From 5ec0b86e5c1ff060720b5a6cd1af9d93ec993650 Mon Sep 17 00:00:00 2001
From: Martin Sehnoutka <msehnout@redhat.com>
Date: Thu, 29 Sep 2016 11:14:03 +0200
Subject: [PATCH 17/59] Fix an issue with timestamps during DST.

vsftpd now checks whether a file was uploaded during DST and
adjust the timestamp accordingly.
---
 sysutil.c | 104 ++++++++++++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 77 insertions(+), 27 deletions(-)

diff --git a/sysutil.c b/sysutil.c
index c848356..2abdd13 100644
--- a/sysutil.c
+++ b/sysutil.c
@@ -26,8 +26,10 @@
 /* For Linux, this adds nothing :-) */
 #include "port/porting_junk.h"
 
+#define F_LOCALTIME "/etc/localtime"
+#define BUFTZSIZ 64
+
 #include <signal.h>
-#include <string.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <sys/types.h>
@@ -56,6 +58,11 @@
 #include <netdb.h>
 #include <sys/resource.h>
 
+#ifndef __USE_GNU
+  #define __USE_GNU
+#endif
+#include <string.h>
+
 /* Private variables to this file */
 /* Current umask() */
 static unsigned int s_current_umask;
@@ -2574,49 +2581,92 @@ error:
   die("reopening standard file descriptors to /dev/null failed");
 }
 
+char* vsf_sysutil_get_tz()
+{
+  char *ret_tz = NULL;
+  char buff[BUFTZSIZ];
+  off_t s_pos, e_pos;
+  size_t rcnt, rest;
+  int fd;
+
+  if ((fd = open(F_LOCALTIME, O_RDONLY)) > -1)
+  {
+    if ((e_pos = lseek(fd, 0, SEEK_END)) <= 0)
+    {
+      close(fd);
+      return NULL;
+    }
+    s_pos = e_pos > BUFTZSIZ ? e_pos - BUFTZSIZ : 0;
+    lseek(fd, s_pos, SEEK_SET);
+    rcnt = read(fd, buff, BUFTZSIZ);
+
+    if (rcnt && buff[rcnt-1] == '\n')
+    {
+      buff[rcnt-1] = 0;
+      e_pos--;
+    }
+
+    do {
+       char *nl = memrchr(buff, '\n', rcnt);
+       if (rcnt && nl)
+       {
+         int offset = (++nl) - buff;
+         int len = e_pos - s_pos - offset;
+         if (len)
+         {
+           lseek(fd, s_pos + offset, SEEK_SET);
+           ret_tz = calloc(1, len+4);
+           memcpy(ret_tz, "TZ=", 3);
+           rcnt = read(fd, ret_tz+3, len);
+         }
+         break;
+       }
+       if (!s_pos)
+       {
+         break;
+       }
+       rest = s_pos > BUFTZSIZ ? s_pos - BUFTZSIZ : 0;
+       s_pos -= rest;
+       lseek(fd, s_pos, SEEK_SET);
+       rcnt = read(fd, buff, rest);
+    } while (rcnt > 0);
+
+    close (fd);
+  }
+
+  return ret_tz;
+}
+
 void
 vsf_sysutil_tzset(void)
 {
   int retval;
-  char tzbuf[sizeof("+HHMM!")];
+  char *tz=NULL, tzbuf[sizeof("+HHMM!")];
   time_t the_time = time(NULL);
   struct tm* p_tm;
+
+  /* Set our timezone in the TZ environment variable to cater for the fact
+   * that modern glibc does not cache /etc/localtime (which becomes inaccessible
+   * when we chroot().
+   */
+  tz = vsf_sysutil_get_tz();;
+  if (tz)
+  {
+    putenv(tz);
+  }
   tzset();
   p_tm = localtime(&the_time);
   if (p_tm == NULL)
   {
     die("localtime");
   }
-  /* Set our timezone in the TZ environment variable to cater for the fact
-   * that modern glibc does not cache /etc/localtime (which becomes inaccessible
-   * when we chroot().
-   */
   retval = strftime(tzbuf, sizeof(tzbuf), "%z", p_tm);
   tzbuf[sizeof(tzbuf) - 1] = '\0';
   if (retval == 5)
   {
-    /* Static because putenv() does not copy the string. */
-    static char envtz[sizeof("TZ=UTC-hh:mm")];
-    /* Insert a colon so we have e.g. -05:00 instead of -0500 */
-    tzbuf[5] = tzbuf[4];
-    tzbuf[4] = tzbuf[3];
-    tzbuf[3] = ':';
-    /* Invert the sign - we just got the offset _from_ UTC but for TZ, we need
-     * the offset _to_ UTC.
-     */
-    if (tzbuf[0] == '+')
-    {
-      tzbuf[0] = '-';
-    }
-    else
-    {
-      tzbuf[0] = '+';
-    }
-    snprintf(envtz, sizeof(envtz), "TZ=UTC%s", tzbuf);
-    putenv(envtz);
     s_timezone = ((tzbuf[1] - '0') * 10 + (tzbuf[2] - '0')) * 60 * 60;
-    s_timezone += ((tzbuf[4] - '0') * 10 + (tzbuf[5] - '0')) * 60;
-    if (tzbuf[0] == '-')
+    s_timezone += ((tzbuf[3] - '0') * 10 + (tzbuf[4] - '0')) * 60;
+    if (tzbuf[0] == '+')
     {
       s_timezone *= -1;
     }
-- 
2.14.4