From ffc931dfb8829c8ae36b171d47f3230e10b67cea Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Sat, 9 Dec 2017 12:57:02 +0200
Subject: Add support for calculating SHA1 checksums

---
 libbutl/sha1.mxx | 107 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 107 insertions(+)
 create mode 100644 libbutl/sha1.mxx

(limited to 'libbutl/sha1.mxx')

diff --git a/libbutl/sha1.mxx b/libbutl/sha1.mxx
new file mode 100644
index 0000000..5259189
--- /dev/null
+++ b/libbutl/sha1.mxx
@@ -0,0 +1,107 @@
+// file      : libbutl/sha1.mxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef __cpp_modules
+#pragma once
+#endif
+
+// C includes.
+
+#ifndef __cpp_lib_modules
+#include <string>
+#include <cstddef>     // size_t
+#include <cstdint>
+#include <cstring>     // strlen()
+#endif
+
+// Other includes.
+
+#ifdef __cpp_modules
+export module butl.sha1;
+#ifdef __cpp_lib_modules
+import std.core;
+#endif
+#endif
+
+#include <libbutl/export.hxx>
+
+LIBBUTL_MODEXPORT namespace butl
+{
+  // SHA1 checksum calculator.
+  //
+  // For a single chunk of data a sum can be obtained in one line, for
+  // example:
+  //
+  // cerr << sha1 ("123").string () << endl;
+  //
+  class LIBBUTL_SYMEXPORT sha1
+  {
+  public:
+    sha1 ();
+
+    // Append binary data.
+    //
+    void
+    append (const void*, std::size_t);
+
+    sha1 (const void* b, std::size_t n): sha1 () {append (b, n);}
+
+    // Append string.
+    //
+    // Note that the hash includes the '\0' terminator. Failed that, a call
+    // with an empty string will be indistinguishable from no call at all.
+    //
+    void
+    append (const std::string& s) {append (s.c_str (), s.size () + 1);}
+
+    void
+    append (const char* s) {append (s, std::strlen (s) + 1);}
+
+    explicit
+    sha1 (const std::string& s): sha1 () {append (s);}
+
+    explicit
+    sha1 (const char* s): sha1 () {append (s);}
+
+    // Extract result.
+    //
+    // It can be obtained as either a 20-byte binary digest or as a 40-
+    // character hex-encoded C-string.
+    //
+    using digest_type = std::uint8_t[20];
+
+    const digest_type&
+    binary () const;
+
+    const char*
+    string () const;
+
+  private:
+    struct context // Note: identical to SHA1_CTX.
+    {
+      union {
+        std::uint8_t b8[20];
+        std::uint32_t b32[5];
+      } h;
+      union {
+        std::uint8_t b8[8];
+        std::uint64_t b64[1];
+      } c;
+      union {
+        std::uint8_t b8[64];
+        std::uint32_t b32[16];
+      } m;
+      std::uint8_t count;
+    };
+
+    union
+    {
+      mutable context ctx_;
+      mutable char buf_[sizeof (context)]; // Also used to store string rep.
+    };
+
+    mutable digest_type bin_;
+    mutable bool done_;
+  };
+}
-- 
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