From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailtransmit04.runbox.com (mailtransmit04.runbox.com [185.226.149.37]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 72F961A9F94 for ; Mon, 23 Feb 2026 10:35:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.226.149.37 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771842945; cv=none; b=nckX7WTEHbZyv0EfJvMRmbaNqzR/yxZ+1GLJlIdY6YlkCtPYqaq6m2kgksR1MZFqE621IYKrpDJdkjVGFDMzd078TEqLp04rTURc+lZjJdGQQRLe0TE0wSCZyeMSwYewVHMEuH1abVKSMIEbgVfJiDJPK9iL1yed829qPeCXtJs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771842945; c=relaxed/simple; bh=axkRjll/NjKc2b5GtSz0IVv9kHyIHeKYwF9Y6Ttb2rQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=pHLTTxK8lYTpNAswMViEXr51UFnaGVc36Qlsl0Oq656osCsavpK7AMgNNaU16gGKuKoiPz7O9mermi1CX79QxniI4UYm4k7PZAi/qZSvXaGuWmkON2+XgOeLkOmxwCaDVx62j0TjO6x+dwtKtBekdJ2k+tzTNugk2YFF06wMnu4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=runbox.com; dkim=pass (2048-bit key) header.d=runbox.com header.i=@runbox.com header.b=DEBvg5M6; arc=none smtp.client-ip=185.226.149.37 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=runbox.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=runbox.com header.i=@runbox.com header.b="DEBvg5M6" Received: from mailtransmit02.runbox ([10.9.9.162] helo=aibo.runbox.com) by mailtransmit04.runbox.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.93) (envelope-from ) id 1vuT1F-00Ggpk-DE; Mon, 23 Feb 2026 11:18:25 +0100 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=runbox.com; s=selector2; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To :Message-Id:Date:Subject:Cc:To:From; bh=23LayPfrort6veHcKA3M54nlZOnM5X+LunSZttk0Bk4=; b=DEBvg5M6uWEshpEiQDPn4+CWHK IgG/HN/YWsk6QUs3o+D89nKjM8z5dQlVBs56QsFsdimlfEtkZMIfc/7RPwHDjmu1Y9aNbjP1/cmL9 05vl24noeHl6fFJ4bLy/5SSTIMG630gnotm1yeR+CrGFI577womHLKIufdRs1dCb32jxgfXA7TMQr OKOIsEurngfjJJYDPrrW6EjVeqCsXRW5wZzE2UzVMG5f1rmSJ5siVXZIqAlQNtBDj76dabKgDf5gc 3jn9PNdIjAHU/sWzN+GJroMq82wSbKgaT1VxNFVrTIifP0koVmOYnzAUZ1A6NZ8M1yvW5wEkiO38O O5XUxDPQ==; Received: from [10.9.9.73] (helo=submission02.runbox) by mailtransmit02.runbox with esmtp (Exim 4.86_2) (envelope-from ) id 1vuT1F-0005QG-1Z; Mon, 23 Feb 2026 11:18:25 +0100 Received: by submission02.runbox with esmtpsa [Authenticated ID (1493616)] (TLS1.2:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.93) id 1vuT15-006AjD-HU; Mon, 23 Feb 2026 11:18:15 +0100 From: david.laight.linux@gmail.com To: Willy Tarreau , =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= , linux-kernel@vger.kernel.org, Cheng Li Cc: David Laight Subject: [PATCH v3 next 13/17] tools/nolibc/printf: Add support for conversion flags Date: Mon, 23 Feb 2026 10:17:31 +0000 Message-Id: <20260223101735.2922-14-david.laight.linux@gmail.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260223101735.2922-1-david.laight.linux@gmail.com> References: <20260223101735.2922-1-david.laight.linux@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: David Laight Add support for: '+' and ' ' Sign characters for non-negative numbers. '#' adds 0x to hex numbers. outputting "(nil)" for NULL pointers. Special code for 0 is needed because "%#x" needs to generate "0" not "0x0". The code is changed to use the length returned by u64toh_r() and prepend the sign (or "0x") after conversion to reduce the changes for the next patch that inserts zero padding between the sign and digits. Add tests for "%#x", "% d", "%+d" and passing NULL to "%p". Signed-off-by: David Laight --- Changes for v3: - Was patch 7 in v2. - Changes for left alignment moved to the next patch. - Rename 'sign' 'sign_prefix'. - Include tests Changes for v2: - Add support for left justifying fields (removed from patch 6). - Merge in the changes from the old patch 8. - Add support for "%#x" (formally part of patch 9). tools/include/nolibc/stdio.h | 68 +++++++++++++++----- tools/testing/selftests/nolibc/nolibc-test.c | 3 + 2 files changed, 55 insertions(+), 16 deletions(-) diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h index 6dd27473ab7f..c21abe085fa6 100644 --- a/tools/include/nolibc/stdio.h +++ b/tools/include/nolibc/stdio.h @@ -296,7 +296,7 @@ int fseek(FILE *stream, long offset, int whence) * - %% generates a single % * - %m outputs strerror(errno). * - %X outputs a..f the same as %x. - * - The modifiers [#-+ 0] are currently ignored. + * - The modifiers [-0] are currently ignored. * - No support for precision or variable widths. * - No support for floating point or wide characters. * - Invalid formats are copied to the output buffer. @@ -345,9 +345,10 @@ int __nolibc_printf(__nolibc_printf_cb cb, void *state, const char *fmt, va_list long long signed_v; int written, width, len; unsigned int flags, ch_flag; - char outbuf[21]; + char outbuf[2 + 22 + 1]; char *out; const char *outstr; + unsigned int sign_prefix; written = 0; while (1) { @@ -409,8 +410,11 @@ int __nolibc_printf(__nolibc_printf_cb cb, void *state, const char *fmt, va_list * so that 'X' can be allowed through. * 'X' gets treated and 'x' because _NOLIBC_PF_FLAG() returns the same * value for both. + * + * We need to check for "%p" or "%#x" later, merging here gives better code. + * But '#' collides with 'c' so shift right. */ - ch_flag = _NOLIBC_PF_FLAG(ch); + ch_flag = _NOLIBC_PF_FLAG(ch) | (flags & _NOLIBC_PF_FLAG('#')) >> 1; if (((ch >= 'a' && ch <= 'z') || ch == 'X') && _NOLIBC_PF_FLAGS_CONTAIN(ch_flag, 'c', 'd', 'i', 'u', 'x', 'p', 's')) { /* 'long' is needed for pointer/string conversions and ltz lengths. @@ -446,32 +450,64 @@ int __nolibc_printf(__nolibc_printf_cb cb, void *state, const char *fmt, va_list goto do_strlen_output; } - out = outbuf; + /* The 'sign_prefix' can be zero, one or two ("0x") characters. */ + sign_prefix = 0; if (_NOLIBC_PF_FLAGS_CONTAIN(ch_flag, 'd', 'i')) { /* "%d" and "%i" - signed decimal numbers. */ if (signed_v < 0) { - *out++ = '-'; + sign_prefix = '-'; v = -(signed_v + 1); v++; + } else if (_NOLIBC_PF_FLAGS_CONTAIN(flags, '+')) { + sign_prefix = '+'; + } else if (_NOLIBC_PF_FLAGS_CONTAIN(flags, ' ')) { + sign_prefix = ' '; } } - /* Convert the number to ascii in the required base. */ - if (_NOLIBC_PF_FLAGS_CONTAIN(ch_flag, 'd', 'i', 'u')) { - /* Base 10 */ - u64toa_r(v, out); - } else { - /* Base 16 */ + /* The value is converted offset into the buffer so that + * the sign/prefix can be added in front. + * The longest digit string is 22 + 1 for octal conversions, the + * space is reserved even though octal isn't currently supported. + */ + out = outbuf + 2; + + if (v == 0) { + /* There are special rules for zero. */ if (_NOLIBC_PF_FLAGS_CONTAIN(ch_flag, 'p')) { - *(out++) = '0'; - *(out++) = 'x'; + /* "%p" match glibc, precision is ignored */ + outstr = "(nil)"; + len = 5; + goto do_output; + } + /* All other formats (including "%#x") just output "0". */ + out[0] = '0'; + len = 1; + } else { + /* Convert the number to ascii in the required base. */ + if (_NOLIBC_PF_FLAGS_CONTAIN(ch_flag, 'd', 'i', 'u')) { + /* Base 10 */ + len = u64toa_r(v, out); + } else { + /* Base 16 */ + if (_NOLIBC_PF_FLAGS_CONTAIN(ch_flag, 'p', '#' - 1)) { + /* "%p" and "%#x" need "0x" prepending. */ + sign_prefix = 'x' | '0' << 8; + } + len = u64toh_r(v, out); } - u64toh_r(v, out); } - outstr = outbuf; - goto do_strlen_output; + /* Add the 0, 1 or 2 ("0x") sign/prefix characters at the front. */ + for (; sign_prefix; sign_prefix >>= 8) { + /* Force gcc to increment len inside the loop. */ + _NOLIBC_OPTIMIZER_HIDE_VAR(len); + len++; + *--out = sign_prefix; + } + outstr = out; + goto do_output; } if (ch == 'm') { diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c index 498d3125eb24..f746711af777 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -1832,6 +1832,7 @@ static int run_printf(int min, int max) CASE_TEST(string); EXPECT_VFPRINTF(1, "foo", "%s", "foo"); break; CASE_TEST(number); EXPECT_VFPRINTF(1, "1234", "%d", 1234); break; CASE_TEST(negnumber); EXPECT_VFPRINTF(1, "-1234", "%d", -1234); break; + CASE_TEST(num_sign); EXPECT_VFPRINTF(1, "| 1|+2|+3|+4|5|", "|% d|%+d|% +d|%+ d|%#d|", 1, 2, 3, 4, 5); break; CASE_TEST(unsigned); EXPECT_VFPRINTF(1, "12345", "%u", 12345); break; CASE_TEST(signed_max); EXPECT_VFPRINTF(1, "2147483647", "%i", ~0u >> 1); break; CASE_TEST(signed_min); EXPECT_VFPRINTF(1, "-2147483648", "%i", (~0u >> 1) + 1); break; @@ -1840,6 +1841,7 @@ static int run_printf(int min, int max) CASE_TEST(hex_nolibc); EXPECT_VFPRINTF(is_nolibc, "|f|d|", "|%x|%X|", 0xf, 0xd); break; CASE_TEST(hex_libc); EXPECT_VFPRINTF(!is_nolibc, "|f|D|", "|%x|%X|", 0xf, 0xd); break; CASE_TEST(pointer); EXPECT_VFPRINTF(1, "0x1", "%p", (void *) 0x1); break; + CASE_TEST(pointer_NULL); EXPECT_VFPRINTF(1, "(nil)", "%p", (void *)0); break; CASE_TEST(percent); EXPECT_VFPRINTF(1, "a%d42%69%", "a%%d%d%%%d%%", 42, 69); break; CASE_TEST(perc_qual); EXPECT_VFPRINTF(1, "a%d2", "a%-14l%d%d", 2); break; CASE_TEST(invalid); EXPECT_VFPRINTF(1, "a%12yx3%y42%P", "a%12yx%d%y%d%P", 3, 42); break; @@ -1850,6 +1852,7 @@ static int run_printf(int min, int max) CASE_TEST(string_width); EXPECT_VFPRINTF(1, " 1", "%10s", "1"); break; CASE_TEST(number_width); EXPECT_VFPRINTF(1, " 1", "%10d", 1); break; CASE_TEST(width_trunc); EXPECT_VFPRINTF(1, " 1", "%30d", 1); break; + CASE_TEST(hex_alt); EXPECT_VFPRINTF(1, "|0x1| 0x2| 0|", "|%#x|%#5x|%#5x|", 1, 2, 0); break; CASE_TEST(errno); EXPECT_VFPRINTF(is_nolibc, "22:errno=22", "%d:%m", errno=22); break; CASE_TEST(errno-neg); EXPECT_VFPRINTF(is_nolibc, "-22: errno=-22", "%d:%12m", errno=-22); break; CASE_TEST(scanf); EXPECT_ZR(1, test_scanf()); break; -- 2.39.5