diff options
Diffstat (limited to 'lib/printfrr.h')
| -rw-r--r-- | lib/printfrr.h | 74 |
1 files changed, 66 insertions, 8 deletions
diff --git a/lib/printfrr.h b/lib/printfrr.h index f98527efd9..95dace7021 100644 --- a/lib/printfrr.h +++ b/lib/printfrr.h @@ -19,6 +19,7 @@ #include <stddef.h> #include <stdarg.h> +#include <stdint.h> #include "compiler.h" #include "memory.h" @@ -75,17 +76,74 @@ char *asnprintfrr(struct memtype *mt, char *out, size_t sz, #undef at #undef atm -struct printfrr_ext { - const char *match; - const char *opts; +/* extension specs must start with a capital letter (this is a restriction + * for both performance's and human understanding's sake.) + * + * Note that the entire thing mostly works because a letter directly following + * a %p print specifier is extremely unlikely to occur (why would you want to + * print "0x12345678HELLO"?) Normally, you'd expect spacing or punctuation + * after a placeholder. That also means that neither of those works well for + * extension purposes, e.g. "%p{foo}" is reasonable to see actually used. + * + * TODO: would be nice to support a "%pF%dF" specifier that consumes 2 + * arguments, e.g. to pass an integer + a list of known values... can be + * done, but a bit tricky. + */ +#define printfrr_ext_char(ch) ((ch) >= 'A' && (ch) <= 'Z') - union { - ssize_t (*print_ptr)(struct fbuf *out, const char *fmt, void *); - ssize_t (*print_int)(struct fbuf *out, const char *fmt, int); - }; +struct printfrr_ext { + /* embedded string to minimize cache line pollution */ + char match[8]; + + /* both can be given, if not the code continues searching + * (you can do %pX and %dX in 2 different entries) + * + * return value: number of bytes consumed from the format string, so + * you can consume extra flags (e.g. register for "%pX", consume + * "%pXfoo" or "%pXbar" for flags.) Convention is to make those flags + * lowercase letters or numbers. + * + * bsz is a compile-time constant in printf; it's gonna be relatively + * small. This isn't designed to print Shakespeare from a pointer. + * + * prec is the precision specifier (the 999 in "%.999p") -1 means + * none given (value in the format string cannot be negative) + */ + ssize_t (*print_ptr)(char *buf, size_t bsz, const char *fmt, int prec, + const void *); + ssize_t (*print_int)(char *buf, size_t bsz, const char *fmt, int prec, + uintmax_t); }; +/* no locking - must be called when single threaded (e.g. at startup.) + * this restriction hopefully won't be a huge bother considering normal usage + * scenarios... + */ void printfrr_ext_reg(const struct printfrr_ext *); -void printfrr_ext_unreg(const struct printfrr_ext *); + +#define printfrr_ext_autoreg_p(matchs, print_fn) \ + static ssize_t print_fn(char *, size_t, const char *, int, \ + const void *); \ + static struct printfrr_ext _printext_##print_fn = { \ + .match = matchs, \ + .print_ptr = print_fn, \ + }; \ + static void _printreg_##print_fn(void) __attribute__((constructor)); \ + static void _printreg_##print_fn(void) { \ + printfrr_ext_reg(&_printext_##print_fn); \ + } \ + /* end */ + +#define printfrr_ext_autoreg_i(matchs, print_fn) \ + static ssize_t print_fn(char *, size_t, const char *, int, uintmax_t); \ + static struct printfrr_ext _printext_##print_fn = { \ + .match = matchs, \ + .print_int = print_fn, \ + }; \ + static void _printreg_##print_fn(void) __attribute__((constructor)); \ + static void _printreg_##print_fn(void) { \ + printfrr_ext_reg(&_printext_##print_fn); \ + } \ + /* end */ #endif |