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Date: Fri, 31 Jul 2015 12:50:40 -0700
Message-ID: <CAOC2fq-MjJb3HuKHs5cuDMRAMxabXGQKW6heUsmyVbnnWWMXAA@mail.gmail.com>
Subject: Re: Seg Fault in strftime
From: Michael Enright <mike@kmcardiff.com>
To: cygwin@cygwin.com
Content-Type: text/plain; charset=UTF-8

On Fri, Jul 31, 2015 at 5:51 AM, Jon TURNEY wrote:
> On 31/07/2015 01:16, Michael Enright wrote:
>>
> It would be very helpful if you could tweak the testcase there and produce
> one which reproduces your problem.
>
> [1]
> https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;a=commitdiff;h=75d5f68aabf62c42884ff935f888b12bbcd00001
> [2] https://sourceware.org/ml/newlib/2015/msg00321.html
>
I have not found it simple to reproduce the symptoms in the
intepreter, but I have found that if I do
struct tm manually_initialized;
manually_initialized.tm_year = 2000;
strftime(buf, buf_size, "%Z", &manually_initialized);
The printed time zone is garbage, which is an indication of danger.
Unlike my complex case, the tzname twins are not corrupted by this
exercise.

If I do
struct tm zeroed = {0};
manually_initialized.tm_year = 2000;
strftime(buf, buf_size, "%Z", &zero_initialized);
The printed time zone is PST (TZ happens to be "America/Los_Angeles")

Aside: I am not super-certain of the zero-initialized semantics with
respect to the language. The idiom I used is defined in C++ but the
program is C.

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