Revise logging code

native/jni/core/logging.cpp

@@ -0,0 +1,160 @@
+#include <sys/uio.h>
+#include <android/log.h>
+
+#include <magisk.hpp>
+#include <utils.hpp>
+#include <daemon.hpp>
+#include <stream.hpp>
+
+#include "core.hpp"
+
+using namespace std;
+
+struct log_meta {
+    int prio;
+    int len;
+    int pid;
+    int tid;
+};
+
+static atomic<int> logd_fd = -1;
+
+void setup_logfile(bool reset) {
+    if (logd_fd < 0)
+        return;
+
+    iovec iov{};
+    log_meta meta = {
+        .prio = -1,
+        .len = reset
+    };
+
+    iov.iov_base = &meta;
+    iov.iov_len = sizeof(meta);
+    writev(logd_fd, &iov, 1);
+}
+
+// Maximum message length for pipes to transfer atomically
+#define MAX_MSG_LEN  (PIPE_BUF - sizeof(log_meta))
+#define TIME_FMT_LEN 35
+
+static void logfile_writer(int pipefd) {
+    run_finally close_socket([=] {
+        // Close up all logging pipes when thread dies
+        close(pipefd);
+        close(logd_fd.exchange(-1));
+    });
+
+    struct {
+        void *data;
+        size_t len;
+    } tmp_buf{};
+    stream *strm = new byte_stream(tmp_buf.data, tmp_buf.len);
+
+    log_meta meta{};
+    char buf[MAX_MSG_LEN + TIME_FMT_LEN];
+
+    for (;;) {
+        // Read meta data
+        if (xread(pipefd, &meta, sizeof(meta)) != sizeof(meta))
+            return;
+
+        if (meta.prio < 0 && tmp_buf.len >= 0) {
+            run_finally free_buf([&] {
+                free(tmp_buf.data);
+                tmp_buf.data = nullptr;
+                tmp_buf.len = -1;
+            });
+
+            if (meta.len)
+                rename(LOGFILE, LOGFILE ".bak");
+
+            int fd = open(LOGFILE, O_WRONLY | O_APPEND | O_CREAT | O_CLOEXEC, 0644);
+            if (fd < 0)
+                return;
+            if (tmp_buf.data)
+                write(fd, tmp_buf.data, tmp_buf.len);
+
+            delete strm;
+            strm = new fd_stream(fd);
+            continue;
+        }
+
+        // Read message
+        if (xread(pipefd, buf + TIME_FMT_LEN + 1, meta.len) != meta.len)
+            return;
+
+        timeval tv;
+        tm tm;
+        gettimeofday(&tv, nullptr);
+        localtime_r(&tv.tv_sec, &tm);
+
+        // Format detailed info
+        char type;
+        switch (meta.prio) {
+            case ANDROID_LOG_DEBUG:
+                type = 'D';
+                break;
+            case ANDROID_LOG_INFO:
+                type = 'I';
+                break;
+            case ANDROID_LOG_WARN:
+                type = 'W';
+                break;
+            default:
+                type = 'E';
+                break;
+        }
+        size_t off = strftime(buf, sizeof(buf), "%m-%d %T", &tm);
+        int ms = tv.tv_usec / 1000;
+        snprintf(buf + off, sizeof(buf) - off,
+                ".%03d %5d %5d %c : ", ms, meta.pid, meta.tid, type);
+
+        strm->write(buf, TIME_FMT_LEN + meta.len);
+    }
+}
+
+static int magisk_log(int prio, const char *fmt, va_list ap) {
+    char buf[MAX_MSG_LEN + 1];
+    int len = vsnprintf(buf, sizeof(buf), fmt, ap);
+
+    if (logd_fd >= 0) {
+        log_meta meta = {
+            .prio = prio,
+            .len = len,
+            .pid = getpid(),
+            .tid = gettid()
+        };
+
+        iovec iov[2];
+        iov[0].iov_base = &meta;
+        iov[0].iov_len = sizeof(meta);
+        iov[1].iov_base = buf;
+        iov[1].iov_len = len;
+
+        if (writev(logd_fd, iov, 2) < 0) {
+            // Stop trying to write to file
+            close(logd_fd.exchange(-1));
+        }
+    }
+    __android_log_write(prio, "Magisk", buf);
+
+    return len;
+}
+
+#define mlog(prio) [](auto fmt, auto ap){ return magisk_log(ANDROID_LOG_##prio, fmt, ap); }
+void magisk_logging() {
+    log_cb.d = mlog(DEBUG);
+    log_cb.i = mlog(INFO);
+    log_cb.w = mlog(WARN);
+    log_cb.e = mlog(ERROR);
+    log_cb.ex = nop_ex;
+}
+
+void start_log_daemon() {
+    int fds[2];
+    if (pipe2(fds, O_CLOEXEC) == 0) {
+        logd_fd = fds[1];
+        new_daemon_thread([fd = fds[0]] { logfile_writer(fd); });
+    }
+}