Fix temporary file handling to avoid it being deleted too soon.

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

diff --git a/misc/build_helpers/windows/installer/installer/installer.cpp b/misc/build_helpers/windows/installer/installer/installer.cpp
index 2baa942da6245fbfb09b228e4ebdb8d2f8b98973..8cd9c10a8ea6fea30a0ed9f78d4cd7b3d8f49642 100644 (file)
--- a/misc/build_helpers/windows/installer/installer/installer.cpp
+++ b/misc/build_helpers/windows/installer/installer/installer.cpp
@@ -4,6 +4,7 @@
 #include "stdafx.h"
 #include <stdio.h>
 #include <stdlib.h>
+#include <io.h>
 
 // Turn off the warnings nagging you to use the more complicated *_s
 // "secure" functions that are actually more difficult to use securely.
@@ -151,7 +152,17 @@ void unzip_from_executable(wchar_t *executable_path, wchar_t *destination_dir) {
        fail_unless(len < MAX_PATH - wcslen(tmp_filename), "Temporary directory path is too long.");
        wcscpy(tmp_path + len, tmp_filename);
 
-       FILE *tmp_file = _wfopen(tmp_path, L"wbTD"); // TD => short-lived temporary file
+       // "TD" => short-lived temporary file. The D flag ensures that the file is guaranteed
+       // to be deleted even if we exit suddenly. In order to reliably flush writes but also
+       // ensure that the temporary file isn't deleted too soon, we duplicate the file handle
+       // while the file is being unzipped.
+       FILE *tmp_file = _wfopen(tmp_path, L"wbTD");
+       fail_unless(tmp_file != NULL && errno == 0 && ferror(f) == 0,
+                       "Could not open temporary zip file.");
+
+       int tmp_file_keepopen = _dup(_fileno(tmp_file));
+       fail_unless(errno == 0, "Could not duplicate file handle for temporary zip file.");
+
        unsigned char buf[16384];
        size_t remaining_length = (size_t) zip_length;
        while (remaining_length > 0) {
@@ -164,10 +175,12 @@ void unzip_from_executable(wchar_t *executable_path, wchar_t *destination_dir) {
                            "Could not write to temporary file.");
                remaining_length -= chunk_length;
        }
-       fclose(tmp_file);
-       fclose(f);
+       int res = fclose(tmp_file);
+       fail_unless(res == 0, "Could not close temporary zip file.");
+       fclose(f); // ignore errors
 
        unzip(tmp_path, destination_dir);
+       _close(tmp_file_keepopen); // ignore errors
 }
 
 // read unsigned little-endian 32-bit integer