Do not modify "our" environment, because it's Explorer's one

This is a fix, suggested by Lode Leroy, to not modify PATH in
"our" environment, because it's actually Explorer's environment.
See env_for_git().

Makefile

@@ -1,4 +1,4 @@
-OBJECTS=ext.o debug.o dll.o factory.o menu.o systeminfo.o registry.o
+OBJECTS=ext.o debug.o dll.o factory.o menu.o systeminfo.o registry.o exec.o
 CFLAGS=-O -g
 
 TARGET=git_shell_ext.dll
@@ -20,9 +20,10 @@ $(TARGET): $(OBJECTS) git_shell_ext.def
 dll.o: dll.h ext.h factory.h systeminfo.h registry.h
 ext.o: ext.h debug.h
 factory.o: factory.h ext.h menu.h
-menu.o: menu.h ext.h debug.h systeminfo.h
+menu.o: menu.h ext.h debug.h systeminfo.h exec.h
 systeminfo.o: systeminfo.h
 registry.o: registry.h
+exec.o: debug.h systeminfo.h exec.h
 
 install: all
 	regsvr32 -s -n -i:machine $(DLL_PATH)

exec.c

@@ -0,0 +1,76 @@
+#include <windows.h>
+#include <stdio.h>
+#include "debug.h"
+#include "systeminfo.h"
+#include "exec.h"
+
+char *env_for_git()
+{
+	static char *environment;
+
+	/*
+	 * if we can't find path to msys in the registry, return NULL and
+	 * the CreateProcess will copy the environment for us
+	 */
+	if (!environment && msys_path()) {
+		char *old = GetEnvironmentStrings();
+		size_t space = 0, path_index = -1, name_len = 0, len2;
+
+		while (old[space]) {
+			/* if it's PATH variable (could be Path= too!) */
+			if (!strnicmp(old + space, "PATH=", 5)) {
+				path_index = space;
+				name_len = 5;
+			}
+
+			while (old[space])
+				space++;
+			space++; /* skip var-terminating NULL */
+		}
+
+		if (path_index == -1)
+			path_index = space;
+
+		environment = malloc(space +
+				2 * strlen(msys_path()) + 32);
+
+		/* copy the block up to the equal sign of PATH var */
+		memcpy(environment, old, path_index);
+		/* insert new segments of the PATH */
+		len2 = sprintf(environment + path_index,
+			"PATH=%s\\bin;%s\\mingw\\bin%s",
+			msys_path(), msys_path(), name_len ? ";" : "");
+		/* append original value of PATH and variables after it */
+		memcpy(environment + path_index + len2,
+			old + path_index + name_len,
+			space + 1 - path_index - name_len);
+
+		FreeEnvironmentStrings(old);
+	}
+
+	return environment;
+}
+
+void exec_gui(char *command, const char *wd)
+{
+	STARTUPINFO si = { sizeof(si) };
+	PROCESS_INFORMATION pi;
+
+	si.dwFlags = STARTF_USESHOWWINDOW;
+	si.wShowWindow = SW_HIDE;
+
+	debug_git("Trying to spawn '%s' in working directory '%s'\n",
+		command, wd);
+	if (CreateProcess(NULL, command, NULL, NULL, FALSE, 0,
+			env_for_git(), wd, &si, &pi))
+	{
+		CloseHandle(pi.hProcess);
+		CloseHandle(pi.hThread);
+	}
+	else
+		debug_git("[ERROR] Could not create process (%d)"
+			"wd: %s; cmd: %s",
+			GetLastError(), wd, command);
+
+}
+

exec.h

@@ -0,0 +1,11 @@
+
+/*
+ * Modifies a copy of the environment to include Git in PATH
+ */
+char *env_for_git();
+
+/*
+ * Executes a console application hidden as in "git gui" to hide git
+ */
+void exec_gui(char *cmd, const char *wd);
+

menu.c

@@ -6,6 +6,7 @@
 #include "ext.h"
 #include "debug.h"
 #include "systeminfo.h"
+#include "exec.h"
 
 /*
  * These are the functions for handling the context menu.
@@ -82,24 +83,6 @@ static char *convert_directory_format(const char *path)
 	return converted;
 }
 
-static void adjust_path_for_git(const char *msys_path)
-{
-	static int initialized = 0;
-
-	if (!initialized) {
-		const char *old_path = getenv("PATH");
-		size_t old_len = strlen(old_path);
-		size_t msys_path_len = strlen(msys_path);
-		char *new_path = malloc(old_len + 2 * msys_path_len + 23);
-		if (!new_path)
-			return;
-		sprintf(new_path, "PATH=%s\\bin;%s\\mingw\\bin;%s",
-			old_path, msys_path, msys_path);
-		putenv(new_path);
-		initialized = 1;
-	}
-}
-
 static STDMETHODIMP invoke_command(void *p,
 				   LPCMINVOKECOMMANDINFO info)
 {
@@ -112,9 +95,6 @@ static STDMETHODIMP invoke_command(void *p,
 
 	if (command == 1)
 	{
-		STARTUPINFO si = { sizeof(si) };
-		PROCESS_INFORMATION pi;
-
 		TCHAR * msysPath = msys_path();
 
 		if (msysPath)
@@ -123,8 +103,7 @@ static STDMETHODIMP invoke_command(void *p,
 			const char *wd;
 			DWORD dwAttr, fa;
 
-			adjust_path_for_git(msysPath);
-			wsprintf(command, TEXT("wish.exe \"%s/bin/git-gui\""),
+			wsprintf(command, TEXT("\"%s\\bin\\git.exe\" gui"),
 				 msysPath);
 
 
@@ -137,30 +116,11 @@ static STDMETHODIMP invoke_command(void *p,
 			if (! (fa & dwAttr))
 				wd = info->lpDirectory;
 
-			debug_git("Trying to spawn '%s' in working directory '%s'\n", command, wd);
-			if (CreateProcess(
-				    NULL,
-				    command,
-				    NULL,
-				    NULL,
-				    FALSE,
-				    0, NULL, wd, &si, &pi))
-			{
-				CloseHandle(pi.hProcess);
-				CloseHandle(pi.hThread);
-			}
-			else
-			{
-				debug_git("[ERROR] %s/%s:%d Could not create git gui process (%d) Command: %s",
-					  __FILE__, __FUNCTION__, __LINE__,
-					  GetLastError(), command);
-			}
+			exec_gui(command, wd);
 		}
 		else
-		{
 			debug_git("[ERROR] %s/%s:%d Could not find msysPath",
 				  __FILE__, __FUNCTION__, __LINE__);
-		}
 
 		return S_OK;
 	}