kernel/linux.git/tools/include/nolibc/stdio.h, branch linux-7.0.y

tools/nolibc/printf: Move snprintf length check to callback

2026-05-23T11:08:32+00:00

[ Upstream commit 4045e7b19bbf7338452cda11e64cfe7ae3361964 ] Move output truncation to the snprintf() callback. This simplifies the main code and fixes truncation of padded fields. Add a zero length callback to 'finalise' the buffer rather than doing it in snprintf() itself. Fixes: e90ce42e81381 ("tools/nolibc: implement width padding in printf()") Signed-off-by: David Laight Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260302101815.3043-3-david.laight.linux@gmail.com [Thomas: clean up Fixes trailer] Signed-off-by: Thomas Weißschuh Signed-off-by: Sasha Levin

tools/nolibc/printf: Change variables 'c' to 'ch' and 'tmpbuf[]' to 'outbuf[]'

2026-05-23T11:08:32+00:00

[ Upstream commit f675ae28fcdf7db93a8c1a6964f062725b1e06a0 ] Changing 'c' makes the code slightly easier to read because the variable stands out from the single character literals (especially 'c'). Change tmpbuf[] to outbuf[] because 'out' points into it. The following patches pretty much rewrite the function so the churn is limited. Signed-off-by: David Laight Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260223101735.2922-7-david.laight.linux@gmail.com Signed-off-by: Thomas Weißschuh Stable-dep-of: 4045e7b19bbf ("tools/nolibc/printf: Move snprintf length check to callback") Signed-off-by: Sasha Levin

tools/nolibc: Add fseek() to stdio.h

2026-01-11T11:47:47+00:00

A very basic wrapper around lseek() that implements fseek(). Signed-off-by: Daniel Palmer Link: https://patch.msgid.link/20260105023629.1502801-3-daniel@thingy.jp Signed-off-by: Thomas Weißschuh

tools/nolibc: Add fread() to stdio.h

2026-01-11T11:47:47+00:00

Add a very basic version of fread() like we already have for fwrite(). Signed-off-by: Daniel Palmer Link: https://patch.msgid.link/20260105023629.1502801-2-daniel@thingy.jp Signed-off-by: Thomas Weißschuh

tools/nolibc: implement %m if errno is not defined

2025-10-29T15:29:15+00:00

For improved compatibility, print %m as "unknown error" when nolibc is compiled using NOLIBC_IGNORE_ERRNO. Signed-off-by: Benjamin Berg Signed-off-by: Thomas Weißschuh

tools/nolibc/stdio: let perror work when NOLIBC_IGNORE_ERRNO is set

2025-10-29T15:29:13+00:00

There is no errno variable when NOLIBC_IGNORE_ERRNO is defined. As such, simply print the message with "unknown error" rather than the integer value of errno. Fixes: acab7bcdb1bc ("tools/nolibc/stdio: add perror() to report the errno value") Signed-off-by: Benjamin Berg Signed-off-by: Thomas Weißschuh

selftests/nolibc: correctly report errors from printf() and friends

2025-07-06T09:02:40+00:00

When an error is encountered by printf() it needs to be reported. errno() is already set by the callback. sprintf() is different, but that keeps working and is already tested. Also add a new test. Fixes: 7e4346f4a3a6 ("tools/nolibc/stdio: add a minimal [vf]printf() implementation") Signed-off-by: Thomas Weißschuh Acked-by: Willy Tarreau Link: https://lore.kernel.org/r/20250704-nolibc-printf-error-v1-2-74b7a092433b@linutronix.de Signed-off-by: Thomas Weißschuh

tools/nolibc: add fopen()

2025-05-21T13:32:14+00:00

This is used in various selftests and will be handy when integrating those with nolibc. Only the standard POSIX modes are supported. No extensions nor the (noop) "b" from ISO C are accepted. Signed-off-by: Thomas Weißschuh Acked-by: Willy Tarreau Link: https://lore.kernel.org/r/20250428-nolibc-misc-v2-13-3c043eeab06c@linutronix.de Signed-off-by: Thomas Weißschuh

tools/nolibc: add %m printf format

2025-05-21T13:32:01+00:00

The %m format can be used to format the current errno. It is non-standard but supported by other commonly used libcs like glibc and musl, so applications do rely on them. Signed-off-by: Thomas Weißschuh Acked-by: Willy Tarreau Link: https://lore.kernel.org/r/20250428-nolibc-misc-v2-2-3c043eeab06c@linutronix.de Signed-off-by: Thomas Weißschuh

tools/nolibc: include nolibc.h early from all header files

2025-05-21T13:31:50+00:00

Inclusion of any nolibc header file should also bring all other headers. On the other hand it should also be possible to include any nolibc header files in any order. Currently this is implemented by including the catch-all nolibc.h after the headers own definitions. This is problematic if one nolibc header depends on another one. The first header has to include the other one before defining any symbols. That in turn will include the rest of nolibc while the current header has not defined anything yet. If any other part of nolibc depends on definitions from the current header, errors are encountered. This is already the case today. Effectively nolibc can only be included in the order of nolibc.h. Restructure the way "nolibc.h" is included. Move it to the beginning of the header files and before the include guards. Now any header will behave exactly like "nolibc.h" while the include guards prevent any duplicate definitions. Signed-off-by: Thomas Weißschuh Acked-by: Willy Tarreau Link: https://lore.kernel.org/r/20250424-nolibc-header-check-v1-2-011576b6ed6f@linutronix.de