lib/printfrr.h

   1 /*
   2  * Copyright (c) 2019  David Lamparter, for NetDEF, Inc.
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15  */
  16
  17 #ifndef _FRR_PRINTFRR_H
  18 #define _FRR_PRINTFRR_H
  19
  20 #include <stddef.h>
  21 #include <stdarg.h>
  22 #include <stdint.h>
  23
  24 #include "compiler.h"
  25 #include "memory.h"
  26
  27 #ifdef __cplusplus
  28 extern "C" {
  29 #endif
  30
  31 struct fbuf {
  32         char *buf;
  33         char *pos;
  34         size_t len;
  35 };
  36
  37 #define at(a, b) PRINTFRR(a, b)
  38 #define atn(a, b) \
  39         at(a, b) __attribute__((nonnull(1) _RET_NONNULL))
  40 #define atm(a, b) \
  41         atn(a, b) __attribute__((malloc))
  42
  43 /* return value is length needed for the full string (excluding \0) in all
  44  * cases.  The functions write as much as they can, but continue regardless,
  45  * so the return value is independent of buffer length.  Both bprintfrr and
  46  * snprintf also accept NULL as output buffer.
  47  */
  48
  49 /* bprintfrr does NOT null terminate! use sparingly (only provided since it's
  50  * the most direct interface) - useful for incrementally building long text
  51  * (call bprintfrr repeatedly with the same buffer)
  52  */
  53 ssize_t vbprintfrr(struct fbuf *out, const char *fmt, va_list) at(2, 0);
  54 ssize_t  bprintfrr(struct fbuf *out, const char *fmt, ...)     at(2, 3);
  55
  56 /* these do null terminate like their snprintf cousins */
  57 ssize_t vsnprintfrr(char *out, size_t sz, const char *fmt, va_list) at(3, 0);
  58 ssize_t  snprintfrr(char *out, size_t sz, const char *fmt, ...)     at(3, 4);
  59
  60 /* c = continue / concatenate (append at the end of the string)
  61  * return value is would-be string length (regardless of buffer length),
  62  * i.e. includes already written chars */
  63 ssize_t vcsnprintfrr(char *out, size_t sz, const char *fmt, va_list) at(3, 0);
  64 ssize_t  csnprintfrr(char *out, size_t sz, const char *fmt, ...)     at(3, 4);
  65
  66 /* memory allocations don't fail in FRR, so you always get something here.
  67  * (in case of error, returns a strdup of the format string) */
  68 char *vasprintfrr(struct memtype *mt, const char *fmt, va_list) atm(2, 0);
  69 char  *asprintfrr(struct memtype *mt, const char *fmt, ...)     atm(2, 3);
  70
  71 /* try to use provided buffer (presumably from stack), allocate if it's too
  72  * short.  Must call XFREE(mt, return value) if return value != out.
  73  */
  74 char *vasnprintfrr(struct memtype *mt, char *out, size_t sz,
  75                    const char *fmt, va_list) atn(4, 0);
  76 char  *asnprintfrr(struct memtype *mt, char *out, size_t sz,
  77                    const char *fmt, ...)     atn(4, 5);
  78
  79 #define printfrr(fmt, ...)                                                     \
  80         do {                                                                   \
  81                 char buf[256], *out;                                           \
  82                 out = asnprintfrr(MTYPE_TMP, buf, sizeof(buf), fmt,            \
  83                                   ##__VA_ARGS__);                              \
  84                 fputs(out, stdout);                                            \
  85                 if (out != buf)                                                \
  86                         XFREE(MTYPE_TMP, out);                                 \
  87         } while (0)
  88
  89 #undef at
  90 #undef atm
  91 #undef atn
  92
  93 /* extension specs must start with a capital letter (this is a restriction
  94  * for both performance's and human understanding's sake.)
  95  *
  96  * Note that the entire thing mostly works because a letter directly following
  97  * a %p print specifier is extremely unlikely to occur (why would you want to
  98  * print "0x12345678HELLO"?)  Normally, you'd expect spacing or punctuation
  99  * after a placeholder.  That also means that neither of those works well for
 100  * extension purposes, e.g. "%p{foo}" is reasonable to see actually used.
 101  *
 102  * TODO: would be nice to support a "%pF%dF" specifier that consumes 2
 103  * arguments, e.g. to pass an integer + a list of known values...  can be
 104  * done, but a bit tricky.
 105  */
 106 #define printfrr_ext_char(ch) ((ch) >= 'A' && (ch) <= 'Z')
 107
 108 struct printfrr_ext {
 109         /* embedded string to minimize cache line pollution */
 110         char match[8];
 111
 112         /* both can be given, if not the code continues searching
 113          * (you can do %pX and %dX in 2 different entries)
 114          *
 115          * return value: number of bytes consumed from the format string, so
 116          * you can consume extra flags (e.g. register for "%pX", consume
 117          * "%pXfoo" or "%pXbar" for flags.)  Convention is to make those flags
 118          * lowercase letters or numbers.
 119          *
 120          * bsz is a compile-time constant in printf;  it's gonna be relatively
 121          * small.  This isn't designed to print Shakespeare from a pointer.
 122          *
 123          * prec is the precision specifier (the 999 in "%.999p")  -1 means
 124          * none given (value in the format string cannot be negative)
 125          */
 126         ssize_t (*print_ptr)(char *buf, size_t bsz, const char *fmt, int prec,
 127                         const void *);
 128         ssize_t (*print_int)(char *buf, size_t bsz, const char *fmt, int prec,
 129                         uintmax_t);
 130 };
 131
 132 /* no locking - must be called when single threaded (e.g. at startup.)
 133  * this restriction hopefully won't be a huge bother considering normal usage
 134  * scenarios...
 135  */
 136 void printfrr_ext_reg(const struct printfrr_ext *);
 137
 138 #define printfrr_ext_autoreg_p(matchs, print_fn)                               \
 139         static ssize_t print_fn(char *, size_t, const char *, int,             \
 140                                 const void *);                                 \
 141         static const struct printfrr_ext _printext_##print_fn = {              \
 142                 .match = matchs,                                               \
 143                 .print_ptr = print_fn,                                         \
 144         };                                                                     \
 145         static void _printreg_##print_fn(void) __attribute__((constructor));   \
 146         static void _printreg_##print_fn(void) {                               \
 147                 printfrr_ext_reg(&_printext_##print_fn);                       \
 148         }                                                                      \
 149         /* end */
 150
 151 #define printfrr_ext_autoreg_i(matchs, print_fn)                               \
 152         static ssize_t print_fn(char *, size_t, const char *, int, uintmax_t); \
 153         static const struct printfrr_ext _printext_##print_fn = {              \
 154                 .match = matchs,                                               \
 155                 .print_int = print_fn,                                         \
 156         };                                                                     \
 157         static void _printreg_##print_fn(void) __attribute__((constructor));   \
 158         static void _printreg_##print_fn(void) {                               \
 159                 printfrr_ext_reg(&_printext_##print_fn);                       \
 160         }                                                                      \
 161         /* end */
 162
 163 /* fbuf helper functions */
 164
 165 static inline ssize_t bputs(struct fbuf *buf, const char *str)
 166 {
 167         size_t len = strlen(str);
 168         size_t ncopy;
 169
 170         if (!buf)
 171                 return len;
 172
 173         ncopy = MIN(len, (size_t)(buf->buf + buf->len - buf->pos));
 174         memcpy(buf->pos, str, ncopy);
 175         buf->pos += ncopy;
 176
 177         return len;
 178 }
 179
 180 static inline ssize_t bputch(struct fbuf *buf, char ch)
 181 {
 182         if (buf && buf->pos < buf->buf + buf->len)
 183                 *buf->pos++ = ch;
 184         return 1;
 185 }
 186
 187 #ifdef __cplusplus
 188 }
 189 #endif
 190
 191 #endif