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c170f3a41b
Update systemd-analyze to follow the coding style of the other tools more closely. Also, update the CODING_STYLE to document this for future additions. Changes: - Always use usec_t for time units, so that we always use the same types everywhere, and format times the same way as everywhere else. - Add "static" to global variables - Make sure we can always distuingish OOM and other errors: ensure we always return useful error codes from all functions. - Always free unit_times array
124 lines
3.6 KiB
Plaintext
124 lines
3.6 KiB
Plaintext
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- 8ch indent, no tabs
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- Variables and functions *must* be static, unless they have a
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protoype, and are supposed to be exported.
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- structs in MixedCase, variables + functions in lower_case
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- The destructors always unregister the object from the next bigger
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object, not the other way around
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- To minimize strict aliasing violations we prefer unions over casting
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- For robustness reasons destructors should be able to destruct
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half-initialized objects, too
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- Error codes are returned as negative Exxx. i.e. return -EINVAL. There
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are some exceptions: for constructors its is OK to return NULL on
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OOM. For lookup functions NULL is fine too for "not found".
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Be strict with this. When you write a function that can fail due to
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more than one cause, it *really* should have "int" as return value
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for the error code.
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- Don't bother with error checking if writing to stdout/stderr worked.
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- Do not log errors from "library" code, only do so from "main
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program" code.
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- Always check OOM. There's no excuse. In program code you can use
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"log_oom()" for then printing a short message.
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- Do not issue NSS requests (that includes user name and host name
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lookups) from the main daemon as this might trigger deadlocks when
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those lookups involve synchronously talking to services that we
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would need to start up
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- Don't synchronously talk to any other service, due to risk of
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deadlocks
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- Avoid fixed sized string buffers, unless you really know the maximum
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size and that maximum size is small. They are a source of errors,
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since they result in strings to be truncated. Often it is nicer to
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use dynamic memory, or alloca(). If you do allocate fixed size
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strings on the stack, then it's probably only OK if you either use a
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maximum size such as LINE_MAX, or count in detail the maximum size a
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string can have. Or in other words, if you use "char buf[256]" then
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you are likely doing something wrong!
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- Stay uniform. For example, always use "usec_t" for time
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values. Don't usec mix msec, and usec and whatnot.
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- Make use of _cleanup_free_ and friends. It makes your code much
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nicer to read!
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- Be exceptionally careful when formatting and parsing floating point
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numbers. Their syntax is locale dependent (i.e. "5.000" in en_US is
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generally understood as 5, while on de_DE as 5000.).
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- Try to use this:
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void foo() {
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}
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instead of this:
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void foo()
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{
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}
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But it's OK if you don't.
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- Don't write "foo ()", write "foo()".
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- Please use streq() and strneq() instead of strcmp(), strncmp() where applicable.
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- Please do not allocate variables on the stack in the middle of code,
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even if C99 allows it. Wrong:
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{
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a = 5;
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int b;
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b = a;
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}
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Right:
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{
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int b;
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a = 5;
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b = a;
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}
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- Unless you allocate an array, "double" is always the better choice
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than "float". Processors speak "double" natively anyway, so this is
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no speed benefit, and on calls like printf() "float"s get upgraded
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to "double"s anyway, so there is no point.
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- Don't invoke functions when you allocate variables on the stack. Wrong:
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{
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int a = foobar();
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uint64_t x = 7;
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}
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Right:
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{
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int a;
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uint64_t x = 7;
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a = foobar();
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}
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- Use "goto" for cleaning up, and only use it for that. i.e. you may
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only jump to the end of a function, and little else.
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- Think about the types you use. If a value cannot sensibly be
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negative don't use "int", but use "unsigned".
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- Don't use types like "short". They *never* make sense. Use ints,
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longs, long longs, all in unsigned+signed fashion, and the fixed
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size types uint32_t and so on, but nothing else.
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