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.
Hi, Peter,
Thanks for the patch. I agree wb==0 should be treated as an error, so the fix direction looks good to me.
I have a small comment:
====
wb = copy_file_range(s->fd, &off, wfd, NULL, BLCKSZ - nwritten, 0);
if (wb < 0)
pg_fatal("error while copying file range from \"%s\" to \"%s\": %m",
s->filename, output_filename);
else if (wb == 0)
pg_fatal("unexpected end of file while copying file range from \"%s\" to \"%s\"",
s->filename, output_filename);
As copy_file_range copies from s->fd, should pg_fatal just s->filename in the error message? In that case, input_filename is no longer used in write_reconstructed_file(), then it might be removed from the argument list.
Regards,
Yingying Chen
