bin: Handle CONT signal properly under leaks command - #11335
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edsiper merged 2 commits intoJan 5, 2026
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On macOS, we need to handle COND signal properly. This is because under controling leaks command, it also sends COND signal after releasing its managing process(es). To mitigate this, we need to use flag to mark for distinguish dump to be requested. And we need to run it inside main loop. Signed-off-by: Hiroshi Hatake <hiroshi@chronosphere.io>
📝 WalkthroughWalkthroughSignal handling was changed to avoid calling flb_dump() directly inside the SIGCONT handler. A new global volatile flag Changes
Sequence Diagram(s)sequenceDiagram
participant OS as OS (signal)
participant SH as SIGCONT handler
participant ML as Main loop
participant Dump as flb_dump()
OS->>SH: deliver SIGCONT
SH-->>SH: set dump_requested = 1
Note right of ML: periodic/loop check
ML->>ML: refresh context
ML->>ML: if dump_requested == 1\ndump_requested = 0
ML->>Dump: call flb_dump(ctx->config)
Dump-->>ML: return
Estimated code review effort🎯 2 (Simple) | ⏱️ ~8 minutes Suggested labels
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Fix all issues with AI Agents 🤖
In @src/fluent-bit.c:
- Around line 1495-1498: The dump block uses ctx->config without ensuring ctx is
non-NULL; update the dump handling to check ctx and ctx->config before calling
flb_dump. Specifically, where dump_requested is handled, guard the flb_dump call
with a conditional like "if (dump_requested) { dump_requested = 0; if (ctx !=
NULL && ctx->config != NULL) flb_dump(ctx->config); }" so flb_dump is only
invoked when ctx and ctx->config are valid.
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📒 Files selected for processing (1)
src/fluent-bit.c
🧰 Additional context used
🧠 Learnings (1)
📚 Learning: 2025-11-21T06:23:29.770Z
Learnt from: cosmo0920
Repo: fluent/fluent-bit PR: 11171
File: include/fluent-bit/flb_lib.h:52-53
Timestamp: 2025-11-21T06:23:29.770Z
Learning: In Fluent Bit core (fluent/fluent-bit repository), function descriptions/documentation are not required for newly added functions in header files.
Applied to files:
src/fluent-bit.c
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🔇 Additional comments (2)
src/fluent-bit.c (2)
77-77: LGTM! Correct type for signal-safe flag.The use of
volatile sig_atomic_tis the appropriate type for a flag that is modified by signal handlers and read by the main program, ensuring atomic and visible operations.
640-640: Excellent fix! Defers non-async-signal-safe operation to main loop.Setting a flag instead of calling
flb_dumpdirectly in the signal handler is the correct approach. This avoids undefined behavior from calling non-async-signal-safe functions within a signal handler, which was the root cause of the SIGSEGV mentioned in the PR description.
Signed-off-by: Hiroshi Hatake <hiroshi@chronosphere.io>
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edsiper
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cosmo0920-prevent-segv-under-leaks-handled-fluent-bit
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January 5, 2026 19:43
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On macOS, we need to handle COND signal properly.
This is because under controling leaks command, it also sends COND signal after releasing its managing process(es).
To mitigate this, we need to use flag to mark for distinguish dump to be requested.
And we need to run it inside main loop.
Enter
[N/A]in the box, if an item is not applicable to your change.Testing
Before we can approve your change; please submit the following in a comment:
Before applying this patch:
SEGV occurred due to free-ed memory region was requested to use.
After applying this patch:
Also, CONT signal is properly processed:
If this is a change to packaging of containers or native binaries then please confirm it works for all targets.
ok-package-testlabel to test for all targets (requires maintainer to do).Documentation
Backporting
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.
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