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