feat(compress): move advanced stream init policy into Rust

Move ZSTD_initCStream_advanced's public initialization policy into the Rust
projection. Rust owns legacy pledged-size normalization and the reset, pledge,
parameter-check, parameter-copy, and dictionary-load ordering while C retains
the private CCtx parameter mutation callbacks.

Test Plan:
- ulimit -v 41943040; CARGO_BUILD_JOBS=1 cargo test --manifest-path rust/Cargo.toml init_cstream_advanced -- --test-threads=1
- ulimit -v 41943040; CARGO_BUILD_JOBS=1 cargo clippy --manifest-path rust/Cargo.toml --all-targets -- -D warnings
- ulimit -v 41943040; make -B -C programs -j1 zstd
- git diff --cached --check

lib/compress/zstd_compress.c

@@ -167,6 +167,35 @@ typedef char ZSTD_rust_init_cstream_using_dict_state_layout[
                 == 3 * sizeof(void*)
          && sizeof(ZSTD_rust_initCStreamUsingDictState) == 4 * sizeof(void*))
         ? 1 : -1];
+typedef size_t (*ZSTD_rust_initCStreamAdvancedCheckCParams_f)(
+        void* context, ZSTD_compressionParameters cParams);
+typedef void (*ZSTD_rust_initCStreamAdvancedSetZstdParams_f)(
+        void* context, const ZSTD_parameters* params);
+typedef struct {
+    void* callbackContext;
+    ZSTD_rust_initCStreamUsingCDictAdvancedReset_f resetSession;
+    ZSTD_rust_initCStreamUsingCDictAdvancedSetPledgedSrcSize_f setPledgedSrcSize;
+    ZSTD_rust_initCStreamAdvancedCheckCParams_f checkCParams;
+    ZSTD_rust_initCStreamAdvancedSetZstdParams_f setZstdParams;
+    ZSTD_rust_initCStreamUsingDictLoadDictionary_f loadDictionary;
+} ZSTD_rust_initCStreamAdvancedState;
+size_t ZSTD_rust_initCStreamAdvanced(
+        const ZSTD_rust_initCStreamAdvancedState* state,
+        const ZSTD_parameters* params, unsigned long long pss,
+        const void* dict, size_t dictSize);
+typedef char ZSTD_rust_init_cstream_advanced_state_layout[
+        (offsetof(ZSTD_rust_initCStreamAdvancedState, callbackContext) == 0
+         && offsetof(ZSTD_rust_initCStreamAdvancedState, resetSession) == sizeof(void*)
+         && offsetof(ZSTD_rust_initCStreamAdvancedState, setPledgedSrcSize)
+                == 2 * sizeof(void*)
+         && offsetof(ZSTD_rust_initCStreamAdvancedState, checkCParams)
+                == 3 * sizeof(void*)
+         && offsetof(ZSTD_rust_initCStreamAdvancedState, setZstdParams)
+                == 4 * sizeof(void*)
+         && offsetof(ZSTD_rust_initCStreamAdvancedState, loadDictionary)
+                == 5 * sizeof(void*)
+         && sizeof(ZSTD_rust_initCStreamAdvancedState) == 6 * sizeof(void*))
+        ? 1 : -1];
 ZSTD_frameProgression ZSTD_rust_frameProgression(U64 consumedSrcSize,
                                                   size_t buffered,
                                                   U64 producedCSize);
@@ -4992,22 +5021,43 @@ size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict)
  * pledgedSrcSize must be exact.
  * if srcSize is not known at init time, use value ZSTD_CONTENTSIZE_UNKNOWN.
  * dict is loaded with default parameters ZSTD_dct_auto and ZSTD_dlm_byCopy. */
+static size_t ZSTD_rust_initCStreamAdvanced_checkCParams(
+        void* context, ZSTD_compressionParameters cParams)
+{
+    (void)context;
+    return ZSTD_checkCParams(cParams);
+}
+
+static void ZSTD_rust_initCStreamAdvanced_setZstdParams(
+        void* context, const ZSTD_parameters* params)
+{
+    ZSTD_CCtx* const zcs = (ZSTD_CCtx*)context;
+    ZSTD_CCtxParams_setZstdParams(&zcs->requestedParams, params);
+}
+
+static size_t ZSTD_rust_initCStreamUsingDict_loadDictionary(
+        void* context, const void* dict, size_t dictSize)
+{
+    return ZSTD_CCtx_loadDictionary((ZSTD_CCtx*)context, dict, dictSize);
+}
+
 size_t ZSTD_initCStream_advanced(ZSTD_CStream* zcs,
                                  const void* dict, size_t dictSize,
                                  ZSTD_parameters params, unsigned long long pss)
 {
+    ZSTD_rust_initCStreamAdvancedState state;
     /* for compatibility with older programs relying on this behavior.
      * Users should now specify ZSTD_CONTENTSIZE_UNKNOWN.
      * This line will be removed in the future.
      */
-    U64 const pledgedSrcSize = (pss==0 && params.fParams.contentSizeFlag==0) ? ZSTD_CONTENTSIZE_UNKNOWN : pss;
     DEBUGLOG(4, "ZSTD_initCStream_advanced");
-    FORWARD_IF_ERROR( ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only) , "");
+    state.callbackContext = zcs;
-    FORWARD_IF_ERROR( ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize) , "");
+    state.resetSession = ZSTD_rust_initCStreamUsingCDictAdvanced_resetSession;
-    FORWARD_IF_ERROR( ZSTD_checkCParams(params.cParams) , "");
+    state.setPledgedSrcSize = ZSTD_rust_initCStreamUsingCDictAdvanced_setPledgedSrcSize;
-    ZSTD_CCtxParams_setZstdParams(&zcs->requestedParams, &params);
+    state.checkCParams = ZSTD_rust_initCStreamAdvanced_checkCParams;
-    FORWARD_IF_ERROR( ZSTD_CCtx_loadDictionary(zcs, dict, dictSize) , "");
+    state.setZstdParams = ZSTD_rust_initCStreamAdvanced_setZstdParams;
-    return 0;
+    state.loadDictionary = ZSTD_rust_initCStreamUsingDict_loadDictionary;
+    return ZSTD_rust_initCStreamAdvanced(&state, &params, pss, dict, dictSize);
 }
 
 static size_t ZSTD_rust_initCStreamSrcSize_setLevel(
@@ -5017,12 +5067,6 @@ static size_t ZSTD_rust_initCStreamSrcSize_setLevel(
             (ZSTD_CCtx*)context, ZSTD_c_compressionLevel, compressionLevel);
 }
 
-static size_t ZSTD_rust_initCStreamUsingDict_loadDictionary(
-        void* context, const void* dict, size_t dictSize)
-{
-    return ZSTD_CCtx_loadDictionary((ZSTD_CCtx*)context, dict, dictSize);
-}
-
 size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, int compressionLevel)
 {
     ZSTD_rust_initCStreamUsingDictState state;

rust/src/zstd_compress.rs

@@ -23,8 +23,9 @@ use crate::zstd_compress_frame::{
 };
 use crate::zstd_compress_literals::min_gain;
 use crate::zstd_compress_params::{
-    ZSTD_rust_params_adjustCParams, ZSTD_rust_params_maxNbSeq, ZSTD_rust_params_selectCParams,
+    ZSTD_compressionParameters, ZSTD_parameters, ZSTD_rust_params_adjustCParams,
-    ZSTD_RUST_CPM_NO_ATTACH_DICT, ZSTD_RUST_PS_AUTO, ZSTD_RUST_PS_DISABLE,
+    ZSTD_rust_params_maxNbSeq, ZSTD_rust_params_selectCParams, ZSTD_RUST_CPM_NO_ATTACH_DICT,
+    ZSTD_RUST_PS_AUTO, ZSTD_RUST_PS_DISABLE,
 };
 use crate::zstd_compress_sequences::SeqDef;
 use crate::zstd_compress_stats::{
@@ -1135,6 +1136,79 @@ pub unsafe extern "C" fn ZSTD_rust_initCStreamUsingDict(
     0
 }
 
+type InitCStreamAdvancedCheckCParamsFn =
+    unsafe extern "C" fn(*mut c_void, ZSTD_compressionParameters) -> usize;
+type InitCStreamAdvancedSetZstdParamsFn = unsafe extern "C" fn(*mut c_void, *const ZSTD_parameters);
+
+/// Explicit projection for `ZSTD_initCStream_advanced`.
+#[repr(C)]
+pub struct ZSTD_rust_initCStreamAdvancedState {
+    callback_context: *mut c_void,
+    reset_session: InitCStreamUsingCDictAdvancedResetFn,
+    set_pledged_src_size: InitCStreamUsingCDictAdvancedSetPledgedSrcSizeFn,
+    check_c_params: InitCStreamAdvancedCheckCParamsFn,
+    set_zstd_params: InitCStreamAdvancedSetZstdParamsFn,
+    load_dictionary: InitCStreamUsingDictLoadDictionaryFn,
+}
+
+const _: () = {
+    assert!(offset_of!(ZSTD_rust_initCStreamAdvancedState, callback_context) == 0);
+    assert!(offset_of!(ZSTD_rust_initCStreamAdvancedState, reset_session) == size_of::<usize>());
+    assert!(
+        offset_of!(ZSTD_rust_initCStreamAdvancedState, set_pledged_src_size)
+            == 2 * size_of::<usize>()
+    );
+    assert!(
+        offset_of!(ZSTD_rust_initCStreamAdvancedState, check_c_params) == 3 * size_of::<usize>()
+    );
+    assert!(
+        offset_of!(ZSTD_rust_initCStreamAdvancedState, set_zstd_params) == 4 * size_of::<usize>()
+    );
+    assert!(
+        offset_of!(ZSTD_rust_initCStreamAdvancedState, load_dictionary) == 5 * size_of::<usize>()
+    );
+    assert!(size_of::<ZSTD_rust_initCStreamAdvancedState>() == 6 * size_of::<usize>());
+};
+
+#[no_mangle]
+pub unsafe extern "C" fn ZSTD_rust_initCStreamAdvanced(
+    state: *const ZSTD_rust_initCStreamAdvancedState,
+    params: *const ZSTD_parameters,
+    pss: u64,
+    dict: *const c_void,
+    dict_size: usize,
+) -> usize {
+    if state.is_null() || params.is_null() {
+        return ERROR(ZstdErrorCode::Generic);
+    }
+    let state = unsafe { &*state };
+    let params = unsafe { &*params };
+    let pledged_src_size = if pss == 0 && params.fParams.contentSizeFlag == 0 {
+        ZSTD_CONTENTSIZE_UNKNOWN
+    } else {
+        pss
+    };
+
+    let result = unsafe { (state.reset_session)(state.callback_context) };
+    if ERR_isError(result) {
+        return result;
+    }
+    let result = unsafe { (state.set_pledged_src_size)(state.callback_context, pledged_src_size) };
+    if ERR_isError(result) {
+        return result;
+    }
+    let result = unsafe { (state.check_c_params)(state.callback_context, params.cParams) };
+    if ERR_isError(result) {
+        return result;
+    }
+    unsafe { (state.set_zstd_params)(state.callback_context, params) };
+    let result = unsafe { (state.load_dictionary)(state.callback_context, dict, dict_size) };
+    if ERR_isError(result) {
+        return result;
+    }
+    0
+}
+
 type CompressStreamBlockFn =
     unsafe extern "C" fn(*mut c_void, *mut c_void, usize, *const c_void, usize) -> usize;
 type CompressStreamResetFn = unsafe extern "C" fn(*mut c_void) -> usize;
@@ -5443,6 +5517,7 @@ pub unsafe extern "C" fn ZSTD_compressStream2(
 mod tests {
     use super::*;
     use crate::errors::ERR_getErrorCode;
+    use crate::zstd_compress_params::ZSTD_frameParameters;
     use std::io::Write;
     use std::process::{Command, Stdio};
 
@@ -8986,12 +9061,14 @@ mod tests {
         pledged_result: usize,
         set_level_result: usize,
         load_dict_result: usize,
+        check_params_result: usize,
         ref_result: usize,
         pledged_src_size: u64,
         compression_level: c_int,
         frame_params: [c_uint; 3],
         cdict: *const c_void,
         dict_size: usize,
+        zstd_params: ZSTD_parameters,
     }
 
     unsafe fn init_cstream_using_cdict_advanced_test_context(
@@ -9040,6 +9117,24 @@ mod tests {
         context.load_dict_result
     }
 
+    unsafe extern "C" fn init_cstream_advanced_test_check_c_params(
+        context: *mut c_void,
+        _c_params: ZSTD_compressionParameters,
+    ) -> usize {
+        let context = unsafe { init_cstream_using_cdict_advanced_test_context(context) };
+        context.events.push("check");
+        context.check_params_result
+    }
+
+    unsafe extern "C" fn init_cstream_advanced_test_set_zstd_params(
+        context: *mut c_void,
+        params: *const ZSTD_parameters,
+    ) {
+        let context = unsafe { init_cstream_using_cdict_advanced_test_context(context) };
+        context.events.push("params");
+        context.zstd_params = unsafe { *params };
+    }
+
     unsafe extern "C" fn init_cstream_using_cdict_advanced_test_set_frame_params(
         context: *mut c_void,
         content_size_flag: c_uint,
@@ -9401,6 +9496,137 @@ mod tests {
         assert_eq!(context.events, ["reset", "level", "load-dict"]);
     }
 
+    fn init_cstream_advanced_test_state(
+        context: &mut InitCStreamUsingCDictAdvancedTestContext,
+    ) -> ZSTD_rust_initCStreamAdvancedState {
+        ZSTD_rust_initCStreamAdvancedState {
+            callback_context: (context as *mut InitCStreamUsingCDictAdvancedTestContext).cast(),
+            reset_session: init_cstream_using_cdict_advanced_test_reset,
+            set_pledged_src_size: init_cstream_using_cdict_advanced_test_set_pledged,
+            check_c_params: init_cstream_advanced_test_check_c_params,
+            set_zstd_params: init_cstream_advanced_test_set_zstd_params,
+            load_dictionary: init_cstream_using_dict_test_load_dictionary,
+        }
+    }
+
+    fn init_cstream_advanced_test_params(content_size_flag: c_int) -> ZSTD_parameters {
+        ZSTD_parameters {
+            cParams: ZSTD_compressionParameters {
+                windowLog: 10,
+                chainLog: 11,
+                hashLog: 12,
+                searchLog: 13,
+                minMatch: 4,
+                targetLength: 5,
+                strategy: 1,
+            },
+            fParams: ZSTD_frameParameters {
+                contentSizeFlag: content_size_flag,
+                checksumFlag: 1,
+                noDictIDFlag: 2,
+            },
+        }
+    }
+
+    #[test]
+    fn init_cstream_advanced_preserves_order_and_normalizes_unknown_pledge() {
+        let params = init_cstream_advanced_test_params(0);
+        let dict = ptr::dangling::<c_void>();
+        let mut context = InitCStreamUsingCDictAdvancedTestContext::default();
+        let state = init_cstream_advanced_test_state(&mut context);
+
+        let result = unsafe { ZSTD_rust_initCStreamAdvanced(&state, &params, 0, dict, 123) };
+
+        assert_eq!(result, 0);
+        assert_eq!(
+            context.events,
+            ["reset", "pledged", "check", "params", "load-dict"]
+        );
+        assert_eq!(context.pledged_src_size, ZSTD_CONTENTSIZE_UNKNOWN);
+        assert_eq!(context.zstd_params, params);
+        assert_eq!(context.cdict, dict);
+        assert_eq!(context.dict_size, 123);
+    }
+
+    #[test]
+    fn init_cstream_advanced_keeps_zero_pledge_for_known_empty_frame() {
+        let params = init_cstream_advanced_test_params(1);
+        let mut context = InitCStreamUsingCDictAdvancedTestContext::default();
+        let state = init_cstream_advanced_test_state(&mut context);
+
+        let result = unsafe { ZSTD_rust_initCStreamAdvanced(&state, &params, 0, ptr::null(), 0) };
+
+        assert_eq!(result, 0);
+        assert_eq!(context.pledged_src_size, 0);
+        assert_eq!(
+            context.events,
+            ["reset", "pledged", "check", "params", "load-dict"]
+        );
+    }
+
+    #[test]
+    fn init_cstream_advanced_stops_after_reset_error() {
+        let params = init_cstream_advanced_test_params(0);
+        let mut context = InitCStreamUsingCDictAdvancedTestContext {
+            reset_result: ERROR(ZstdErrorCode::MemoryAllocation),
+            ..InitCStreamUsingCDictAdvancedTestContext::default()
+        };
+        let state = init_cstream_advanced_test_state(&mut context);
+
+        let result = unsafe { ZSTD_rust_initCStreamAdvanced(&state, &params, 77, ptr::null(), 0) };
+
+        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
+        assert_eq!(context.events, ["reset"]);
+    }
+
+    #[test]
+    fn init_cstream_advanced_stops_after_pledged_size_error() {
+        let params = init_cstream_advanced_test_params(0);
+        let mut context = InitCStreamUsingCDictAdvancedTestContext {
+            pledged_result: ERROR(ZstdErrorCode::StageWrong),
+            ..InitCStreamUsingCDictAdvancedTestContext::default()
+        };
+        let state = init_cstream_advanced_test_state(&mut context);
+
+        let result = unsafe { ZSTD_rust_initCStreamAdvanced(&state, &params, 77, ptr::null(), 0) };
+
+        assert_eq!(result, ERROR(ZstdErrorCode::StageWrong));
+        assert_eq!(context.events, ["reset", "pledged"]);
+    }
+
+    #[test]
+    fn init_cstream_advanced_stops_after_parameter_error() {
+        let params = init_cstream_advanced_test_params(0);
+        let mut context = InitCStreamUsingCDictAdvancedTestContext {
+            check_params_result: ERROR(ZstdErrorCode::ParameterOutOfBound),
+            ..InitCStreamUsingCDictAdvancedTestContext::default()
+        };
+        let state = init_cstream_advanced_test_state(&mut context);
+
+        let result = unsafe { ZSTD_rust_initCStreamAdvanced(&state, &params, 77, ptr::null(), 0) };
+
+        assert_eq!(result, ERROR(ZstdErrorCode::ParameterOutOfBound));
+        assert_eq!(context.events, ["reset", "pledged", "check"]);
+    }
+
+    #[test]
+    fn init_cstream_advanced_propagates_dictionary_error_last() {
+        let params = init_cstream_advanced_test_params(0);
+        let mut context = InitCStreamUsingCDictAdvancedTestContext {
+            load_dict_result: ERROR(ZstdErrorCode::DictionaryCreationFailed),
+            ..InitCStreamUsingCDictAdvancedTestContext::default()
+        };
+        let state = init_cstream_advanced_test_state(&mut context);
+
+        let result = unsafe { ZSTD_rust_initCStreamAdvanced(&state, &params, 77, ptr::null(), 0) };
+
+        assert_eq!(result, ERROR(ZstdErrorCode::DictionaryCreationFailed));
+        assert_eq!(
+            context.events,
+            ["reset", "pledged", "check", "params", "load-dict"]
+        );
+    }
+
     #[test]
     fn pledged_src_size_writes_the_init_stage_value_plus_one() {
         let mut pledged_src_size_plus_one = 0;