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From: Willy Tarreau <w@1wt.eu>
To: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Mark Brown <broonie@kernel.org>,
	linux-kernel@vger.kernel.org, Willy Tarreau <w@1wt.eu>
Subject: [PATCH 41/42] tools/nolibc: also mention how to build by just setting the include path
Date: Mon,  7 Feb 2022 17:23:53 +0100	[thread overview]
Message-ID: <20220207162354.14293-42-w@1wt.eu> (raw)
In-Reply-To: <20220207162354.14293-1-w@1wt.eu>

Now that a few basic include files are provided, some simple portable
programs may build, which will save them from having to surround their
includes with #ifndef NOLIBC. This patch mentions how to proceed, and
enumerates the list of files that are covered.

A comprehensive list of required include files is available here:

  https://en.cppreference.com/w/c/header

Signed-off-by: Willy Tarreau <w@1wt.eu>
---
 tools/include/nolibc/nolibc.h | 30 ++++++++++++++++++++----------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/tools/include/nolibc/nolibc.h b/tools/include/nolibc/nolibc.h
index 561dcdb83cee..b2bc48d3cfe4 100644
--- a/tools/include/nolibc/nolibc.h
+++ b/tools/include/nolibc/nolibc.h
@@ -57,22 +57,32 @@
  * having to specify anything.
  *
  * Finally some very common libc-level functions are provided. It is the case
- * for a few functions usually found in string.h, ctype.h, or stdlib.h. Nothing
- * is currently provided regarding stdio emulation.
+ * for a few functions usually found in string.h, ctype.h, or stdlib.h.
  *
- * The macro NOLIBC is always defined, so that it is possible for a program to
- * check this macro to know if it is being built against and decide to disable
- * some features or simply not to include some standard libc files.
- *
- * Ideally this file should be split in multiple files for easier long term
- * maintenance, but provided as a single file as it is now, it's quite
- * convenient to use. Maybe some variations involving a set of includes at the
- * top could work.
+ * The nolibc.h file is only a convenient entry point which includes all other
+ * files. It also defines the NOLIBC macro, so that it is possible for a
+ * program to check this macro to know if it is being built against and decide
+ * to disable some features or simply not to include some standard libc files.
  *
  * A simple static executable may be built this way :
  *      $ gcc -fno-asynchronous-unwind-tables -fno-ident -s -Os -nostdlib \
  *            -static -include nolibc.h -o hello hello.c -lgcc
  *
+ * Simple programs meant to be reasonably portable to various libc and using
+ * only a few common includes, may also be built by simply making the include
+ * path point to the nolibc directory:
+ *      $ gcc -fno-asynchronous-unwind-tables -fno-ident -s -Os -nostdlib \
+ *            -I../nolibc -o hello hello.c -lgcc
+ *
+ * The available standard (but limited) include files are:
+ *   ctype.h, errno.h, signal.h, stdio.h, stdlib.h, string.h, time.h
+ *
+ * In addition, the following ones are expected to be provided by the compiler:
+ *   float.h, stdarg.h, stddef.h
+ *
+ * The following ones which are part to the C standard are not provided:
+ *   assert.h, locale.h, math.h, setjmp.h, limits.h
+ *
  * A very useful calling convention table may be found here :
  *      http://man7.org/linux/man-pages/man2/syscall.2.html
  *
-- 
2.35.1


  parent reply	other threads:[~2022-02-07 16:31 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-07 16:23 [PATCH 00/42] nolibc: update to resync with out-of-tree project Willy Tarreau
2022-02-07 16:23 ` [PATCH 01/42] tools/nolibc: use pselect6 on RISCV Willy Tarreau
2022-02-07 16:23 ` [PATCH 02/42] tools/nolibc: guard the main file against multiple inclusion Willy Tarreau
2022-02-07 16:23 ` [PATCH 03/42] tools/nolibc/std: move the standard type definitions to std.h Willy Tarreau
2022-02-07 16:23 ` [PATCH 04/42] tools/nolibc/types: split syscall-specific definitions into their own files Willy Tarreau
2022-02-07 16:23 ` [PATCH 05/42] tools/nolibc/arch: split arch-specific code into individual files Willy Tarreau
2022-02-07 16:23 ` [PATCH 06/42] tools/nolibc/sys: split the syscall definitions into their own file Willy Tarreau
2022-02-07 16:23 ` [PATCH 07/42] tools/nolibc/stdlib: extract the stdlib-specific functions to " Willy Tarreau
2022-02-07 16:23 ` [PATCH 08/42] tools/nolibc/string: split the string functions into string.h Willy Tarreau
2022-02-07 16:23 ` [PATCH 09/42] tools/nolibc/ctype: split the is* functions to ctype.h Willy Tarreau
2022-02-07 16:23 ` [PATCH 10/42] tools/nolibc/ctype: add the missing is* functions Willy Tarreau
2022-02-07 16:23 ` [PATCH 11/42] tools/nolibc/types: move the FD_* functions to macros in types.h Willy Tarreau
2022-02-07 17:05   ` David Laight
2022-02-08  5:14     ` Willy Tarreau
2022-02-13  8:52   ` [PATCH v2 " Willy Tarreau
2022-02-07 16:23 ` [PATCH 12/42] tools/nolibc/types: make FD_SETSIZE configurable Willy Tarreau
2022-02-13  8:53   ` [PATCH v2 " Willy Tarreau
2022-02-14 20:17     ` Paul E. McKenney
2022-02-07 16:23 ` [PATCH 13/42] tools/nolibc/types: move makedev to types.h and make it a macro Willy Tarreau
2022-02-07 16:23 ` [PATCH 14/42] tools/nolibc/stdlib: move ltoa() to stdlib.h Willy Tarreau
2022-02-07 16:23 ` [PATCH 15/42] tools/nolibc/stdlib: replace the ltoa() function with more efficient ones Willy Tarreau
2022-02-07 16:23 ` [PATCH 16/42] tools/nolibc/stdlib: add i64toa() and u64toa() Willy Tarreau
2022-02-07 16:23 ` [PATCH 17/42] tools/nolibc/stdlib: add utoh() and u64toh() Willy Tarreau
2022-02-07 16:23 ` [PATCH 18/42] tools/nolibc/stdio: add a minimal set of stdio functions Willy Tarreau
2022-02-07 16:23 ` [PATCH 19/42] tools/nolibc/stdio: add stdin/stdout/stderr and fget*/fput* functions Willy Tarreau
2022-02-07 16:23 ` [PATCH 20/42] tools/nolibc/stdio: add fwrite() to stdio Willy Tarreau
2022-02-07 16:23 ` [PATCH 21/42] tools/nolibc/stdio: add a minimal [vf]printf() implementation Willy Tarreau
2022-02-07 16:23 ` [PATCH 22/42] tools/nolibc/types: define EXIT_SUCCESS and EXIT_FAILURE Willy Tarreau
2022-02-07 16:23 ` [PATCH 23/42] tools/nolibc/stdio: add perror() to report the errno value Willy Tarreau
2022-02-07 16:23 ` [PATCH 24/42] tools/nolibc/sys: make open() take a vararg on the 3rd argument Willy Tarreau
2022-02-07 16:23 ` [PATCH 25/42] tools/nolibc/stdlib: avoid a 64-bit shift in u64toh_r() Willy Tarreau
2022-02-07 16:23 ` [PATCH 26/42] tools/nolibc/stdlib: make raise() use the lower level syscalls only Willy Tarreau
2022-02-07 16:23 ` [PATCH 27/42] tools/nolibc/sys: make getpgrp(), getpid(), gettid() not set errno Willy Tarreau
2022-02-07 16:23 ` [PATCH 28/42] tools/nolibc/string: use unidirectional variants for memcpy() Willy Tarreau
2022-02-07 16:23 ` [PATCH 29/42] tools/nolibc/string: slightly simplify memmove() Willy Tarreau
2022-02-07 16:23 ` [PATCH 30/42] tools/nolibc/string: add strncpy() and strlcpy() Willy Tarreau
2022-02-07 16:23 ` [PATCH 31/42] tools/nolibc/string: add tiny versions of strncat() and strlcat() Willy Tarreau
2022-02-07 16:23 ` [PATCH 32/42] tools/nolibc: move exported functions to their own section Willy Tarreau
2022-02-07 16:23 ` [PATCH 33/42] tools/nolibc/arch: mark the _start symbol as weak Willy Tarreau
2022-02-07 16:23 ` [PATCH 34/42] tools/nolibc/types: define PATH_MAX and MAXPATHLEN Willy Tarreau
2022-02-07 16:23 ` [PATCH 35/42] tools/nolibc/string: export memset() and memmove() Willy Tarreau
2022-02-07 16:23 ` [PATCH 36/42] tools/nolibc/errno: extract errno.h from sys.h Willy Tarreau
2022-02-07 16:23 ` [PATCH 37/42] tools/nolibc/unistd: extract msleep(), sleep(), tcsetpgrp() to unistd.h Willy Tarreau
2022-02-07 16:23 ` [PATCH 38/42] tools/nolibc/unistd: add usleep() Willy Tarreau
2022-02-07 16:23 ` [PATCH 39/42] tools/nolibc/signal: move raise() to signal.h Willy Tarreau
2022-02-07 16:23 ` [PATCH 40/42] tools/nolibc/time: create time.h with time() Willy Tarreau
2022-02-07 16:23 ` Willy Tarreau [this message]
2022-02-07 16:23 ` [PATCH 42/42] tools/nolibc/stdlib: implement abort() Willy Tarreau
2022-02-08  0:00 ` [PATCH 00/42] nolibc: update to resync with out-of-tree project Paul E. McKenney
2022-02-08  4:41   ` Willy Tarreau
2022-02-08  5:10     ` Paul E. McKenney

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