Check duplicate issues.
Description
When deleting a tree from a file, the resulting file is slightly corrupt. It goes usually unnoticed because TFile::Recover() cleans up.
Reproducer
The following script creates a file that on reopen triggers recovery. According to a preliminary analysis, the error occurs when the free segment list is written.
void test()
{
auto f = TFile::Open("t.root", "RECREATE");
auto t = new TTree("t", "");
f->Write();
f->Close();
delete f;
f = TFile::Open("t.root", "UPDATE");
t = f->Get<TTree>("t");
t->Delete("all");
f->Write();
f->Close();
delete f;
}Map of the resulting file:
20250724/165917 At:100 N=118 TFile
20250724/165917 At:218 N=49 KeysList
20250724/165917 At:267 N=65 FreeSegments
Address = 332 Nbytes = -136 =====G A P===========
20250724/165917 At:468 N=4075 StreamerInfo CX = 3.09
Address = 4543 Nbytes = -1999995458 =====G A P===========
19950000/000000 At:4598 N=1 END
Map of the file after the new keys list was written (after TDirectoryFile::Close()) but before the new free list was written:
20250724/164705 At:100 N=148 TFile
20250724/164935 At:248 N=64 KeysList
Address = 312 Nbytes = -363 =====G A P===========
20250724/164705 At:675 N=4646 StreamerInfo CX = 3.05
Address = 5321 Nbytes = -100 =====G A P===========
20250724/164705 At:5421 N=70 FreeSegments
20250724/164705 At:5491 N=1 END
ROOT version
master
Installation method
from sources
Operating system
n/a
Additional context
Found while working on #19251
Check duplicate issues.
Description
When deleting a tree from a file, the resulting file is slightly corrupt. It goes usually unnoticed because TFile::Recover() cleans up.
Reproducer
The following script creates a file that on reopen triggers recovery. According to a preliminary analysis, the error occurs when the free segment list is written.
Map of the resulting file:
Map of the file after the new keys list was written (after
TDirectoryFile::Close()) but before the new free list was written:ROOT version
master
Installation method
from sources
Operating system
n/a
Additional context
Found while working on #19251