From fc9f1470458ad6bdeb1f56c1150d651814a0a164 Mon Sep 17 00:00:00 2001
From: Ian Butterworth <i.r.butterworth@gmail.com>
Date: Mon, 23 Sep 2024 18:48:18 -0400
Subject: [PATCH] fall back to slower stat filesize if optimized filesize fails
 (#55641)

---
 base/iostream.jl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/base/iostream.jl b/base/iostream.jl
index 762f881cfbecb..74908344e078e 100644
--- a/base/iostream.jl
+++ b/base/iostream.jl
@@ -230,8 +230,8 @@ end
 function filesize(s::IOStream)
     sz = @_lock_ios s ccall(:ios_filesize, Int64, (Ptr{Cvoid},), s.ios)
     if sz == -1
-        err = Libc.errno()
-        throw(IOError(string("filesize: ", Libc.strerror(err), " for ", s.name), err))
+        # if `s` is not seekable `ios_filesize` can fail, so fall back to slower stat method
+        sz = filesize(stat(s))
     end
     return sz
 end