Fix handling of copy_file_range() return value

Treat copy_file_range() return value of zero as an error: it indicates
that no bytes could be copied (perhaps the source file is shorter than
expected), and the existing retry loop would otherwise spin forever
since nwritten would never reach BLCKSZ.

The other uses of copy_file_range() in the tree don't have this
problem.

Reviewed-by: Nazir Bilal Yavuz <byavuz81@gmail.com>
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-by: Yingying Chen <cyy9255@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/3208cf7a-c7f3-41eb-92f6-33cbeff4df40%40eisentraut.org

diff --git a/src/bin/pg_combinebackup/reconstruct.c b/src/bin/pg_combinebackup/reconstruct.c
index 3349aa2441d29f650cc9832abc953658632519fe..38e756be7ef8208903bd07961f70c81cd0b88102 100644 (file)
--- a/src/bin/pg_combinebackup/reconstruct.c
+++ b/src/bin/pg_combinebackup/reconstruct.c
@@ -705,6 +705,9 @@ write_reconstructed_file(char *input_filename,
                                if (wb < 0)
                                        pg_fatal("error while copying file range from \"%s\" to \"%s\": %m",
                                                         input_filename, output_filename);
+                               else if (wb == 0)
+                                       pg_fatal("unexpected end of file while copying file range from \"%s\" to \"%s\"",
+                                                        input_filename, output_filename);
 
                                nwritten += wb;