refactor(cli): move file-removal policy to Rust

Keep FIO_removeFile responsible for the filesystem operation, exact diagnostics, and C return wrapper, but route its status classification through a Rust policy bridge. Unknown statuses are explicitly treated as failed removal. ABI value assertions and focused mapping tests preserve the C contract.

Test Plan: Not run in this atomic commit; the capped serial Rust, native, smoke, and original test-suite verification follows.

programs/fileio.c

@@ -435,6 +435,31 @@ void FIO_rust_freeDict(int dictBufferType,
                        size_t* bufferSize,
                        void** dictHandle);
 int FIO_rust_removeFile(const char* path);
+enum {
+    FIO_REMOVE_SUCCESS = 0,
+    FIO_REMOVE_STAT_FAILED = 1,
+    FIO_REMOVE_NON_REGULAR = 2,
+    FIO_REMOVE_FAILED = 3
+};
+enum {
+    FIO_RUST_REMOVE_FILE_ACTION_SUCCESS = 0,
+    FIO_RUST_REMOVE_FILE_ACTION_STAT_FAILED = 1,
+    FIO_RUST_REMOVE_FILE_ACTION_NON_REGULAR = 2,
+    FIO_RUST_REMOVE_FILE_ACTION_FAILED = 3,
+    FIO_RUST_REMOVE_FILE_ACTION_INVALID = 4
+};
+typedef char FIO_rust_remove_file_status_values[
+        (FIO_REMOVE_SUCCESS == 0
+         && FIO_REMOVE_STAT_FAILED == 1
+         && FIO_REMOVE_NON_REGULAR == 2
+         && FIO_REMOVE_FAILED == 3) ? 1 : -1];
+typedef char FIO_rust_remove_file_action_values[
+        (FIO_RUST_REMOVE_FILE_ACTION_SUCCESS == 0
+         && FIO_RUST_REMOVE_FILE_ACTION_STAT_FAILED == 1
+         && FIO_RUST_REMOVE_FILE_ACTION_NON_REGULAR == 2
+         && FIO_RUST_REMOVE_FILE_ACTION_FAILED == 3
+         && FIO_RUST_REMOVE_FILE_ACTION_INVALID == 4) ? 1 : -1];
+int FIO_rust_removeFileAction(int status);
 int FIO_rust_passThrough(ReadPoolCtx_t* readCtx, WritePoolCtx_t* writeCtx);
 enum {
     FIO_RUST_ZSTD_FRAME_OK = 0,
@@ -647,21 +672,21 @@ int FIO_LZ4_GetBlockSize_FromBlockId(int id);
  * @result : Unlink `fileName`, even if it's read-only */
 static int FIO_removeFile(const char* path)
 {
-    enum {
-        FIO_REMOVE_SUCCESS = 0,
-        FIO_REMOVE_STAT_FAILED = 1,
-        FIO_REMOVE_NON_REGULAR = 2,
-    };
     int const status = FIO_rust_removeFile(path);
-    if (status == FIO_REMOVE_STAT_FAILED) {
+    switch (FIO_rust_removeFileAction(status)) {
+    case FIO_RUST_REMOVE_FILE_ACTION_STAT_FAILED:
         DISPLAYLEVEL(2, "zstd: Failed to stat %s while trying to remove it\n", path);
         return 0;
-    }
+    case FIO_RUST_REMOVE_FILE_ACTION_NON_REGULAR:
-    if (status == FIO_REMOVE_NON_REGULAR) {
         DISPLAYLEVEL(2, "zstd: Refusing to remove non-regular file %s\n", path);
         return 0;
+    case FIO_RUST_REMOVE_FILE_ACTION_SUCCESS:
+        return 0;
+    case FIO_RUST_REMOVE_FILE_ACTION_FAILED:
+    case FIO_RUST_REMOVE_FILE_ACTION_INVALID:
+    default:
+        return 1;
     }
-    return status == FIO_REMOVE_SUCCESS ? 0 : 1;
 }
 
 /** FIO_openSrcFile() :

rust/src/fileio_prefs.rs

@@ -22,6 +22,10 @@ const FIO_LDM_PARAM_NOTSET: c_int = 9999;
 const FIO_PATCH_MEM_LIMIT_SUCCESS: c_int = 0;
 const FIO_PATCH_MEM_LIMIT_UNKNOWN_SIZE: c_int = 1;
 const FIO_PATCH_MEM_LIMIT_TOO_LARGE: c_int = 2;
+const FIO_REMOVE_SUCCESS: c_int = 0;
+const FIO_REMOVE_STAT_FAILED: c_int = 1;
+const FIO_REMOVE_NON_REGULAR: c_int = 2;
+const FIO_REMOVE_FAILED: c_int = 3;
 const FIO_MULTI_FILES_ACTION_PROCEED: c_int = 0;
 const FIO_MULTI_FILES_ACTION_FATAL_STDOUT_REMOVE: c_int = 1;
 const FIO_MULTI_FILES_ACTION_FATAL_TEST_REMOVE: c_int = 2;
@@ -39,6 +43,11 @@ pub const FIO_RUST_LIST_FILE_ACTION_NOT_ZSTD: c_int = 2;
 pub const FIO_RUST_LIST_FILE_ACTION_FILE_ERROR: c_int = 3;
 pub const FIO_RUST_LIST_FILE_ACTION_TRUNCATED_INPUT: c_int = 4;
 pub const FIO_RUST_LIST_FILE_ACTION_INVALID: c_int = 5;
+pub const FIO_RUST_REMOVE_FILE_ACTION_SUCCESS: c_int = 0;
+pub const FIO_RUST_REMOVE_FILE_ACTION_STAT_FAILED: c_int = 1;
+pub const FIO_RUST_REMOVE_FILE_ACTION_NON_REGULAR: c_int = 2;
+pub const FIO_RUST_REMOVE_FILE_ACTION_FAILED: c_int = 3;
+pub const FIO_RUST_REMOVE_FILE_ACTION_INVALID: c_int = 4;
 const UTIL_FILESIZE_UNKNOWN: u64 = u64::MAX;
 const COMPRESSED_FILE_EXTENSIONS: &[&[u8]] = &[
     b".zst",
@@ -734,6 +743,27 @@ pub extern "C" fn FIO_rust_listFileStatusAction(status: c_int) -> c_int {
     list_file_status_action(status)
 }
 
+#[inline]
+fn remove_file_action(status: c_int) -> c_int {
+    match status {
+        FIO_REMOVE_SUCCESS => FIO_RUST_REMOVE_FILE_ACTION_SUCCESS,
+        FIO_REMOVE_STAT_FAILED => FIO_RUST_REMOVE_FILE_ACTION_STAT_FAILED,
+        FIO_REMOVE_NON_REGULAR => FIO_RUST_REMOVE_FILE_ACTION_NON_REGULAR,
+        FIO_REMOVE_FAILED => FIO_RUST_REMOVE_FILE_ACTION_FAILED,
+        _ => FIO_RUST_REMOVE_FILE_ACTION_INVALID,
+    }
+}
+
+/// Map the C-owned file-removal result to its policy action.
+///
+/// C retains the filesystem operation, exact diagnostics, and return-value
+/// wrapper. Rust owns only the status classification, with unknown statuses
+/// remaining a failed removal for the C caller.
+#[no_mangle]
+pub extern "C" fn FIO_rust_removeFileAction(status: c_int) -> c_int {
+    remove_file_action(status)
+}
+
 /// Callback projection for the C-owned `--list` file operations.
 #[repr(C)]
 pub struct FIO_listMultipleFilesCallbacks_t {
@@ -2612,6 +2642,41 @@ mod tests {
         }
     }
 
+    #[test]
+    fn remove_file_action_preserves_status_mapping_and_unknown_failure_policy() {
+        for (status, action) in [
+            (
+                FIO_REMOVE_SUCCESS,
+                FIO_RUST_REMOVE_FILE_ACTION_SUCCESS,
+            ),
+            (
+                FIO_REMOVE_STAT_FAILED,
+                FIO_RUST_REMOVE_FILE_ACTION_STAT_FAILED,
+            ),
+            (
+                FIO_REMOVE_NON_REGULAR,
+                FIO_RUST_REMOVE_FILE_ACTION_NON_REGULAR,
+            ),
+            (
+                FIO_REMOVE_FAILED,
+                FIO_RUST_REMOVE_FILE_ACTION_FAILED,
+            ),
+            (-1, FIO_RUST_REMOVE_FILE_ACTION_INVALID),
+            (c_int::MAX, FIO_RUST_REMOVE_FILE_ACTION_INVALID),
+        ] {
+            assert_eq!(
+                remove_file_action(status),
+                action,
+                "unexpected action for remove status {status}"
+            );
+            assert_eq!(
+                FIO_rust_removeFileAction(status),
+                action,
+                "C ABI disagrees for remove status {status}"
+            );
+        }
+    }
+
     #[test]
     fn source_exclusion_preserves_case_sensitive_suffixes_and_null_policy() {
         let cases = [