Identify the FD hold by parent process

Issue:
There is no directly way to get the FD
hold by parent process which asked do fuse mount.

Use Case:
For auto_unmount case, identify the FD can easy to close
the FD and make automatically unmount manually and explicitly.
The FD[1] can be got via getenv(FUSE_COMMFD2_ENV).
One potential use case is to satisfy FD-Leak checks.

Solution:
Add an extra env _FUSE_COMMFD2 to store the FD.
This will provide a easy way to get the FD via FUSE_COMMFD2_ENV.

Signed-off-by: Zegang Luo <zegang.luo@qq.com>

diff --git a/lib/mount.c b/lib/mount.c
index aedd9b92eeb7e05b3d68d592eea0fd2a568f8283..7dd727ce25d780b1ca93ca3cf0252af491c96f05 100644 (file)
--- a/lib/mount.c
+++ b/lib/mount.c
@@ -48,6 +48,7 @@
 
 #define FUSERMOUNT_PROG                "fusermount3"
 #define FUSE_COMMFD_ENV                "_FUSE_COMMFD"
+#define FUSE_COMMFD2_ENV       "_FUSE_COMMFD2"
 
 #ifndef MS_DIRSYNC
 #define MS_DIRSYNC 128
@@ -367,6 +368,14 @@ static int setup_auto_unmount(const char *mountpoint, int quiet)
        char arg_fd_entry[30];
        snprintf(arg_fd_entry, sizeof(arg_fd_entry), "%i", fds[0]);
        setenv(FUSE_COMMFD_ENV, arg_fd_entry, 1);
+       /*
+        * This helps to identify the FD hold by parent process.
+        * In auto-unmount case, parent process can close this FD explicitly to do unmount.
+        * The FD[1] can be got via getenv(FUSE_COMMFD2_ENV).
+        * One potential use case is to satisfy FD-Leak checks.
+        */
+       snprintf(arg_fd_entry, sizeof(arg_fd_entry), "%i", fds[1]);
+       setenv(FUSE_COMMFD2_ENV, arg_fd_entry, 1);
 
        char const *const argv[] = {
                FUSERMOUNT_PROG,
@@ -431,6 +440,14 @@ static int fuse_mount_fusermount(const char *mountpoint, struct mount_opts *mo,
        char arg_fd_entry[30];
        snprintf(arg_fd_entry, sizeof(arg_fd_entry), "%i", fds[0]);
        setenv(FUSE_COMMFD_ENV, arg_fd_entry, 1);
+       /*
+        * This helps to identify the FD hold by parent process.
+        * In auto-unmount case, parent process can close this FD explicitly to do unmount.
+        * The FD[1] can be got via getenv(FUSE_COMMFD2_ENV).
+        * One potential use case is to satisfy FD-Leak checks.
+        */
+       snprintf(arg_fd_entry, sizeof(arg_fd_entry), "%i", fds[1]);
+       setenv(FUSE_COMMFD2_ENV, arg_fd_entry, 1);
 
        char const *const argv[] = {
                FUSERMOUNT_PROG,