feat(cli): move decompressed filename policy to Rust

Port destination-name derivation to the Rust file-I/O preference module. Preserve build-configured suffix matching, tar-name conversion, stdin/stdout sentinels, output-directory handling, diagnostics, static-buffer reuse, and allocation behavior through the existing C adapter.

Test Plan:\n- cargo test --manifest-path rust/cli/Cargo.toml --no-default-features --features cli,compression,decompression,benchmark\n- cargo test --manifest-path rust/cli/Cargo.toml --no-default-features --features helpers\n- cargo clippy --manifest-path rust/cli/Cargo.toml --all-targets --no-default-features --features cli,compression,decompression,benchmark\n- cargo clippy --manifest-path rust/cli/Cargo.toml --all-targets --no-default-features --features helpers\n- make -B -C programs -j2 zstd zstd-small zstd-frugal\n- make -C tests -j2 test-cli-tests

programs/fileio.c

@@ -312,6 +312,8 @@ unsigned long long FIO_rust_getLargestFileSize(const char** inFileNames, unsigne
 void FIO_rust_setInBuffer(ZSTD_inBuffer* output, const void* buf, size_t s, size_t pos);
 void FIO_rust_setOutBuffer(ZSTD_outBuffer* output, void* buf, size_t s, size_t pos);
 const char* FIO_rust_determineCompressedName(const char* srcFileName, const char* outDirName, const char* suffix);
+const char* FIO_rust_determineDstName(const char* srcFileName, const char* outDirName,
+                                      const char* const* suffixList, const char* suffixListStr);
 #ifdef ZSTD_LZ4COMPRESS
 int FIO_rust_LZ4_GetBlockSize_FromBlockId(int id);
 #endif
@@ -690,20 +692,6 @@ int FIO_checkFilenameCollisions(const char** filenameTable, unsigned nbFiles) {
     return FIO_rust_checkFilenameCollisions(filenameTable, nbFiles);
 }
 
-char* UTIL_createFilenameFromOutDir(const char* path, const char* outDirName,
-                                    size_t suffixLen);
-
-/* FIO_createFilename_fromOutDir() :
- * Takes a source file name and specified output directory, and
- * allocates memory for and returns a pointer to final path.
- * This function never returns an error (it may abort() in case of pb)
- */
-static char*
-FIO_createFilename_fromOutDir(const char* path, const char* outDirName, const size_t suffixLen)
-{
-    return UTIL_createFilenameFromOutDir(path, outDirName, suffixLen);
-}
-
 /* FIO_highbit64() :
  * gives position of highest bit.
  * note : only works for v > 0 !
@@ -2705,88 +2693,7 @@ static const char *suffixListStr =
 static const char*
 FIO_determineDstName(const char* srcFileName, const char* outDirName)
 {
-    static size_t dfnbCapacity = 0;
-    static char* dstFileNameBuffer = NULL;   /* using static allocation : this function cannot be multi-threaded */
-    size_t dstFileNameEndPos;
-    char* outDirFilename = NULL;
-    const char* dstSuffix = "";
-    size_t dstSuffixLen = 0;
-
-    size_t sfnSize = strlen(srcFileName);
-
-    size_t srcSuffixLen;
-    const char* const srcSuffix = strrchr(srcFileName, '.');
-
-    if(!strcmp(srcFileName, stdinmark)) {
-        return stdoutmark;
-    }
-
-    if (srcSuffix == NULL) {
-        DISPLAYLEVEL(1,
-            "zstd: %s: unknown suffix (%s expected). "
-            "Can't derive the output file name. "
-            "Specify it with -o dstFileName. Ignoring.\n",
-            srcFileName, suffixListStr);
-        return NULL;
-    }
-    srcSuffixLen = strlen(srcSuffix);
-
-    {
-        const char** matchedSuffixPtr;
-        for (matchedSuffixPtr = suffixList; *matchedSuffixPtr != NULL; matchedSuffixPtr++) {
-            if (!strcmp(*matchedSuffixPtr, srcSuffix)) {
-                break;
-            }
-        }
-
-        /* check suffix is authorized */
-        if (sfnSize <= srcSuffixLen || *matchedSuffixPtr == NULL) {
-            DISPLAYLEVEL(1,
-                "zstd: %s: unknown suffix (%s expected). "
-                "Can't derive the output file name. "
-                "Specify it with -o dstFileName. Ignoring.\n",
-                srcFileName, suffixListStr);
-            return NULL;
-        }
-
-        if ((*matchedSuffixPtr)[1] == 't') {
-            dstSuffix = ".tar";
-            dstSuffixLen = strlen(dstSuffix);
-        }
-    }
-
-    if (outDirName) {
-        outDirFilename = FIO_createFilename_fromOutDir(srcFileName, outDirName, 0);
-        sfnSize = strlen(outDirFilename);
-        assert(outDirFilename != NULL);
-    }
-
-    if (dfnbCapacity+srcSuffixLen <= sfnSize+1+dstSuffixLen) {
-        /* allocate enough space to write dstFilename into it */
-        free(dstFileNameBuffer);
-        dfnbCapacity = sfnSize + 20;
-        dstFileNameBuffer = (char*)malloc(dfnbCapacity);
-        if (dstFileNameBuffer==NULL)
-            EXM_THROW(74, "%s : not enough memory for dstFileName",
-                      strerror(errno));
-    }
-
-    /* return dst name == src name truncated from suffix */
-    assert(dstFileNameBuffer != NULL);
-    dstFileNameEndPos = sfnSize - srcSuffixLen;
-    if (outDirFilename) {
-        memcpy(dstFileNameBuffer, outDirFilename, dstFileNameEndPos);
-        free(outDirFilename);
-    } else {
-        memcpy(dstFileNameBuffer, srcFileName, dstFileNameEndPos);
-    }
-
-    /* The short tar extensions tzst, tgz, txz and tlz4 files should have "tar"
-     * extension on decompression. Also writes terminating null. */
-    strcpy(dstFileNameBuffer + dstFileNameEndPos, dstSuffix);
-    return dstFileNameBuffer;
-
-    /* note : dstFileNameBuffer memory is not going to be free */
+    return FIO_rust_determineDstName(srcFileName, outDirName, suffixList, suffixListStr);
 }
 
 int

rust/src/fileio_prefs.rs

@@ -23,6 +23,8 @@ static STDOUT_MARK: &[u8] = b"/*stdout*\\\0";
 
 static mut COMPRESSED_NAME_CAPACITY: usize = 0;
 static mut COMPRESSED_NAME_BUFFER: *mut c_char = ptr::null_mut();
+static mut DESTINATION_NAME_CAPACITY: usize = 0;
+static mut DESTINATION_NAME_BUFFER: *mut c_char = ptr::null_mut();
 
 #[repr(C)]
 pub struct FIO_inBuffer {
@@ -649,6 +651,131 @@ pub unsafe extern "C" fn FIO_rust_determineCompressedName(
     }
 }
 
+fn display_unknown_suffix(source: &[u8], suffix_list: &[u8]) {
+    let enabled = unsafe { (*display_prefs()).displayLevel >= 1 };
+    if !enabled {
+        return;
+    }
+
+    let mut stderr = io::stderr().lock();
+    let _ = stderr.write_all(b"zstd: ");
+    let _ = stderr.write_all(source);
+    let _ = stderr.write_all(b": unknown suffix (");
+    let _ = stderr.write_all(suffix_list);
+    let _ = stderr.write_all(
+        b" expected). Can't derive the output file name. Specify it with -o dstFileName. Ignoring.\n",
+    );
+}
+
+/// Build the decompressed destination name used by the multi-file CLI path.
+///
+/// The suffix table and its display string come from C because both are
+/// selected by the C build configuration.  As with the original helper, the
+/// returned pointer refers to a static buffer and is overwritten by the next
+/// successful call.
+#[no_mangle]
+pub unsafe extern "C" fn FIO_rust_determineDstName(
+    src_file_name: *const c_char,
+    out_dir_name: *const c_char,
+    suffix_list: *const *const c_char,
+    suffix_list_str: *const c_char,
+) -> *const c_char {
+    let source = unsafe { CStr::from_ptr(src_file_name).to_bytes() };
+    let suffix_display = unsafe { CStr::from_ptr(suffix_list_str).to_bytes() };
+
+    if source == b"/*stdin*\\" {
+        return STDOUT_MARK.as_ptr().cast();
+    }
+
+    let Some(src_suffix_start) = source.iter().rposition(|&byte| byte == b'.') else {
+        display_unknown_suffix(source, suffix_display);
+        return ptr::null();
+    };
+    let src_suffix = &source[src_suffix_start..];
+    let src_suffix_len = src_suffix.len();
+
+    let mut matched_suffix = ptr::null();
+    let mut suffix_ptr = suffix_list;
+    unsafe {
+        while !suffix_ptr.is_null() {
+            let candidate = *suffix_ptr;
+            if candidate.is_null() {
+                break;
+            }
+            if CStr::from_ptr(candidate).to_bytes() == src_suffix {
+                matched_suffix = candidate;
+                break;
+            }
+            suffix_ptr = suffix_ptr.add(1);
+        }
+    }
+
+    if source.len() <= src_suffix_len || matched_suffix.is_null() {
+        display_unknown_suffix(source, suffix_display);
+        return ptr::null();
+    }
+
+    let matched_suffix_bytes = unsafe { CStr::from_ptr(matched_suffix).to_bytes() };
+    let dst_suffix: &[u8] = if matched_suffix_bytes.get(1) == Some(&b't') {
+        b".tar\0"
+    } else {
+        b"\0"
+    };
+    let dst_suffix_len = dst_suffix.len() - 1;
+
+    let mut out_dir_filename = ptr::null_mut();
+    let source_for_destination = if out_dir_name.is_null() {
+        source
+    } else {
+        out_dir_filename =
+            unsafe { crate::util::UTIL_createFilenameFromOutDir(src_file_name, out_dir_name, 0) };
+        assert!(!out_dir_filename.is_null());
+        unsafe { CStr::from_ptr(out_dir_filename).to_bytes() }
+    };
+    let source_len = source_for_destination.len();
+
+    unsafe {
+        let capacity = ptr::addr_of_mut!(DESTINATION_NAME_CAPACITY);
+        let buffer = ptr::addr_of_mut!(DESTINATION_NAME_BUFFER);
+        if capacity.read().wrapping_add(src_suffix_len)
+            <= source_len.wrapping_add(1).wrapping_add(dst_suffix_len)
+        {
+            libc::free(buffer.read().cast::<c_void>());
+            let new_capacity = source_len.wrapping_add(20);
+            let new_buffer = libc::malloc(new_capacity).cast::<c_char>();
+            if new_buffer.is_null() {
+                throw(
+                    74,
+                    &format!(
+                        "{} : not enough memory for dstFileName",
+                        std::io::Error::last_os_error()
+                    ),
+                );
+            }
+            capacity.write(new_capacity);
+            buffer.write(new_buffer);
+        }
+
+        let destination = buffer.read();
+        assert!(!destination.is_null());
+        let destination_end = source_len - src_suffix_len;
+        ptr::copy_nonoverlapping(
+            source_for_destination.as_ptr(),
+            destination.cast::<u8>(),
+            destination_end,
+        );
+        ptr::copy_nonoverlapping(
+            dst_suffix.as_ptr(),
+            destination.add(destination_end).cast::<u8>(),
+            dst_suffix.len(),
+        );
+        if !out_dir_filename.is_null() {
+            libc::free(out_dir_filename.cast::<c_void>());
+        }
+        destination.cast()
+    }
+}
+
 #[inline]
 fn filename_path_separator() -> u8 {
     if cfg!(windows) {
@@ -877,6 +1004,79 @@ mod tests {
         }
     }
 
+    #[test]
+    fn destination_filename_shim_preserves_suffixes_tar_names_and_sentinels() {
+        let zst = CString::new(".zst").unwrap();
+        let tzst = CString::new(".tzst").unwrap();
+        let gz = CString::new(".gz").unwrap();
+        let tgz = CString::new(".tgz").unwrap();
+        let suffixes = [
+            zst.as_ptr(),
+            tzst.as_ptr(),
+            gz.as_ptr(),
+            tgz.as_ptr(),
+            ptr::null(),
+        ];
+        let suffixes_display = CString::new(".zst/.tzst/.gz/.tgz").unwrap();
+        let source = CString::new("input/nested/file.zst").unwrap();
+        let tar_source = CString::new("input/nested/archive.tzst").unwrap();
+        let tar_gzip_source = CString::new("archive.tgz").unwrap();
+        let output_dir = CString::new("out").unwrap();
+        let stdin = CString::new("/*stdin*\\").unwrap();
+
+        unsafe {
+            let name = FIO_rust_determineDstName(
+                source.as_ptr(),
+                ptr::null(),
+                suffixes.as_ptr(),
+                suffixes_display.as_ptr(),
+            );
+            assert_eq!(CStr::from_ptr(name).to_bytes(), b"input/nested/file");
+
+            let name = FIO_rust_determineDstName(
+                tar_source.as_ptr(),
+                output_dir.as_ptr(),
+                suffixes.as_ptr(),
+                suffixes_display.as_ptr(),
+            );
+            assert_eq!(CStr::from_ptr(name).to_bytes(), b"out/archive.tar");
+
+            let name = FIO_rust_determineDstName(
+                tar_gzip_source.as_ptr(),
+                ptr::null(),
+                suffixes.as_ptr(),
+                suffixes_display.as_ptr(),
+            );
+            assert_eq!(CStr::from_ptr(name).to_bytes(), b"archive.tar");
+
+            let name = FIO_rust_determineDstName(
+                stdin.as_ptr(),
+                output_dir.as_ptr(),
+                suffixes.as_ptr(),
+                suffixes_display.as_ptr(),
+            );
+            assert_eq!(CStr::from_ptr(name).to_bytes(), b"/*stdout*\\");
+        }
+    }
+
+    #[test]
+    fn destination_filename_shim_rejects_unknown_suffix() {
+        let zst = CString::new(".zst").unwrap();
+        let suffixes = [zst.as_ptr(), ptr::null()];
+        let suffixes_display = CString::new(".zst").unwrap();
+        let source = CString::new("input/file.zip").unwrap();
+
+        unsafe {
+            assert!(FIO_rust_determineDstName(
+                source.as_ptr(),
+                ptr::null(),
+                suffixes.as_ptr(),
+                suffixes_display.as_ptr(),
+            )
+            .is_null());
+        }
+    }
+
     #[test]
     fn c_layouts_match_the_headers() {
         let word = size_of::<usize>();