journal: add native protocol to journald, and client side API to send journal messages

1 files changed, 196 insertions, 0 deletions

diff --git a/src/journal/journal-send.c b/src/journal/journal-send.c
new file mode 100644
index 000000000..e2575a980
--- /dev/null
+++ b/src/journal/journal-send.c
@@ -0,0 +1,196 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2011 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <errno.h>
+#include <stddef.h>
+
+#include "sd-journal.h"
+#include "util.h"
+
+/* We open a single fd, and we'll share it with the current process,
+ * all its threads, and all its subprocesses. This means we need to
+ * initialize it atomically, and need to operate on it atomically
+ * never assuming we are the only user */
+
+static int journal_fd(void) {
+        int fd;
+        static int fd_plus_one = 0;
+
+retry:
+        if (fd_plus_one > 0)
+                return fd_plus_one - 1;
+
+        fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0);
+        if (fd < 0)
+                return -errno;
+
+        if (!__sync_bool_compare_and_swap(&fd_plus_one, 0, fd+1)) {
+                close_nointr_nofail(fd);
+                goto retry;
+        }
+
+        return fd;
+}
+
+int sd_journal_print(const char *format, ...) {
+        int r;
+        va_list ap;
+
+        va_start(ap, format);
+        r = sd_journal_printv(format, ap);
+        va_end(ap);
+
+        return r;
+}
+
+int sd_journal_printv(const char *format, va_list ap) {
+        char buffer[8 + LINE_MAX];
+        struct iovec iov;
+
+        memcpy(buffer, "MESSAGE=", 8);
+        vsnprintf(buffer+8, sizeof(buffer) - 8, format, ap);
+
+        char_array_0(buffer);
+
+        zero(iov);
+        IOVEC_SET_STRING(iov, buffer);
+
+        return sd_journal_sendv(&iov, 1);
+}
+
+int sd_journal_send(const char *format, ...) {
+        int r, n = 0, i = 0, j;
+        va_list ap;
+        struct iovec *iov = NULL;
+
+        va_start(ap, format);
+        while (format) {
+                struct iovec *c;
+                char *buffer;
+
+                if (i >= n) {
+                        n = MAX(i*2, 4);
+                        c = realloc(iov, n * sizeof(struct iovec));
+                        if (!c) {
+                                r = -ENOMEM;
+                                goto fail;
+                        }
+
+                        iov = c;
+                }
+
+                if (vasprintf(&buffer, format, ap) < 0) {
+                        r = -ENOMEM;
+                        goto fail;
+                }
+
+                IOVEC_SET_STRING(iov[i++], buffer);
+
+                format = va_arg(ap, char *);
+        }
+        va_end(ap);
+
+        r = sd_journal_sendv(iov, i);
+
+fail:
+        for (j = 0; j < i; j++)
+                free(iov[j].iov_base);
+
+        free(iov);
+
+        return r;
+}
+
+int sd_journal_sendv(const struct iovec *iov, int n) {
+        int fd;
+        struct iovec *w;
+        uint64_t *l;
+        int i, j = 0;
+        struct msghdr mh;
+        struct sockaddr_un sa;
+
+        if (!iov || n <= 0)
+                return -EINVAL;
+
+        w = alloca(sizeof(struct iovec) * n * 5);
+        l = alloca(sizeof(uint64_t) * n);
+
+        for (i = 0; i < n; i++) {
+                char *c, *nl;
+
+                c = memchr(iov[i].iov_base, '=', iov[i].iov_len);
+                if (!c)
+                        return -EINVAL;
+
+                nl = memchr(iov[i].iov_base, '\n', iov[i].iov_len);
+                if (nl) {
+                        if (nl < c)
+                                return -EINVAL;
+
+                        /* Already includes a newline? Bummer, then
+                         * let's write the variable name, then a
+                         * newline, then the size (64bit LE), followed
+                         * by the data and a final newline */
+
+                        w[j].iov_base = iov[i].iov_base;
+                        w[j].iov_len = c - (char*) iov[i].iov_base;
+                        j++;
+
+                        IOVEC_SET_STRING(w[j++], "\n");
+
+                        l[i] = htole64(iov[i].iov_len - (c - (char*) iov[i].iov_base) - 1);
+                        w[j].iov_base = &l[i];
+                        w[j].iov_len = sizeof(uint64_t);
+                        j++;
+
+                        w[j].iov_base = c + 1;
+                        w[j].iov_len = iov[i].iov_len - (c - (char*) iov[i].iov_base) - 1;
+                        j++;
+
+                } else
+                        /* Nothing special? Then just add the line and
+                         * append a newline */
+                        w[j++] = iov[i];
+
+                IOVEC_SET_STRING(w[j++], "\n");
+        }
+
+        fd = journal_fd();
+        if (fd < 0)
+                return fd;
+
+        zero(sa);
+        sa.sun_family = AF_UNIX;
+        strncpy(sa.sun_path,"/run/systemd/journal", sizeof(sa.sun_path));
+
+        zero(mh);
+        mh.msg_name = &sa;
+        mh.msg_namelen = offsetof(struct sockaddr_un, sun_path) + strlen(sa.sun_path);
+        mh.msg_iov = w;
+        mh.msg_iovlen = j;
+
+        if (sendmsg(fd, &mh, MSG_NOSIGNAL) < 0)
+                return -errno;
+
+        return 0;
+}