cosmopolitan/libc/fmt/atoi.c
Justine Tunney e557058ac8
Improve cosmo's conformance to libc-test
This change addresses various open source compatibility issues, so that
we pass 313/411 of the tests in https://github.com/jart/libc-test where
earlier today we were passing about 30/411 of them, due to header toil.
Please note that Glibc only passes 341/411 so 313 today is pretty good!

- Make the conformance of libc/isystem/ headers nearly perfect
- Import more of the remaining math library routines from Musl
- Fix inconsistencies with type signatures of calls like umask
- Write tests for getpriority/setpriority which work great now
- conform to `struct sockaddr *` on remaining socket functions
- Import a bunch of uninteresting stdlib functions e.g. rand48
- Introduce readdir_r, scandir, pthread_kill, sigsetjmp, etc..

Follow the instructions in our `tool/scripts/cosmocc` toolchain to run
these tests yourself. You use `make CC=cosmocc` on the test repository
2022-10-10 17:52:41 -07:00

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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
'-'│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/errno.h"
#include "libc/fmt/conv.h"
#include "libc/limits.h"
#include "libc/str/str.h"
/**
* Decodes decimal integer from ASCII string.
*
* atoi 10⁸ 22𝑐 7𝑛𝑠
* strtol 10⁸ 37𝑐 12𝑛𝑠
* strtoul 10⁸ 35𝑐 11𝑛𝑠
* wcstol 10⁸ 30𝑐 10𝑛𝑠
* wcstoul 10⁸ 30𝑐 10𝑛𝑠
* strtoimax 10⁸ 80𝑐 26𝑛𝑠
* strtoumax 10⁸ 78𝑐 25𝑛𝑠
* wcstoimax 10⁸ 77𝑐 25𝑛𝑠
* wcstoumax 10⁸ 76𝑐 25𝑛𝑠
*
* @param s is a non-null nul-terminated string
* @return the decoded signed saturated integer
* @raise ERANGE on overflow
*/
int atoi(const char *s) {
int x, c, d;
do {
c = *s++;
} while (c == ' ' || c == '\t');
d = c == '-' ? -1 : 1;
if (c == '-' || c == '+') c = *s++;
for (x = 0; isdigit(c); c = *s++) {
if (__builtin_mul_overflow(x, 10, &x) ||
__builtin_add_overflow(x, (c - '0') * d, &x)) {
errno = ERANGE;
if (d > 0) {
return INT_MAX;
} else {
return INT_MIN;
}
}
}
return x;
}