d, alloc, &reallocated);
*data = d;
}
@ -417,8 +414,9 @@ datalist_shrink (GData **data, GData **d_to_free)
v = d->len;
if (v != alloc_by_4)
{
/* d->alloc is a power of two. Usually, we remove one element at a
* time, then we will just reach reach a quarter of that.
/* d->alloc is a power of two (unless it's G_MAXUINT32). Usually, we
* remove one element at a time, then we will just reach reach a quarter
* of that.
*
* However, with g_datalist_id_remove_multiple(), len can be smaller
* at once. In that case, find first the next power of two. */
@ -428,7 +426,7 @@ datalist_shrink (GData **data, GData **d_to_free)
#if G_ENABLE_DEBUG
g_assert (v > d->len);
g_assert (v <= d->alloc / 2u);
g_assert (v <= (d->alloc == G_MAXUINT32 ? 0x80000000u : d->alloc / 2u));
#endif
d = datalist_realloc (d, v, &reallocated);