feat: backup and restore named pipes (FIFOs)

7 files changed, 37 insertions, 2 deletions

diff --git a/obnam.md b/obnam.md
index e386b17..240dcf0 100644
--- a/obnam.md
+++ b/obnam.md
@@ -1286,7 +1286,10 @@ then command fails
 ## Irregular files
 
 This scenario verifies that Obnam backs up and restores files that
-aren't regular files or directories.
+aren't regular files, directories, or symbolic links. Specifically,
+Unix domain sockets and named pipes (FIFOs). However, block and
+character device nodes are not tested, as that would require running
+the test suite with `root` permissions and that would be awkward.
 
 ~~~scenario
 given an installed obnam
@@ -1294,6 +1297,7 @@ and a running chunk server
 and a client config based on smoke.yaml
 and a file live/data.dat containing some random data
 and a Unix socket live/socket
+and a named pipe live/pipe
 and a manifest of the directory live in live.yaml
 when I run obnam --config smoke.yaml backup
 when I invoke obnam --config smoke.yaml restore latest rest
diff --git a/src/client.rs b/src/client.rs
index 9d1e8ff..7d1613c 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -164,6 +164,7 @@ impl BackupClient {
             FilesystemKind::Directory => vec![],
             FilesystemKind::Symlink => vec![],
             FilesystemKind::Socket => vec![],
+            FilesystemKind::Fifo => vec![],
         };
         info!("upload OK for {:?}", path);
         Ok(ids)
diff --git a/src/cmd/list_files.rs b/src/cmd/list_files.rs
index 4982cc2..ec3e52e 100644
--- a/src/cmd/list_files.rs
+++ b/src/cmd/list_files.rs
@@ -36,6 +36,7 @@ fn format_entry(e: &FilesystemEntry, reason: Reason) -> String {
         FilesystemKind::Directory => "d",
         FilesystemKind::Symlink => "l",
         FilesystemKind::Socket => "s",
+        FilesystemKind::Fifo => "p",
     };
     format!("{} {} ({})", kind, e.pathbuf().display(), reason)
 }
diff --git a/src/cmd/restore.rs b/src/cmd/restore.rs
index 147a56b..b394d7d 100644
--- a/src/cmd/restore.rs
+++ b/src/cmd/restore.rs
@@ -5,7 +5,7 @@ use crate::error::ObnamError;
 use crate::fsentry::{FilesystemEntry, FilesystemKind};
 use crate::generation::{LocalGeneration, LocalGenerationError};
 use indicatif::{ProgressBar, ProgressStyle};
-use libc::{chmod, timespec, utimensat, AT_FDCWD};
+use libc::{chmod, mkfifo, timespec, utimensat, AT_FDCWD};
 use log::{debug, error, info};
 use std::ffi::CString;
 use std::io::prelude::*;
@@ -73,6 +73,9 @@ struct Opt {
 
 #[derive(Debug, thiserror::Error)]
 pub enum RestoreError {
+    #[error("Could not create named pipe (FIFO) {0}")]
+    NamedPipeCreationError(PathBuf),
+
     #[error(transparent)]
     ClientError(#[from] ClientError),
 
@@ -112,6 +115,7 @@ fn restore_generation(
         FilesystemKind::Directory => restore_directory(&to)?,
         FilesystemKind::Symlink => restore_symlink(&to, &entry)?,
         FilesystemKind::Socket => restore_socket(&to, &entry)?,
+        FilesystemKind::Fifo => restore_fifo(&to, &entry)?,
     }
     Ok(())
 }
@@ -188,6 +192,18 @@ fn restore_socket(path: &Path, entry: &FilesystemEntry) -> RestoreResult<()> {
     Ok(())
 }
 
+fn restore_fifo(path: &Path, entry: &FilesystemEntry) -> RestoreResult<()> {
+    debug!("creating fifo {:?}", path);
+    let filename = path_to_cstring(path);
+    match unsafe { mkfifo(filename.as_ptr(), 0) } {
+        -1 => {
+            return Err(RestoreError::NamedPipeCreationError(path.to_path_buf()));
+        }
+        _ => restore_metadata(path, entry)?,
+    }
+    Ok(())
+}
+
 fn restore_metadata(path: &Path, entry: &FilesystemEntry) -> RestoreResult<()> {
     debug!("restoring metadata for {}", entry.pathbuf().display());
 
diff --git a/src/fsentry.rs b/src/fsentry.rs
index 9384ec6..570877a 100644
--- a/src/fsentry.rs
+++ b/src/fsentry.rs
@@ -129,6 +129,7 @@ pub enum FilesystemKind {
     Directory,
     Symlink,
     Socket,
+    Fifo,
 }
 
 impl FilesystemKind {
@@ -141,6 +142,8 @@ impl FilesystemKind {
             FilesystemKind::Symlink
         } else if file_type.is_socket() {
             FilesystemKind::Socket
+        } else if file_type.is_fifo() {
+            FilesystemKind::Fifo
         } else {
             panic!("unknown file type {:?}", file_type);
         }
@@ -152,6 +155,7 @@ impl FilesystemKind {
             FilesystemKind::Directory => 1,
             FilesystemKind::Symlink => 2,
             FilesystemKind::Socket => 3,
+            FilesystemKind::Fifo => 4,
         }
     }
 
@@ -161,6 +165,7 @@ impl FilesystemKind {
             1 => Ok(FilesystemKind::Directory),
             2 => Ok(FilesystemKind::Symlink),
             3 => Ok(FilesystemKind::Socket),
+            4 => Ok(FilesystemKind::Fifo),
             _ => Err(FsEntryError::UnknownFileKindCode(code).into()),
         }
     }
@@ -182,6 +187,7 @@ mod test {
         one_file_kind_round_trip(FilesystemKind::Directory);
         one_file_kind_round_trip(FilesystemKind::Symlink);
         one_file_kind_round_trip(FilesystemKind::Socket);
+        one_file_kind_round_trip(FilesystemKind::Fifo);
     }
 
     fn one_file_kind_round_trip(kind: FilesystemKind) {
diff --git a/subplot/data.py b/subplot/data.py
index 3c369d1..0c1a4a5 100644
--- a/subplot/data.py
+++ b/subplot/data.py
@@ -24,6 +24,10 @@ def create_unix_socket(ctx, filename=None):
     fd.bind(filename)
 
 
+def create_fifo(ctx, filename=None):
+    os.mkfifo(filename)
+
+
 def create_nonutf8_filename(ctx, dirname=None):
     filename = "\x88"
     os.mkdir(dirname)
diff --git a/subplot/data.yaml b/subplot/data.yaml
index 97e6eed..0e13abd 100644
--- a/subplot/data.yaml
+++ b/subplot/data.yaml
@@ -7,6 +7,9 @@
 - given: "a Unix socket {filename}"
   function: create_unix_socket
 
+- given: "a named pipe {filename}"
+  function: create_fifo
+
 - given: "a file in {dirname} with a non-UTF8 filename"
   function: create_nonutf8_filename