pal: platform abstraction layer and strerror_r(3) wrapper

[altimeter-130ft]

This PR is for the following changes:

• Introduce the pal module, the platform abstraction layer.
• Add flb_strerror_r(), the wrapper of strerror_r(3).

Fixed Issue

#8379

Background

The strerror_r(3) implementations of glibc and POSIX.1-2001 have the different signatures and usages, which causes a build error and/or an unexpected behaviour.

Please refer to Issue #8379 for the detailed analysis.

Changes

This fix implements flb_strerror_r(), the POSIX.1-2001-compliant wrapper of strerror_r(3) into pal, the new core module dedicated to encapsulate the platform dependency found on the common external features. The goal of pal is similar to the AC_LIBOBJ() macro of GNU Autoconf, except that pal holds all wrapper functions in a single source.

The wrapper functions in pal are intended for the Fluent Bit core and plugins only. The third-party libraries under lib must not call them, in order to keep their independency.

pal Source Files

• src/flb_pal.c
• include/fluent-bit/flb_pal.h

pal Internal Test Files

• tests/internal/pal.c

New pal Function

• int flb_strerror_r(int errnum, char *buf, size_t buflen); The wrapper of strerror_r(3) with the signature and semantics of POSIX.1-2001. Available if strerror_r(3) exists in the platform, regardless from its implementation.

flb_strerror_r() Callers

The strerror_r(3) calls in the following files have been converted to flb_strerror_r():

• src/flb_io.c
• src/flb_log.c
• src/flb_network.c

Tested Environments

• Debian x86_64 12.2 (strerror_r(3) standard: glibc)
• FreeBSD/amd64 14.0-RELEASE (strerror_r(3) standard: POSIX.1-2001)
  • fluent/fluent-bit/pull/8376 included for the coverage report.

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Testing

• N/A Example configuration file for the change The issue does not depend on a specific configuration.

• [x] Debug log output from testing the change

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

Test Results

• Debian x86_64 12.2: logs-fluent-bit-topic-pal-strerror_r-wrapper-github-pr-debian_x86_64_12_2.zip
  • fluent-bit-cmake-topic-pal-strerror_r-wrapper-github-pr-debian_x86_64_12_2.log The cmake log.
  • fluent-bit-make-topic-pal-strerror_r-wrapper-github-pr-debian_x86_64_12_2.log The make log.
  • fluent-bit-ctest-topic-pal-strerror_r-wrapper-github-pr-debian_x86_64_12_2.log The ctest log.
  • fluent-bit-ctest-topic-pal-strerror_r-wrapper-github-pr-debian_x86_64_12_2-LastTest.log The LastTest.log file out of ctest.
  • fluent-bit-valgrind-topic-pal-strerror_r-wrapper-github-pr-debian_x86_64_12_2.log The valgrind --leak-check=full log. No memory leak happened.
  • gcov-tests-topic-pal-strerror_r-wrapper-github-pr-debian_x86_64_12_2.tar.xz The lcov coverage report.
    • The new code has been covered except for one.
      • Can we depend on the glibc strerror_r(3) never returning NULL?
• FreeBSD/amd64 14.0-RELEASE: logs-fluent-bit-topic-pal-strerror_r-wrapper-freebsd_amd64_14_0_release.zip
  • fluent-bit-cmake-topic-pal-strerror_r-wrapper-freebsd_amd64_14_0_release.log The cmake log.
  • fluent-bit-make-topic-pal-strerror_r-wrapper-freebsd_amd64_14_0_release.log The make log.
  • fluent-bit-ctest-topic-pal-strerror_r-wrapper-freebsd_amd64_14_0_release.log The ctest log.
  • fluent-bit-ctest-topic-pal-strerror_r-wrapper-freebsd_amd64_14_0_release-LastTest.log The LastTest.log file out of ctest.
  • fluent-bit-valgrind-topic-pal-strerror_r-wrapper-freebsd_amd64_14_0_release.log The valgrind --leak-check=full log.
    • The coverage is disabled because of the Valgrind problem that makes an assertion failure.
    • Many conditional jumps or moves on uninitialised value.
      • These are the false errors; no conditional instructions have been found out of the codewalk.
    • 3 blocks are still reachable with flb_strerror_r().
      • These are for the NLS message catalogue, read only once and staying until the process exits.
    • The rest of the leaks do not involve the Fluent Bit implementation.
  • llvm-cov-tests-topic-pal-strerror_r-wrapper-freebsd_amd64_14_0_release.tar.xz The LLVM coverage report.
    • The new code has been covered.

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

• N/A Run local packaging test showing all targets (including any new ones) build.
• N/A Set ok-package-test label to test for all targets (requires maintainer to do). Packaging is not affected.

Documentation

• ? Documentation required for this feature The pal paragraph in DEVELOPER_GUIDE.md?

Backporting

• [x] Backport to latest stable release. This PR is the fix to a build breakage.

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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.

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