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man: fix sd_journal_*_with_location's func argument
`sd_journal_print_with_location` and similar functions behave inconsistently compared to their documentation, which says: sd_journal_print_with_location(), sd_journal_printv_with_location(), sd_journal_send_with_location(), sd_journal_sendv_with_location(), and sd_journal_perror_with_location() [...] accept additional parameters to explicitly set the source file name, function, and line. Those arguments must contain valid journal entries including the variable name, e.g. "CODE_FILE=src/foo.c", "CODE_LINE=666", "CODE_FUNC=myfunc". Calling e.g. `sd_journal_sendv_with_location` with `CODE_FUNC=myfunction` as the value of the argument `func` results in "CODE_FUNC" : "CODE_FUNC=myfunction" because `sd_journal_*_with_location` implicitly prefix the argument `func` with `CODE_FUNC=`. For example: _public_ int sd_journal_sendv_with_location( const char *file, const char *line, const char *func, const struct iovec *iov, int n) { [...] char *f; [...] niov = newa(struct iovec, n + 3); [...] ALLOCA_CODE_FUNC(f, func); [...] niov[n++] = IOVEC_MAKE_STRING(f); return sd_journal_sendv(niov, n); } where `ALLOCA_CODE_FUNC` is: #define ALLOCA_CODE_FUNC(f, func) \ do { \ size_t _fl; \ const char *_func = (func); \ char **_f = &(f); \ _fl = strlen(_func) + 1; \ *_f = newa(char, _fl + 10); \ memcpy(*_f, "CODE_FUNC=", 10); \ memcpy(*_f + 10, _func, _fl); \ } while (false) The arguments `file` and `line` are _not_ prefixed similarly but expected to be prefixed already with `CODE_FILE=` and `CODE_LINE=` respectively and sent as is like the documentation describes. That is, the argument `func` is treated differently and behaves inconsistently compared to the arguments `file` and `line`. The behavior seems still intentional: _public_ int sd_journal_printv_with_location(int priority, const char *file, const char *line, const char *func, const char *format, va_list ap) { [...] /* func is initialized from __func__ which is not a macro, but * a static const char[], hence cannot easily be prefixed with * CODE_FUNC=, hence let's do it manually here. */ ALLOCA_CODE_FUNC(f, func); [...] } Thus, change the documentation to match the actual behavior. Note: `sd_journal_{print,send}` and `sd_journal_{print,send}v` work as expected as they only pass the function name (i.e. without `CODE_FUNC=`) to the `func` argument of the `sd_journal_*_with_location` functions they call. For example: #define sd_journal_print(priority, ...) sd_journal_print_with_location(priority, "CODE_FILE=" __FILE__, "CODE_LINE=" _SD_STRINGIFY(__LINE__), __func__, __VA_ARGS__)
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