Merge 'git-wrapper' into HEAD

Use msysGit's `git-wrapper` instead of the builtins. This works around
two issues:

- when the file system does not allow hard links, we would waste over
  800 megabyte by having 109 copies of a multi-megabyte executable

- even when the file system allows hard links, the Windows Explorer
  counts the disk usage as if it did not. Many users complained about
  Git for Windows using too much space (when it actually did not). We
  can easily avoid those user complaints by merging this branch.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Makefile

@@ -1655,11 +1655,17 @@ version.sp version.s version.o: EXTRA_CPPFLAGS = \
 	'-DGIT_VERSION="$(GIT_VERSION)"' \
 	'-DGIT_USER_AGENT=$(GIT_USER_AGENT_CQ_SQ)'
 
+ifeq (,$(BUILT_IN_WRAPPER))
 $(BUILT_INS): git$X
 	$(QUIET_BUILT_IN)$(RM) $@ && \
 	ln $< $@ 2>/dev/null || \
 	ln -s $< $@ 2>/dev/null || \
 	cp $< $@
+else
+$(BUILT_INS): $(BUILT_IN_WRAPPER)
+	$(QUIET_BUILT_IN)$(RM) $@ && \
+	cp $< $@
+endif
 
 common-cmds.h: ./generate-cmdlist.sh command-list.txt
 
@@ -2222,6 +2228,24 @@ profile-install: profile
 profile-fast-install: profile-fast
 	$(MAKE) install
 
+ifeq (,$(BUILT_IN_WRAPPER))
+LN_OR_CP_BUILT_IN_BINDIR = \
+	test -z "$(NO_INSTALL_HARDLINKS)" && \
+	ln "$$bindir/git$X" "$$bindir/$$p" 2>/dev/null || \
+	ln -s "git$X" "$$bindir/$$p" 2>/dev/null || \
+	cp "$$bindir/git$X" "$$bindir/$$p" || exit;
+LN_OR_CP_BUILT_IN_EXECDIR = \
+	test -z "$(NO_INSTALL_HARDLINKS)" && \
+	ln "$$exectir/git$X" "$$exectir/$$p" 2>/dev/null || \
+	ln -s "git$X" "$$exectir/$$p" 2>/dev/null || \
+	cp "$$exectir/git$X" "$$exectir/$$p" || exit;
+else
+LN_OR_CP_BUILT_IN_BINDIR = \
+	cp "$(BUILT_IN_WRAPPER)" "$$bindir/$$p" || exit;
+LN_OR_CP_BUILT_IN_EXECDIR = \
+	cp "$(BUILT_IN_WRAPPER)" "$$execdir/$$p" || exit;
+endif
+
 install: all
 	$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$(bindir_SQ)'
 	$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$(gitexec_instdir_SQ)'
@@ -2260,17 +2284,11 @@ endif
 	} && \
 	for p in $(filter $(install_bindir_programs),$(BUILT_INS)); do \
 		$(RM) "$$bindir/$$p" && \
-		test -z "$(NO_INSTALL_HARDLINKS)" && \
-		ln "$$bindir/git$X" "$$bindir/$$p" 2>/dev/null || \
-		ln -s "git$X" "$$bindir/$$p" 2>/dev/null || \
-		cp "$$bindir/git$X" "$$bindir/$$p" || exit; \
+		$(LN_OR_CP_BUILT_IN_BINDIR) \
 	done && \
 	for p in $(BUILT_INS); do \
 		$(RM) "$$execdir/$$p" && \
-		test -z "$(NO_INSTALL_HARDLINKS)" && \
-		ln "$$execdir/git$X" "$$execdir/$$p" 2>/dev/null || \
-		ln -s "git$X" "$$execdir/$$p" 2>/dev/null || \
-		cp "$$execdir/git$X" "$$execdir/$$p" || exit; \
+		$(LN_OR_CP_BUILT_IN_EXECDIR) \
 	done && \
 	remote_curl_aliases="$(REMOTE_CURL_ALIASES)" && \
 	for p in $$remote_curl_aliases; do \

compat/terminal.c

@@ -1,4 +1,6 @@
+#include <inttypes.h>
 #include "git-compat-util.h"
+#include "run-command.h"
 #include "compat/terminal.h"
 #include "sigchain.h"
 #include "strbuf.h"
@@ -91,6 +93,53 @@ static int disable_echo(void)
 	return 0;
 }
 
+static char *xterm_prompt(const char *prompt, int echo)
+{
+	const char *env = getenv("MSYS_TTY_HANDLES");
+	const char *echo_off[] = { "sh", "-c", "stty -echo </dev/tty", NULL };
+	const char *echo_on[] = { "sh", "-c", "stty echo </dev/tty", NULL };
+	static char buffer[1024];
+	DWORD len, dummy;
+	size_t tty0, tty1, tty2;
+	HANDLE in_handle, out_handle;
+
+	if (!env || 3 != sscanf(env,
+	    " %" SCNuPTR " %" SCNuPTR " %" SCNuPTR " ",
+	    &tty0, &tty1, &tty2)) {
+		warning("Cannot read from xterm");
+		return NULL;
+	}
+
+	in_handle = (HANDLE)tty0;
+	out_handle = (HANDLE)tty1;
+
+	if (!echo && run_command_v_opt(echo_off, 0))
+		warning("Could not disable echo on xterm");
+
+	if (!WriteFile(out_handle, prompt, strlen(prompt), &dummy, NULL)) {
+		warning("Could not write to xterm");
+		return NULL;
+	}
+
+	if (!ReadFile(in_handle, buffer, 1024, &len, NULL)) {
+		warning("Could not read from xterm");
+		return NULL;
+	}
+
+	if (len && buffer[len - 1] == '\n')
+		buffer[--len] = '\0';
+	if (len && buffer[len - 1] == '\r')
+		buffer[--len] = '\0';
+
+	if (!echo) {
+		if(run_command_v_opt(echo_on, 0))
+			warning("Could not re-enable echo on xterm");
+		WriteFile(out_handle, "\n", 1, &dummy, NULL);
+	}
+
+	return len == 0 ? NULL : buffer;
+}
+
 #endif
 
 #ifndef FORCE_TEXT
@@ -102,6 +151,12 @@ char *git_terminal_prompt(const char *prompt, int echo)
 	static struct strbuf buf = STRBUF_INIT;
 	int r;
 	FILE *input_fh, *output_fh;
+#ifdef GIT_WINDOWS_NATIVE
+	const char *term = getenv("TERM");
+
+	if (term && starts_with(term, "xterm"))
+		return xterm_prompt(prompt, echo);
+#endif
 
 	input_fh = fopen(INPUT_PATH, "r" FORCE_TEXT);
 	if (!input_fh)