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Fix padding+minus flag on numbers for printf-family functions (#787)

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The C standard states, for conversions using the d, i, b, B, o, u, x or X conversion specifiers:
> The precision specifies the minimum number of digits to appear; if
> the value being converted can be represented in fewer digits, it is
> expanded with leading zeros.
- C standard, 7.23.6.1. The fprintf function

However, cosmopolitan currently suppresses the addition of leading
zeros when the minus flag is set. This is not reflected by anything
within the C standard, meaning that behavior is incorrect.

This patch fixes this.
This commit is contained in:
Gabriel Ravier 2023-03-25 19:39:25 +01:00 • committed by GitHub
parent 2d6ea2fbc9
commit 792b1c84c0
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GPG key ID: 4AEE18F83AFDEB23
2 changed files with 30 additions and 13 deletions
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24
libc/fmt/ntoa.c
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@ -34,17 +34,15 @@ static int __fmt_ntoa_format(int out(const char *, void *, size_t), void *arg,
unsigned char flags) {
unsigned i;
/* pad leading zeros */
if (!(flags & FLAGS_LEFT)) {
if (width && (flags & FLAGS_ZEROPAD) &&
(negative || (flags & (FLAGS_PLUS | FLAGS_SPACE)))) {
width--;
}
while ((len < prec) && (len < BUFFER_SIZE)) {
buf[len++] = '0';
}
while ((flags & FLAGS_ZEROPAD) && (len < width) && (len < BUFFER_SIZE)) {
buf[len++] = '0';
}
if (width && (flags & FLAGS_ZEROPAD) &&
(negative || (flags & (FLAGS_PLUS | FLAGS_SPACE)))) {
width--;
}
while ((len < prec) && (len < BUFFER_SIZE)) {
buf[len++] = '0';
}
while ((flags & FLAGS_ZEROPAD) && (len < width) && (len < BUFFER_SIZE)) {
buf[len++] = '0';
}
/* handle hash */
if (flags & FLAGS_HASH) {
@ -134,8 +132,8 @@ int __fmt_ntoa(int out(const char *, void *, size_t), void *arg, va_list va,
bool neg;
uint128_t value, sign;
/* ignore '0' flag when prec is given */
if (flags & FLAGS_PRECISION) {
/* ignore '0' flag when prec or minus flag is given */
if (flags & (FLAGS_PRECISION | FLAGS_LEFT)) {
flags &= ~FLAGS_ZEROPAD;
}