mirror of
https://github.com/systemd/systemd.git
synced 2024-11-27 12:13:33 +08:00
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
|
|
- 8ch indent, no tabs
|
|
|
|
- Variables and functions *must* be static, unless they have a
|
|
protoype, and are supposed to be exported.
|
|
|
|
- structs in MixedCase, variables + functions in lower_case
|
|
|
|
- The destructors always unregister the object from the next bigger
|
|
object, not the other way around
|
|
|
|
- To minimize strict aliasing violations we prefer unions over casting
|
|
|
|
- For robustness reasons destructors should be able to destruct
|
|
half-initialized objects, too
|
|
|
|
- Error codes are returned as negative Exxx. i.e. return -EINVAL. There
|
|
are some exceptions: for constructors its is OK to return NULL on
|
|
OOM. For lookup functions NULL is fine too for "not found".
|
|
|
|
Be strict with this. When you write a function that can fail due to
|
|
more than one cause, it *really* should have "int" as return value
|
|
for the error code.
|
|
|
|
- Don't bother with error checking if writing to stdout/stderr worked.
|
|
|
|
- Do not log errors from "library" code, only do so from "main
|
|
program" code.
|
|
|
|
- Always check OOM. There's no excuse. In program code you can use
|
|
"log_oom()" for then printing a short message.
|
|
|
|
- Do not issue NSS requests (that includes user name and host name
|
|
lookups) from the main daemon as this might trigger deadlocks when
|
|
those lookups involve synchronously talking to services that we
|
|
would need to start up
|
|
|
|
- Don't synchronously talk to any other service, due to risk of
|
|
deadlocks
|
|
|
|
- Avoid fixed sized string buffers, unless you really know the maximum
|
|
size and that maximum size is small. They are a source of errors,
|
|
since they result in strings to be truncated. Often it is nicer to
|
|
use dynamic memory, or alloca(). If you do allocate fixed size
|
|
strings on the stack, then it's probably only OK if you either use a
|
|
maximum size such as LINE_MAX, or count in detail the maximum size a
|
|
string can have. Or in other words, if you use "char buf[256]" then
|
|
you are likely doing something wrong!
|
|
|
|
- Stay uniform. For example, always use "usec_t" for time
|
|
values. Don't usec mix msec, and usec and whatnot.
|
|
|
|
- Make use of _cleanup_free_ and friends. It makes your code much
|
|
nicer to read!
|
|
|
|
- Be exceptionally careful when formatting and parsing floating point
|
|
numbers. Their syntax is locale dependent (i.e. "5.000" in en_US is
|
|
generally understood as 5, while on de_DE as 5000.).
|
|
|
|
- Try to use this:
|
|
|
|
void foo() {
|
|
}
|
|
|
|
instead of this:
|
|
|
|
void foo()
|
|
{
|
|
}
|
|
|
|
But it's OK if you don't.
|
|
|
|
- Don't write "foo ()", write "foo()".
|
|
|
|
- Please use streq() and strneq() instead of strcmp(), strncmp() where applicable.
|
|
|
|
- Please do not allocate variables on the stack in the middle of code,
|
|
even if C99 allows it. Wrong:
|
|
|
|
{
|
|
a = 5;
|
|
int b;
|
|
b = a;
|
|
}
|
|
|
|
Right:
|
|
|
|
{
|
|
int b;
|
|
a = 5;
|
|
b = a;
|
|
}
|
|
|
|
- Unless you allocate an array, "double" is always the better choice
|
|
than "float". Processors speak "double" natively anyway, so this is
|
|
no speed benefit, and on calls like printf() "float"s get upgraded
|
|
to "double"s anyway, so there is no point.
|
|
|
|
- Don't invoke functions when you allocate variables on the stack. Wrong:
|
|
|
|
{
|
|
int a = foobar();
|
|
uint64_t x = 7;
|
|
}
|
|
|
|
Right:
|
|
|
|
{
|
|
int a;
|
|
uint64_t x = 7;
|
|
|
|
a = foobar();
|
|
}
|
|
|
|
- Use "goto" for cleaning up, and only use it for that. i.e. you may
|
|
only jump to the end of a function, and little else.
|
|
|
|
- Think about the types you use. If a value cannot sensibly be
|
|
negative don't use "int", but use "unsigned".
|
|
|
|
- Don't use types like "short". They *never* make sense. Use ints,
|
|
longs, long longs, all in unsigned+signed fashion, and the fixed
|
|
size types uint32_t and so on, but nothing else.
|