From 446ba28d31650067c0094952aa686a0e51daabd5 Mon Sep 17 00:00:00 2001
From: Ting-Wei Lan <lantw@src.gnome.org>
Date: Mon, 24 Jun 2019 01:47:26 +0800
Subject: [PATCH] gutils: Don't limit the length of the host name to 99
It is unclear that why the size of the buffer was chosen to be 100
because the commit introduced the code didn't mention the reason.
POSIX defines _POSIX_HOST_NAME_MAX to be 255 and provides a way to
determine the suitable value with sysconf, so we should use it instead
of hard-coding a small value.
---
glib/gutils.c | 33 +++++++++++++++++++++++++++++++--
1 file changed, 31 insertions(+), 2 deletions(-)
diff --git a/glib/gutils.c b/glib/gutils.c
index 87db6a1f3..62a64d912 100644
--- a/glib/gutils.c
+++ b/glib/gutils.c
@@ -1003,8 +1003,37 @@ g_get_host_name (void)
gchar *utmp;
#ifndef G_OS_WIN32
- gchar *tmp = g_malloc (sizeof (gchar) * 100);
- failed = (gethostname (tmp, sizeof (gchar) * 100) == -1);
+ glong max;
+ gsize size;
+ /* The number 256 * 256 is taken from the value of _POSIX_HOST_NAME_MAX,
+ * which is 255. Since we use _POSIX_HOST_NAME_MAX + 1 (= 256) in the
+ * fallback case, we pick 256 * 256 as the size of the larger buffer here.
+ * It should be large enough. It doesn't looks reasonable to name a host
+ * with a string that is longer than 64 KiB.
+ */
+ const gsize size_large = (gsize) 256 * 256;
+ gchar *tmp;
+
+ max = sysconf (_SC_HOST_NAME_MAX);
+ if (max > 0 && max <= G_MAXSIZE - 1)
+ size = (gsize) max + 1;
+ else
+#ifdef HOST_NAME_MAX
+ size = HOST_NAME_MAX + 1;
+#else
+ size = _POSIX_HOST_NAME_MAX + 1;
+#endif
+
+ tmp = g_malloc (size);
+ failed = (gethostname (tmp, size) == -1);
+ if (failed && size < size_large)
+ {
+ /* Try again with a larger buffer if 'size' may be too small. */
+ g_free (tmp);
+ tmp = g_malloc (size_large);
+ failed = (gethostname (tmp, size_large) == -1);
+ }
+
if (failed)
g_clear_pointer (&tmp, g_free);
utmp = tmp;