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[122.26.212.247]) by smtp.googlemail.com with ESMTPSA id d9443c01a7336-2a2f3d4cbdasm438563655ad.65.2026.01.04.18.36.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 04 Jan 2026 18:36:52 -0800 (PST) From: Daniel Palmer To: w@1wt.eu, linux@weissschuh.net Cc: david.laight.linux@gmail.com, linux-kernel@vger.kernel.org, Daniel Palmer Subject: [PATCH v2 1/3] tools/nolibc: Add fread() to stdio.h Date: Mon, 5 Jan 2026 11:36:27 +0900 Message-ID: <20260105023629.1502801-2-daniel@thingy.jp> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260105023629.1502801-1-daniel@thingy.jp> References: <20260105023629.1502801-1-daniel@thingy.jp> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add a very basic version of fread() like we already have for fwrite(). Signed-off-by: Daniel Palmer --- tools/include/nolibc/stdio.h | 34 +++++++++++++++++++++++++++++++++- 1 file changed, 33 insertions(+), 1 deletion(-) diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h index 1f16dab2ac88..6904252df97d 100644 --- a/tools/include/nolibc/stdio.h +++ b/tools/include/nolibc/stdio.h @@ -170,7 +170,7 @@ int putchar(int c) } =20 =20 -/* fwrite(), puts(), fputs(). Note that puts() emits '\n' but not fputs().= */ +/* fwrite(), fread(), puts(), fputs(). Note that puts() emits '\n' but not= fputs(). */ =20 /* internal fwrite()-like function which only takes a size and returns 0 on * success or EOF on error. It automatically retries on short writes. @@ -204,6 +204,38 @@ size_t fwrite(const void *s, size_t size, size_t nmemb= , FILE *stream) return written; } =20 +/* internal fread()-like function which only takes a size and returns 0 on + * success or EOF on error. It automatically retries on short reads. + */ +static __attribute__((unused)) +int _fread(void *buf, size_t size, FILE *stream) +{ + int fd =3D fileno(stream); + ssize_t ret; + + while (size) { + ret =3D read(fd, buf, size); + if (ret <=3D 0) + return EOF; + size -=3D ret; + buf +=3D ret; + } + return 0; +} + +static __attribute__((unused)) +size_t fread(void *s, size_t size, size_t nmemb, FILE *stream) +{ + size_t nread; + + for (nread =3D 0; nread < nmemb; nread++) { + if (_fread(s, size, stream) !=3D 0) + break; + s +=3D size; + } + return nread; +} + static __attribute__((unused)) int fputs(const char *s, FILE *stream) { --=20 2.51.0 From nobody Wed Jan 7 22:50:05 2026 Received: from mail-pl1-f170.google.com (mail-pl1-f170.google.com [209.85.214.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 65DD63168E4 for ; Mon, 5 Jan 2026 02:36:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.170 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767580618; cv=none; b=KS3/sc7X2KFnwl+iRXKJ4FLEagpM5rrsdjEySlhWI3CyH9ER8TubfLnXO2RBkRbnqsAsPKZypzP8hz5usspgSmIFSszRj9NWze7u2KNbDIn00vx7WH+lE4dS2XQVS+KQvZhjtS82MJREp3YOXm4iH3KeYK9DGZ/UXL8VjJn36wQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767580618; c=relaxed/simple; bh=kMjEKFnH+ts5syaXQCmYEnenT8/vZzuQamMWE2j9un0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qEsNste2s09JQ/EIzL4abGYrHtmOI+oTfaFCG8CamaQ53hQ6r8woamM+8lVZz8FzyqxVcxWsizoXbF97BTX/n3bxKs+cS2DPc5cpWOo1CQ+rEcC/8JWPUaZqQCI+sVAoo3Yo5vfMvBNdE57s8SVEbczLRvTep2kXGEMQ5076qvM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=thingy.jp; spf=pass smtp.mailfrom=0x0f.com; dkim=pass (1024-bit key) header.d=thingy.jp header.i=@thingy.jp header.b=ZamI93JA; arc=none smtp.client-ip=209.85.214.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=thingy.jp Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=0x0f.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=thingy.jp header.i=@thingy.jp header.b="ZamI93JA" Received: by mail-pl1-f170.google.com with SMTP id d9443c01a7336-2a07fac8aa1so147357245ad.1 for ; Sun, 04 Jan 2026 18:36:56 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=thingy.jp; s=google; t=1767580616; x=1768185416; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=rhhXKuCUD46GPo5xZVQFBV+umT35igV/xtK7M65/KtM=; b=ZamI93JAYifeE5gqOj/yq/bRDQw4cIaMHanwHV/JYcWmEFS0ceUkDJIqEP8pIOZzjG lsgEdv8ad10+TKVsjMjx+xOaVyKNjjbsRkki+0fkr2243CoiK9zdLYtVN1YUQITsytpJ fdcta0R9nfsFhs1kE56/SBQC6JNgMs4N2J5Dc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1767580616; x=1768185416; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=rhhXKuCUD46GPo5xZVQFBV+umT35igV/xtK7M65/KtM=; b=nj5Z5yaL/D7Pn/+e29yjOWHSvXXeG2ozBImcY+Ln2TSR8As5IfoseGiUJlMfM1mzhj V8PivVgm3bqTw0OwU3Q7T0+wMXqrMjXJOd105lDWannv+r/FukaitYGjwt4axf7GKQMK 8yBhNoPpWJrx7Grb1g+u7RXt3fef41eR9W913DbyH8GWKSh/T8AmGR0Wh+ZYyGan4JmX MbEQaRY+UbzALkq05mtqkfpyk9+1A7UcV427jTPiQb1nNc+lwQ4fMeeq2G4Z2Q1SzQA6 kU82PXqjjtE4tEqG04K8lC6afC1bngURMSQ9xzjYHy9uGT9V4cIywEOlJ7+X0LAnuZxO 3DGQ== X-Forwarded-Encrypted: i=1; AJvYcCVABY+0MhZlNCFvnKvzhdkR1dnTKb3oVFrBclgAhOUrr/ozkvAgMOndKHfG1a/KJLOm8cRaa6e2kwqcYhM=@vger.kernel.org X-Gm-Message-State: AOJu0YzisDYxz6xslCUK6kpe/BbTu48k23yQoMFNTiT2iaf4fvNuQ33n kxOB1bCewj8zh0NnVYjdQ19fPl9onBnNUieksqqKHX7e6diq4Rp1U7opcnz3hxQxntL2PCoTmrb p//xNTPw= X-Gm-Gg: AY/fxX4WfOsP3EJbVCx6Pkvj/+qfhPK4Mtew6dzrkUwjlyIlV31wNyZCLl/exviwRy1 Vqh6OPGQcPsErRQ0URBu+yLayE3VWXLaZrpGrrNELKMQdFihEMni9q4qfBXCx+HGt9ai9gSISsQ t3GqkcYWlis7WayGglXG8sXwCfIOofMp4KQOUv6sJ3rQ/WAzejZaL2bwyLSvIXpC8fOxt7hAsgk DtfD9Cl9xR63ClRW8VaWIDcSnf8zkej6iEBGbpCOz4dchBc7EgSLCoLw34br3QTBBJRKwyQq1Tt xcD2PWSUD0+TQeP4S2mbdEDwUz7hK+u/2PkNCGDcKT7+PtGkPubxG0L379zMaIUVtWsPIgHfext xr+smQI/tuqA7M2OAxsBxzlr17uGKfitKDxEmJnY1hUPI74Ydgqr03w3nPmoyKHPGopQzQkz5kv 0WF0mnXDo5Ox3X/J4O3NNeOSQXCOIqH3RiQmZVIzj8SJZ7NxK+6vSHNSNxftY311ELbNw8y4Iof 38= X-Google-Smtp-Source: AGHT+IFcL3Lp268viLSm+N46mc5baIHAN+F+i0Djk0vdHJPGpr6m88C4k6vS3EW+nzK7J/Sv6fWn/g== X-Received: by 2002:a17:902:fc8d:b0:2a0:ccef:a5d3 with SMTP id d9443c01a7336-2a2f2202fdamr519397465ad.3.1767580615693; Sun, 04 Jan 2026 18:36:55 -0800 (PST) Received: from kinako.work.home.arpa (p1536247-ipxg00c01sizuokaden.shizuoka.ocn.ne.jp. [122.26.212.247]) by smtp.googlemail.com with ESMTPSA id d9443c01a7336-2a2f3d4cbdasm438563655ad.65.2026.01.04.18.36.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 04 Jan 2026 18:36:55 -0800 (PST) From: Daniel Palmer To: w@1wt.eu, linux@weissschuh.net Cc: david.laight.linux@gmail.com, linux-kernel@vger.kernel.org, Daniel Palmer Subject: [PATCH v2 2/3] tools/nolibc: Add fseek() to stdio.h Date: Mon, 5 Jan 2026 11:36:28 +0900 Message-ID: <20260105023629.1502801-3-daniel@thingy.jp> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260105023629.1502801-1-daniel@thingy.jp> References: <20260105023629.1502801-1-daniel@thingy.jp> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" A very basic wrapper around lseek() that implements fseek(). Signed-off-by: Daniel Palmer --- tools/include/nolibc/stdio.h | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h index 6904252df97d..233318b0d0f0 100644 --- a/tools/include/nolibc/stdio.h +++ b/tools/include/nolibc/stdio.h @@ -272,6 +272,25 @@ char *fgets(char *s, int size, FILE *stream) } =20 =20 +/* fseek */ +static __attribute__((unused)) +int fseek(FILE *stream, long offset, int whence) +{ + int fd =3D fileno(stream); + off_t ret; + + ret =3D lseek(fd, offset, whence); + + /* lseek() and fseek() differ in that lseek returns the new + * position or -1, fseek() returns either 0 or -1. + */ + if (ret >=3D 0) + return 0; + + return -1; +} + + /* minimal printf(). 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[122.26.212.247]) by smtp.googlemail.com with ESMTPSA id d9443c01a7336-2a2f3d4cbdasm438563655ad.65.2026.01.04.18.36.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 04 Jan 2026 18:36:57 -0800 (PST) From: Daniel Palmer To: w@1wt.eu, linux@weissschuh.net Cc: david.laight.linux@gmail.com, linux-kernel@vger.kernel.org, Daniel Palmer Subject: [PATCH v2 3/3] tools/nolibc: Add a simple test for writing to a FILE and reading it back Date: Mon, 5 Jan 2026 11:36:29 +0900 Message-ID: <20260105023629.1502801-4-daniel@thingy.jp> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260105023629.1502801-1-daniel@thingy.jp> References: <20260105023629.1502801-1-daniel@thingy.jp> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add a test that exercises create->write->seek->read to check that using the stream functions (fwrite() etc) is not totally broken. The only edge cases this is testing for are: - Reading the file after writing but without rewinding reads nothing. - Trying to read more items than the file contains returns the count of fully read items. Signed-off-by: Daniel Palmer --- tools/testing/selftests/nolibc/nolibc-test.c | 53 ++++++++++++++++++++ 1 file changed, 53 insertions(+) diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/s= elftests/nolibc/nolibc-test.c index 3c5a226dad3a..6d99698005c4 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -877,6 +877,58 @@ int test_file_stream(void) return 0; } =20 +int test_file_stream_wsr(void) +{ + const char dataout[] =3D "foo"; + const size_t datasz =3D sizeof(dataout); + char datain[datasz]; + int fd, r; + FILE *f; + + fd =3D open("/tmp", O_TMPFILE | O_RDWR, 0644); + if (fd =3D=3D -1) + return -1; + + f =3D fdopen(fd, "w+"); + if (!f) + return -1; + + errno =3D 0; + r =3D fwrite(dataout, 1, datasz, f); + if (r !=3D datasz) + return -1; + + /* Attempt to read from the file without rewinding, + * we should read 0 items. + */ + r =3D fread(datain, 1, datasz, f); + if (r) + return -1; + + /* Rewind the file to the start */ + r =3D fseek(f, 0, SEEK_SET); + if (r) + return -1; + + /* Attempt to read back more than was written to + * make sure we handle short reads properly. + * fread() should return the number of complete items. + */ + r =3D fread(datain, 1, datasz + 1, f); + if (r !=3D datasz) + return -1; + + /* Data we read should match the data we just wrote */ + if (memcmp(datain, dataout, datasz) !=3D 0) + return -1; + + r =3D fclose(f); + if (r) + return -1; + + return 0; +} + enum fork_type { FORK_STANDARD, FORK_VFORK, @@ -1351,6 +1403,7 @@ int run_syscall(int min, int max) CASE_TEST(fchdir_stdin); EXPECT_SYSER(1, fchdir(STDIN_FILENO), -1, = ENOTDIR); break; CASE_TEST(fchdir_badfd); EXPECT_SYSER(1, fchdir(-1), -1, EBADF); br= eak; CASE_TEST(file_stream); EXPECT_SYSZR(1, test_file_stream()); break; + CASE_TEST(file_stream_wsr); EXPECT_SYSZR(1, test_file_stream_wsr()); b= reak; CASE_TEST(fork); EXPECT_SYSZR(1, test_fork(FORK_STANDARD));= break; CASE_TEST(getdents64_root); EXPECT_SYSNE(1, test_getdents64("/"), -1);= break; CASE_TEST(getdents64_null); EXPECT_SYSER(1, test_getdents64("/dev/null= "), -1, ENOTDIR); break; --=20 2.51.0