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From: david.laight.linux@gmail.com
To: "Willy Tarreau" <w@1wt.eu>,
	"Thomas Weißschuh" <linux@weissschuh.net>,
	linux-kernel@vger.kernel.org, "Cheng Li" <lechain@gmail.com>
Cc: David Laight <david.laight.linux@gmail.com>
Subject: [PATCH v4 next 20/23] tools/nolibc/printf: Add support for left aligning fields
Date: Mon,  2 Mar 2026 10:18:12 +0000	[thread overview]
Message-ID: <20260302101815.3043-21-david.laight.linux@gmail.com> (raw)
In-Reply-To: <20260302101815.3043-1-david.laight.linux@gmail.com>

From: David Laight <david.laight.linux@gmail.com>

Output the characters before or after the pad - writing the pad takes more code.

Include additional/changed tests

Signed-off-by: David Laight <david.laight.linux@gmail.com>
---

Unchanged for v4.

Changes for v3:
- Formally part of patch 7.

 tools/include/nolibc/stdio.h                 | 6 +++++-
 tools/testing/selftests/nolibc/nolibc-test.c | 4 +++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h
index ef8e7069d5cf..695676b44151 100644
--- a/tools/include/nolibc/stdio.h
+++ b/tools/include/nolibc/stdio.h
@@ -544,7 +544,11 @@ int __nolibc_printf(__nolibc_printf_cb cb, void *state, const char *fmt, va_list
 		/* Stop gcc back-merging this code into one of the conditionals above. */
 		_NOLIBC_OPTIMIZER_HIDE_VAR(len);
 
+		/* Output the characters on the required side of any padding. */
 		width -= len;
+		flags = _NOLIBC_PF_FLAGS_CONTAIN(flags, '-');
+		if (flags && cb(state, outstr, len) != 0)
+			return -1;
 		while (width > 0) {
 			/* Output pad in 16 byte blocks with the small block first. */
 			int pad_len = ((width - 1) & 15) + 1;
@@ -553,7 +557,7 @@ int __nolibc_printf(__nolibc_printf_cb cb, void *state, const char *fmt, va_list
 			if (cb(state, "                ", pad_len) != 0)
 				return -1;
 		}
-		if (cb(state, outstr, len) != 0)
+		if (!flags && cb(state, outstr, len) != 0)
 			return -1;
 	}
 
diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 4267c69ec37c..89ded1dd7318 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -1845,9 +1845,11 @@ static int run_printf(int min, int max)
 		CASE_TEST(truncation);   EXPECT_VFPRINTF(1, "0123456789012345678901234", "%s", "0123456789012345678901234"); break;
 		CASE_TEST(string_width); EXPECT_VFPRINTF(1, "         1", "%10s", "1"); break;
 		CASE_TEST(number_width); EXPECT_VFPRINTF(1, "         1", "%10d", 1); break;
+		CASE_TEST(number_left);  EXPECT_VFPRINTF(1, "|-5      |", "|%-8d|", -5); break;
+		CASE_TEST(string_align); EXPECT_VFPRINTF(1, "|foo     |", "|%-8s|", "foo"); break;
 		CASE_TEST(width_trunc);  EXPECT_VFPRINTF(1, "                        1", "%25d", 1); break;
 		CASE_TEST(errno);        errno = 22; EXPECT_VFPRINTF(is_nolibc, "errno=22", "%m"); break;
-		CASE_TEST(errno-neg);    errno = -22; EXPECT_VFPRINTF(is_nolibc, "   errno=-22", "%12m"); break;
+		CASE_TEST(errno-neg);    errno = -22; EXPECT_VFPRINTF(is_nolibc, "errno=-22   ", "%-12m"); break;
 		CASE_TEST(scanf);        EXPECT_ZR(1, test_scanf()); break;
 		CASE_TEST(printf_error); EXPECT_ZR(1, test_printf_error()); break;
 		case __LINE__:
-- 
2.39.5


  parent reply	other threads:[~2026-03-02 10:18 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-02 10:17 [PATCH v4 next 00/23] Enhance printf() david.laight.linux
2026-03-02 10:17 ` [PATCH v4 next 01/23] tools/nolibc: Add _NOLIBC_OPTIMIZER_HIDE_VAR() to compiler.h david.laight.linux
2026-03-07 10:50   ` Willy Tarreau
2026-03-02 10:17 ` [PATCH v4 next 02/23] tools/nolibc/printf: Move snprintf length check to callback david.laight.linux
2026-03-07 10:48   ` Willy Tarreau
2026-03-02 10:17 ` [PATCH v4 next 03/23] selftests/nolibc: Return correct value when printf test fails david.laight.linux
2026-03-02 10:17 ` [PATCH v4 next 04/23] selftests/nolibc: check vsnprintf() output buffer before the length david.laight.linux
2026-03-02 10:17 ` [PATCH v4 next 05/23] selftests/nolibc: Use length of 'expected' string to check snprintf() output david.laight.linux
2026-03-02 10:17 ` [PATCH v4 next 06/23] selftests/nolibc: Check that snprintf() doesn't write beyond the buffer end david.laight.linux
2026-03-02 10:17 ` [PATCH v4 next 07/23] selftests/nolibc: Let EXPECT_VFPRINTF() tests be skipped david.laight.linux
2026-03-02 10:18 ` [PATCH 08/23] selftests/nolibc: Rename w to written in expect_vfprintf() david.laight.linux
2026-03-02 10:18 ` [PATCH v4 next 09/23] tools/nolibc: Implement strerror() in terms of strerror_r() david.laight.linux
2026-03-07 10:18   ` Willy Tarreau
2026-03-07 11:31     ` David Laight
2026-03-07 11:37       ` Willy Tarreau
2026-03-07 16:55         ` David Laight
2026-03-07 17:17           ` Willy Tarreau
2026-03-02 10:18 ` [PATCH v4 next 10/23] tools/nolibc: Rename the 'errnum' parameter to strerror() david.laight.linux
2026-03-07 10:19   ` Willy Tarreau
2026-03-02 10:18 ` [PATCH v4 next 11/23] tools/nolibc/printf: Output pad characters in 16 byte chunks david.laight.linux
2026-03-02 10:18 ` [PATCH 12/23] tools/nolibc/printf: Simplify __nolibc_printf() david.laight.linux
2026-03-02 10:18 ` [PATCH v4 next 13/23] tools/nolibc/printf: Use goto and reduce indentation david.laight.linux
2026-03-07 10:30   ` Willy Tarreau
2026-03-02 10:18 ` [PATCH 14/23] tools/nolibc/printf: Use bit-masks to hold requested flag, length and conversion chars david.laight.linux
2026-03-02 10:18 ` [PATCH v4 next 15/23] tools/nolibc/printf: Add support for length modifiers tzqL and formats iX david.laight.linux
2026-03-02 10:18 ` [PATCH v4 next 16/23] tools/nolibc/printf: Handle "%s" with the numeric formats david.laight.linux
2026-03-07 10:32   ` Willy Tarreau
2026-03-02 10:18 ` [PATCH 17/23] tools/nolibc/printf: Prepend sign to converted number david.laight.linux
2026-03-07 10:40   ` Willy Tarreau
2026-03-02 10:18 ` [PATCH v4 next 18/23] tools/nolibc/printf: Add support for conversion flags space and plus david.laight.linux
2026-03-07 10:46   ` Willy Tarreau
2026-03-02 10:18 ` [PATCH v4 next 19/23] tools/nolibc/printf: Special case 0 and add support for %#x david.laight.linux
2026-03-07 10:46   ` Willy Tarreau
2026-03-02 10:18 ` david.laight.linux [this message]
2026-03-07 10:46   ` [PATCH v4 next 20/23] tools/nolibc/printf: Add support for left aligning fields Willy Tarreau
2026-03-02 10:18 ` [PATCH v4 next 21/23] tools/nolibc/printf: Add support for zero padding and field precision david.laight.linux
2026-03-02 10:18 ` [PATCH v4 next 22/23] tools/nolibc/printf: Add support for octal output david.laight.linux
2026-03-07 10:45   ` Willy Tarreau
2026-03-02 10:18 ` [PATCH v4 next 23/23] selftests/nolibc: Use printf variable field widths and precisions david.laight.linux
2026-03-07 10:53 ` [PATCH v4 next 00/23] Enhance printf() Willy Tarreau
2026-03-07 18:02 ` Thomas Weißschuh
2026-03-07 22:03   ` David Laight
2026-03-07 22:20     ` Thomas Weißschuh
2026-03-08  9:23   ` Willy Tarreau

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