r2613: use a talloc destructor to ensure that file descriptors are not leaked

on abnormal termination of a connection. As long as the top level
connection structure is freed then that should cascade down to the
file structure, and call this destructor which will close the open file descriptor.

In general I'd like to use this technique in any place in Samba4 where
we hold operating system resources that we need to make sure are
released on abnormal termination.
(This used to be commit ed87b7fcbd9fedc155528ce6dd8ab5d5fce637b2)

1 files changed, 26 insertions, 2 deletions

diff --git a/source4/ntvfs/posix/pvfs_open.c b/source4/ntvfs/posix/pvfs_open.c
index 1c6ecc1eb2..a1c6dcdcfe 100644
--- a/source4/ntvfs/posix/pvfs_open.c
+++ b/source4/ntvfs/posix/pvfs_open.c
@@ -39,6 +39,21 @@ struct pvfs_file *pvfs_find_fd(struct pvfs_state *pvfs, uint16_t fnum)
 }
 
 /*
+  by using a destructor we make sure that abnormal cleanup will not 
+  leak file descriptors (assuming at least the top level pointer is freed, which
+  will cascade down to here)
+*/
+static int pvfs_fd_destructor(void *p)
+{
+	struct pvfs_file *f = p;
+	if (f->fd != -1) {
+		close(f->fd);
+		f->fd = -1;
+	}
+	return 0;
+}
+
+/*
   open a file
   TODO: this is a temporary implementation derived from the simple backend
   its purpose is to allow other tests to run 
@@ -132,6 +147,10 @@ do_open:
 	f->fd = fd;
 	f->name = talloc_steal(f, name);
 
+	/* setup a destructor to avoid file descriptor leaks on
+	   abnormal termination */
+	talloc_set_destructor(f, pvfs_fd_destructor);
+
 	DLIST_ADD(pvfs->open_files, f);
 
 	ZERO_STRUCT(io->generic.out);
@@ -157,6 +176,7 @@ NTSTATUS pvfs_close(struct smbsrv_request *req, union smb_close *io)
 {
 	NTVFS_GET_PRIVATE(pvfs_state, pvfs, req);
 	struct pvfs_file *f;
+	NTSTATUS status;
 
 	if (io->generic.level != RAW_CLOSE_CLOSE) {
 		/* we need a mapping function */
@@ -169,12 +189,16 @@ NTSTATUS pvfs_close(struct smbsrv_request *req, union smb_close *io)
 	}
 
 	if (close(f->fd) != 0) {
-		return pvfs_map_errno(pvfs, errno);
+		status = pvfs_map_errno(pvfs, errno);
+	} else {
+		status = NT_STATUS_OK;
 	}
 
+	talloc_set_destructor(f, NULL);
+
 	DLIST_REMOVE(pvfs->open_files, f);
 	talloc_free(f);
 
-	return NT_STATUS_OK;
+	return status;
 }