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author | Lennart Poettering <lennart@poettering.net> | 2019-04-12 16:49:02 +0200 |
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committer | Lennart Poettering <lennart@poettering.net> | 2019-04-12 16:49:02 +0200 |
commit | 96f6cfbf62f80906bec564a279f5dfaa2a0ec957 (patch) | |
tree | 090a92882f5a7db02abbad973d0a356e594fbfd3 /docs | |
parent | CODING_STYLE: export section about exporting symbols (diff) | |
download | systemd-96f6cfbf62f80906bec564a279f5dfaa2a0ec957.tar.xz systemd-96f6cfbf62f80906bec564a279f5dfaa2a0ec957.zip |
CODING_STYLE: split out section about logging
Diffstat (limited to 'docs')
-rw-r--r-- | docs/CODING_STYLE.md | 57 |
1 files changed, 29 insertions, 28 deletions
diff --git a/docs/CODING_STYLE.md b/docs/CODING_STYLE.md index c8ec482def..6a743fb493 100644 --- a/docs/CODING_STYLE.md +++ b/docs/CODING_STYLE.md @@ -110,34 +110,6 @@ title: Coding Style only jump to the end of a function, and little else. Never jump backwards! -- For every function you add, think about whether it is a "logging" - function or a "non-logging" function. "Logging" functions do logging - on their own, "non-logging" function never log on their own and - expect their callers to log. All functions in "library" code, - i.e. in `src/shared/` and suchlike must be "non-logging". Every time a - "logging" function calls a "non-logging" function, it should log - about the resulting errors. If a "logging" function calls another - "logging" function, then it should not generate log messages, so - that log messages are not generated twice for the same errors. - -- If possible, do a combined log & return operation: - - ```c - r = operation(...); - if (r < 0) - return log_(error|warning|notice|...)_errno(r, "Failed to ...: %m"); - ``` - - If the error value is "synthetic", i.e. it was not received from - the called function, use `SYNTHETIC_ERRNO` wrapper to tell the logging - system to not log the errno value, but still return it: - - ```c - n = read(..., s, sizeof s); - if (n != sizeof s) - return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to read ..."); - ``` - - Avoid static variables, except for caches and very few other cases. Think about thread-safety! While most of our code is never used in threaded environments, at least the library code should make @@ -351,6 +323,35 @@ title: Coding Style - When returning a return code from `main()`, please preferably use `EXIT_FAILURE` and `EXIT_SUCCESS` as defined by libc. +## Logging + +- For every function you add, think about whether it is a "logging" function or + a "non-logging" function. "Logging" functions do logging on their own, + "non-logging" function never log on their own and expect their callers to + log. All functions in "library" code, i.e. in `src/shared/` and suchlike must + be "non-logging". Every time a "logging" function calls a "non-logging" + function, it should log about the resulting errors. If a "logging" function + calls another "logging" function, then it should not generate log messages, + so that log messages are not generated twice for the same errors. + +- If possible, do a combined log & return operation: + + ```c + r = operation(...); + if (r < 0) + return log_(error|warning|notice|...)_errno(r, "Failed to ...: %m"); + ``` + + If the error value is "synthetic", i.e. it was not received from + the called function, use `SYNTHETIC_ERRNO` wrapper to tell the logging + system to not log the errno value, but still return it: + + ```c + n = read(..., s, sizeof s); + if (n != sizeof s) + return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to read ..."); + ``` + ## Memory Allocation - Always check OOM. There is no excuse. In program code, you can use |