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Diffstat (limited to 'lib/printfrr.h')
| -rw-r--r-- | lib/printfrr.h | 315 |
1 files changed, 315 insertions, 0 deletions
diff --git a/lib/printfrr.h b/lib/printfrr.h new file mode 100644 index 0000000..b8bef56 --- /dev/null +++ b/lib/printfrr.h @@ -0,0 +1,315 @@ +// SPDX-License-Identifier: ISC +/* + * Copyright (c) 2019 David Lamparter, for NetDEF, Inc. + */ + +#ifndef _FRR_PRINTFRR_H +#define _FRR_PRINTFRR_H + +#include <stddef.h> +#include <stdarg.h> +#include <stdint.h> + +#include "compiler.h" +#include "memory.h" + +#ifdef __cplusplus +extern "C" { +#endif + +struct fmt_outpos { + unsigned int off_start, off_end; +}; + +struct fbuf { + char *buf; + char *pos; + size_t len; + + struct fmt_outpos *outpos; + size_t outpos_n, outpos_i; +}; + +#define at(a, b) PRINTFRR(a, b) +#define atn(a, b) \ + at(a, b) __attribute__((nonnull(1) _RET_NONNULL)) +#define atm(a, b) \ + atn(a, b) __attribute__((malloc)) + +/* return value is length needed for the full string (excluding \0) in all + * cases. The functions write as much as they can, but continue regardless, + * so the return value is independent of buffer length. Both bprintfrr and + * snprintf also accept NULL as output buffer. + */ + +/* bprintfrr does NOT null terminate! use sparingly (only provided since it's + * the most direct interface) - useful for incrementally building long text + * (call bprintfrr repeatedly with the same buffer) + */ +ssize_t vbprintfrr(struct fbuf *out, const char *fmt, va_list) at(2, 0); +ssize_t bprintfrr(struct fbuf *out, const char *fmt, ...) at(2, 3); + +/* these do null terminate like their snprintf cousins */ +ssize_t vsnprintfrr(char *out, size_t sz, const char *fmt, va_list) at(3, 0); +ssize_t snprintfrr(char *out, size_t sz, const char *fmt, ...) at(3, 4); + +/* c = continue / concatenate (append at the end of the string) + * return value is would-be string length (regardless of buffer length), + * i.e. includes already written chars */ +ssize_t vcsnprintfrr(char *out, size_t sz, const char *fmt, va_list) at(3, 0); +ssize_t csnprintfrr(char *out, size_t sz, const char *fmt, ...) at(3, 4); + +/* memory allocations don't fail in FRR, so you always get something here. + * (in case of error, returns a strdup of the format string) */ +char *vasprintfrr(struct memtype *mt, const char *fmt, va_list) atm(2, 0); +char *asprintfrr(struct memtype *mt, const char *fmt, ...) atm(2, 3); + +/* try to use provided buffer (presumably from stack), allocate if it's too + * short. Must call XFREE(mt, return value) if return value != out. + */ +char *vasnprintfrr(struct memtype *mt, char *out, size_t sz, + const char *fmt, va_list) atn(4, 0); +char *asnprintfrr(struct memtype *mt, char *out, size_t sz, + const char *fmt, ...) atn(4, 5); + +#define printfrr(fmt, ...) \ + do { \ + char buf[256], *out; \ + out = asnprintfrr(MTYPE_TMP, buf, sizeof(buf), fmt, \ + ##__VA_ARGS__); \ + fputs(out, stdout); \ + if (out != buf) \ + XFREE(MTYPE_TMP, out); \ + } while (0) + +#undef at +#undef atm +#undef atn + +/* 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') + +struct printfrr_eargs; + +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 that would be printed if the buffer + * was large enough. be careful about not under-reporting this; + * otherwise asnprintf() & co. will get broken. Returning -1 means + * something went wrong & default %p/%d handling should be executed. + * + * to consume extra input flags after %pXY, increment *fmt. It points + * at the first character after %pXY at entry. Convention is to make + * those flags lowercase letters or numbers. + */ + ssize_t (*print_ptr)(struct fbuf *buf, struct printfrr_eargs *info, + const void *); + ssize_t (*print_int)(struct fbuf *buf, struct printfrr_eargs *info, + uintmax_t); +}; + +/* additional information passed to extended formatters */ + +struct printfrr_eargs { + /* position in the format string. Points to directly after the + * extension specifier. Increment when consuming extra "flag + * characters". + */ + const char *fmt; + + /* %.1234x / %.*x + * not POSIX compatible when used with %p, will cause warnings from + * GCC & clang. Usable with %d. Not used by the printfrr() itself + * for extension specifiers, so essentially available as a "free" + * parameter. -1 if not specified. Value in the format string + * cannot be negative, but negative values can be passed with %.*x + */ + int precision; + + /* %1234x / %*x + * regular width specification. Internally handled by printfrr(), set + * to 0 if consumed by the extension in order to suppress standard + * width/padding behavior. 0 if not specified. + * + * NB: always positive, even if a negative value is passed in with + * %*x. (The sign is used for the - flag.) + */ + int width; + + /* %#x + * "alternate representation" flag, not POSIX compatible when used + * with %p or %d, will cause warnings from GCC & clang. Not used by + * printfrr() itself for extension specifiers. + */ + bool alt_repr; + + /* %-x + * left-pad flag. Internally handled by printfrr() if width is + * nonzero. Only use if the extension sets width to 0. + */ + bool leftadj; +}; + +/* for any extension that needs a buffer length */ + +static inline ssize_t printfrr_ext_len(struct printfrr_eargs *ea) +{ + ssize_t rv; + + if (ea->precision >= 0) + rv = ea->precision; + else if (ea->width >= 0) { + rv = ea->width; + ea->width = -1; + } else + rv = -1; + + return rv; +} + +/* 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 *); + +#define printfrr_ext_autoreg_p(matchs, print_fn) \ + static ssize_t print_fn(struct fbuf *, struct printfrr_eargs *, \ + const void *); \ + static const 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); \ + } \ + MACRO_REQUIRE_SEMICOLON() + +#define printfrr_ext_autoreg_i(matchs, print_fn) \ + static ssize_t print_fn(struct fbuf *, struct printfrr_eargs *, \ + uintmax_t); \ + static const 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); \ + } \ + MACRO_REQUIRE_SEMICOLON() + +/* fbuf helper functions - note all 3 of these return the length that would + * be written regardless of how much space was available in the buffer, as + * needed for implementing printfrr extensions. (They also accept NULL buf + * for that.) + */ + +static inline ssize_t bputs(struct fbuf *buf, const char *str) +{ + size_t len = strlen(str); + size_t ncopy; + + if (!buf) + return len; + + ncopy = MIN(len, (size_t)(buf->buf + buf->len - buf->pos)); + memcpy(buf->pos, str, ncopy); + buf->pos += ncopy; + + return len; +} + +static inline ssize_t bputch(struct fbuf *buf, char ch) +{ + if (buf && buf->pos < buf->buf + buf->len) + *buf->pos++ = ch; + return 1; +} + +static inline ssize_t bputhex(struct fbuf *buf, uint8_t val) +{ + static const char hexch[] = "0123456789abcdef"; + + if (buf && buf->pos < buf->buf + buf->len) + *buf->pos++ = hexch[(val >> 4) & 0xf]; + if (buf && buf->pos < buf->buf + buf->len) + *buf->pos++ = hexch[val & 0xf]; + return 2; +} + +/* %pVA extension, equivalent to Linux kernel %pV */ + +struct va_format { + const char *fmt; + va_list *va; +}; + +#ifdef _FRR_ATTRIBUTE_PRINTFRR +#pragma FRR printfrr_ext "%pFB" (struct fbuf *) +#pragma FRR printfrr_ext "%pVA" (struct va_format *) + +#pragma FRR printfrr_ext "%pHX" (signed char *) +#pragma FRR printfrr_ext "%pHX" (unsigned char *) +#pragma FRR printfrr_ext "%pHX" (void *) +#pragma FRR printfrr_ext "%pHS" (signed char *) +#pragma FRR printfrr_ext "%pHS" (unsigned char *) +#pragma FRR printfrr_ext "%pHS" (void *) + +#pragma FRR printfrr_ext "%pSE" (char *) +#pragma FRR printfrr_ext "%pSQ" (char *) + +#pragma FRR printfrr_ext "%pTS" (struct timespec *) +#pragma FRR printfrr_ext "%pTV" (struct timeval *) +#pragma FRR printfrr_ext "%pTT" (time_t *) +#endif + +/* when using non-ISO-C compatible extension specifiers... */ + +#ifdef _FRR_ATTRIBUTE_PRINTFRR +#define FMT_NSTD_BEGIN +#define FMT_NSTD_END +#else /* !_FRR_ATTRIBUTE_PRINTFRR */ +#define FMT_NSTD_BEGIN \ + _Pragma("GCC diagnostic push") \ + _Pragma("GCC diagnostic ignored \"-Wformat\"") \ + /* end */ +#define FMT_NSTD_END \ + _Pragma("GCC diagnostic pop") \ + /* end */ +#endif + +#define FMT_NSTD(expr) \ + ({ \ + FMT_NSTD_BEGIN \ + typeof(expr) _v; \ + _v = expr; \ + FMT_NSTD_END \ + _v; \ + }) \ + /* end */ + +#ifdef __cplusplus +} +#endif + +#endif |