From 27f6cfa7b056556a07b6568fca92bfa857125d7c Mon Sep 17 00:00:00 2001 From: manu0401 Date: Tue, 19 Nov 2024 22:14:43 +0100 Subject: [PATCH] Add an environement variable to control stdio mode (#759) * Add an environement variable to control stdio mode stdio descriptors (stdin, stdout and stderr) can be operated in various modes by win32compat code. The behavior is set very early in fd_table_initialize() by setting pio->type. In https://github.com/PowerShell/Win32-OpenSSH/issues/1427 it was chosen to set pio->type to NONSOCK_SYNC_FD to resolve an I/O hang problem. Unfortunately this introduce problems for other ssh usage. sshfs-wiun uses ssh and has at leas 6 open issues for the same problem introduced by this NONSOCK_SYNC_FD change: https://github.com/winfsp/sshfs-win/issues?q=is%3Aissue+cb+%3A87 The sshfs-win workaround it to use an older ssh.exe from cygwin, which is bundled with sshfs-win. This program is unable to use ssh-agent, which is quite frustrating. And if PATH is not set to use it, sshfs-win cannot work. This change introduce an OPENSSH_STDIO_MODE environment variable that can be set to the following values: unknown, sock, nonsock, nonsock_sync. It cause pio->type to be set to UNKNOWN_FD, SOCK_FD, NONSOCK_FD, and NONSOCK_SYNC_FD respecitively. The default behavior when the variable is not set is unchanged (which means NONSOCK_SYNC_FD). Setting OPENSSH_STDIO_MODE="nonsock" lets sshfs-win work again with openssh-portable ssh.exe. ssh-agent can be used, and this is good. * Leave out UNKNOWN_FD as the possible rtpes for stdio descriptors An assert(pio->type != UNKNOWN_FD) in fd_table_set() causes that case to fail early anyway. --- contrib/win32/win32compat/w32fd.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/contrib/win32/win32compat/w32fd.c b/contrib/win32/win32compat/w32fd.c index 080714242..35a5b9646 100644 --- a/contrib/win32/win32compat/w32fd.c +++ b/contrib/win32/win32compat/w32fd.c @@ -88,6 +88,19 @@ fd_table_initialize() { struct w32_io *pio; HANDLE wh; + char *stdio_mode_env; + int stdio_mode = NONSOCK_SYNC_FD; + + stdio_mode_env = getenv("OPENSSH_STDIO_MODE"); + if (stdio_mode_env != NULL) { + if (strcmp(stdio_mode_env, "sock") == 0) + stdio_mode = SOCK_FD; + else if (strcmp(stdio_mode_env, "nonsock") == 0) + stdio_mode = NONSOCK_FD; + else if (strcmp(stdio_mode_env, "nonsock_sync") == 0) + stdio_mode = NONSOCK_SYNC_FD; + } + /* table entries representing std in, out and error*/ DWORD wh_index[] = { STD_INPUT_HANDLE , STD_OUTPUT_HANDLE , STD_ERROR_HANDLE }; int fd_num = 0; @@ -104,7 +117,7 @@ fd_table_initialize() return -1; } memset(pio, 0, sizeof(struct w32_io)); - pio->type = NONSOCK_SYNC_FD; + pio->type = stdio_mode; pio->handle = wh; fd_table_set(pio, fd_num); }