From d9ba6150909818beb05573f54f26232063492c5b Mon Sep 17 00:00:00 2001
From: Emmanuel Fleury <emmanuel.fleury@gmail.com>
Date: Mon, 1 Aug 2022 19:05:14 +0200
Subject: [PATCH] Handling collision between standard i/o file descriptors and
 newly created ones

Though unlikely to happen, it may happen that newly created file
descriptor take the value 0 (stdin), 1 (stdout) or 2 (stderr) if one
of the standard ones have been dismissed in between. So, it may
confuse the program if it is unaware of this change.

The point of this patch is to avoid a reasign of standard file
descriptors on newly created ones.

Closes issue #16
---
 glib/glib-unix.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/glib/glib-unix.c b/glib/glib-unix.c
index d2dea10ef..d67b8a357 100644
--- a/glib/glib-unix.c
+++ b/glib/glib-unix.c
@@ -108,6 +108,17 @@ g_unix_open_pipe (int     *fds,
     ecode = pipe2 (fds, pipe2_flags);
     if (ecode == -1 && errno != ENOSYS)
       return g_unix_set_error_from_errno (error, errno);
+    /* Don't reassign pipes to stdin, stdout, stderr if closed meanwhile */
+    else if (fds[0] < 3 || fds[1] < 3)
+      {
+        int old_fds[2] = { fds[0], fds[1] };
+        gboolean result = g_unix_open_pipe (fds, flags, error);
+        close (old_fds[0]);
+        close (old_fds[1]);
+
+        if (!result)
+          g_unix_set_error_from_errno (error, errno);
+      }
     else if (ecode == 0)
       return TRUE;
     /* Fall through on -ENOSYS, we must be running on an old kernel */
@@ -116,6 +127,19 @@ g_unix_open_pipe (int     *fds,
   ecode = pipe (fds);
   if (ecode == -1)
     return g_unix_set_error_from_errno (error, errno);
+  /* Don't reassign pipes to stdin, stdout, stderr if closed meanwhile */
+  else if (fds[0] < 3 || fds[1] < 3)
+    {
+      int old_fds[2] = { fds[0], fds[1] };
+      gboolean result = g_unix_open_pipe (fds, flags, error);
+      close (old_fds[0]);
+      close (old_fds[1]);
+
+      if (!result)
+        g_unix_set_error_from_errno (error, errno);
+
+      return result;
+    }
 
   if (flags == 0)
     return TRUE;