From f4c74b6b09d9b312f7c36010dfecafa9cdac8fc3 Mon Sep 17 00:00:00 2001
From: florian <florian@freepascal.org>
Date: Thu, 21 Jan 2021 21:08:13 +0000
Subject: [PATCH]   * fix TBufferedFileStream.Seek(0,soBeginning) as proposed
 by Andrey Zubarev, resolves #38351

git-svn-id: trunk@48282 -
---
 .gitattributes                     |  1 +
 packages/fcl-base/src/bufstream.pp |  2 +-
 tests/webtbs/tw38351.pp            | 33 ++++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 tests/webtbs/tw38351.pp

diff --git a/.gitattributes b/.gitattributes
index d03722d41b..fd76923363 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -18642,6 +18642,7 @@ tests/webtbs/tw38316.pp svneol=native#text/plain
 tests/webtbs/tw3833.pp svneol=native#text/plain
 tests/webtbs/tw38337.pp svneol=native#text/plain
 tests/webtbs/tw38339.pp svneol=native#text/plain
+tests/webtbs/tw38351.pp -text svneol=native#text/pascal
 tests/webtbs/tw3840.pp svneol=native#text/plain
 tests/webtbs/tw3841.pp svneol=native#text/plain
 tests/webtbs/tw3863.pp svneol=native#text/plain
diff --git a/packages/fcl-base/src/bufstream.pp b/packages/fcl-base/src/bufstream.pp
index 81ae8d377a..2517542e97 100644
--- a/packages/fcl-base/src/bufstream.pp
+++ b/packages/fcl-base/src/bufstream.pp
@@ -812,7 +812,7 @@ begin
         lNewOffset:=FCacheStreamPosition+Offset;
       end;
   end;
-  if lNewOffset>0 then begin
+  if lNewOffset>=0 then begin
     FCacheStreamPosition:=lNewOffset;
     Result:=lNewOffset;
   end else begin
diff --git a/tests/webtbs/tw38351.pp b/tests/webtbs/tw38351.pp
new file mode 100644
index 0000000000..d76d639b4c
--- /dev/null
+++ b/tests/webtbs/tw38351.pp
@@ -0,0 +1,33 @@
+{$MODE OBJFPC}
+{$APPTYPE CONSOLE}
+
+uses Classes, BufStream, Sysutils;
+
+procedure TestBufferedFileStream;
+var
+  F: TStream;
+  pf: File;
+begin
+  Assign(pf,'tw38351.tmp');
+  Rewrite(pf,1);
+  Seek(pf,100);
+  Close(pf);
+  F := TBufferedFileStream.Create('tw38351.tmp', fmOpenRead);
+  try
+    Writeln(F.Position);
+    if F.Position<>0 then
+      halt(1);
+    Writeln(F.Seek(0, soBeginning)); // TFileStream = 0, TBufferedFileStream = -1
+    Writeln(F.Position);
+    if F.Position<>0 then
+      halt(1);
+  finally
+    F.Free;
+    DeleteFile('tw38351.tmp');
+  end;
+end;
+
+begin
+  TestBufferedFileStream;
+  writeln('ok');
+end.