7eb3abdb3b
If /dev/kmsg already exists, it's unnecessary for klog_init()
to create it's own copy. This avoids needing to grant the mknod
permission to everyone who uses kmsg. Typically the only time
/dev/kmsg doesn't exist is before ueventd starts.
(cherrypicked from commit 4d32a486fe)
Bug: 21242418
Change-Id: I0c88d80feca6899fcdbc8c9f2f99448ee0a3422d
77 lines
1.9 KiB
C
77 lines
1.9 KiB
C
/*
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* Copyright (C) 2008 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <errno.h>
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#include <fcntl.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <cutils/klog.h>
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static int klog_fd = -1;
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static int klog_level = KLOG_DEFAULT_LEVEL;
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int klog_get_level(void) {
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return klog_level;
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}
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void klog_set_level(int level) {
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klog_level = level;
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}
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void klog_init(void) {
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if (klog_fd >= 0) return; /* Already initialized */
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klog_fd = open("/dev/kmsg", O_WRONLY | O_CLOEXEC);
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if (klog_fd >= 0) {
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return;
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}
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static const char* name = "/dev/__kmsg__";
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if (mknod(name, S_IFCHR | 0600, (1 << 8) | 11) == 0) {
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klog_fd = open(name, O_WRONLY | O_CLOEXEC);
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unlink(name);
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}
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}
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#define LOG_BUF_MAX 512
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void klog_writev(int level, const struct iovec* iov, int iov_count) {
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if (level > klog_level) return;
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if (klog_fd < 0) klog_init();
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if (klog_fd < 0) return;
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TEMP_FAILURE_RETRY(writev(klog_fd, iov, iov_count));
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}
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void klog_write(int level, const char* fmt, ...) {
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char buf[LOG_BUF_MAX];
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va_list ap;
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va_start(ap, fmt);
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vsnprintf(buf, sizeof(buf), fmt, ap);
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va_end(ap);
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buf[LOG_BUF_MAX - 1] = 0;
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struct iovec iov[1];
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iov[0].iov_base = buf;
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iov[0].iov_len = strlen(buf);
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klog_writev(level, iov, 1);
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}
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