Skip to content

libc: minimal: add missing ctype.h functions #99451

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 3 commits into
base: main
Choose a base branch
from
+31 −11
Open

libc: minimal: add missing ctype.h functions #99451

Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
d2e5a0c
libc: minimal: ctype: use unsigned int instead of unsigned
cfriedt Nov 16, 2025
8c0261d
libc: minimal: ctype: express ctype limits in more direct fashion
cfriedt Nov 16, 2025
c99031e
libc: minimal: add missing ctype.h functions
cfriedt Nov 15, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
42 changes: 31 additions & 11 deletions lib/libc/minimal/include/ctype.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -15,42 +15,57 @@ extern "C" {

static inline int isupper(int a)
{
return (int)(((unsigned)(a)-(unsigned)'A') < 26U);
return (int)(((int)'A' <= a) && (a <= (int)'Z'));
Copy link
Contributor

@keith-packard keith-packard Nov 16, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

You don't need any casts in this expression -- character constants are of type int, the relational operators result is of type int and the logical AND operator result is of type int. This should be just return 'A' <= a && a <= 'Z';
Feel free to add parentheses if you like, they aren't required as the precedence works correctly for this case.

}

static inline int isalpha(int c)
{
return (int)((((unsigned)c|32u)-(unsigned)'a') < 26U);
/* force to lowercase */
c |= 32U;

return (int)(((int)'a' <= c) && (c <= (int)'z'));
}

static inline int isblank(int c)
{
return (int)((c == (int)' ') || (c == (int)'\t'));
}

static inline int isspace(int c)
Copy link
Contributor

@keith-packard keith-packard Nov 15, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I'd let the compiler do something cute if it likes, but express these in a direct fashion.

static inline int isspace (int c)
{
    return c == ' ' || ('\t' <= c && c <= '\r');
}

Similarly for the other functions. There's no reason to obscure what these functions do; having to check that there are 5 'blank' values between '\t' and '\r' is something the compiler should do, not us.

Copy link
Member Author

@cfriedt cfriedt Nov 16, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I'll prepend a commit for that, since it's technically not related to the bugfix.

Copy link
Member Author

@cfriedt cfriedt Nov 16, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I could also prepend a commit that would eliminate linter issues as well (and fix up the commit I added).

{
return (int)(c == (int)' ' || ((unsigned)c-(unsigned)'\t') < 5U);
return (int)((c == (int)' ') || (((int)'\t' <= c) && (c <= (int)'\r')));
}

static inline int isgraph(int c)
{
return (int)((((unsigned)c) > ' ') &&
(((unsigned)c) <= (unsigned)'~'));
return (int)(((int)' ' < c) && (c <= (int)'~'));
}

static inline int isprint(int c)
{
return (int)((((unsigned)c) >= ' ') &&
(((unsigned)c) <= (unsigned)'~'));
return (int)(((int)' ' <= c) && (c <= (int)'~'));
}

static inline int isdigit(int a)
{
return (int)(((unsigned)(a)-(unsigned)'0') < 10U);
return (int)(((int)'0' <= a) && (a <= (int)'9'));
}

static inline int islower(int c)
{
return (int)(((int)'a' <= c) && (c <= (int)'z'));
}

static inline int isxdigit(int a)
{
unsigned int ua = (unsigned int)a;
if (isdigit(a) != 0) {
return 1;
}

/* force to lowercase */
a |= 32U;
Copy link
Contributor

@keith-packard keith-packard Nov 16, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

tolower uses addition instead of bitwise OR; I'd be consistent here.


return (int)(((ua - (unsigned)'0') < 10U) ||
((ua | 32U) - (unsigned)'a' < 6U));
return (int)(((int)'a' <= a) && (a <= (int)'f'));
}

static inline int tolower(int chr)
Expand All @@ -69,6 +84,11 @@ static inline int isalnum(int chr)
return (int)(isalpha(chr) || isdigit(chr));
}

static inline int ispunct(int c)
{
return (int)(isgraph(c) && !isalnum(c));
}

static inline int iscntrl(int c)
{
return (int)((((unsigned int)c) <= 31U) || (((unsigned int)c) == 127U));
Expand Down