1 files changed, 138 insertions, 0 deletions
diff --git a/libnetdata/log/journal.c b/libnetdata/log/journal.c
new file mode 100644
index 00000000..21978cf5
--- /dev/null
+++ b/libnetdata/log/journal.c
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "journal.h"
+
+bool is_path_unix_socket(const char *path) {
+    if(!path || !*path)
+        return false;
+
+    struct stat statbuf;
+
+    // Check if the path is valid
+    if (!path || !*path)
+        return false;
+
+    // Use stat to check if the file exists and is a socket
+    if (stat(path, &statbuf) == -1)
+        // The file does not exist or cannot be accessed
+        return false;
+
+    // Check if the file is a socket
+    if (S_ISSOCK(statbuf.st_mode))
+        return true;
+
+    return false;
+}
+
+bool is_stderr_connected_to_journal(void) {
+    const char *journal_stream = getenv("JOURNAL_STREAM");
+    if (!journal_stream)
+        return false; // JOURNAL_STREAM is not set
+
+    struct stat stderr_stat;
+    if (fstat(STDERR_FILENO, &stderr_stat) < 0)
+        return false; // Error in getting stderr info
+
+    // Parse device and inode from JOURNAL_STREAM
+    char *endptr;
+    long journal_dev = strtol(journal_stream, &endptr, 10);
+    if (*endptr != ':')
+        return false; // Format error in JOURNAL_STREAM
+
+    long journal_ino = strtol(endptr + 1, NULL, 10);
+
+    return (stderr_stat.st_dev == (dev_t)journal_dev) && (stderr_stat.st_ino == (ino_t)journal_ino);
+}
+
+int journal_direct_fd(const char *path) {
+    if(!path || !*path)
+        path = JOURNAL_DIRECT_SOCKET;
+
+    if(!is_path_unix_socket(path))
+        return -1;
+
+    int fd = socket(AF_UNIX, SOCK_DGRAM, 0);
+    if (fd < 0) return -1;
+
+    struct sockaddr_un addr;
+    memset(&addr, 0, sizeof(struct sockaddr_un));
+    addr.sun_family = AF_UNIX;
+    strncpy(addr.sun_path, path, sizeof(addr.sun_path) - 1);
+
+    // Connect the socket (optional, but can simplify send operations)
+    if (connect(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
+        close(fd);
+        return -1;
+    }
+
+    return fd;
+}
+
+static inline bool journal_send_with_memfd(int fd, const char *msg, size_t msg_len) {
+#if defined(__NR_memfd_create) && defined(MFD_ALLOW_SEALING) && defined(F_ADD_SEALS) && defined(F_SEAL_SHRINK) && defined(F_SEAL_GROW) && defined(F_SEAL_WRITE)
+    // Create a memory file descriptor
+    int memfd = (int)syscall(__NR_memfd_create, "journald", MFD_ALLOW_SEALING);
+    if (memfd < 0) return false;
+
+    // Write data to the memfd
+    if (write(memfd, msg, msg_len) != (ssize_t)msg_len) {
+        close(memfd);
+        return false;
+    }
+
+    // Seal the memfd to make it immutable
+    if (fcntl(memfd, F_ADD_SEALS, F_SEAL_SHRINK | F_SEAL_GROW | F_SEAL_WRITE) < 0) {
+        close(memfd);
+        return false;
+    }
+
+    struct iovec iov = {0};
+    struct msghdr msghdr = {0};
+    struct cmsghdr *cmsghdr;
+    char cmsgbuf[CMSG_SPACE(sizeof(int))];
+
+    msghdr.msg_iov = &iov;
+    msghdr.msg_iovlen = 1;
+    msghdr.msg_control = cmsgbuf;
+    msghdr.msg_controllen = sizeof(cmsgbuf);
+
+    cmsghdr = CMSG_FIRSTHDR(&msghdr);
+    cmsghdr->cmsg_level = SOL_SOCKET;
+    cmsghdr->cmsg_type = SCM_RIGHTS;
+    cmsghdr->cmsg_len = CMSG_LEN(sizeof(int));
+    memcpy(CMSG_DATA(cmsghdr), &memfd, sizeof(int));
+
+    ssize_t r = sendmsg(fd, &msghdr, 0);
+
+    close(memfd);
+    return r >= 0;
+#else
+    return false;
+#endif
+}
+
+bool journal_direct_send(int fd, const char *msg, size_t msg_len) {
+    // Send the datagram
+    if (send(fd, msg, msg_len, 0) < 0) {
+        if(errno != EMSGSIZE)
+            return false;
+
+        // datagram is too large, fallback to memfd
+        if(!journal_send_with_memfd(fd, msg, msg_len))
+            return false;
+    }
+
+    return true;
+}
+
+void journal_construct_path(char *dst, size_t dst_len, const char *host_prefix, const char *namespace_str) {
+    if(!host_prefix)
+        host_prefix = "";
+
+    if(namespace_str)
+        snprintfz(dst, dst_len, "%s/run/systemd/journal.%s/socket",
+                  host_prefix, namespace_str);
+    else
+        snprintfz(dst, dst_len, "%s" JOURNAL_DIRECT_SOCKET,
+                  host_prefix);
+}