mirror/postgresql
2
0
Fork 0
mirror of https://git.postgresql.org/git/postgresql.git synced 2025-02-17 19:30:00 +08:00
Code Issues Packages Projects Releases Wiki Activity

Skip memcpy(x, x) in qunique().

Browse Source 
It has undefined behavior.  Follow the precedent of commit
9a9473f3cc.  No back-patch, since the
master branch alone has this function.

Discussion: https://postgr.es/m/20191229070221.GA13873@gust.leadboat.com
This commit is contained in:
Noah Misch 2020-01-04 11:31:42 -08:00
parent fac1c04fec
commit 5b630501e9
1 changed files with 6 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
src/include/lib/qunique.h
View File

@ -30,8 +30,9 @@ qunique(void *array, size_t elements, size_t width,
for (i = 1, j = 0; i < elements; ++i)
{
if (compare(bytes + i * width, bytes + j * width) != 0)
memcpy(bytes + ++j * width, bytes + i * width, width);
if (compare(bytes + i * width, bytes + j * width) != 0 &&
++j != i)
memcpy(bytes + j * width, bytes + i * width, width);
}
return j + 1;
@ -55,8 +56,9 @@ qunique_arg(void *array, size_t elements, size_t width,
for (i = 1, j = 0; i < elements; ++i)
{
if (compare(bytes + i * width, bytes + j * width, arg) != 0)
memcpy(bytes + ++j * width, bytes + i * width, width);
if (compare(bytes + i * width, bytes + j * width, arg) != 0 &&
++j != i)
memcpy(bytes + j * width, bytes + i * width, width);
}
return j + 1;