config_format: windows: Handle static config on windows correctly

[cosmo0920]

In the current master on Fluent Bit, we didn't follow the changes of enabling FLB_STATIC_CONF case.
With tons of changes after we introduced that option on cmake, this option does not work for using enabling with -DFLB_STATIC_CONF=/path/to/confdir.

I followed the subsequent changes since that feature was introduced and plug a NULL pointer exception for feof(3).
This is because this is always needed for reading from the actual configuration files. However, reading from buffer on memory is not needed to check the end of the contents for Fluent Bit configuration.

I supposed that we can omit that checker when enabling static config.

Closes #9556.

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Testing
Before we can approve your change; please submit the following in a comment:

• Example configuration file for the change

[SERVICE]
    log_level debug
    Log_File /path/to/fluent-bit-debug.log

[INPUT]
    Name cpu
    Tag  cpu_metrics

[OUTPUT]
    Name stdout
    Match *

• Debug log output from testing the change

Fluent Bit v3.2.0
* Copyright (C) 2015-2024 The Fluent Bit Authors
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* https://fluentbit.io

______ _                  _    ______ _ _           _____  _____ 
|  ___| |                | |   | ___ (_) |         |____ |/ __  \
| |_  | |_   _  ___ _ __ | |_  | |_/ /_| |_  __   __   / /`' / /'
|  _| | | | | |/ _ \ '_ \| __| | ___ \ | __| \ \ / /   \ \  / /  
| |   | | |_| |  __/ | | | |_  | |_/ / | |_   \ V /.___/ /./ /___
\_|   |_|\__,_|\___|_| |_|\__| \____/|_|\__|   \_/ \____(_)_____/


[2024/11/13 15:50:33] [ info] Configuration:
[2024/11/13 15:50:33] [ info]  flush time     | 1.000000 seconds
[2024/11/13 15:50:33] [ info]  grace          | 5 seconds
[2024/11/13 15:50:33] [ info]  daemon         | 0
[2024/11/13 15:50:33] [ info] ___________
[2024/11/13 15:50:33] [ info]  inputs:
[2024/11/13 15:50:33] [ info]      cpu
[2024/11/13 15:50:33] [ info] ___________
[2024/11/13 15:50:33] [ info]  filters:
[2024/11/13 15:50:33] [ info] ___________
[2024/11/13 15:50:33] [ info]  outputs:
[2024/11/13 15:50:33] [ info]      stdout.0
[2024/11/13 15:50:33] [ info] ___________
[2024/11/13 15:50:33] [ info]  collectors:
[0] cpu_metrics: [[1731480634.533452284, {}], {"cpu_p"=>0.500000, "user_p"=>0.392857, "system_p"=>0.107143, "cpu0.p_cpu"=>0.000000, "cpu0.p_user"=>0.000000, "cpu0.p_system"=>0.000000, "cpu1.p_cpu"=>1.000000, "cpu1.p_user"=>0.000000, "cpu1.p_system"=>1.000000, "cpu2.p_cpu"=>1.000000, "cpu2.p_user"=>1.000000, "cpu2.p_system"=>0.000000, "cpu3.p_cpu"=>0.000000, "cpu3.p_user"=>0.000000, "cpu3.p_system"=>0.000000, "cpu4.p_cpu"=>0.000000, "cpu4.p_user"=>0.000000, "cpu4.p_system"=>0.000000, "cpu5.p_cpu"=>0.000000, "cpu5.p_user"=>0.000000, "cpu5.p_system"=>0.000000, "cpu6.p_cpu"=>1.000000, "cpu6.p_user"=>1.000000, "cpu6.p_system"=>0.000000, "cpu7.p_cpu"=>0.000000, "cpu7.p_user"=>0.000000, "cpu7.p_system"=>0.000000, "cpu8.p_cpu"=>1.000000, "cpu8.p_user"=>1.000000, "cpu8.p_system"=>0.000000, "cpu9.p_cpu"=>0.000000, "cpu9.p_user"=>0.000000, "cpu9.p_system"=>0.000000, "cpu10.p_cpu"=>5.000000, "cpu10.p_user"=>5.000000, "cpu10.p_system"=>0.000000, "cpu11.p_cpu"=>0.000000, "cpu11.p_user"=>0.000000, "cpu11.p_system"=>0.000000, "cpu12.p_cpu"=>1.000000, "cpu12.p_user"=>1.000000, "cpu12.p_system"=>0.000000, "cpu13.p_cpu"=>0.000000, "cpu13.p_user"=>0.000000, "cpu13.p_system"=>0.000000, "cpu14.p_cpu"=>0.000000, "cpu14.p_user"=>0.000000, "cpu14.p_system"=>0.000000, "cpu15.p_cpu"=>0.000000, "cpu15.p_user"=>0.000000, "cpu15.p_system"=>0.000000, "cpu16.p_cpu"=>0.000000, "cpu16.p_user"=>0.000000, "cpu16.p_system"=>0.000000, "cpu17.p_cpu"=>0.000000, "cpu17.p_user"=>0.000000, "cpu17.p_system"=>0.000000, "cpu18.p_cpu"=>0.000000, "cpu18.p_user"=>0.000000, "cpu18.p_system"=>0.000000, "cpu19.p_cpu"=>0.000000, "cpu19.p_user"=>0.000000, "cpu19.p_system"=>0.000000, "cpu20.p_cpu"=>0.000000, "cpu20.p_user"=>0.000000, "cpu20.p_system"=>0.000000, "cpu21.p_cpu"=>0.000000, "cpu21.p_user"=>0.000000, "cpu21.p_system"=>0.000000, "cpu22.p_cpu"=>1.000000, "cpu22.p_user"=>1.000000, "cpu22.p_system"=>0.000000, "cpu23.p_cpu"=>0.000000, "cpu23.p_user"=>0.000000, "cpu23.p_system"=>0.000000, "cpu24.p_cpu"=>0.000000, "cpu24.p_user"=>0.000000, "cpu24.p_system"=>0.000000, "cpu25.p_cpu"=>0.000000, "cpu25.p_user"=>0.000000, "cpu25.p_system"=>0.000000, "cpu26.p_cpu"=>1.000000, "cpu26.p_user"=>1.000000, "cpu26.p_system"=>0.000000, "cpu27.p_cpu"=>2.000000, "cpu27.p_user"=>1.000000, "cpu27.p_system"=>1.000000}]
^C[2024/11/13 15:50:35] [engine] caught signal (SIGINT)
[0] cpu_metrics: [[1731480635.529347000, {}], {"cpu_p"=>0.357143, "user_p"=>0.214286, "system_p"=>0.142857, "cpu0.p_cpu"=>0.000000, "cpu0.p_user"=>0.000000, "cpu0.p_system"=>0.000000, "cpu1.p_cpu"=>2.000000, "cpu1.p_user"=>0.000000, "cpu1.p_system"=>2.000000, "cpu2.p_cpu"=>0.000000, "cpu2.p_user"=>0.000000, "cpu2.p_system"=>0.000000, "cpu3.p_cpu"=>0.000000, "cpu3.p_user"=>0.000000, "cpu3.p_system"=>0.000000, "cpu4.p_cpu"=>0.000000, "cpu4.p_user"=>0.000000, "cpu4.p_system"=>0.000000, "cpu5.p_cpu"=>0.000000, "cpu5.p_user"=>0.000000, "cpu5.p_system"=>0.000000, "cpu6.p_cpu"=>0.000000, "cpu6.p_user"=>0.000000, "cpu6.p_system"=>0.000000, "cpu7.p_cpu"=>0.000000, "cpu7.p_user"=>0.000000, "cpu7.p_system"=>0.000000, "cpu8.p_cpu"=>0.000000, "cpu8.p_user"=>0.000000, "cpu8.p_system"=>0.000000, "cpu9.p_cpu"=>0.000000, "cpu9.p_user"=>0.000000, "cpu9.p_system"=>0.000000, "cpu10.p_cpu"=>4.000000, "cpu10.p_user"=>4.000000, "cpu10.p_system"=>0.000000, "cpu11.p_cpu"=>0.000000, "cpu11.p_user"=>0.000000, "cpu11.p_system"=>0.000000, "cpu12.p_cpu"=>0.000000, "cpu12.p_user"=>0.000000, "cpu12.p_system"=>0.000000, "cpu13.p_cpu"=>0.000000, "cpu13.p_user"=>0.000000, "cpu13.p_system"=>0.000000, "cpu14.p_cpu"=>0.000000, "cpu14.p_user"=>0.000000, "cpu14.p_system"=>0.000000, "cpu15.p_cpu"=>0.000000, "cpu15.p_user"=>0.000000, "cpu15.p_system"=>0.000000, "cpu16.p_cpu"=>0.000000, "cpu16.p_user"=>0.000000, "cpu16.p_system"=>0.000000, "cpu17.p_cpu"=>0.000000, "cpu17.p_user"=>0.000000, "cpu17.p_system"=>0.000000, "cpu18.p_cpu"=>1.000000, "cpu18.p_user"=>1.000000, "cpu18.p_system"=>0.000000, "cpu19.p_cpu"=>0.000000, "cpu19.p_user"=>0.000000, "cpu19.p_system"=>0.000000, "cpu20.p_cpu"=>0.000000, "cpu20.p_user"=>0.000000, "cpu20.p_system"=>0.000000, "cpu21.p_cpu"=>0.000000, "cpu21.p_user"=>0.000000, "cpu21.p_system"=>0.000000, "cpu22.p_cpu"=>0.000000, "cpu22.p_user"=>0.000000, "cpu22.p_system"=>0.000000, "cpu23.p_cpu"=>0.000000, "cpu23.p_user"=>0.000000, "cpu23.p_system"=>0.000000, "cpu24.p_cpu"=>0.000000, "cpu24.p_user"=>0.000000, "cpu24.p_system"=>0.000000, "cpu25.p_cpu"=>0.000000, "cpu25.p_user"=>0.000000, "cpu25.p_system"=>0.000000, "cpu26.p_cpu"=>0.000000, "cpu26.p_user"=>0.000000, "cpu26.p_system"=>0.000000, "cpu27.p_cpu"=>0.000000, "cpu27.p_user"=>0.000000, "cpu27.p_system"=>0.000000}]

• Attached Valgrind output that shows no leaks or memory corruption was found

==1445132== 
==1445132== HEAP SUMMARY:
==1445132==     in use at exit: 0 bytes in 0 blocks
==1445132==   total heap usage: 2,985 allocs, 2,985 frees, 1,094,104 bytes allocated
==1445132== 
==1445132== All heap blocks were freed -- no leaks are possible
==1445132== 
==1445132== For lists of detected and suppressed errors, rerun with: -s
==1445132== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

If this is a change to packaging of containers or native binaries then please confirm it works for all targets.

• Run local packaging test showing all targets (including any new ones) build.
• Set ok-package-test label to test for all targets (requires maintainer to do).

Documentation

• Documentation required for this feature

Backporting

• Backport to latest stable release.

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Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.