From 8300a8742b2abc487594a09b5e6ee726dbd30771 Mon Sep 17 00:00:00 2001 From: Richard Levitte Date: Tue, 20 Oct 2020 06:48:10 +0200 Subject: Work around Windows ftell() bug as per Microsoft engineering's suggestion See https://developercommunity.visualstudio.com/content/problem/425878/fseek-ftell-fail-in-text-mode-for-unix-style-text.html Reviewed-by: Paul Dale (Merged from https://github.com/openssl/openssl/pull/13190) --- crypto/bio/bss_file.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/crypto/bio/bss_file.c b/crypto/bio/bss_file.c index a57bd973f7..986fba874a 100644 --- a/crypto/bio/bss_file.c +++ b/crypto/bio/bss_file.c @@ -237,6 +237,15 @@ static long file_ctrl(BIO *b, int cmd, long num, void *ptr) _setmode(fd, _O_TEXT); else _setmode(fd, _O_BINARY); + /* + * Reports show that ftell() isn't trustable in text mode. + * This has been confirmed as a bug in the Universal C RTL, see + * https://developercommunity.visualstudio.com/content/problem/425878/fseek-ftell-fail-in-text-mode-for-unix-style-text.html + * The suggested work-around from Microsoft engineering is to + * turn off buffering until the bug is resolved. + */ + if ((num & BIO_FP_TEXT) != 0) + setvbuf((FILE *)ptr, NULL, _IONBF, 0); # elif defined(OPENSSL_SYS_MSDOS) int fd = fileno((FILE *)ptr); /* Set correct text/binary mode */ -- cgit v1.2.3