in_calyptia_fleet: rewrite error handling code for get_calyptia_file to fix warnings.

[pwhelan]

Summary

The following warning appears when using clang 15.0.0:

/Users/pwhelan/Code/fluent-bit/plugins/in_calyptia_fleet/in_calyptia_fleet.c:1002:9: warning: variable 'fname' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
    if (ret < 0) {
        ^~~~~~~
/Users/pwhelan/Code/fluent-bit/plugins/in_calyptia_fleet/in_calyptia_fleet.c:1053:21: note: uninitialized use occurs here
    flb_sds_destroy(fname);
                    ^~~~~
/Users/pwhelan/Code/fluent-bit/plugins/in_calyptia_fleet/in_calyptia_fleet.c:1002:5: note: remove the 'if' if its condition is always false
    if (ret < 0) {
    ^~~~~~~~~~~~~~
/Users/pwhelan/Code/fluent-bit/plugins/in_calyptia_fleet/in_calyptia_fleet.c:987:20: note: initialize the variable 'fname' to silence this warning
    flb_sds_t fname;

This PR fixes the code to both eliminate this warning and to make it more legible.

[ 81%] Building C object plugins/in_calyptia_fleet/CMakeFiles/flb-plugin-in_calyptia_fleet.dir/in_calyptia_fleet.c.o
[ 81%] Linking C static library ../../library/libflb-plugin-in_calyptia_fleet.a

---

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

• Example configuration file for the change
• Debug log output from testing the change

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

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.

[pwhelan]

Here is a sample run with the patch applied:

./build/bin/fluent-bit -c fleet.conf
Fluent Bit v2.2.1
* Copyright (C) 2015-2023 The Fluent Bit Authors
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* https://fluentbit.io

[2023/12/11 20:59:04] [ info] [fluent bit] version=2.2.1, commit=469652f625, pid=48075
[2023/12/11 20:59:04] [ info] [custom:calyptia:calyptia.0] custom initialized!
[2023/12/11 20:59:04] [ info] [storage] ver=1.5.1, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2023/12/11 20:59:04] [ info] [cmetrics] version=0.6.5
[2023/12/11 20:59:04] [ info] [ctraces ] version=0.3.1
[2023/12/11 20:59:04] [ info] [input:fluentbit_metrics:fluentbit_metrics.0] initializing
[2023/12/11 20:59:04] [ info] [input:fluentbit_metrics:fluentbit_metrics.0] storage_strategy='memory' (memory only)
[2023/12/11 20:59:04] [ info] [input:calyptia_fleet:calyptia_fleet.1] initializing
[2023/12/11 20:59:04] [ info] [input:calyptia_fleet:calyptia_fleet.1] storage_strategy='memory' (memory only)
[2023/12/11 20:59:04] [ info] [input:calyptia_fleet:calyptia_fleet.1] initializing calyptia fleet input.
[2023/12/11 20:59:04] [ warn] [read_glob] glob: [/tmp/calyptia-fleet/99d70f0171de7aec9b8ae68b1f6e32b7dd65763b0b73dd603ed95a112b0bf8ee/fleet-script-file/*.conf] no match
[2023/12/11 20:59:04] [error] [input:calyptia_fleet:calyptia_fleet.1] unable to read fleet directory for conf files: /tmp/calyptia-fleet/99d70f0171de7aec9b8ae68b1f6e32b7dd65763b0b73dd603ed95a112b0bf8ee/fleet-script-file/*.conf
[2023/12/11 20:59:04] [ warn] [input:calyptia_fleet:calyptia_fleet.1] unable to find latest configuration file
[2023/12/11 20:59:04] [ info] [sp] stream processor started
[2023/12/11 20:59:20] [ info] [input:calyptia_fleet:calyptia_fleet.1] loading configuration from /tmp/calyptia-fleet/99d70f0171de7aec9b8ae68b1f6e32b7dd65763b0b73dd603ed95a112b0bf8ee/fleet-script-file/new.conf.
[2023/12/11 20:59:20] [ info] [input:calyptia_fleet:calyptia_fleet.1] changing to config dir: /tmp/calyptia-fleet/99d70f0171de7aec9b8ae68b1f6e32b7dd65763b0b73dd603ed95a112b0bf8ee/fleet-script-file/1700004854
[2023/12/11 20:59:20] [ info] [input:calyptia_fleet:calyptia_fleet.1] changing to config dir: /tmp/calyptia-fleet/99d70f0171de7aec9b8ae68b1f6e32b7dd65763b0b73dd603ed95a112b0bf8ee/fleet-script-file/1700004854
[2023/12/11 20:59:25] [engine] caught signal (SIGHUP)
[2023/12/11 20:59:25] [ info] reloading instance pid=48075 tid=0x7ffff6df7ac0
[2023/12/11 20:59:25] [ info] [reload] stop everything of the old context
[2023/12/11 20:59:25] [ warn] [engine] service will shutdown when all remaining tasks are flushed
[2023/12/11 20:59:25] [ info] [input] pausing fluentbit_metrics.0
[2023/12/11 20:59:25] [ info] [input] pausing calyptia_fleet.1
[2023/12/11 20:59:25] [ info] [engine] service has stopped (0 pending tasks)
[2023/12/11 20:59:25] [ info] [input] pausing fluentbit_metrics.0
[2023/12/11 20:59:25] [ info] [input] pausing calyptia_fleet.1
[2023/12/11 20:59:25] [ info] [reload] start everything
[2023/12/11 20:59:25] [ info] [fluent bit] version=2.2.1, commit=469652f625, pid=48075
[2023/12/11 20:59:25] [ info] [custom:calyptia:calyptia.0] custom initialized!
[2023/12/11 20:59:25] [ info] [storage] ver=1.5.1, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2023/12/11 20:59:25] [ info] [cmetrics] version=0.6.5
[2023/12/11 20:59:25] [ info] [ctraces ] version=0.3.1
[2023/12/11 20:59:25] [ info] [input:dummy:dummy.0] initializing
[2023/12/11 20:59:25] [ info] [input:dummy:dummy.0] storage_strategy='memory' (memory only)
[2023/12/11 20:59:25] [ info] [input:fluentbit_metrics:fluentbit_metrics.1] initializing
[2023/12/11 20:59:25] [ info] [input:fluentbit_metrics:fluentbit_metrics.1] storage_strategy='memory' (memory only)
[2023/12/11 20:59:25] [ info] [input:calyptia_fleet:calyptia_fleet.2] initializing
[2023/12/11 20:59:25] [ info] [input:calyptia_fleet:calyptia_fleet.2] storage_strategy='memory' (memory only)
[2023/12/11 20:59:25] [ info] [input:calyptia_fleet:calyptia_fleet.2] initializing calyptia fleet input.
[2023/12/11 20:59:25] [ info] [output:stdout:stdout.0] worker #0 started
[2023/12/11 20:59:25] [ info] [output:calyptia:calyptia.1] connected to Calyptia, agent_id='3367b469-eb0d-42e3-8043-976222296359'
[2023/12/11 20:59:25] [ info] [sp] stream processor started
[0] dummy: [[1702339166.539031648, {}], {"powered_by"=>"calyptia", "message"=>"unscripted #13"}]
[0] dummy: [[1702339167.539034336, {}], {"powered_by"=>"calyptia", "message"=>"unscripted #13"}]
[0] dummy: [[1702339168.539040635, {}], {"powered_by"=>"calyptia", "message"=>"unscripted #13"}]
[0] dummy: [[1702339169.539036162, {}], {"powered_by"=>"calyptia", "message"=>"unscripted #13"}]
[0] dummy: [[1702339170.539286517, {}], {"powered_by"=>"calyptia", "message"=>"unscripted #13"}]
[0] dummy: [[1702339171.539036545, {}], {"powered_by"=>"calyptia", "message"=>"unscripted #13"}]
^C[2023/12/11 20:59:32] [engine] caught signal (SIGINT)
[0] dummy: [[1702339172.539036042, {}], {"powered_by"=>"calyptia", "message"=>"unscripted #13"}]
[2023/12/11 20:59:32] [ warn] [engine] service will shutdown in max 5 seconds
[2023/12/11 20:59:32] [ info] [input] pausing dummy.0
[2023/12/11 20:59:32] [ info] [input] pausing fluentbit_metrics.1
[2023/12/11 20:59:32] [ info] [input] pausing calyptia_fleet.2
[2023/12/11 20:59:33] [ info] [engine] service has stopped (0 pending tasks)
[2023/12/11 20:59:33] [ info] [input] pausing dummy.0
[2023/12/11 20:59:33] [ info] [input] pausing fluentbit_metrics.1
[2023/12/11 20:59:33] [ info] [input] pausing calyptia_fleet.2
[2023/12/11 20:59:33] [ info] [output:stdout:stdout.0] thread worker #0 stopping...
[2023/12/11 20:59:33] [ info] [output:stdout:stdout.0] thread worker #0 stopped

[edsiper]

@pwhelan please fix the commit, it needs to start with in_calyptia_fleet: ...