Set the extcap working directory on Windows.

On Windows, prepend the main program directory to %Path% when spawning
extcap processes. This lets us place androiddump in extcap while allowing
it to locate its DLLs.

Change-Id: I406c47ce71323266d5f14fb596931398464e452d
Reviewed-on: https://code.wireshark.org/review/8057
Reviewed-by: Pascal Quantin <pascal.quantin@gmail.com>
Petri-Dish: Pascal Quantin <pascal.quantin@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Gerald Combs <gerald@wireshark.org>

1 files changed, 23 insertions, 1 deletions

diff --git a/extcap.c b/extcap.c
index 6d9a5e5aed..6353e2153b 100644
--- a/extcap.c
+++ b/extcap.c
@@ -139,11 +139,28 @@ static void extcap_foreach(gint argc, gchar **args, extcap_cb_t cb,
     const gchar *file;
     gboolean keep_going;
     gchar **argv;
+#ifdef WIN32
+    gchar **dll_search_envp;
+    gchar *progfile_dir;
+#endif
 
     keep_going = TRUE;
 
     argv = (gchar **) g_malloc0(sizeof(gchar *) * (argc + 2));
 
+#ifdef WIN32
+    /*
+     * Make sure executables can find dependent DLLs and that they're *our*
+     * DLLs: https://msdn.microsoft.com/en-us/library/windows/desktop/ms682586.aspx
+     * Alternatively we could create a simple wrapper exe similar to Create
+     * Hidden Process (http://www.commandline.co.uk/chp/).
+     */
+    dll_search_envp = g_get_environ();
+    progfile_dir = g_strdup_printf("%s;%s", get_progfile_dir(), g_environ_getenv(dll_search_envp, "Path"));
+    dll_search_envp = g_environ_setenv(dll_search_envp, "Path", progfile_dir, TRUE);
+    g_free(progfile_dir);
+#endif
+
     if ((dir = g_dir_open(dirname, 0, NULL)) != NULL) {
 #ifdef WIN32
         dirname = g_strescape(dirname,NULL);
@@ -156,12 +173,14 @@ static void extcap_foreach(gint argc, gchar **args, extcap_cb_t cb,
             gint i;
             gint exit_status = 0;
             GError *error = NULL;
+            gchar **envp = NULL;
 
             /* full path to extcap binary */
             extcap_string = g_string_new("");
 #ifdef WIN32
             g_string_printf(extcap_string, "%s\\\\%s",dirname,file);
             extcap = g_string_free(extcap_string, FALSE);
+            envp = dll_search_envp;
 #else
             g_string_printf(extcap_string, "%s/%s", dirname, file);
             extcap = g_string_free(extcap_string, FALSE);
@@ -174,7 +193,7 @@ static void extcap_foreach(gint argc, gchar **args, extcap_cb_t cb,
                 argv[i+1] = args[i];
             argv[argc+1] = NULL;
 
-            status = g_spawn_sync(dirname, argv, NULL,
+            status = g_spawn_sync(dirname, argv, envp,
                 (GSpawnFlags) 0, NULL, NULL,
                     &command_output, NULL, &exit_status, &error);
 
@@ -188,6 +207,9 @@ static void extcap_foreach(gint argc, gchar **args, extcap_cb_t cb,
         g_dir_close(dir);
     }
 
+#ifdef WIN32
+    g_strfreev(dll_search_envp);
+#endif
     g_free(argv);
 }