refactor(cli): move decompression diagnostic mapping to Rust

Move the status-to-diagnostic policy for decompression failures into the
Rust fileio layer.  C retains the user-facing strings and callback display
logic, while Rust returns a stable diagnostic classification across the ABI
and leaves silent statuses silent.

Test Plan:
- ulimit -v 41943040; CARGO_BUILD_JOBS=1 cargo +nightly fmt --manifest-path rust/Cargo.toml -- --check
- ulimit -v 41943040; CARGO_BUILD_JOBS=1 cargo clippy --manifest-path rust/Cargo.toml --all-targets -- -D warnings
- ulimit -v 41943040; CARGO_BUILD_JOBS=1 cargo test --manifest-path rust/Cargo.toml --all-targets (775 passed)
- ulimit -v 41943040; CARGO_BUILD_JOBS=1 cargo clippy --manifest-path rust/cli/Cargo.toml --all-targets -- -D warnings
- ulimit -v 41943040; CARGO_BUILD_JOBS=1 cargo test --manifest-path rust/cli/Cargo.toml --all-targets (179 passed)
- ulimit -v 41943040; make -j1
- ulimit -v 41943040; make -j1 -C tests test (all tests completed successfully)

programs/fileio.c

@@ -434,6 +434,15 @@ enum {
     FIO_RUST_DECOMPRESS_PASS_THROUGH_ERROR = 9,
     FIO_RUST_DECOMPRESS_ZSTD_UNSUPPORTED = 10
 };
+enum {
+    FIO_RUST_DECOMPRESS_DIAGNOSTIC_NONE = 0,
+    FIO_RUST_DECOMPRESS_DIAGNOSTIC_EMPTY_INPUT = 1,
+    FIO_RUST_DECOMPRESS_DIAGNOSTIC_SHORT_INPUT = 2,
+    FIO_RUST_DECOMPRESS_DIAGNOSTIC_GZIP_UNSUPPORTED = 3,
+    FIO_RUST_DECOMPRESS_DIAGNOSTIC_LZMA_UNSUPPORTED = 4,
+    FIO_RUST_DECOMPRESS_DIAGNOSTIC_LZ4_UNSUPPORTED = 5,
+    FIO_RUST_DECOMPRESS_DIAGNOSTIC_UNSUPPORTED_FORMAT = 6
+};
 typedef int (*FIO_rust_decompress_frame_fn)(void* opaque,
                                             const char* srcFileName,
                                             U64 alreadyDecoded,
@@ -466,6 +475,7 @@ int FIO_rust_finishDecompressFrames(int status,
                                     const char* srcFileName,
                                     U64 decodedSize,
                                     const FIO_rust_decompress_callbacks_t* callbacks);
+int FIO_rust_decompressStatusDiagnostic(int status);
 
 typedef void (*FIO_rust_decompress_read_fill_fn)(
         void* opaque, size_t requested, const unsigned char** buffer, size_t* loaded);
@@ -4122,23 +4132,23 @@ static void FIO_rust_decompressStatusCallback(void* opaque,
                                                const char* srcFileName)
 {
     (void)opaque;
-    switch (status) {
+    switch (FIO_rust_decompressStatusDiagnostic(status)) {
-        case FIO_RUST_DECOMPRESS_EMPTY_INPUT:
+        case FIO_RUST_DECOMPRESS_DIAGNOSTIC_EMPTY_INPUT:
             DISPLAYLEVEL(1, "zstd: %s: unexpected end of file \n", srcFileName);
             break;
-        case FIO_RUST_DECOMPRESS_SHORT_INPUT:
+        case FIO_RUST_DECOMPRESS_DIAGNOSTIC_SHORT_INPUT:
             DISPLAYLEVEL(1, "zstd: %s: unknown header \n", srcFileName);
             break;
-        case FIO_RUST_DECOMPRESS_GZIP_UNSUPPORTED:
+        case FIO_RUST_DECOMPRESS_DIAGNOSTIC_GZIP_UNSUPPORTED:
             DISPLAYLEVEL(1, "zstd: %s: gzip file cannot be uncompressed (zstd compiled without HAVE_ZLIB) -- ignored \n", srcFileName);
             break;
-        case FIO_RUST_DECOMPRESS_LZMA_UNSUPPORTED:
+        case FIO_RUST_DECOMPRESS_DIAGNOSTIC_LZMA_UNSUPPORTED:
             DISPLAYLEVEL(1, "zstd: %s: xz/lzma file cannot be uncompressed (zstd compiled without HAVE_LZMA) -- ignored \n", srcFileName);
             break;
-        case FIO_RUST_DECOMPRESS_LZ4_UNSUPPORTED:
+        case FIO_RUST_DECOMPRESS_DIAGNOSTIC_LZ4_UNSUPPORTED:
             DISPLAYLEVEL(1, "zstd: %s: lz4 file cannot be uncompressed (zstd compiled without HAVE_LZ4) -- ignored \n", srcFileName);
             break;
-        case FIO_RUST_DECOMPRESS_UNSUPPORTED_FORMAT:
+        case FIO_RUST_DECOMPRESS_DIAGNOSTIC_UNSUPPORTED_FORMAT:
             DISPLAYLEVEL(1, "zstd: %s: unsupported format \n", srcFileName);
             break;
         default:

rust/src/fileio_asyncio.rs

@@ -49,6 +49,30 @@ pub const FIO_RUST_DECOMPRESS_UNSUPPORTED_FORMAT: c_int = 8;
 pub const FIO_RUST_DECOMPRESS_PASS_THROUGH_ERROR: c_int = 9;
 pub const FIO_RUST_DECOMPRESS_ZSTD_UNSUPPORTED: c_int = 10;
 
+pub const FIO_RUST_DECOMPRESS_DIAGNOSTIC_NONE: c_int = 0;
+pub const FIO_RUST_DECOMPRESS_DIAGNOSTIC_EMPTY_INPUT: c_int = 1;
+pub const FIO_RUST_DECOMPRESS_DIAGNOSTIC_SHORT_INPUT: c_int = 2;
+pub const FIO_RUST_DECOMPRESS_DIAGNOSTIC_GZIP_UNSUPPORTED: c_int = 3;
+pub const FIO_RUST_DECOMPRESS_DIAGNOSTIC_LZMA_UNSUPPORTED: c_int = 4;
+pub const FIO_RUST_DECOMPRESS_DIAGNOSTIC_LZ4_UNSUPPORTED: c_int = 5;
+pub const FIO_RUST_DECOMPRESS_DIAGNOSTIC_UNSUPPORTED_FORMAT: c_int = 6;
+
+/// Maps decompression results to the diagnostics that the C CLI displays.
+/// Statuses without a legacy diagnostic deliberately map to `NONE`, retaining
+/// the previous C callback's silent default case.
+#[no_mangle]
+pub extern "C" fn FIO_rust_decompressStatusDiagnostic(status: c_int) -> c_int {
+    match status {
+        FIO_RUST_DECOMPRESS_EMPTY_INPUT => FIO_RUST_DECOMPRESS_DIAGNOSTIC_EMPTY_INPUT,
+        FIO_RUST_DECOMPRESS_SHORT_INPUT => FIO_RUST_DECOMPRESS_DIAGNOSTIC_SHORT_INPUT,
+        FIO_RUST_DECOMPRESS_GZIP_UNSUPPORTED => FIO_RUST_DECOMPRESS_DIAGNOSTIC_GZIP_UNSUPPORTED,
+        FIO_RUST_DECOMPRESS_LZMA_UNSUPPORTED => FIO_RUST_DECOMPRESS_DIAGNOSTIC_LZMA_UNSUPPORTED,
+        FIO_RUST_DECOMPRESS_LZ4_UNSUPPORTED => FIO_RUST_DECOMPRESS_DIAGNOSTIC_LZ4_UNSUPPORTED,
+        FIO_RUST_DECOMPRESS_UNSUPPORTED_FORMAT => FIO_RUST_DECOMPRESS_DIAGNOSTIC_UNSUPPORTED_FORMAT,
+        _ => FIO_RUST_DECOMPRESS_DIAGNOSTIC_NONE,
+    }
+}
+
 type FIO_rust_frame_progress_fn = Option<unsafe extern "C" fn(*mut c_void, *const c_char, u64)>;
 pub type FIO_rust_decompress_frame_fn =
     unsafe extern "C" fn(*mut c_void, *const c_char, u64, *mut u64, *mut usize, c_int) -> c_int;
@@ -5011,6 +5035,53 @@ impl PoolInner {
 mod tests {
     use super::*;
 
+    #[test]
+    fn decompression_status_diagnostic_preserves_cli_mapping() {
+        for (status, diagnostic) in [
+            (
+                FIO_RUST_DECOMPRESS_EMPTY_INPUT,
+                FIO_RUST_DECOMPRESS_DIAGNOSTIC_EMPTY_INPUT,
+            ),
+            (
+                FIO_RUST_DECOMPRESS_SHORT_INPUT,
+                FIO_RUST_DECOMPRESS_DIAGNOSTIC_SHORT_INPUT,
+            ),
+            (
+                FIO_RUST_DECOMPRESS_GZIP_UNSUPPORTED,
+                FIO_RUST_DECOMPRESS_DIAGNOSTIC_GZIP_UNSUPPORTED,
+            ),
+            (
+                FIO_RUST_DECOMPRESS_LZMA_UNSUPPORTED,
+                FIO_RUST_DECOMPRESS_DIAGNOSTIC_LZMA_UNSUPPORTED,
+            ),
+            (
+                FIO_RUST_DECOMPRESS_LZ4_UNSUPPORTED,
+                FIO_RUST_DECOMPRESS_DIAGNOSTIC_LZ4_UNSUPPORTED,
+            ),
+            (
+                FIO_RUST_DECOMPRESS_UNSUPPORTED_FORMAT,
+                FIO_RUST_DECOMPRESS_DIAGNOSTIC_UNSUPPORTED_FORMAT,
+            ),
+        ] {
+            assert_eq!(FIO_rust_decompressStatusDiagnostic(status), diagnostic);
+        }
+
+        for status in [
+            FIO_RUST_DECOMPRESS_OK,
+            FIO_RUST_DECOMPRESS_PASS_THROUGH,
+            FIO_RUST_DECOMPRESS_FRAME_ERROR,
+            FIO_RUST_DECOMPRESS_PASS_THROUGH_ERROR,
+            FIO_RUST_DECOMPRESS_ZSTD_UNSUPPORTED,
+            -1,
+            99,
+        ] {
+            assert_eq!(
+                FIO_rust_decompressStatusDiagnostic(status),
+                FIO_RUST_DECOMPRESS_DIAGNOSTIC_NONE
+            );
+        }
+    }
+
     const SOURCE_POLICY_STAT: u8 = 1;
     const SOURCE_POLICY_EXCLUDED: u8 = 2;
     const SOURCE_POLICY_OPEN: u8 = 3;