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=J+9QIqrp; dkim-atps=neutral Received: from mail.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) by passt.top (Postfix) with ESMTPS id A67525A0619 for ; Thu, 16 Oct 2025 08:30:35 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=202510; t=1760596233; bh=qXMU0O1MGVLI3/Rlf32x5hyKEXcEOPSr55Jogzq1wII=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=J+9QIqrpBhFHqDR4MhHSXtlnCKbjzuRStrnQE+YyT6mlvTBYA4ZeszVgNfzRQSUtx ArY7la+mc3Ryqb/T6cq02+bYb+lAhmoms+mJeAR87AwcSlLAAXs+XLK0TU9BmeEzAi h6XLypnNURXdFk/bcW5Q/+rGKArY66BB5ed12tJe7/g97sBhIJzl+whLf3IJgT6i8J 0aO/APipPKaBE9aYOKmbvPFSKwOM5TVnrfCfOgNM3+WVf06jgzbnSJOMiV/vkwrL3d 4MPGVEpgTUDuQVVy+QRJKR1UIiz9UhK+hn2lEBzuo08uzNHzsL1HIS9Ifh4hj4T/A0 i89hvMtmsIZWw== Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4cnJ3s1Q7xz4wB8; Thu, 16 Oct 2025 17:30:33 +1100 (AEDT) Date: Thu, 16 Oct 2025 17:30:27 +1100 From: David Gibson To: Yumei Huang Subject: Re: [PATCH v4 2/4] util: Introduce read_file() and read_file_integer() function Message-ID: References: <20251016023423.8923-1-yuhuang@redhat.com> <20251016023423.8923-3-yuhuang@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="YU+AjO9XtEST+v8t" Content-Disposition: inline In-Reply-To: <20251016023423.8923-3-yuhuang@redhat.com> Message-ID-Hash: 63ESNZQCTUTBAZ2JL7462IDGH3IYAL4W X-Message-ID-Hash: 63ESNZQCTUTBAZ2JL7462IDGH3IYAL4W 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: --YU+AjO9XtEST+v8t Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Oct 16, 2025 at 10:34:21AM +0800, Yumei Huang wrote: > Signed-off-by: Yumei Huang > --- > util.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > util.h | 3 +++ > 2 files changed, 87 insertions(+) >=20 > diff --git a/util.c b/util.c > index c492f90..197677e 100644 > --- a/util.c > +++ b/util.c > @@ -579,6 +579,90 @@ 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 buffer > + * @path: File to read > + * @buf: Buffer to store file contents > + * @buf_size: Size of buffer > + * > + * Return: number of bytes read on success, -1 on any error, -2 on trunc= ation > +*/ > +int 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_perror("File %s truncated, buffer too small", path); > + return -2; > + } > + > + buf[total_read] =3D '\0'; > + > + return (int)total_read; Probably makes more sense for total_read and the return type to be ssize_t. > +} > + > +/** > + * read_file_integer() - Read an integer value from a file > + * @path: 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) > +{ > + char buf[INTMAX_STRLEN]; > + char *end; passt coding style is to list (where possible) local variables in reverse order of line length, so this should go after bytes_read. > + intmax_t value; > + int bytes_read; > + > + 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("Invalid format in %s", path); > + return fallback; > + } > + if (errno) { > + debug("Invalid 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..887d795 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); > +int 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); > @@ -249,6 +251,7 @@ static inline const char *af_name(sa_family_t af) > } > =20 > #define UINT16_STRLEN (sizeof("65535")) > +#define INTMAX_STRLEN (sizeof("-9223372036854775808")) It's correct for now, and probably for any systems we're likely to run on, but I dislike hard-assuming the size of intmax_t here. I feel like there must be a better way to derive the correct string length, but I haven't figured out what it is yet :(. > =20 > /* inet address (- '\0') + port (u16) (- '\0') + ':' + '\0' */ > #define SOCKADDR_INET_STRLEN \ > --=20 > 2.47.0 >=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 --YU+AjO9XtEST+v8t Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEO+dNsU4E3yXUXRK2zQJF27ox2GcFAmjwkPMACgkQzQJF27ox 2Ge5zQ/9HyZrGK8/PMO8P1+6vbMfKdpQBv66amgKd3fC5ykD+VbyibBPW3q+WptO 7UK6LzWMGno02duqQavRXm/eOAhkqUjUv2iIzNYeiGhV0oVhEYXMmA8yD+WCzdNB dO37mvvJ2zcX51VSQAc8xff7zvZPbLE/NKTA21661dbsEKLNj6oNtss7Q1VjUdhz 0KZw/kWDWwN+71hoCV+PJhF+cpRA76wiHSVayFOlDQNfbrMi/DZq+kBW8UCbMdTm ziW2RcH/mjP8jqaSutLFOt6kVzye9QxCenv9tBpdSooZLX2IihF0mwlG52fJwH8W RdEivykz8XL+LvAfGzdWCLmRHh5jZBjkwZM+x3tQ7Z9W9gwcZyq2mDGFIUG3JBHb vto0lwTuIjHB4s6VY20kSq4Er29nnmjBH/K8KLedjiTyOC6Zw6lCz3KflSOuDQ5q YrPUI+kZ07KLgxKNosrO7Us/J0vZljM/6Cy5EfjfYMVELVNU5VVIsqRUcVfM1oHL gJxj+bHnZuMsSX/R7xXtDVR0EAxDKb9bab512xz67PguPrlPZJhZEKsUWwygVYHq x6+mTdADsq+x5w4ZAp0f3rdVxN1SxLfxsZ7rZ4UY7cbyTOQVpUBFrmOsjZ68RnwE 6UhsKPsCIcYpXxASDbAJJhtRJeQpi/hFb2v4w+E/zMshy00V7GU= =eQ7t -----END PGP SIGNATURE----- --YU+AjO9XtEST+v8t--