3 files changed, 70 insertions, 0 deletions
diff --git a/src/tool_doswin.c b/src/tool_doswin.c
index c3a8826ff..012ede5ac 100644
--- a/src/tool_doswin.c
+++ b/src/tool_doswin.c
@@ -28,6 +28,7 @@
 #endif
 
 #ifdef WIN32
+#  include <tlhelp32.h>
 #  include "tool_cfgable.h"
 #  include "tool_libinfo.h"
 #endif
@@ -670,6 +671,58 @@ CURLcode FindWin32CACert(struct OperationConfig *config,
   return result;
 }
 
+
+/* Get a list of all loaded modules with full paths.
+ * Returns slist on success or NULL on error.
+ */
+struct curl_slist *GetLoadedModulePaths(void)
+{
+  HANDLE hnd = INVALID_HANDLE_VALUE;
+  MODULEENTRY32 mod = { sizeof(mod), };
+  struct curl_slist *slist = NULL;
+
+  do {
+    hnd = CreateToolhelp32Snapshot(TH32CS_SNAPMODULE, 0);
+  } while(hnd == INVALID_HANDLE_VALUE && GetLastError() == ERROR_BAD_LENGTH);
+
+  if(hnd == INVALID_HANDLE_VALUE)
+    goto error;
+
+  if(!Module32First(hnd, &mod))
+    goto error;
+
+  do {
+    char *path; /* points to stack allocated buffer */
+    struct curl_slist *temp;
+
+#ifdef UNICODE
+    /* sizeof(mod.szExePath) is the max total bytes of wchars. the max total
+       bytes of multibyte chars won't be more than twice that. */
+    char buffer[sizeof(mod.szExePath) * 2];
+    if(!WideCharToMultiByte(CP_ACP, 0, mod.szExePath, -1,
+                            buffer, sizeof(buffer), NULL, NULL))
+      goto error;
+    path = buffer;
+#else
+    path = mod.szExePath;
+#endif
+    temp = curl_slist_append(slist, path);
+    if(!temp)
+      goto error;
+    slist = temp;
+  } while(Module32Next(hnd, &mod));
+
+  goto cleanup;
+
+error:
+  curl_slist_free_all(slist);
+  slist = NULL;
+cleanup:
+  if(hnd != INVALID_HANDLE_VALUE)
+    CloseHandle(hnd);
+  return slist;
+}
+
 #endif /* WIN32 */
 
 #endif /* MSDOS || WIN32 */
diff --git a/src/tool_doswin.h b/src/tool_doswin.h
index 6398390f1..415fac27e 100644
--- a/src/tool_doswin.h
+++ b/src/tool_doswin.h
@@ -60,6 +60,7 @@ char **__crt0_glob_function(char *arg);
 CURLcode FindWin32CACert(struct OperationConfig *config,
                          curl_sslbackend backend,
                          const char *bundle_file);
+struct curl_slist *GetLoadedModulePaths(void);
 
 #endif /* WIN32 */
 
diff --git a/src/tool_main.c b/src/tool_main.c
index 6dc74d923..3089ee37f 100644
--- a/src/tool_main.c
+++ b/src/tool_main.c
@@ -38,6 +38,7 @@
 
 #include "tool_cfgable.h"
 #include "tool_convert.h"
+#include "tool_doswin.h"
 #include "tool_msgs.h"
 #include "tool_operate.h"
 #include "tool_panykey.h"
@@ -305,6 +306,21 @@ int main(int argc, char *argv[])
   /* Initialize the curl library - do not call any libcurl functions before
      this point */
   result = main_init(&global);
+
+#ifdef WIN32
+  /* Undocumented diagnostic option to list the full paths of all loaded
+     modules, regardless of whether or not initialization succeeded. */
+  if(argc == 2 && !strcmp(argv[1], "--dump-module-paths")) {
+    struct curl_slist *item, *head = GetLoadedModulePaths();
+    for(item = head; item; item = item->next) {
+      printf("%s\n", item->data);
+    }
+    curl_slist_free_all(head);
+    if(!result)
+      main_free(&global);
+  }
+  else
+#endif /* WIN32 */
   if(!result) {
     /* Start our curl operation */
     result = operate(&global, argc, argv);