From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: passt.top; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: passt.top; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=UUxy6OOu; dkim-atps=neutral Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by passt.top (Postfix) with ESMTPS id 9983F5A026F for ; Fri, 17 Oct 2025 08:29:04 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1760682543; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=rW8HDM6D4QP3ZSspGyaIt32Is6YWJXRU+JyXlryYXaI=; b=UUxy6OOuWjLG2WNkT5mlJegZK82Ek8DjfLrn7h6/Q8PqIn2Gq2HDyTV37/5m57qbF4AQvw aZP9jIyz/Qp2T/j5/+Zd7VcuvHp6JOooLGeK8PcAR5bngtq0Ref0lTv7nreR8UV9eIaAca /Y4jDsHlWN40/lNi3zO0jYimCOHGmpM= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-17-GjcVSECDOmC9Jz9aL7Uwbg-1; Fri, 17 Oct 2025 02:28:59 -0400 X-MC-Unique: GjcVSECDOmC9Jz9aL7Uwbg-1 X-Mimecast-MFC-AGG-ID: GjcVSECDOmC9Jz9aL7Uwbg_1760682539 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id DC14A180899A; Fri, 17 Oct 2025 06:28:58 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.72.112.60]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id CFA711954126; Fri, 17 Oct 2025 06:28:55 +0000 (UTC) From: Yumei Huang To: passt-dev@passt.top, sbrivio@redhat.com Subject: [PATCH v6 2/4] util: Introduce read_file() and read_file_integer() function Date: Fri, 17 Oct 2025 14:28:36 +0800 Message-ID: <20251017062838.21041-3-yuhuang@redhat.com> In-Reply-To: <20251017062838.21041-1-yuhuang@redhat.com> References: <20251017062838.21041-1-yuhuang@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: HINhwbryKlNTmH0rCM6rpm9niX8UC3P3IjGZIeeEiXQ_1760682539 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true Message-ID-Hash: BSCQRQAUC4ANNVU2GLOOXJIO3OLBPSAY X-Message-ID-Hash: BSCQRQAUC4ANNVU2GLOOXJIO3OLBPSAY X-MailFrom: yuhuang@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: david@gibson.dropbear.id.au, yuhuang@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: 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. + */ +#define INTMAX_STRLEN (sizeof(intmax_t) * 3 + 2) + /* inet address (- '\0') + port (u16) (- '\0') + ':' + '\0' */ #define SOCKADDR_INET_STRLEN \ (INET_ADDRSTRLEN-1 + UINT16_STRLEN-1 + sizeof(":")) -- 2.47.0