st

Mahdi's build of st
git clone git://mahdi.pw/st.git
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commit 1140859409ee1a2cf7d1b1ddd8482d04b758f46a
parent 6b63b6ef58c0628f2ac0918d916595778b6db391
Author: Mahdi Mirzade <me@mahdi.pw>
Date:   Tue, 12 Apr 2022 14:55:30 +0430

base64_digits: reduce scope, implicit zero, +1 size

the array is not accessed outside of base64dec() so it makes sense to
limit it's scope to the related function. the static-storage duration of
the array is kept intact.

this also removes unnecessary explicit zeroing from the start and end of
the array. anything that wasn't explicitly zero-ed will now be
implicitly zero-ed instead.

the validity of the new array can be easily confirmed via running this
trivial loop:

    for (int i = 0; i < 255; ++i)
        assert(base64_digits[i] == base64_digits_old[i]);

lastly, as pointed out by Roberto, the array needs to have 256 elements
in order to able access it as any unsigned char as an index; the
previous array had 255.

however, this array will only be accessed at indexes which are
isprint() || '=' (see `base64dec_getc()`), so reducing the size of the
array to the highest printable ascii char (127 AFAIK) + 1 might also be
a valid strategy.

Diffstat:
Mst.c | 22+++++++---------------
1 file changed, 7 insertions(+), 15 deletions(-)

diff --git a/st.c b/st.c @@ -390,21 +390,6 @@ utf8validate(Rune *u, size_t i) return i; } -static const char base64_digits[] = { - 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, - 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 62, 0, 0, 0, - 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 0, 0, 0, -1, 0, 0, 0, 0, 1, - 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, - 22, 23, 24, 25, 0, 0, 0, 0, 0, 0, 26, 27, 28, 29, 30, 31, 32, 33, 34, - 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 0, - 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, - 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, - 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, - 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, - 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, - 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 -}; - char base64dec_getc(const char **src) { @@ -418,6 +403,13 @@ base64dec(const char *src) { size_t in_len = strlen(src); char *result, *dst; + static const char base64_digits[256] = { + [43] = 62, 0, 0, 0, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, + 0, 0, 0, -1, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, + 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 0, 0, 0, 0, + 0, 0, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, + 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 + } if (in_len % 4) in_len += 4 - (in_len % 4);