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acddc0ed 1// SPDX-License-Identifier: ISC
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2/*
3 * Copyright (c) 2019 David Lamparter, for NetDEF, Inc.
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4 */
5
6#ifndef _FRR_PRINTFRR_H
7#define _FRR_PRINTFRR_H
8
9#include <stddef.h>
10#include <stdarg.h>
bf4d3d80 11#include <stdint.h>
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12
13#include "compiler.h"
14#include "memory.h"
15
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16#ifdef __cplusplus
17extern "C" {
18#endif
19
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20struct fmt_outpos {
21 unsigned int off_start, off_end;
22};
23
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24struct fbuf {
25 char *buf;
26 char *pos;
27 size_t len;
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28
29 struct fmt_outpos *outpos;
30 size_t outpos_n, outpos_i;
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31};
32
fb84c629 33#define at(a, b) PRINTFRR(a, b)
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34#define atn(a, b) \
35 at(a, b) __attribute__((nonnull(1) _RET_NONNULL))
36#define atm(a, b) \
37 atn(a, b) __attribute__((malloc))
38
39/* return value is length needed for the full string (excluding \0) in all
40 * cases. The functions write as much as they can, but continue regardless,
41 * so the return value is independent of buffer length. Both bprintfrr and
42 * snprintf also accept NULL as output buffer.
43 */
44
45/* bprintfrr does NOT null terminate! use sparingly (only provided since it's
46 * the most direct interface) - useful for incrementally building long text
47 * (call bprintfrr repeatedly with the same buffer)
48 */
49ssize_t vbprintfrr(struct fbuf *out, const char *fmt, va_list) at(2, 0);
50ssize_t bprintfrr(struct fbuf *out, const char *fmt, ...) at(2, 3);
51
52/* these do null terminate like their snprintf cousins */
53ssize_t vsnprintfrr(char *out, size_t sz, const char *fmt, va_list) at(3, 0);
54ssize_t snprintfrr(char *out, size_t sz, const char *fmt, ...) at(3, 4);
55
56/* c = continue / concatenate (append at the end of the string)
57 * return value is would-be string length (regardless of buffer length),
58 * i.e. includes already written chars */
59ssize_t vcsnprintfrr(char *out, size_t sz, const char *fmt, va_list) at(3, 0);
60ssize_t csnprintfrr(char *out, size_t sz, const char *fmt, ...) at(3, 4);
61
62/* memory allocations don't fail in FRR, so you always get something here.
63 * (in case of error, returns a strdup of the format string) */
64char *vasprintfrr(struct memtype *mt, const char *fmt, va_list) atm(2, 0);
65char *asprintfrr(struct memtype *mt, const char *fmt, ...) atm(2, 3);
66
67/* try to use provided buffer (presumably from stack), allocate if it's too
68 * short. Must call XFREE(mt, return value) if return value != out.
69 */
70char *vasnprintfrr(struct memtype *mt, char *out, size_t sz,
71 const char *fmt, va_list) atn(4, 0);
72char *asnprintfrr(struct memtype *mt, char *out, size_t sz,
73 const char *fmt, ...) atn(4, 5);
74
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75#define printfrr(fmt, ...) \
76 do { \
77 char buf[256], *out; \
78 out = asnprintfrr(MTYPE_TMP, buf, sizeof(buf), fmt, \
79 ##__VA_ARGS__); \
80 fputs(out, stdout); \
81 if (out != buf) \
82 XFREE(MTYPE_TMP, out); \
83 } while (0)
84
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85#undef at
86#undef atm
07ef3e34 87#undef atn
5c25bd87 88
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89/* extension specs must start with a capital letter (this is a restriction
90 * for both performance's and human understanding's sake.)
91 *
92 * Note that the entire thing mostly works because a letter directly following
93 * a %p print specifier is extremely unlikely to occur (why would you want to
94 * print "0x12345678HELLO"?) Normally, you'd expect spacing or punctuation
95 * after a placeholder. That also means that neither of those works well for
96 * extension purposes, e.g. "%p{foo}" is reasonable to see actually used.
97 *
98 * TODO: would be nice to support a "%pF%dF" specifier that consumes 2
99 * arguments, e.g. to pass an integer + a list of known values... can be
100 * done, but a bit tricky.
101 */
102#define printfrr_ext_char(ch) ((ch) >= 'A' && (ch) <= 'Z')
5c25bd87 103
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104struct printfrr_eargs;
105
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106struct printfrr_ext {
107 /* embedded string to minimize cache line pollution */
108 char match[8];
109
110 /* both can be given, if not the code continues searching
111 * (you can do %pX and %dX in 2 different entries)
112 *
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113 * return value: number of bytes that would be printed if the buffer
114 * was large enough. be careful about not under-reporting this;
115 * otherwise asnprintf() & co. will get broken. Returning -1 means
116 * something went wrong & default %p/%d handling should be executed.
bf4d3d80 117 *
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118 * to consume extra input flags after %pXY, increment *fmt. It points
119 * at the first character after %pXY at entry. Convention is to make
120 * those flags lowercase letters or numbers.
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121 */
122 ssize_t (*print_ptr)(struct fbuf *buf, struct printfrr_eargs *info,
123 const void *);
124 ssize_t (*print_int)(struct fbuf *buf, struct printfrr_eargs *info,
125 uintmax_t);
126};
127
128/* additional information passed to extended formatters */
129
130struct printfrr_eargs {
131 /* position in the format string. Points to directly after the
132 * extension specifier. Increment when consuming extra "flag
133 * characters".
134 */
135 const char *fmt;
136
137 /* %.1234x / %.*x
138 * not POSIX compatible when used with %p, will cause warnings from
139 * GCC & clang. Usable with %d. Not used by the printfrr() itself
140 * for extension specifiers, so essentially available as a "free"
141 * parameter. -1 if not specified. Value in the format string
142 * cannot be negative, but negative values can be passed with %.*x
143 */
144 int precision;
145
146 /* %1234x / %*x
147 * regular width specification. Internally handled by printfrr(), set
148 * to 0 if consumed by the extension in order to suppress standard
149 * width/padding behavior. 0 if not specified.
bf4d3d80 150 *
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151 * NB: always positive, even if a negative value is passed in with
152 * %*x. (The sign is used for the - flag.)
153 */
154 int width;
155
156 /* %#x
157 * "alternate representation" flag, not POSIX compatible when used
158 * with %p or %d, will cause warnings from GCC & clang. Not used by
159 * printfrr() itself for extension specifiers.
160 */
161 bool alt_repr;
162
163 /* %-x
164 * left-pad flag. Internally handled by printfrr() if width is
165 * nonzero. Only use if the extension sets width to 0.
bf4d3d80 166 */
3ea79430 167 bool leftadj;
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168};
169
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170/* for any extension that needs a buffer length */
171
172static inline ssize_t printfrr_ext_len(struct printfrr_eargs *ea)
173{
174 ssize_t rv;
175
176 if (ea->precision >= 0)
177 rv = ea->precision;
178 else if (ea->width >= 0) {
179 rv = ea->width;
180 ea->width = -1;
181 } else
182 rv = -1;
183
184 return rv;
185}
186
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187/* no locking - must be called when single threaded (e.g. at startup.)
188 * this restriction hopefully won't be a huge bother considering normal usage
189 * scenarios...
190 */
5c25bd87 191void printfrr_ext_reg(const struct printfrr_ext *);
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192
193#define printfrr_ext_autoreg_p(matchs, print_fn) \
3ea79430 194 static ssize_t print_fn(struct fbuf *, struct printfrr_eargs *, \
bf4d3d80 195 const void *); \
2b64873d 196 static const struct printfrr_ext _printext_##print_fn = { \
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197 .match = matchs, \
198 .print_ptr = print_fn, \
199 }; \
200 static void _printreg_##print_fn(void) __attribute__((constructor)); \
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201 static void _printreg_##print_fn(void) \
202 { \
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203 printfrr_ext_reg(&_printext_##print_fn); \
204 } \
54929fd3 205 MACRO_REQUIRE_SEMICOLON()
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206
207#define printfrr_ext_autoreg_i(matchs, print_fn) \
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208 static ssize_t print_fn(struct fbuf *, struct printfrr_eargs *, \
209 uintmax_t); \
2b64873d 210 static const struct printfrr_ext _printext_##print_fn = { \
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211 .match = matchs, \
212 .print_int = print_fn, \
213 }; \
214 static void _printreg_##print_fn(void) __attribute__((constructor)); \
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215 static void _printreg_##print_fn(void) \
216 { \
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217 printfrr_ext_reg(&_printext_##print_fn); \
218 } \
54929fd3 219 MACRO_REQUIRE_SEMICOLON()
5c25bd87 220
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221/* fbuf helper functions - note all 3 of these return the length that would
222 * be written regardless of how much space was available in the buffer, as
223 * needed for implementing printfrr extensions. (They also accept NULL buf
224 * for that.)
225 */
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226
227static inline ssize_t bputs(struct fbuf *buf, const char *str)
228{
229 size_t len = strlen(str);
230 size_t ncopy;
231
232 if (!buf)
233 return len;
234
235 ncopy = MIN(len, (size_t)(buf->buf + buf->len - buf->pos));
236 memcpy(buf->pos, str, ncopy);
237 buf->pos += ncopy;
238
239 return len;
240}
241
242static inline ssize_t bputch(struct fbuf *buf, char ch)
243{
244 if (buf && buf->pos < buf->buf + buf->len)
245 *buf->pos++ = ch;
246 return 1;
247}
248
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249static inline ssize_t bputhex(struct fbuf *buf, uint8_t val)
250{
251 static const char hexch[] = "0123456789abcdef";
252
253 if (buf && buf->pos < buf->buf + buf->len)
254 *buf->pos++ = hexch[(val >> 4) & 0xf];
255 if (buf && buf->pos < buf->buf + buf->len)
256 *buf->pos++ = hexch[val & 0xf];
257 return 2;
258}
259
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260/* %pVA extension, equivalent to Linux kernel %pV */
261
262struct va_format {
263 const char *fmt;
264 va_list *va;
265};
266
267#ifdef _FRR_ATTRIBUTE_PRINTFRR
bb12115e 268#pragma FRR printfrr_ext "%pFB" (struct fbuf *)
9c4380da 269#pragma FRR printfrr_ext "%pVA" (struct va_format *)
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270
271#pragma FRR printfrr_ext "%pHX" (signed char *)
272#pragma FRR printfrr_ext "%pHX" (unsigned char *)
273#pragma FRR printfrr_ext "%pHX" (void *)
274#pragma FRR printfrr_ext "%pHS" (signed char *)
275#pragma FRR printfrr_ext "%pHS" (unsigned char *)
276#pragma FRR printfrr_ext "%pHS" (void *)
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277
278#pragma FRR printfrr_ext "%pSE" (char *)
279#pragma FRR printfrr_ext "%pSQ" (char *)
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280
281#pragma FRR printfrr_ext "%pTS" (struct timespec *)
282#pragma FRR printfrr_ext "%pTV" (struct timeval *)
283#pragma FRR printfrr_ext "%pTT" (time_t *)
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284#endif
285
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286/* when using non-ISO-C compatible extension specifiers... */
287
288#ifdef _FRR_ATTRIBUTE_PRINTFRR
289#define FMT_NSTD_BEGIN
290#define FMT_NSTD_END
291#else /* !_FRR_ATTRIBUTE_PRINTFRR */
292#define FMT_NSTD_BEGIN \
293 _Pragma("GCC diagnostic push") \
294 _Pragma("GCC diagnostic ignored \"-Wformat\"") \
295 /* end */
296#define FMT_NSTD_END \
297 _Pragma("GCC diagnostic pop") \
298 /* end */
299#endif
300
301#define FMT_NSTD(expr) \
302 ({ \
cb4928ce 303 FMT_NSTD_BEGIN \
faaa9431 304 typeof(expr) _v; \
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305 _v = expr; \
306 FMT_NSTD_END \
307 _v; \
308 }) \
309 /* end */
310
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311#ifdef __cplusplus
312}
313#endif
314
5c25bd87 315#endif