[PATCH v6 proxmox-backup 15/18] client: Fail early if the same pipe is specified for multiple inputs

[Robert Obkircher <r.obkircher@proxmox.com>]

The pipe needs to be closed to finish the first archive, so the second
one would always end up being empty.

Duplicates are detected using the device id and inode number of the
metadata. The inode number alone would not be sufficient for named
pipes in a specific file system.

Signed-off-by: Robert Obkircher <r.obkircher@proxmox.com>
---
 proxmox-backup-client/src/main.rs | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/proxmox-backup-client/src/main.rs b/proxmox-backup-client/src/main.rs
index 1a51e88f..dcf7f84d 100644
--- a/proxmox-backup-client/src/main.rs
+++ b/proxmox-backup-client/src/main.rs
@@ -832,6 +832,7 @@ async fn create_backup(
 
     let mut upload_list = vec![];
     let mut target_set = HashSet::new();
+    let mut pipe_set = HashSet::new();
 
     for backupspec in backupspec_list {
         let pbs_client::BackupSpecification {
@@ -845,7 +846,7 @@ async fn create_backup(
         }
         target_set.insert(target.clone());
 
-        use std::os::unix::fs::FileTypeExt;
+        use std::os::unix::fs::{FileTypeExt, MetadataExt};
 
         let metadata = std::fs::metadata(&filename).map_err(|err| {
             if filename == "-" {
@@ -870,6 +871,11 @@ async fn create_backup(
                     }
                     size
                 } else if file_type.is_fifo() {
+                    // dev is needed for named pipes
+                    if !pipe_set.insert((metadata.dev(), metadata.ino())) {
+                        // The second archive would be empty
+                        bail!("got duplicate pipe '{filename}'");
+                    }
                     0
                 } else {
                     if file_type.is_char_device() {
@@ -917,6 +923,7 @@ async fn create_backup(
             }
         }
     }
+    drop(pipe_set);
 
     let backup_time = backup_time_opt.unwrap_or_else(epoch_i64);
 
-- 
2.47.3