From 6e65ac1ff26071024cfcf24d15819aa6b72af137 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 11 Oct 2025 21:16:12 -0400 Subject: [PATCH v3 4/4] Fix issues with reading zero bytes in Gzip_read and Zstd_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. Zstd_read got the right result, but only after doing a lot more work than necessary, because it checked at the bottom of the loop not the top. The Gzip_read fix perhaps should be back-patched, because it breaks the nominally-supported case of manually gzip'ing the toc.dat file within a directory-style dump. Author: Tom Lane Discussion: https://postgr.es/m/3515357.1760128017@sss.pgh.pa.us --- src/bin/pg_dump/compress_gzip.c | 4 ++++ src/bin/pg_dump/compress_zstd.c | 5 +---- 2 files changed, 5 insertions(+), 4 deletions(-) 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); /* diff --git a/src/bin/pg_dump/compress_zstd.c b/src/bin/pg_dump/compress_zstd.c index 5fe2279faae..36c1fd264ee 100644 --- a/src/bin/pg_dump/compress_zstd.c +++ b/src/bin/pg_dump/compress_zstd.c @@ -287,7 +287,7 @@ Zstd_read_internal(void *ptr, size_t size, CompressFileHandle *CFH, bool exit_on output->dst = ptr; output->pos = 0; - for (;;) + while (output->pos < output->size) { Assert(input->pos <= input->size); Assert(input->size <= input_allocated_size); @@ -341,9 +341,6 @@ Zstd_read_internal(void *ptr, size_t size, CompressFileHandle *CFH, bool exit_on if (res == 0) break; /* End of frame */ } - - if (output->pos == output->size) - break; /* We read all the data that fits */ } return output->pos; -- 2.43.7