dropshell release 2025.0513.2134

build_arm64/_deps/zstd-src/doc/educational_decoder/.gitignore

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+# Build artifacts
+harness

build_arm64/_deps/zstd-src/doc/educational_decoder/README.md

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+Educational Decoder
+===================
+
+`zstd_decompress.c` is a self-contained implementation in C99 of a decoder,
+according to the [Zstandard format specification].
+While it does not implement as many features as the reference decoder,
+such as the streaming API or content checksums, it is written to be easy to
+follow and understand, to help understand how the Zstandard format works.
+It's laid out to match the [format specification],
+so it can be used to understand how complex segments could be implemented.
+It also contains implementations of Huffman and FSE table decoding.
+
+[Zstandard format specification]: https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md
+[format specification]: https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md
+
+While the library's primary objective is code clarity,
+it also happens to compile into a small object file.
+The object file can be made even smaller by removing error messages,
+using the macro directive `ZDEC_NO_MESSAGE` at compilation time.
+This can be reduced even further by foregoing dictionary support,
+by defining `ZDEC_NO_DICTIONARY`.
+
+`harness.c` provides a simple test harness around the decoder:
+
+    harness <input-file> <output-file> [dictionary]
+
+As an additional resource to be used with this decoder,
+see the `decodecorpus` tool in the [tests] directory.
+It generates valid Zstandard frames that can be used to verify
+a Zstandard decoder implementation.
+Note that to use the tool to verify this decoder implementation,
+the --content-size flag should be set,
+as this decoder does not handle streaming decoding,
+and so it must know the decompressed size in advance.
+
+[tests]: https://github.com/facebook/zstd/blob/dev/tests/

build_arm64/_deps/zstd-src/doc/educational_decoder/harness.c

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+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "zstd_decompress.h"
+
+typedef unsigned char u8;
+
+// If the data doesn't have decompressed size with it, fallback on assuming the
+// compression ratio is at most 16
+#define MAX_COMPRESSION_RATIO (16)
+
+// Protect against allocating too much memory for output
+#define MAX_OUTPUT_SIZE ((size_t)1024 * 1024 * 1024)
+
+// Error message then exit
+#define ERR_OUT(...) { fprintf(stderr, __VA_ARGS__); exit(1); }
+
+
+typedef struct {
+    u8* address;
+    size_t size;
+} buffer_s;
+
+static void freeBuffer(buffer_s b) { free(b.address); }
+
+static buffer_s read_file(const char *path)
+{
+    FILE* const f = fopen(path, "rb");
+    if (!f) ERR_OUT("failed to open file %s \n", path);
+
+    fseek(f, 0L, SEEK_END);
+    size_t const size = (size_t)ftell(f);
+    rewind(f);
+
+    void* const ptr = malloc(size);
+    if (!ptr) ERR_OUT("failed to allocate memory to hold %s \n", path);
+
+    size_t const read = fread(ptr, 1, size, f);
+    if (read != size) ERR_OUT("error while reading file %s \n", path);
+
+    fclose(f);
+    buffer_s const b = { ptr, size };
+    return b;
+}
+
+static void write_file(const char* path, const u8* ptr, size_t size)
+{
+    FILE* const f = fopen(path, "wb");
+    if (!f) ERR_OUT("failed to open file %s \n", path);
+
+    size_t written = 0;
+    while (written < size) {
+        written += fwrite(ptr+written, 1, size, f);
+        if (ferror(f)) ERR_OUT("error while writing file %s\n", path);
+    }
+
+    fclose(f);
+}
+
+int main(int argc, char **argv)
+{
+    if (argc < 3)
+        ERR_OUT("usage: %s <file.zst> <out_path> [dictionary] \n", argv[0]);
+
+    buffer_s const input = read_file(argv[1]);
+
+    buffer_s dict = { NULL, 0 };
+    if (argc >= 4) {
+        dict = read_file(argv[3]);
+    }
+
+    size_t out_capacity = ZSTD_get_decompressed_size(input.address, input.size);
+    if (out_capacity == (size_t)-1) {
+        out_capacity = MAX_COMPRESSION_RATIO * input.size;
+        fprintf(stderr, "WARNING: Compressed data does not contain "
+                        "decompressed size, going to assume the compression "
+                        "ratio is at most %d (decompressed size of at most "
+                        "%u) \n",
+                MAX_COMPRESSION_RATIO, (unsigned)out_capacity);
+    }
+    if (out_capacity > MAX_OUTPUT_SIZE)
+        ERR_OUT("Required output size too large for this implementation \n");
+
+    u8* const output = malloc(out_capacity);
+    if (!output) ERR_OUT("failed to allocate memory \n");
+
+    dictionary_t* const parsed_dict = create_dictionary();
+    if (dict.size) {
+#if defined (ZDEC_NO_DICTIONARY)
+        printf("dict.size = %zu \n", dict.size);
+        ERR_OUT("no dictionary support \n");
+#else
+        parse_dictionary(parsed_dict, dict.address, dict.size);
+#endif
+    }
+    size_t const decompressed_size =
+        ZSTD_decompress_with_dict(output, out_capacity,
+                                  input.address, input.size,
+                                  parsed_dict);
+
+    free_dictionary(parsed_dict);
+
+    write_file(argv[2], output, decompressed_size);
+
+    freeBuffer(input);
+    freeBuffer(dict);
+    free(output);
+    return 0;
+}

build_arm64/_deps/zstd-src/doc/educational_decoder/zstd_decompress.h

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+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+#include <stddef.h>   /* size_t */
+
+/******* EXPOSED TYPES ********************************************************/
+/*
+* Contains the parsed contents of a dictionary
+* This includes Huffman and FSE tables used for decoding and data on offsets
+*/
+typedef struct dictionary_s dictionary_t;
+/******* END EXPOSED TYPES ****************************************************/
+
+/******* DECOMPRESSION FUNCTIONS **********************************************/
+/// Zstandard decompression functions.
+/// `dst` must point to a space at least as large as the reconstructed output.
+size_t ZSTD_decompress(void *const dst, const size_t dst_len,
+                    const void *const src, const size_t src_len);
+
+/// If `dict != NULL` and `dict_len >= 8`, does the same thing as
+/// `ZSTD_decompress` but uses the provided dict
+size_t ZSTD_decompress_with_dict(void *const dst, const size_t dst_len,
+                              const void *const src, const size_t src_len,
+                              dictionary_t* parsed_dict);
+
+/// Get the decompressed size of an input stream so memory can be allocated in
+/// advance
+/// Returns -1 if the size can't be determined
+/// Assumes decompression of a single frame
+size_t ZSTD_get_decompressed_size(const void *const src, const size_t src_len);
+/******* END DECOMPRESSION FUNCTIONS ******************************************/
+
+/******* DICTIONARY MANAGEMENT ***********************************************/
+/*
+ * Return a valid dictionary_t pointer for use with dictionary initialization
+ * or decompression
+ */
+dictionary_t* create_dictionary(void);
+
+/*
+ * Parse a provided dictionary blob for use in decompression
+ * `src` -- must point to memory space representing the dictionary
+ * `src_len` -- must provide the dictionary size
+ * `dict` -- will contain the parsed contents of the dictionary and
+ *        can be used for decompression
+ */
+void parse_dictionary(dictionary_t *const dict, const void *src,
+                             size_t src_len);
+
+/*
+ * Free internal Huffman tables, FSE tables, and dictionary content
+ */
+void free_dictionary(dictionary_t *const dict);
+/******* END DICTIONARY MANAGEMENT *******************************************/