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Re: [PATCH v2 2/2] mingw: fix mingw_open_append to work with named pipes

On 9/10/2018 6:00 PM, Junio C Hamano wrote:
Johannes Sixt <j6t@xxxxxxxx> writes:

   +#define IS_SBS(ch) (((ch) == '/') || ((ch) == '\\'))

I think you already have mingw_is_dir_sep() and its shorter alias
is_dir_sep() available to you.

good catch. thanks.

+ * Does the pathname map to the local named pipe filesystem?
+ * That is, does it have a "//./pipe/" prefix?
+ */
+static int mingw_is_local_named_pipe_path(const char *filename)

There is no need to prefix mingw_ to this function that is file
local static.  Isn't is_local_named_pipe() descriptive and unique

right. will do.

+	return (IS_SBS(filename[0]) &&
+		IS_SBS(filename[1]) &&
+		filename[2] == '.'  &&
+		IS_SBS(filename[3]) &&
+		!strncasecmp(filename+4, "pipe", 4) &&
+		IS_SBS(filename[8]) &&
+		filename[9]);
+#undef IS_SBS

It is kind-of surprising that there hasn't been any existing need
for a helper function that would allow us to write this function
like so:

	static int is_local_named_pipe(const char *path)
		return path_is_in_directory(path, "//./pipe/");

Not a suggestion to add such a thing; as long as we know there is no
other codepath that would benefit from having one, a generalization
like that can and should wait.

Yeah, I don't think we need something that general just yet.  Named
pipes exist in a special namespace using the UNC/network-share syntax
(rather than the DOS drive-letter syntax), and we don't do much with
UNC paths yet.

Perhaps, later we could have something to try splitting a UNC
path into <server>, <volume>, and <relative-path> and then have
is_local_named_pipe() verify the first 2 are as expected.
Or have a function like is_path_in_volume(path, server, volume)
that does the tests without cutting up strings and allocating.
We could do either, but I don't think we need to be that general