kernel/linux.git/tools/include/nolibc/stdio.h, branch v7.1

tools/nolibc: add support for asprintf()

2026-04-06T17:46:51+00:00

Add support for dynamically allocating formatted strings through asprintf() and vasprintf(). Signed-off-by: Thomas Weißschuh Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260401-nolibc-asprintf-v1-3-46292313439f@weissschuh.net

tools/nolibc/printf: Support negative variable width and precision

2026-04-01T16:02:37+00:00

For (eg) "%*.*s" treat a negative field width as a request to left align the output (the same as the '-' flag), and a negative precision to request the default precision. Set the default precision to -1 (not INT_MAX) and add explicit checks to the string handling for negative values (makes the tet unsigned). For numeric output check for 'precision >= 0' instead of testing _NOLIBC_PF_FLAGS_CONTAIN(flags, '.'). This needs an inverted test, some extra goto and removes an indentation. The changed conditionals fix printf("%0-#o", 0) - but '0' and '-' shouldn't both be specified. Signed-off-by: David Laight Link: https://patch.msgid.link/20260323112247.3196-1-david.laight.linux@gmail.com Signed-off-by: Thomas Weißschuh

tools/nolibc/printf: Add support for octal output

2026-03-20T16:58:24+00:00

Octal output isn't often used, but adding it costs very little. Supporting "%#o" is mildly annoying, it has to add a leading '0' if there isn't one present. In simple cases this is the same as adding a sign of '0' - but that adds an extra '0' in a few places. So you need 3 tests, %o, # and no leading '0' (which can only be checked after the zero pad for precision). If all the test are deferred until after zero padding then too many values are 'live' across the call to _nolibc_u64toa_base() and get spilled to stack. Hence the check that ignores the 'sign' if it is the same as the first character of the output string. Add tests for octal output. Signed-off-by: David Laight Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260308113742.12649-17-david.laight.linux@gmail.com [Thomas: avoid a -Wsign-compare] Signed-off-by: Thomas Weißschuh

tools/nolibc/printf: Add support for zero padding and field precision

2026-03-20T16:58:10+00:00

Includes support for variable field widths (eg "%*.*d"). Zero padding is limited to 31 zero characters. This is wider than the largest numeric field so shouldn't be a problem. All the standard printf formats are now supported except octal and floating point. Add tests for new features Signed-off-by: David Laight Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260308113742.12649-16-david.laight.linux@gmail.com [Thomas: fixup testcases for musl libc] Signed-off-by: Thomas Weißschuh

tools/nolibc/printf: Add support for left aligning fields

2026-03-20T16:57:21+00:00

Output the characters before or after the pad - writing the pad takes more code. Include additional/changed tests Signed-off-by: David Laight Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260308113742.12649-15-david.laight.linux@gmail.com Signed-off-by: Thomas Weißschuh

tools/nolibc/printf: Special case 0 and add support for %#x

2026-03-20T16:57:08+00:00

The output for %#x is almost the same as that for %p, both output in hexadecimal with a leading "0x". However for zero %#x should just output "0" (the same as decimal and ocal). For %p match glibc and output "(nil)" rather than "0x0" or "0". Add tests for "%#x", "% d", "%+d" and passing NULL to "%p". Signed-off-by: David Laight Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260308113742.12649-14-david.laight.linux@gmail.com [Thomas: fix up testcases for musl libc] Signed-off-by: Thomas Weißschuh

tools/nolibc/printf: Add support for conversion flags space and plus

2026-03-20T16:55:52+00:00

Flags ' ' and '+' are sign characters for positive numbers. Signed-off-by: David Laight Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260308113742.12649-13-david.laight.linux@gmail.com Signed-off-by: Thomas Weißschuh

tools/nolibc/printf: Prepend sign to converted number

2026-03-20T16:55:51+00:00

Instead of appending the converted number to the sign, convert first and then prepend the sign (or "0x"). Use the length returned by u64toh_r() instead of calling strlen(). Needed so that zero padding can be inserted between the sign and digits in an upcoming patch. Signed-off-by: David Laight Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260308113742.12649-12-david.laight.linux@gmail.com Signed-off-by: Thomas Weißschuh

tools/nolibc/printf: Handle "%s" with the numeric formats

2026-03-20T16:55:50+00:00

Avoids the extra va_arg() call with is non-trivial on a lot of modern ABI. Signed-off-by: David Laight Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260308113742.12649-11-david.laight.linux@gmail.com Signed-off-by: Thomas Weißschuh

tools/nolibc/printf: Add support for length modifiers tzqL and formats iX

2026-03-20T16:55:28+00:00

Length modifiers t (ptrdiff_t) and z (size_t) are aliases for l (long), q and L are 64bit the same as j (intmax). Format i is an alias for d and X similar to x but upper case. Supporting them is mostly just adding the relevant bit to the bit pattern used for matching characters. Although %X is detected the output will be lower case. Change/add tests to use conversions i and X, and length modifiers L and ll. Use the correct minimum value for "%Li". Signed-off-by: David Laight Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260308113742.12649-10-david.laight.linux@gmail.com [Thomas: Fix up testcases for musl libc] Signed-off-by: Thomas Weißschuh