main: allow indirect linking with libsystemd.so

[rjarry]

Avoid the following error when linking to DPDK dynamic libraries which are indirectly linked to libsystemd:

/usr/bin/x86_64-linux-gnu-ld.bfd: /usr/lib/x86_64-linux-gnu/libsystemd.a(src_libsystemd_sd-daemon_sd-daemon.c.o): in function `sd_notifyf':
(.text+0x2030): multiple definition of `sd_notifyf'; grout.p/main_sd_notify.c.o:./obj-x86_64-linux-gnu/../main/sd_notify.c:36: first defined here

Define our symbol as weak so that it can be overridden.

Changes

main/sd_notify.h

Created new header file declaring sd_notifyf with __attribute__((format(printf, 2, 3), weak)). The weak attribute allows the symbol to be overridden by libsystemd's definition when linking against DPDK dynamic libraries that indirectly depend on libsystemd. The format(printf, 2, 3) attribute enables compile-time format string validation.

Rationale

Resolves multiple definition linker error:

/usr/bin/x86_64-linux-gnu-ld.bfd: /usr/lib/x86_64-linux-gnu/libsystemd.a(...): 
in function `sd_notifyf': multiple definition of `sd_notifyf'

By marking the locally-defined sd_notifyf symbol as weak, the linker preferentially uses libsystemd's definition instead of rejecting the duplicate symbol.

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR adds compile-time validation metadata and weak linkage semantics to the sd_notifyf function declaration in the public header main/sd_notify.h. The function now carries a GCC/Clang format(printf, 2, 3) attribute for printf-style format string checking, plus a weak attribute to preserve weak symbol semantics. This is a minimal header-only change.

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@main/sd_notify.h`:
- Around line 7-8: The sd_notifyf declaration is marked weak in the header but
the implementation of sd_notifyf (the function definition) is not, causing
possible multiple-definition/link conflicts; update the sd_notifyf definition to
include the weak attribute (same as the header: __attribute__((format(printf, 2,
3), weak))) or add an equivalent weak alias for sd_notifyf in the implementation
so libsystemd can override it, ensuring the symbol is weak at the definition
site (target the sd_notifyf function definition/implementation).

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

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Run ID: e68044b3-ac79-492f-bff1-3a6e3a8fecdb

📥 Commits

Reviewing files that changed from the base of the PR and between ee3b837 and 7706b31.

📒 Files selected for processing (1)

• main/sd_notify.h

[coderabbitai]

⚠️ Potential issue | 🔴 Critical | ⚡ Quick win

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
# Description: Check if sd_notifyf definition has weak attribute

# Search for the function definition and surrounding context
rg -n -A 5 -B 2 'sd_notifyf.*\{' main/sd_notify.c

Repository: DPDK/grout

Length of output: 305

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Apply weak to the sd_notifyf definition (not just the header declaration)
main/sd_notify.h marks the sd_notifyf declaration as __attribute__((format(printf, 2, 3), weak)), but main/sd_notify.c defines sd_notifyf without the weak attribute (function definition starts at int sd_notifyf(...) {). To allow libsystemd’s sd_notifyf to override and prevent multiple-definition link errors, the weak attribute needs to be on the definition (or an equivalent weak symbol/alias must be created there).

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@main/sd_notify.h` around lines 7 - 8, The sd_notifyf declaration is marked
weak in the header but the implementation of sd_notifyf (the function
definition) is not, causing possible multiple-definition/link conflicts; update
the sd_notifyf definition to include the weak attribute (same as the header:
__attribute__((format(printf, 2, 3), weak))) or add an equivalent weak alias for
sd_notifyf in the implementation so libsystemd can override it, ensuring the
symbol is weak at the definition site (target the sd_notifyf function
definition/implementation).