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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.

ref. https://git.suckless.org/st/commit/ef0551932fb162f907b40185d2f48c3b497708ee.html
This commit is contained in:
bakkeby 2022-03-28 11:23:52 +02:00
parent addd5e9749
commit d8ec7a396c
2 changed files with 8 additions and 16 deletions
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2
README.md
View File

@ -1,4 +1,4 @@
Similar to [dwm-flexipatch](https://github.com/bakkeby/dwm-flexipatch) this st 0.8.5 (2aefa34, 2022-03-13) project has a different take on st patching. It uses preprocessor directives to decide whether or not to include a patch during build time. Essentially this means that this build, for better or worse, contains both the patched _and_ the original code. The aim being that you can select which patches to include and the build will contain that code and nothing more. Similar to [dwm-flexipatch](https://github.com/bakkeby/dwm-flexipatch) this st 0.8.5 (ef05519, 2022-03-18) project has a different take on st patching. It uses preprocessor directives to decide whether or not to include a patch during build time. Essentially this means that this build, for better or worse, contains both the patched _and_ the original code. The aim being that you can select which patches to include and the build will contain that code and nothing more.
For example to include the `alpha` patch then you would only need to flip this setting from 0 to 1 in [patches.h](https://github.com/bakkeby/st-flexipatch/blob/master/patches.def.h): For example to include the `alpha` patch then you would only need to flip this setting from 0 to 1 in [patches.h](https://github.com/bakkeby/st-flexipatch/blob/master/patches.def.h):
```c ```c

22
st.c
View File

@ -379,21 +379,6 @@ utf8validate(Rune *u, size_t i)
return 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 char
base64dec_getc(const char **src) base64dec_getc(const char **src)
{ {
@ -407,6 +392,13 @@ base64dec(const char *src)
{ {
size_t in_len = strlen(src); size_t in_len = strlen(src);
char *result, *dst; 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) if (in_len % 4)
in_len += 4 - (in_len % 4); in_len += 4 - (in_len % 4);