win32: disable urandom/zero devices if dd is disabled

Support for /dev/urandom and /dev/zero relies on having a working
dd.  If the dd applet is disabled attempts to access them should
fail.

Theoretically a third-party dd utility could also work, but let's
not encourage that sort of heresy.

2 files changed, 12 insertions, 2 deletions

diff --git a/win32/mingw.c b/win32/mingw.c
index e58665c5b..254306222 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -404,8 +404,13 @@ static inline mode_t file_attr_to_st_mode(DWORD attr)
 static int get_file_attr(const char *fname, WIN32_FILE_ATTRIBUTE_DATA *fdata)
 {
         char *want_dir;
+        int dev = get_dev_type(fname);
 
-        if (get_dev_type(fname) != NOT_DEVICE || get_dev_fd(fname) >= 0) {
+#if !ENABLE_DD
+        // /dev/urandom and /dev/zero aren't supported without dd
+        if (dev != DEV_URANDOM && dev != DEV_ZERO)
+#endif
+        if (dev != NOT_DEVICE || get_dev_fd(fname) >= 0) {
                 /* Fake attributes for special devices */
                 FILETIME epoch = {0xd53e8000, 0x019db1de};      // Unix epoch as FILETIME
                 fdata->dwFileAttributes = FILE_ATTRIBUTE_DEVICE;
diff --git a/win32/popen.c b/win32/popen.c
index 4010608ce..daf481d42 100644
--- a/win32/popen.c
+++ b/win32/popen.c
@@ -142,13 +142,18 @@ FILE *mingw_popen(const char *cmd, const char *mode)
 }
 
 // Only called for /dev/urandom and /dev/zero
-int mingw_popen_special(const char *device)
+int mingw_popen_special(const char *device IF_NOT_DD(UNUSED_PARAM))
 {
+#if ENABLE_DD
         char cmd[32];
 
         /* Create the pipe */
         strcat(strcpy(cmd, "dd if="), device);
         return mingw_popen_internal(NULL, "dd", cmd, "r", -1, NULL);
+#else
+        errno = ENOSYS;
+        return -1;
+#endif
 }
 
 /*