At Mon, 22 Jun 2026 09:19:59 +0200, Peter Eisentraut <[email protected]> wrote in > While checking return/error handling of file system calls, I found > that the copy_file_range() call in pg_combinebackup has a potential > problem. If copy_file_range() returns 0, which is a documented > condition, then the loop never makes progress and could spin forever. > > The other uses of copy_file_range() in the tree are surrounded by > different logic and don't appear to have this problem. > > My suggested fix is to make a return value of 0 an error. It most > likely indicates that the source file has an unexpected size.
Good catch. I agree with the analysis, and the proposed fix looks reasonable to me. I also checked the other four uses of copy_file_range() in the tree. All but one handle a zero return value as EOF, and the remaining case (check_copy_file_range()) appears safe because it is only testing whether copy_file_range() is usable. Regards, -- Kyotaro Horiguchi NTT Open Source Software Center
