xref: /linux/tools/include/nolibc/stdlib.h (revision 87807f77a03d0271211b75f84b2a8b88f4e8e5d4) 
1 /* SPDX-License-Identifier: LGPL-2.1 OR MIT */
2 /*
3  * stdlib function definitions for NOLIBC
4  * Copyright (C) 2017-2021 Willy Tarreau <w@1wt.eu>
5  */
6 
7 #ifndef _NOLIBC_STDLIB_H
8 #define _NOLIBC_STDLIB_H
9 
10 #include "std.h"
11 #include "arch.h"
12 #include "types.h"
13 #include "sys.h"
14 #include "string.h"
15 #include <linux/auxvec.h>
16 
17 struct nolibc_heap {
18 	size_t	len;
19 	char	user_p[] __attribute__((__aligned__));
20 };
21 
22 /* Buffer used to store int-to-ASCII conversions. Will only be implemented if
23  * any of the related functions is implemented. The area is large enough to
24  * store "18446744073709551615" or "-9223372036854775808" and the final zero.
25  */
26 static __attribute__((unused)) char itoa_buffer[21];
27 
28 /*
29  * As much as possible, please keep functions alphabetically sorted.
30  */
31 
32 /* must be exported, as it's used by libgcc for various divide functions */
33 __attribute__((weak,unused,noreturn,section(".text.nolibc_abort")))
34 void abort(void)
35 {
36 	sys_kill(sys_getpid(), SIGABRT);
37 	for (;;);
38 }
39 
40 static __attribute__((unused))
41 long atol(const char *s)
42 {
43 	unsigned long ret = 0;
44 	unsigned long d;
45 	int neg = 0;
46 
47 	if (*s == '-') {
48 		neg = 1;
49 		s++;
50 	}
51 
52 	while (1) {
53 		d = (*s++) - '0';
54 		if (d > 9)
55 			break;
56 		ret *= 10;
57 		ret += d;
58 	}
59 
60 	return neg ? -ret : ret;
61 }
62 
63 static __attribute__((unused))
64 int atoi(const char *s)
65 {
66 	return atol(s);
67 }
68 
69 static __attribute__((unused))
70 void free(void *ptr)
71 {
72 	struct nolibc_heap *heap;
73 
74 	if (!ptr)
75 		return;
76 
77 	heap = container_of(ptr, struct nolibc_heap, user_p);
78 	munmap(heap, heap->len);
79 }
80 
81 /* getenv() tries to find the environment variable named <name> in the
82  * environment array pointed to by global variable "environ" which must be
83  * declared as a char **, and must be terminated by a NULL (it is recommended
84  * to set this variable to the "envp" argument of main()). If the requested
85  * environment variable exists its value is returned otherwise NULL is
86  * returned. getenv() is forcefully inlined so that the reference to "environ"
87  * will be dropped if unused, even at -O0.
88  */
89 static __attribute__((unused))
90 char *_getenv(const char *name, char **environ)
91 {
92 	int idx, i;
93 
94 	if (environ) {
95 		for (idx = 0; environ[idx]; idx++) {
96 			for (i = 0; name[i] && name[i] == environ[idx][i];)
97 				i++;
98 			if (!name[i] && environ[idx][i] == '=')
99 				return &environ[idx][i+1];
100 		}
101 	}
102 	return NULL;
103 }
104 
105 static inline __attribute__((unused,always_inline))
106 char *getenv(const char *name)
107 {
108 	extern char **environ;
109 	return _getenv(name, environ);
110 }
111 
112 static __attribute__((unused))
113 unsigned long getauxval(unsigned long type)
114 {
115 	const unsigned long *auxv = _auxv;
116 	unsigned long ret;
117 
118 	if (!auxv)
119 		return 0;
120 
121 	while (1) {
122 		if (!auxv[0] && !auxv[1]) {
123 			ret = 0;
124 			break;
125 		}
126 
127 		if (auxv[0] == type) {
128 			ret = auxv[1];
129 			break;
130 		}
131 
132 		auxv += 2;
133 	}
134 
135 	return ret;
136 }
137 
138 static __attribute__((unused))
139 void *malloc(size_t len)
140 {
141 	struct nolibc_heap *heap;
142 
143 	/* Always allocate memory with size multiple of 4096. */
144 	len  = sizeof(*heap) + len;
145 	len  = (len + 4095UL) & -4096UL;
146 	heap = mmap(NULL, len, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE,
147 		    -1, 0);
148 	if (__builtin_expect(heap == MAP_FAILED, 0))
149 		return NULL;
150 
151 	heap->len = len;
152 	return heap->user_p;
153 }
154 
155 static __attribute__((unused))
156 void *calloc(size_t size, size_t nmemb)
157 {
158 	size_t x = size * nmemb;
159 
160 	if (__builtin_expect(size && ((x / size) != nmemb), 0)) {
161 		SET_ERRNO(ENOMEM);
162 		return NULL;
163 	}
164 
165 	/*
166 	 * No need to zero the heap, the MAP_ANONYMOUS in malloc()
167 	 * already does it.
168 	 */
169 	return malloc(x);
170 }
171 
172 static __attribute__((unused))
173 void *realloc(void *old_ptr, size_t new_size)
174 {
175 	struct nolibc_heap *heap;
176 	size_t user_p_len;
177 	void *ret;
178 
179 	if (!old_ptr)
180 		return malloc(new_size);
181 
182 	heap = container_of(old_ptr, struct nolibc_heap, user_p);
183 	user_p_len = heap->len - sizeof(*heap);
184 	/*
185 	 * Don't realloc() if @user_p_len >= @new_size, this block of
186 	 * memory is still enough to handle the @new_size. Just return
187 	 * the same pointer.
188 	 */
189 	if (user_p_len >= new_size)
190 		return old_ptr;
191 
192 	ret = malloc(new_size);
193 	if (__builtin_expect(!ret, 0))
194 		return NULL;
195 
196 	memcpy(ret, heap->user_p, heap->len);
197 	munmap(heap, heap->len);
198 	return ret;
199 }
200 
201 /* Converts the unsigned long integer <in> to its hex representation into
202  * buffer <buffer>, which must be long enough to store the number and the
203  * trailing zero (17 bytes for "ffffffffffffffff" or 9 for "ffffffff"). The
204  * buffer is filled from the first byte, and the number of characters emitted
205  * (not counting the trailing zero) is returned. The function is constructed
206  * in a way to optimize the code size and avoid any divide that could add a
207  * dependency on large external functions.
208  */
209 static __attribute__((unused))
210 int utoh_r(unsigned long in, char *buffer)
211 {
212 	signed char pos = (~0UL > 0xfffffffful) ? 60 : 28;
213 	int digits = 0;
214 	int dig;
215 
216 	do {
217 		dig = in >> pos;
218 		in -= (uint64_t)dig << pos;
219 		pos -= 4;
220 		if (dig || digits || pos < 0) {
221 			if (dig > 9)
222 				dig += 'a' - '0' - 10;
223 			buffer[digits++] = '0' + dig;
224 		}
225 	} while (pos >= 0);
226 
227 	buffer[digits] = 0;
228 	return digits;
229 }
230 
231 /* converts unsigned long <in> to an hex string using the static itoa_buffer
232  * and returns the pointer to that string.
233  */
234 static inline __attribute__((unused))
235 char *utoh(unsigned long in)
236 {
237 	utoh_r(in, itoa_buffer);
238 	return itoa_buffer;
239 }
240 
241 /* Converts the unsigned long integer <in> to its string representation into
242  * buffer <buffer>, which must be long enough to store the number and the
243  * trailing zero (21 bytes for 18446744073709551615 in 64-bit, 11 for
244  * 4294967295 in 32-bit). The buffer is filled from the first byte, and the
245  * number of characters emitted (not counting the trailing zero) is returned.
246  * The function is constructed in a way to optimize the code size and avoid
247  * any divide that could add a dependency on large external functions.
248  */
249 static __attribute__((unused))
250 int utoa_r(unsigned long in, char *buffer)
251 {
252 	unsigned long lim;
253 	int digits = 0;
254 	int pos = (~0UL > 0xfffffffful) ? 19 : 9;
255 	int dig;
256 
257 	do {
258 		for (dig = 0, lim = 1; dig < pos; dig++)
259 			lim *= 10;
260 
261 		if (digits || in >= lim || !pos) {
262 			for (dig = 0; in >= lim; dig++)
263 				in -= lim;
264 			buffer[digits++] = '0' + dig;
265 		}
266 	} while (pos--);
267 
268 	buffer[digits] = 0;
269 	return digits;
270 }
271 
272 /* Converts the signed long integer <in> to its string representation into
273  * buffer <buffer>, which must be long enough to store the number and the
274  * trailing zero (21 bytes for -9223372036854775808 in 64-bit, 12 for
275  * -2147483648 in 32-bit). The buffer is filled from the first byte, and the
276  * number of characters emitted (not counting the trailing zero) is returned.
277  */
278 static __attribute__((unused))
279 int itoa_r(long in, char *buffer)
280 {
281 	char *ptr = buffer;
282 	int len = 0;
283 
284 	if (in < 0) {
285 		in = -in;
286 		*(ptr++) = '-';
287 		len++;
288 	}
289 	len += utoa_r(in, ptr);
290 	return len;
291 }
292 
293 /* for historical compatibility, same as above but returns the pointer to the
294  * buffer.
295  */
296 static inline __attribute__((unused))
297 char *ltoa_r(long in, char *buffer)
298 {
299 	itoa_r(in, buffer);
300 	return buffer;
301 }
302 
303 /* converts long integer <in> to a string using the static itoa_buffer and
304  * returns the pointer to that string.
305  */
306 static inline __attribute__((unused))
307 char *itoa(long in)
308 {
309 	itoa_r(in, itoa_buffer);
310 	return itoa_buffer;
311 }
312 
313 /* converts long integer <in> to a string using the static itoa_buffer and
314  * returns the pointer to that string. Same as above, for compatibility.
315  */
316 static inline __attribute__((unused))
317 char *ltoa(long in)
318 {
319 	itoa_r(in, itoa_buffer);
320 	return itoa_buffer;
321 }
322 
323 /* converts unsigned long integer <in> to a string using the static itoa_buffer
324  * and returns the pointer to that string.
325  */
326 static inline __attribute__((unused))
327 char *utoa(unsigned long in)
328 {
329 	utoa_r(in, itoa_buffer);
330 	return itoa_buffer;
331 }
332 
333 /* Converts the unsigned 64-bit integer <in> to its hex representation into
334  * buffer <buffer>, which must be long enough to store the number and the
335  * trailing zero (17 bytes for "ffffffffffffffff"). The buffer is filled from
336  * the first byte, and the number of characters emitted (not counting the
337  * trailing zero) is returned. The function is constructed in a way to optimize
338  * the code size and avoid any divide that could add a dependency on large
339  * external functions.
340  */
341 static __attribute__((unused))
342 int u64toh_r(uint64_t in, char *buffer)
343 {
344 	signed char pos = 60;
345 	int digits = 0;
346 	int dig;
347 
348 	do {
349 		if (sizeof(long) >= 8) {
350 			dig = (in >> pos) & 0xF;
351 		} else {
352 			/* 32-bit platforms: avoid a 64-bit shift */
353 			uint32_t d = (pos >= 32) ? (in >> 32) : in;
354 			dig = (d >> (pos & 31)) & 0xF;
355 		}
356 		if (dig > 9)
357 			dig += 'a' - '0' - 10;
358 		pos -= 4;
359 		if (dig || digits || pos < 0)
360 			buffer[digits++] = '0' + dig;
361 	} while (pos >= 0);
362 
363 	buffer[digits] = 0;
364 	return digits;
365 }
366 
367 /* converts uint64_t <in> to an hex string using the static itoa_buffer and
368  * returns the pointer to that string.
369  */
370 static inline __attribute__((unused))
371 char *u64toh(uint64_t in)
372 {
373 	u64toh_r(in, itoa_buffer);
374 	return itoa_buffer;
375 }
376 
377 /* Converts the unsigned 64-bit integer <in> to its string representation into
378  * buffer <buffer>, which must be long enough to store the number and the
379  * trailing zero (21 bytes for 18446744073709551615). The buffer is filled from
380  * the first byte, and the number of characters emitted (not counting the
381  * trailing zero) is returned. The function is constructed in a way to optimize
382  * the code size and avoid any divide that could add a dependency on large
383  * external functions.
384  */
385 static __attribute__((unused))
386 int u64toa_r(uint64_t in, char *buffer)
387 {
388 	unsigned long long lim;
389 	int digits = 0;
390 	int pos = 19; /* start with the highest possible digit */
391 	int dig;
392 
393 	do {
394 		for (dig = 0, lim = 1; dig < pos; dig++)
395 			lim *= 10;
396 
397 		if (digits || in >= lim || !pos) {
398 			for (dig = 0; in >= lim; dig++)
399 				in -= lim;
400 			buffer[digits++] = '0' + dig;
401 		}
402 	} while (pos--);
403 
404 	buffer[digits] = 0;
405 	return digits;
406 }
407 
408 /* Converts the signed 64-bit integer <in> to its string representation into
409  * buffer <buffer>, which must be long enough to store the number and the
410  * trailing zero (21 bytes for -9223372036854775808). The buffer is filled from
411  * the first byte, and the number of characters emitted (not counting the
412  * trailing zero) is returned.
413  */
414 static __attribute__((unused))
415 int i64toa_r(int64_t in, char *buffer)
416 {
417 	char *ptr = buffer;
418 	int len = 0;
419 
420 	if (in < 0) {
421 		in = -in;
422 		*(ptr++) = '-';
423 		len++;
424 	}
425 	len += u64toa_r(in, ptr);
426 	return len;
427 }
428 
429 /* converts int64_t <in> to a string using the static itoa_buffer and returns
430  * the pointer to that string.
431  */
432 static inline __attribute__((unused))
433 char *i64toa(int64_t in)
434 {
435 	i64toa_r(in, itoa_buffer);
436 	return itoa_buffer;
437 }
438 
439 /* converts uint64_t <in> to a string using the static itoa_buffer and returns
440  * the pointer to that string.
441  */
442 static inline __attribute__((unused))
443 char *u64toa(uint64_t in)
444 {
445 	u64toa_r(in, itoa_buffer);
446 	return itoa_buffer;
447 }
448 
449 /* make sure to include all global symbols */
450 #include "nolibc.h"
451 
452 #endif /* _NOLIBC_STDLIB_H */
453