[fix][uab-packager] Enhance statvfs failure logs with system error details

[zhaohai666]

Summary

When the statvfs() syscall fails, original error messages only printed the target path without the detailed system error description derived from errno. This lack of context makes troubleshooting difficult for issues such as insufficient permissions or missing directories.

Changes

Updated four statvfs error log statements to append human-readable system error text via std::generic_category().message(errno) using formatted strings:

1. Original: couldn't stat module files directory " + path
   Revised: fmt::format("couldn't stat module files directory {}: {}", path, std::generic_category().message(errno))
2. Original: couldn't stat files directory " + path
   Revised with the same formatting pattern
3. Original: couldn't stat layers directory " + path
   Revised with the same formatting pattern
4. Original: couldn't stat layer directory " + path
   Revised with the same formatting pattern

Modified File

• libs/linglong/src/linglong/package/uab_packager.cpp

Benefits

• Complete error logs include root causes like permission denied, no such file or directory
• Faster diagnosis of disk stat failures without extra debugging
• Follow standard C++ error reporting conventions instead of plain path-only logs

[deepin-ci-robot]

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This pull-request has been approved by: zhaohai666

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[gemini-code-assist]

Code Review

This pull request improves error reporting in uab_packager.cpp by using fmt::format to include the directory path and the system error message when statvfs fails. The reviewer feedback correctly points out that errno is volatile and can be overwritten by intermediate function calls (such as .string() or memory allocations) before it is evaluated. It is recommended to capture errno immediately after the failing system call to ensure the correct error message is logged.

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[gemini-code-assist]

The value of errno is highly volatile and can be overwritten by subsequent function calls (such as moduleFilesDir.string() or memory allocations inside fmt::format's arguments evaluation) before std::generic_category().message(errno) is evaluated. To ensure the correct error code is logged, capture errno immediately after the failing system call.

                const int err = errno;
                return LINGLONG_ERR(fmt::format("couldn't stat module files directory {}: {}",
                                                moduleFilesDir.string(),
                                                std::generic_category().message(err)));

[gemini-code-assist]

The value of errno is highly volatile and can be overwritten by subsequent function calls (such as layer.filesDirPath().string() or memory allocations inside fmt::format's arguments evaluation) before std::generic_category().message(errno) is evaluated. To ensure the correct error code is logged, capture errno immediately after the failing system call.

                const int err = errno;
                return LINGLONG_ERR(fmt::format("couldn't stat files directory {}: {}",
                                                layer.filesDirPath().string(),
                                                std::generic_category().message(err)));

[gemini-code-assist]

The value of errno is highly volatile and can be overwritten by subsequent function calls (such as layersDir.string() or memory allocations inside fmt::format's arguments evaluation) before std::generic_category().message(errno) is evaluated. To ensure the correct error code is logged, capture errno immediately after the failing system call.

        const int err = errno;
        return LINGLONG_ERR(fmt::format("couldn't stat layers directory {}: {}",
                                        layersDir.string(),
                                        std::generic_category().message(err)));

[gemini-code-assist]

The value of errno is highly volatile and can be overwritten by subsequent function calls (such as layerPath.string() or memory allocations inside fmt::format's arguments evaluation) before std::generic_category().message(errno) is evaluated. To ensure the correct error code is logged, capture errno immediately after the failing system call.

            const int err = errno;
            return LINGLONG_ERR(fmt::format("couldn't stat layer directory {}: {}",
                                            layerPath.string(),
                                            std::generic_category().message(err)));