From a9ed0916785fa69b4a6e8b045405fb522431b064 Mon Sep 17 00:00:00 2001
From: Jerry Xiao <optifinecapemain@gmail.com>
Date: Mon, 12 Oct 2026 06:37:23 +0000
Subject: [PATCH] seekable_format: return -1 from unreachable default in seek
 callbacks

With -DNDEBUG, assert(0) in the default case of the buffer seek
callbacks compiles away, so newOffset is read uninitialized and
gcc warns with -Wmaybe-uninitialized. Return -1 (the error value
the callback already uses for an out-of-range offset) after the
assert, in ZSTD_seekable_seek_buff() and the copy in seekable_tests.c.
---
 contrib/seekable_format/tests/seekable_tests.c | 1 +
 contrib/seekable_format/zstdseek_decompress.c  | 1 +
 2 files changed, 2 insertions(+)

diff --git a/contrib/seekable_format/tests/seekable_tests.c b/contrib/seekable_format/tests/seekable_tests.c
index 809ea6425eb..c50bc6dff79 100644
--- a/contrib/seekable_format/tests/seekable_tests.c
+++ b/contrib/seekable_format/tests/seekable_tests.c
@@ -45,6 +45,7 @@ static int seekBuffWithTotal(void* opaque, long long offset, int origin)
         break;
     default:
         assert(0);  /* not possible */
+        return -1;
     }
     if (newOffset > buff->size) {
         return -1;
diff --git a/contrib/seekable_format/zstdseek_decompress.c b/contrib/seekable_format/zstdseek_decompress.c
index ab9088a1061..ce08917ec1c 100644
--- a/contrib/seekable_format/zstdseek_decompress.c
+++ b/contrib/seekable_format/zstdseek_decompress.c
@@ -186,6 +186,7 @@ static int ZSTD_seekable_seek_buff(void* opaque, long long offset, int origin)
         break;
     default:
         assert(0);  /* not possible */
+        return -1;
     }
     if (newOffset > buff->size) {
         return -1;