From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: passt.top; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: passt.top; dkim=pass (2048-bit key; secure) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.a=rsa-sha256 header.s=202510 header.b=OAkH2SGn; dkim-atps=neutral Received: from mail.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) by passt.top (Postfix) with ESMTPS id AA7ED5A061A for ; Mon, 03 Nov 2025 02:10:32 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=202510; t=1762132229; bh=PQFn/mdQVX/2Z2IdWcAK78q1uqfsggb2XmGpJjqDW78=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=OAkH2SGn8P6+jO/h1QVY69N5aMIzykrJiWkwyJ0zhpfc5cSCNfTJhhamw5eFytUF6 kdbhv80fBeoWvlLO6lzumNHLO7XnM2q8wM/bPB26Gs43xmSmksnKnwbpXtYtzsUv8P SNX5aPRQ++Y0pEp2nBMII0b///E3g9591z+9TX1zAYPNHIgUPTZ3jvO4xSKKiEZy6s /njwm7Yyi6zPFlYq9cBLFD1VIyEXIzqpP99FNoz/Kp3ZZMzCTeM0Or1GaDtqDt+NsN o1xhEl0V5xWAtw3h39rX1I5DFbswMnEzQL5k0zLSgYJu4wGSt2sWcGaJaIeCrIEmjV 4KxrN8qiSP0HQ== Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4d0D6F2XQvz4wCy; Mon, 03 Nov 2025 12:10:29 +1100 (AEDT) Date: Mon, 3 Nov 2025 11:53:19 +1100 From: David Gibson To: Yumei Huang Subject: Re: [PATCH v7 2/5] util: Introduce read_file() and read_file_integer() function Message-ID: References: <20251031054242.7334-1-yuhuang@redhat.com> <20251031054242.7334-3-yuhuang@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="cc3AI03neYz0ZGrd" Content-Disposition: inline In-Reply-To: <20251031054242.7334-3-yuhuang@redhat.com> Message-ID-Hash: UFHUQR7RNZ4D43VMKWBXNFTRLFFEQQJ4 X-Message-ID-Hash: UFHUQR7RNZ4D43VMKWBXNFTRLFFEQQJ4 X-MailFrom: dgibson@gandalf.ozlabs.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: passt-dev@passt.top, sbrivio@redhat.com X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: --cc3AI03neYz0ZGrd Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Oct 31, 2025 at 01:42:39PM +0800, Yumei Huang wrote: > Signed-off-by: Yumei Huang Reviewed-by: David Gibson > --- > util.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > util.h | 2 ++ > 2 files changed, 88 insertions(+) >=20 > diff --git a/util.c b/util.c > index c492f90..b83de0d 100644 > --- a/util.c > +++ b/util.c > @@ -579,6 +579,92 @@ int write_file(const char *path, const char *buf) > return len =3D=3D 0 ? 0 : -1; > } > =20 > +/** > + * read_file() - Read contents of file into a NULL-terminated buffer > + * @path: Path to file to read > + * @buf: Buffer to store file contents > + * @buf_size: Size of buffer > + * > + * Return: number of bytes read on success, -1 on error, -ENOBUFS on tru= ncation > +*/ > +ssize_t read_file(const char *path, char *buf, size_t buf_size) > +{ > + int fd =3D open(path, O_RDONLY | O_CLOEXEC); > + size_t total_read =3D 0; > + ssize_t rc; > + > + if (fd < 0) { > + warn_perror("Could not open %s", path); > + return -1; > + } > + > + while (total_read < buf_size) { > + rc =3D read(fd, buf + total_read, buf_size - total_read); > + > + if (rc < 0) { > + warn_perror("Couldn't read from %s", path); > + close(fd); > + return -1; > + } > + > + if (rc =3D=3D 0) > + break; > + > + total_read +=3D rc; > + } > + > + close(fd); > + > + if (total_read =3D=3D buf_size) { > + warn("File %s contents exceed buffer size %zu", path, > + buf_size); > + buf[buf_size - 1] =3D '\0'; > + return -ENOBUFS; > + } > + > + buf[total_read] =3D '\0'; > + > + return total_read; > +} > + > +/** > + * read_file_integer() - Read an integer value from a file > + * @path: Path to file to read > + * @fallback: Default value if file can't be read > + * > + * Return: integer value, @fallback on failure > +*/ > +intmax_t read_file_integer(const char *path, intmax_t fallback) > +{ > + ssize_t bytes_read; > + char buf[BUFSIZ]; > + intmax_t value; > + char *end; > + > + bytes_read =3D read_file(path, buf, sizeof(buf)); > + > + if (bytes_read < 0) > + return fallback; > + > + if (bytes_read =3D=3D 0) { > + debug("Empty file %s", path); > + return fallback; > + } > + > + errno =3D 0; > + value =3D strtoimax(buf, &end, 10); > + if (*end && *end !=3D '\n') { > + debug("Non-numeric content in %s", path); > + return fallback; > + } > + if (errno) { > + debug("Out of range value in %s: %s", path, buf); > + return fallback; > + } > + > + return value; > +} > + > #ifdef __ia64__ > /* Needed by do_clone() below: glibc doesn't export the prototype of __c= lone2(), > * use the description from clone(2). > diff --git a/util.h b/util.h > index 22eaac5..595a17d 100644 > --- a/util.h > +++ b/util.h > @@ -222,6 +222,8 @@ void pidfile_write(int fd, pid_t pid); > int __daemon(int pidfile_fd, int devnull_fd); > int fls(unsigned long x); > int write_file(const char *path, const char *buf); > +ssize_t read_file(const char *path, char *buf, size_t buf_size); > +intmax_t read_file_integer(const char *path, intmax_t fallback); > int write_all_buf(int fd, const void *buf, size_t len); > int write_remainder(int fd, const struct iovec *iov, size_t iovcnt, size= _t skip); > int read_all_buf(int fd, void *buf, size_t len); > --=20 > 2.49.0 >=20 --=20 David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson --cc3AI03neYz0ZGrd Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEO+dNsU4E3yXUXRK2zQJF27ox2GcFAmkH/OAACgkQzQJF27ox 2GcAahAAjnjWFir2Ud+CoRKI19LdhuorUKO/H947/Ye+LbpTvrumVHbarwNmsscy ugCXZBc79zQndxUrzVn/+tMYZOGL6AQyWiS/7RanGsUINqfW6t3wFPpY40nKLuS5 94C4F5V8JlPZ4lA6eC9XglN0BLYEk2F9z0RY5bQmw2BnOW2Ym97yIuJucUj8UEbb MHK9UivJPanZ7VbVgg3827ANWMV0hUdSjRdpYDG6jo/kSZbSOpfhQTL1Fgx3faLg Tu86LZWN/XBnbUW1e2yyoNkIZwi/LwDB5l1WLj40s9ZhrLFwvbT3G00FXvTTNrQW ksw1ONlNFYbbC56Zn4LNAj+WN5OfhJod1uOPlS9ODYjYJDExun13zS087X3cXpLK NTva33g/CNQICWHznmNw542Ylsh4jI2nrUJ60lVhiv19a3e4Rm8I5cDXYzCMdxxN R51dSpDv7TK4T8erYa0ka3fOglRbKSr6OEZZ6AmIFwt0qUrf9X1yWtsvMtXdCywZ 6V38C0pXLAMSGR/37kJc2p52QbZC7p5dxgtYz/oxz7zwpCdL29EqjMbh10VPI88M kvlRWajaTbsYdqv1ZPjLCee8A9bSw4M1Z27HHqoz1cLJ1a3vOkJ1H9ViuRTbLoaH V0v4t7roEAv2SXQ/bIPlCudQM+eA73sIEOulbCI5bw0NGZaljAE= =iBbM -----END PGP SIGNATURE----- --cc3AI03neYz0ZGrd--