[PATCH] vfs_default: Fix passing of errno from async calls

[Christof Schmitt]

I found this while testing with a system where the actual write() system
call returned an error. This led to Samba hanging and never continuing
with the result of the write. The attached patch fixes the problem. From
what i understand, errno was never passed correctly back to the callers.

Christof
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From 3b9133f42f7f11c655b54d5657722dbed953fa15 Mon Sep 17 00:00:00 2001
From: Christof Schmitt <cs at samba.org>
Date: Wed, 23 Aug 2017 14:37:28 -0700
Subject: [PATCH] vfs_default: Fix passing of errno from async calls

Current code assigns errno from async pthreadpool calls to the
vfs_default internal vfswrap_*_state.  The callers of the vfs_*_recv
functions expect the value from errno in vfs_aio_state.error.

Correctly assign errno to vfs_aio_state.error and remove the unused
internal err variable.

Signed-off-by: Christof Schmitt <cs at samba.org>
---
 source3/modules/vfs_default.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/source3/modules/vfs_default.c b/source3/modules/vfs_default.c
index fbfe654..458e878 100644
--- a/source3/modules/vfs_default.c
+++ b/source3/modules/vfs_default.c
@@ -738,7 +738,6 @@ static int vfswrap_init_pool(struct smbd_server_connection *conn)
 
 struct vfswrap_pread_state {
 	ssize_t ret;
-	int err;
 	int fd;
 	void *buf;
 	size_t count;
@@ -812,7 +811,7 @@ static void vfs_pread_do(void *private_data)
 				   state->offset);
 	} while ((state->ret == -1) && (errno == EINTR));
 
-	state->err = errno;
+	state->vfs_aio_state.error = errno;
 
 	PROFILE_TIMESTAMP(&end_time);
 
@@ -861,7 +860,6 @@ static ssize_t vfswrap_pread_recv(struct tevent_req *req,
 
 struct vfswrap_pwrite_state {
 	ssize_t ret;
-	int err;
 	int fd;
 	const void *buf;
 	size_t count;
@@ -935,7 +933,7 @@ static void vfs_pwrite_do(void *private_data)
 				   state->offset);
 	} while ((state->ret == -1) && (errno == EINTR));
 
-	state->err = errno;
+	state->vfs_aio_state.error = errno;
 
 	PROFILE_TIMESTAMP(&end_time);
 
@@ -984,7 +982,6 @@ static ssize_t vfswrap_pwrite_recv(struct tevent_req *req,
 
 struct vfswrap_fsync_state {
 	ssize_t ret;
-	int err;
 	int fd;
 
 	struct vfs_aio_state vfs_aio_state;
@@ -1045,7 +1042,7 @@ static void vfs_fsync_do(void *private_data)
 		state->ret = fsync(state->fd);
 	} while ((state->ret == -1) && (errno == EINTR));
 
-	state->err = errno;
+	state->vfs_aio_state.error = errno;
 
 	PROFILE_TIMESTAMP(&end_time);
 
-- 
1.8.3.1