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[176.103.220.4]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47152959b55sm91346115e9.6.2025.10.19.03.07.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 Oct 2025 03:07:13 -0700 (PDT) Date: Sun, 19 Oct 2025 12:07:12 +0200 From: Stefano Brivio To: Yumei Huang Subject: Re: [PATCH v6 2/4] util: Introduce read_file() and read_file_integer() function Message-ID: <20251019120712.6f232804@elisabeth> In-Reply-To: <20251017062838.21041-3-yuhuang@redhat.com> References: <20251017062838.21041-1-yuhuang@redhat.com> <20251017062838.21041-3-yuhuang@redhat.com> Organization: Red Hat X-Mailer: Claws Mail 4.2.0 (GTK 3.24.49; x86_64-pc-linux-gnu) MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: alD2ZKY6hyYnuQa8-SmVlVtXISwGy0CITU-kdop93b4_1760868434 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-ID-Hash: ZGM5I5WFO4YENMNEMDYJVIWLNZCMW4SV X-Message-ID-Hash: ZGM5I5WFO4YENMNEMDYJVIWLNZCMW4SV X-MailFrom: sbrivio@redhat.com 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, david@gibson.dropbear.id.au 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: On Fri, 17 Oct 2025 14:28:36 +0800 Yumei Huang wrote: > Signed-off-by: Yumei Huang > --- > util.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > util.h | 8 ++++++ > 2 files changed, 92 insertions(+) > > diff --git a/util.c b/util.c > index c492f90..5c8c4bc 100644 > --- a/util.c > +++ b/util.c > @@ -579,6 +579,90 @@ int write_file(const char *path, const char *buf) > return len == 0 ? 0 : -1; > } > > +/** > + * 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 truncation > +*/ > +ssize_t read_file(const char *path, char *buf, size_t buf_size) > +{ > + int fd = open(path, O_RDONLY | O_CLOEXEC); > + size_t total_read = 0; > + ssize_t rc; > + > + if (fd < 0) { > + warn_perror("Could not open %s", path); > + return -1; > + } > + > + while (total_read < buf_size) { > + rc = 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 == 0) > + break; > + > + total_read += rc; > + } > + > + close(fd); > + > + if (total_read == buf_size) { > + warn("File %s truncated, buffer too small", path); > + return -2; > + } > + > + buf[total_read] = '\0'; > + > + return total_read; > +} > + > +/** > + * 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]; > + ssize_t bytes_read; > + intmax_t value; > + char *end; > + > + bytes_read = read_file(path, buf, sizeof(buf)); > + > + if (bytes_read < 0) > + return fallback; > + > + if (bytes_read == 0) { > + debug("Empty file %s", path); > + return fallback; > + } > + > + errno = 0; > + value = strtoimax(buf, &end, 10); > + if (*end && *end != '\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 __clone2(), > * use the description from clone(2). > diff --git a/util.h b/util.h > index 22eaac5..3f9f296 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); > @@ -250,6 +252,12 @@ static inline const char *af_name(sa_family_t af) > > #define UINT16_STRLEN (sizeof("65535")) > > +/* Each byte expands to at most 3 decimal digits since 0xff == 255. > + * Plus 2 extra bytes for the sign and null terminator. > + * See https://stackoverflow.com/a/10536254. This is not an acceptable form of attribution according to the CC BY-SA 3.0 terms. See: https://stackoverflow.com/help/licensing https://creativecommons.org/licenses/by-sa/3.0/ and checksum.h in this tree for some examples of how to combine different licensing terms in a single file, in a way that's human-readable but still machine-friendly (for license / compliance scanners such as REUSE). As I commented on a previous version, anyway, I don't think we need this at all. I guess my comment was ignored though. Note that I didn't review this patch or the rest of this series, yet. -- Stefano