BLI_string_ref: add copy_bytes_truncated method

Needed to copy non UTF8 bytes into a null terminated string.

Ref !144052

source/blender/blenlib/BLI_string_ref.hh

@@ -77,6 +77,17 @@ class StringRefBase {
   void copy_utf8_truncated(char *dst, int64_t dst_size) const;
   template<size_t N> void copy_utf8_truncated(char (&dst)[N]) const;
 
+  /**
+   * Copy the string into a char array. The copied string will be null-terminated. If it does not
+   * fit, it will be truncated.
+   *
+   * \note #copy_utf8_truncated should be used UTF8 strings,
+   * this should be used for strings which are allowed to contain arbitrary
+   * byte sequences without a known encoding such as file-paths.
+   */
+  void copy_bytes_truncated(char *dst, int64_t dst_size) const;
+  template<size_t N> void copy_bytes_truncated(char (&dst)[N]) const;
+
   /**
    * Copy the string into a buffer. The buffer has to be one byte larger than the size of the
    * string, because the copied string will be null-terminated. Only use this when you are
@@ -231,6 +242,11 @@ template<size_t N> inline void StringRefBase::copy_utf8_truncated(char (&dst)[N]
   this->copy_utf8_truncated(dst, N);
 }
 
+template<size_t N> inline void StringRefBase::copy_bytes_truncated(char (&dst)[N]) const
+{
+  this->copy_bytes_truncated(dst, N);
+}
+
 /**
  * Return true when the string starts with the given prefix.
  */

source/blender/blenlib/intern/string_ref.cc

@@ -44,4 +44,20 @@ void StringRefBase::copy_utf8_truncated(char *dst, const int64_t dst_size) const
   dst[new_len] = '\0';
 }
 
+void StringRefBase::copy_bytes_truncated(char *dst, const int64_t dst_size) const
+{
+  /* Destination must at least hold the null terminator. */
+  BLI_assert(dst_size >= 1);
+
+  /* Common case when the string can just be copied over entirely. */
+  if (size_ < dst_size) {
+    this->copy_unsafe(dst);
+    return;
+  }
+
+  const int64_t new_len = std::min(size_, dst_size - 1);
+  memcpy(dst, data_, new_len);
+  dst[new_len] = '\0';
+}
+
 }  // namespace blender

source/blender/blenlib/tests/BLI_string_ref_test.cc

@@ -464,6 +464,58 @@ TEST(string_ref, CopyUtf8Truncated)
   }
 }
 
+TEST(string_ref, CopyBytesTruncated)
+{
+  {
+    StringRef ref("hello");
+    char dst[10];
+    memset(dst, 0xFF, 10);
+    ref.copy_bytes_truncated(dst);
+    EXPECT_EQ(dst[5], '\0');
+    EXPECT_EQ(dst[6], 0xFF);
+    EXPECT_EQ(ref, dst);
+  }
+  {
+    StringRef ref("0123456789");
+    char dst[4];
+    memset(dst, 0xFF, 4);
+    ref.copy_bytes_truncated(dst);
+    EXPECT_EQ(dst[0], '0');
+    EXPECT_EQ(dst[1], '1');
+    EXPECT_EQ(dst[2], '2');
+    EXPECT_EQ(dst[3], '\0');
+  }
+  {
+    /* Simple 4 byte string. */
+    StringRef ref("01234");
+    {
+      char dst[1];
+      ref.copy_bytes_truncated(dst);
+      EXPECT_EQ(dst[0], '\0');
+    }
+    {
+      char dst[2];
+      ref.copy_bytes_truncated(dst);
+      EXPECT_EQ(dst[0], '0');
+    }
+    {
+      char dst[3];
+      ref.copy_bytes_truncated(dst);
+      EXPECT_EQ(StringRef(dst), "01");
+    }
+    {
+      char dst[4];
+      ref.copy_bytes_truncated(dst);
+      EXPECT_EQ(StringRef(dst), "012");
+    }
+    {
+      char dst[5];
+      ref.copy_bytes_truncated(dst);
+      EXPECT_EQ(StringRef(dst), "0123");
+    }
+  }
+}
+
 TEST(string_ref, FromStringView)
 {
   std::string_view view = "hello";