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Re: [Gumstix-users] gettimeofday()

From: Grahame Jordan <gbj@th...> - 2009-09-29 04:17

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Dave Hylands wrote:
<blockquote
 cite="mid:c32efac40909280718g223ba1e3o8af70feddecf71b6@..."
 type="cite">
  <pre wrap="">Hi Grahame,

  </pre>
  <blockquote type="cite">
    <pre wrap="">In OE using glibC the /etc/TZ variable has no effect upon the result of
gettimeofday(), it comes out as UTC.
If I set the TZ variable: export TZ="UTC-10" date gives me the correct
date but not gettimeofday() still in UTC
    </pre>
  </blockquote>
  <pre wrap=""><!---->
It's my understanding  that gettimeofday and time should return the
same value (for the seconds portion), and in both the cases, the time
should be UTC time.

localtime is the function that should respect the timezone setting and
do the conversion.

  </pre>
</blockquote>
Yes I am actually using localtime() in the part of my code that gives
me the string representation of the time.<br>
This behaves differently between the uClibC build and the glibC build.<br>
<br>
In glibC if I link /usr/share/zoneinfo/Australia/Melbourne
/etc/localtime it all works<br>
In uClibC all I need to do is put some entry in /etc/TZ such as
"UTC-10" and it works<br>
<br>
The reason I am wanting to use /etc/TZ method is that I can set the
time from the Host OS on the Gumstix by parsing seconds|milliseconds|
tzoffset<br>
The tzoffset I&nbsp; convert to -offsetHours and put that value into /etc/TZ
as UTC${offsetHours}&nbsp; eg. UTC-10 or any other combination of UTC+-XX<br>
<br>
With glibC this seems to make things more complicated.&nbsp; Maybe there is
a simple way with glibC?<br>
<br>
<br>
<br>
<br>
</body>
</html>

Thread View

Thread	Author	Date
[Gumstix-users] gettimeofday()	Grahame Jordan <gbj@th...>

Re: [Gumstix-users] gettimeofday()

From: Dave Hylands <dhylands@gm...> - 2009-09-28 14:18

Hi Grahame,

> In OE using glibC the /etc/TZ variable has no effect upon the result of
> gettimeofday(), it comes out as UTC.
> If I set the TZ variable: export TZ="UTC-10" date gives me the correct
> date but not gettimeofday() still in UTC

It's my understanding  that gettimeofday and time should return the
same value (for the seconds portion), and in both the cases, the time
should be UTC time.

localtime is the function that should respect the timezone setting and
do the conversion.

-- 
Dave Hylands
Shuswap, BC, Canada
http://www.DaveHylands.com/

Re: [Gumstix-users] gettimeofday()

From: Grahame Jordan <gbj@th...> - 2009-09-29 04:17

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
  <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
</head>
<body bgcolor="#ffffff" text="#000000">
Dave Hylands wrote:
<blockquote
 cite="mid:c32efac40909280718g223ba1e3o8af70feddecf71b6@..."
 type="cite">
  <pre wrap="">Hi Grahame,

  </pre>
  <blockquote type="cite">
    <pre wrap="">In OE using glibC the /etc/TZ variable has no effect upon the result of
gettimeofday(), it comes out as UTC.
If I set the TZ variable: export TZ="UTC-10" date gives me the correct
date but not gettimeofday() still in UTC
    </pre>
  </blockquote>
  <pre wrap=""><!---->
It's my understanding  that gettimeofday and time should return the
same value (for the seconds portion), and in both the cases, the time
should be UTC time.

localtime is the function that should respect the timezone setting and
do the conversion.

  </pre>
</blockquote>
Yes I am actually using localtime() in the part of my code that gives
me the string representation of the time.<br>
This behaves differently between the uClibC build and the glibC build.<br>
<br>
In glibC if I link /usr/share/zoneinfo/Australia/Melbourne
/etc/localtime it all works<br>
In uClibC all I need to do is put some entry in /etc/TZ such as
"UTC-10" and it works<br>
<br>
The reason I am wanting to use /etc/TZ method is that I can set the
time from the Host OS on the Gumstix by parsing seconds|milliseconds|
tzoffset<br>
The tzoffset I&nbsp; convert to -offsetHours and put that value into /etc/TZ
as UTC${offsetHours}&nbsp; eg. UTC-10 or any other combination of UTC+-XX<br>
<br>
With glibC this seems to make things more complicated.&nbsp; Maybe there is
a simple way with glibC?<br>
<br>
<br>
<br>
<br>
</body>
</html>

Re: [Gumstix-users] gettimeofday()

From: Dave Hylands <dhylands@gm...> - 2009-09-29 05:49

Hi Grahame,

> Yes I am actually using localtime() in the part of my code that gives me the
> string representation of the time.
> This behaves differently between the uClibC build and the glibC build.
>
> In glibC if I link /usr/share/zoneinfo/Australia/Melbourne /etc/localtime it
> all works
> In uClibC all I need to do is put some entry in /etc/TZ such as "UTC-10" and
> it works
>
> The reason I am wanting to use /etc/TZ method is that I can set the time
> from the Host OS on the Gumstix by parsing seconds|milliseconds| tzoffset
> The tzoffset I  convert to -offsetHours and put that value into /etc/TZ as
> UTC${offsetHours}  eg. UTC-10 or any other combination of UTC+-XX
>
> With glibC this seems to make things more complicated.  Maybe there is a
> simple way with glibC?

You should be able to set the TZ environment variable. I tested this
under ubuntu and it works fine.

export TZ=UTC-10

You can also use setenv from with a C program (affects the C program
and any child processes).

-- 
Dave Hylands
Shuswap, BC, Canada
http://www.DaveHylands.com/

Re: [Gumstix-users] gettimeofday()

From: Grahame Jordan <gbj@th...> - 2009-09-30 03:33

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
  <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
</head>
<body bgcolor="#ffffff" text="#000000">
Dave Hylands wrote:
<blockquote
 cite="mid:c32efac40909282249h785ff386ka0992e60324268a@..."
 type="cite">
  <pre wrap="">Hi Grahame,

  </pre>
  <blockquote type="cite">
    <pre wrap="">Yes I am actually using localtime() in the part of my code that gives me the
string representation of the time.
This behaves differently between the uClibC build and the glibC build.

In glibC if I link /usr/share/zoneinfo/Australia/Melbourne /etc/localtime it
all works
In uClibC all I need to do is put some entry in /etc/TZ such as "UTC-10" and
it works

The reason I am wanting to use /etc/TZ method is that I can set the time
from the Host OS on the Gumstix by parsing seconds|milliseconds| tzoffset
The tzoffset I&nbsp; convert to -offsetHours and put that value into /etc/TZ as
UTC${offsetHours}&nbsp; eg. UTC-10 or any other combination of UTC+-XX

With glibC this seems to make things more complicated.&nbsp; Maybe there is a
simple way with glibC?
    </pre>
  </blockquote>
  <pre wrap=""><!---->
You should be able to set the TZ environment variable. I tested this
under ubuntu and it works fine.

export TZ=UTC-10

You can also use setenv from with a C program (affects the C program
and any child processes).

  </pre>
</blockquote>
Yes setenv() does the trick.<br>
<br>
Many Thanks<br>
<br>
Grahame Jordan<br>
</body>
</html>