From 896b3694ca062d747cd67e9e9ba246adb3fc706b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Lyson=C4=9Bk?= <olysonek@redhat.com>
Date: Mon, 5 Aug 2019 13:55:37 +0200
Subject: [PATCH 2/3] Repeat pututxline() if it fails with EINTR

This is a partial fix for rhbz#1688848. We cannot resolve it
completely until glibc bug rhbz#1734791 is fixed. See
https://bugzilla.redhat.com/show_bug.cgi?id=1688848#c13.

The maximum number of attempts is currently 2, which might seem
low. However setting it to 2 was a decision based on data - see
https://bugzilla.redhat.com/show_bug.cgi?id=1688848#c16.

Resolves: rhbz#1688848
---
 sysdeputil.c | 53 +++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 46 insertions(+), 7 deletions(-)

diff --git a/sysdeputil.c b/sysdeputil.c
index bd1e8c9..4fbcca7 100644
--- a/sysdeputil.c
+++ b/sysdeputil.c
@@ -1203,6 +1203,8 @@ void
 vsf_insert_uwtmp(const struct mystr* p_user_str,
                  const struct mystr* p_host_str)
 {
+  int attempts;
+
   if (sizeof(s_utent.ut_line) < 16)
   {
     return;
@@ -1231,16 +1233,35 @@ vsf_insert_uwtmp(const struct mystr* p_user_str,
   vsf_sysutil_strcpy(s_utent.ut_host, str_getbuf(p_host_str),
                      sizeof(s_utent.ut_host));
   s_utent.ut_tv.tv_sec = vsf_sysutil_get_time_sec();
-  setutxent();
-  (void) pututxline(&s_utent);
-  endutxent();
-  s_uwtmp_inserted = 1;
+  for (attempts = 2; attempts > 0; --attempts)
+  {
+    struct utmpx* p_res;
+    setutxent();
+    p_res = pututxline(&s_utent);
+    /* For now we'll ignore errors other than EINTR and EAGAIN */
+    if (p_res != NULL || (errno != EINTR && errno != EAGAIN))
+    {
+      break;
+    }
+  }
+  if (attempts == 0)
+  {
+    /* This makes us skip pututxline() in vsf_remove_uwtmp() */
+    s_uwtmp_inserted = -1;
+  }
+  else
+  {
+    s_uwtmp_inserted = 1;
+    endutxent();
+  }
   updwtmpx(WTMPX_FILE, &s_utent);
 }
 
 void
 vsf_remove_uwtmp(void)
 {
+  int attempts;
+
   if (!s_uwtmp_inserted)
   {
     return;
@@ -1249,9 +1270,27 @@ vsf_remove_uwtmp(void)
   vsf_sysutil_memclr(s_utent.ut_user, sizeof(s_utent.ut_user));
   vsf_sysutil_memclr(s_utent.ut_host, sizeof(s_utent.ut_host));
   s_utent.ut_tv.tv_sec = 0;
-  setutxent();
-  (void) pututxline(&s_utent);
-  endutxent();
+  if (s_uwtmp_inserted == 1)
+  {
+    for (attempts = 2; attempts > 0; --attempts)
+    {
+      struct utmpx* p_res;
+      setutxent();
+      p_res = pututxline(&s_utent);
+      /* For now we'll ignore errors other than EINTR and EAGAIN */
+      if (p_res != NULL || (errno != EINTR && errno != EAGAIN))
+      {
+        break;
+      }
+    }
+    if (attempts != 0)
+    {
+      endutxent();
+    }
+  }
+  /* Set s_uwtmp_inserted to 0 regardless of the result of
+   * pututxline() to make sure we won't run this function twice.
+   */
   s_uwtmp_inserted = 0;
   s_utent.ut_tv.tv_sec = vsf_sysutil_get_time_sec();
   updwtmpx(WTMPX_FILE, &s_utent);
-- 
2.20.1