From 6a4009747c3687bf1fdfef5f0b75c33681f37a10 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 13 Oct 2025 12:44:20 -0400 Subject: [PATCH] Fix issue with reading zero bytes in Gzip_read. pg_dump expects a read request of zero bytes to be a no-op; see for example ReadStr(). Gzip_read got this wrong and falsely supposed that the resulting gzret == 0 indicated an error. We could complicate that error-checking logic some more, but it seems best to just fall out immediately when passed size == 0. This bug breaks the nominally-supported case of manually gzip'ing the toc.dat file within a directory-style dump, so back-patch to v16 where this code came in. (Prior branches already have a short-circuit for size == 0 before their only gzread call.) Author: Tom Lane Reviewed-by: Chao Li Discussion: https://postgr.es/m/3515357.1760128017@sss.pgh.pa.us Backpatch-through: 16 --- src/bin/pg_dump/compress_gzip.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/src/bin/pg_dump/compress_gzip.c b/src/bin/pg_dump/compress_gzip.c index 4a067e1402c..ad3b6486027 100644 --- a/src/bin/pg_dump/compress_gzip.c +++ b/src/bin/pg_dump/compress_gzip.c @@ -257,6 +257,10 @@ Gzip_read(void *ptr, size_t size, CompressFileHandle *CFH) gzFile gzfp = (gzFile) CFH->private_data; int gzret; + /* Reading zero bytes must be a no-op */ + if (size == 0) + return 0; + gzret = gzread(gzfp, ptr, size); /*