[Bug libc/5184] strftime stats /etc/localtime too much

["jakub at redhat dot com" <sourceware-bugzilla@sourceware.org>]

------- Additional Comments From jakub at redhat dot com  2007-10-16 08:13 -------
I think the complaint in this case is that strftime, instead of doing tzset
just once, does it 5 times.
#include <time.h>

#define DBG(str) write (-1, str, sizeof (str) - 1)

int
main (void)
{
  char buf[40];
  time_t now;
  struct tm *tmp;

  now = time (0);
  tmp = localtime (&now);
  strftime (buf, sizeof (buf), "%F %T", tmp);
  DBG ("before time");
  now = time (0);
  DBG ("before localtime");
  tmp = localtime (&now);
  DBG ("before strftime");
  strftime (buf, sizeof (buf), "%F %T", tmp);
  DBG ("after strftime");
  return 0;
}

strace ./Y # against CVS glibc
...
write(4294967295, "before time", 11)    = -1 EBADF (Bad file descriptor)
write(4294967295, "before localtime", 16) = -1 EBADF (Bad file descriptor)
write(4294967295, "before strftime", 15) = -1 EBADF (Bad file descriptor)
stat("/etc/localtime", {st_mode=S_IFREG|0644, st_size=2246, ...}) = 0
stat("/etc/localtime", {st_mode=S_IFREG|0644, st_size=2246, ...}) = 0
stat("/etc/localtime", {st_mode=S_IFREG|0644, st_size=2246, ...}) = 0
stat("/etc/localtime", {st_mode=S_IFREG|0644, st_size=2246, ...}) = 0
stat("/etc/localtime", {st_mode=S_IFREG|0644, st_size=2246, ...}) = 0
write(4294967295, "after strftime", 14) = -1 EBADF (Bad file descriptor)

That is IMHO easily fixable with some rearrangments of strftime_l.c - changing
the my_strftime function to an an internal helper with an additional argument,
writing a tiny wrapper and not calling tzset () if it has been called already by
an outer strftime in case of recursion.

BTW, doesn't localtime have to stat /etc/localtime?
http://www.opengroup.org/onlinepubs/009695399/functions/localtime.html
Local timezone information is used as though localtime() calls tzset().

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=5184

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