Update upstream source from tag 'upstream/4.7'

Update to upstream version '4.7'
with Debian dir d3e11463c915e5c39507206197eb3acd42bb8f5f

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+=================
+Memory containers
+=================
+
+The HXmc series of functions provide scripting-like semantics for strings,
+especially automatically resizing the buffer on demand. They can also be used
+to store a binary block of data together with its length. (Hence the name: mc =
+memory container.)
+
+The benefit of using the HXmc functions is that one does not have to
+meticulously watch buffer and string sizes anymore.
+
+Improvement of string safety over time:
+
+.. code-block:: c
+
+	/* Step 1 */
+
+	char buf[long_enough] = "helloworld";
+	if (strlen(buf) + strlen(".txt") < sizeof(buf))
+		strcat(s, ".txt"); /* may go over end of buffer */
+
+	/* Step 2 */
+
+	char buf[long_enough] = "helloworld";
+	strlcat(s, ".txt", sizeof(buf)); /* may truncate */
+
+	/* Step 3 */
+
+	hxmc_t *buf = HXmc_strinit("helloworld");
+	HXmc_strcat(&s, ".txt");
+
+This makes it quite similar to the string operations (and append seems to be
+the most commonly used one to me) supported in scripting languages that also do
+without a size argument. The essential part of such memory containers is that
+their internal (hidden) metadata structure contains the length of the memory
+block in the container. For binary data this may be the norm, but for C-style
+strings, the stored and auto-updated length field serves as an accelerator
+cache. For more details, see ``HXmc_length``.
+
+Of course, the automatic management of memory comes with a bit of overhead as
+the string expands beyond its preallocated region. Such may be mitigated by
+doing explicit (re)sizing.
+
+
+Structural overview
+===================
+
+HXmc functions do not actually return a pointer to the memory container (e.g.
+struct) itself, but a pointer to the data block. Conversely, input parameters
+to HXmc functions will be the data block pointer. It is of type ``hxmc_t *``,
+which is typedef'ed to ``char *`` and therefore has properties of a char
+pointer. Pointer arithmetic is thus supported. It also means you can just pass
+it to functions that take a ``char *`` without having to do a member access
+like ``s.c_str()`` in C++. The drawback is that many functions operating on the
+memory container need a ``hxmc_t **`` (a level-two indirection), because not
+only does the memory block move, but also the memory container itself. This is
+due to the implementation of the container metadata which immediately and
+always precedes the writable memory block.
+
+HXmc ensures that the data block is terminated by the \0 byte (unless you trash
+it), so you do not have to, and of course, to be on the safe side. But, the
+automatic \0 byte is not part of the region allocated by the user. That is,
+when one uses the classic approach with ``malloc(4096)``, the user will have
+control of 4096 bytes and has to stuff the \0 byte in there somehow on his own;
+for strings this means the maximum string length is 4095. Requesting space for
+a 4096-byte sized HXmc container gives you the possibility to use all 4096
+bytes for the string, because HXmc provides a \0 byte.
+
+By the way, ``hxmc_t`` is the only typedef in this entire library, to
+distinguish it from regular ``char *`` that does not have a backing memory
+cointainer.
+
+Constructors, destructors
+=========================
+
+.. code-block:: c
+
+	#include <libHX/string.h>
+
+	hxmc_t *HXmc_strinit(const char *s);
+	hxmc_t *HXmc_meminit(const void *ptr, size_t size);
+	void HXmc_free(hxmc_t *s);
+	void HXmc_zvecfree(hxmc_t **s);
+
+``HXmc_strinit``
+	Creates a new ``hxmc_t`` object from the supplied string and returns
+	it.
+
+``HXmc_meminit``
+	Creates a new ``hxmc_t`` object from the supplied memory buffer of the
+	given size and returns it. ``HXmc_meminit(NULL, len)`` may be used to
+	obtain an empty container with a preallocated region of len bytes (zero
+	is accepted for ``len``).
+
+``HXmc_free``
+	Frees the hxmc object.
+
+``HXmc_zvecfree``
+	Frees all hxmc objects in the ``NULL``-terminated array, and finally
+	frees the array itself, similar to ``HX_zvecfree``.
+
+Data manipulation
+=================
+
+Binary-based
+------------
+
+.. code-block:: c
+
+	hxmc_t *HXmc_trunc(hxmc_t **mc, size_t len);HXmc_trunc
+	hxmc_t *HXmc_setlen(hxmc_t **mc, size_t len);HXmc_setlen
+	hxmc_t *HXmc_memcpy(hxmc_t **mc, const void *ptr, size_t len);
+	hxmc_t *HXmc_memcat(hxmc_t **mc, const void *ptr, size_t len);
+	hxmc_t *HXmc_mempcat(hxmc_t **mc, const void *ptr, size_t len);
+	hxmc_t *HXmc_memins(hxmc_t **mc, size_t pos, const void *ptr, size_t len);
+	hxmc_t *HXmc_memdel(hxmc_t **mc, size_t pos, size_t len);
+
+When ``ptr`` is ``NULL``, each call behaves as if ``len`` would be ``zero``.
+Specifically, no undefined behavior will result of the use of ``NULL``.
+
+``HXmc_trunc``
+	Truncates the container's data to ``len`` size. If ``len`` is greater
+	than the current data size of the container, the length is in fact not
+	updated, but a reallocation may be triggered, which can be used to do
+	explicit allocation.
+
+``HXmc_setlen``
+	Sets the data length, doing a reallocation of the memory container if
+	needed. The newly available bytes are uninitialized. Make use of this
+	function when letting 3rd party functions write to the buffer, but it
+	should not be used with ``HXmc_str*``.
+
+``HXmc_memcpy``
+	Truncates the container's data and copies ``len`` bytes from the memory
+	area pointed to by ``ptr`` to the container.
+
+``HXmc_memcat``
+	Concatenates (appends) ``len`` bytes from the memory area pointed to by
+	``ptr`` to the container's data.
+
+``HXmc_mempcat``
+	Prepends ``len`` bytes from the memory area pointed to by ``ptr`` to
+	the container's data.
+
+``HXmc_memins``
+	Prepends ``len`` bytes from the memory area pointed to by ``ptr`` to
+	the ``pos``'th byte of the container's data.
+
+``HXmc_memdel``
+	Deletes ``len`` bytes from the container beginning at position ``pos``.
+
+In case of a memory allocation failure, the ``HXmc_*`` functions will return
+``NULL``.
+
+String-based
+------------
+
+The string-based functions correspond to their binary-based equivalents with a
+len argument of strlen(s).
+
+.. code-block:: c
+
+	hxmc_t *HXmc_strcpy(hxmc_t **mc, const char *s);
+	hxmc_t *HXmc_strcat(hxmc_t **mc, const char *s);
+	hxmc_t *HXmc_strpcat(hxmc_t **mc, const char *s);
+	hxmc_t *HXmc_strins(hxmc_t **mc, size_t pos, const char *s);
+
+``HXmc_strcpy``
+	Copies the string pointed to by ``s`` into the memory container given
+	by ``mc``. If ``mc`` is ``NULL``, the memory container will be
+	deallocated, that is, ``*mc`` becomes ``NULL``.
+
+From auxiliary sources
+----------------------
+
+.. code-block:: c
+
+	hxmc_t *HX_getl(hxmc_t **mc, FILE *fp);HX_getl
+
+``HX_getl``
+	Reads the next line from ``fp`` and store the result in the container.
+	Returns ``NULL`` on error, or when end of file occurs while no
+	characters have been read.
+
+Container properties
+--------------------
+
+.. code-block:: c
+
+	size_t HXmc_length(const hxmc_t **mc);
+
+``HXmc_length``
+	Returns the length of the memory container. This is not always equal to
+	the actual string length. For example, if ``HX_chomp`` was used on an
+	MC-backed string, ``strlen`` will return less than ``HXmc_length`` if
+	newline control characters (``\r`` and ``\n``) were removed.