dmesg: refactoring for kmsg support

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/sys-utils/dmesg.c b/sys-utils/dmesg.c
index 133d126b1ec754522eeaebb63ceb8716c2b41ae7..9606f0fcde1d05a0bcf1d5f7450470a8a9884fcc 100644 (file)
--- a/sys-utils/dmesg.c
+++ b/sys-utils/dmesg.c
@@ -108,6 +108,7 @@ static const struct dmesg_name facility_names[] =
 /* supported methods to read message buffer
  */
 enum {
+       DMESG_METHOD_KMSG,      /* read messages from /dev/kmsg (default) */
        DMESG_METHOD_SYSLOG,    /* klogctl() buffer */
        DMESG_METHOD_MMAP       /* mmap file with records (see --file) */
 };
@@ -123,6 +124,7 @@ struct dmesg_control {
        int             action;         /* SYSLOG_ACTION_* */
        int             method;         /* DMESG_METHOD_* */
        size_t          bufsize;        /* size of buffer created by read_buffer() */
+       int             kmsg;           /* /dev/kmsg file descriptor */
 
        /*
         * For the --file option we mmap whole file. The unnecessary (already
@@ -498,11 +500,16 @@ static void safe_fwrite(const char *buf, size_t size, FILE *out)
        }
 }
 
-static int get_next_record(struct dmesg_control *ctl, struct dmesg_record *rec)
+static int get_next_syslog_record(struct dmesg_control *ctl,
+                                 struct dmesg_record *rec)
 {
        size_t i;
        const char *begin = NULL;
 
+       if (ctl->method != DMESG_METHOD_MMAP &&
+           ctl->method != DMESG_METHOD_SYSLOG)
+               return -1;
+
        if (!rec->next || !rec->next_size)
                return 1;
 
@@ -628,6 +635,54 @@ static void raw_print(struct dmesg_control *ctl, const char *buf, size_t size)
                putchar('\n');
 }
 
+static void print_record(struct dmesg_control *ctl, struct dmesg_record *rec)
+{
+       char tbuf[256];
+
+       if (!accept_record(ctl, rec))
+               return;
+
+       if (!rec->mesg_size) {
+               putchar('\n');
+               return;
+       }
+
+       if (ctl->decode && rec->level >= 0 && rec->facility >= 0)
+               printf("%-6s:%-6s: ", facility_names[rec->facility].name,
+                                     level_names[rec->level].name);
+
+       *tbuf = '\0';
+       if (ctl->ctime) {
+               time_t t = ctl->boot_time + rec->tv.tv_sec;
+               if (strftime(tbuf, sizeof(tbuf), "%a %b %e %H:%M:%S %Y",
+                            localtime(&t)) == 0)
+                       *tbuf = '\0';
+       }
+       if (ctl->delta) {
+               double delta = 0;
+
+               if (timerisset(&ctl->lasttime))
+                       delta = time_diff(&rec->tv, &ctl->lasttime);
+               ctl->lasttime = rec->tv;
+
+               if (ctl->ctime && *tbuf)
+                       printf("[%s ", tbuf);
+               else if (ctl->notime)
+                       putchar('[');
+               else
+                       printf("[%5d.%06d ", (int) rec->tv.tv_sec,
+                                            (int) rec->tv.tv_usec);
+               printf("<%12.06f>] ", delta);
+       } else if (ctl->ctime && *tbuf) {
+               printf("[%s] ", tbuf);
+       }
+
+       safe_fwrite(rec->mesg, rec->mesg_size, stdout);
+
+       if (*(rec->mesg + rec->mesg_size - 1) != '\n')
+               putchar('\n');
+}
+
 /*
  * Prints the 'buf' kernel ring buffer; the messages are filtered out according
  * to 'levels' and 'facilities' bitarrays.
@@ -636,58 +691,20 @@ static void print_buffer(struct dmesg_control *ctl,
                        const char *buf, size_t size)
 {
        struct dmesg_record rec = { .next = buf, .next_size = size };
-       char tbuf[256];
 
        if (ctl->raw) {
                raw_print(ctl, buf, size);
                return;
        }
 
-       while (get_next_record(ctl, &rec) == 0) {
-
-               if (!accept_record(ctl, &rec))
-                       continue;
-
-               if (!rec.mesg_size) {
-                       putchar('\n');
-                       continue;
-               }
-
-               if (ctl->decode && rec.level >= 0 && rec.facility >= 0)
-                       printf("%-6s:%-6s: ", facility_names[rec.facility].name,
-                                             level_names[rec.level].name);
-
-               *tbuf = '\0';
-               if (ctl->ctime) {
-                       time_t t = ctl->boot_time + rec.tv.tv_sec;
-                       if (strftime(tbuf, sizeof(tbuf), "%a %b %e %H:%M:%S %Y",
-                                    localtime(&t)) == 0)
-                               *tbuf = '\0';
-               }
-               if (ctl->delta) {
-                       double delta = 0;
-
-                       if (timerisset(&ctl->lasttime))
-                               delta = time_diff(&rec.tv, &ctl->lasttime);
-                       ctl->lasttime = rec.tv;
-
-                       if (ctl->ctime && *tbuf)
-                               printf("[%s ", tbuf);
-                       else if (ctl->notime)
-                               putchar('[');
-                       else
-                               printf("[%5d.%06d ", (int) rec.tv.tv_sec,
-                                                    (int) rec.tv.tv_usec);
-                       printf("<%12.06f>] ", delta);
-               } else if (ctl->ctime && *tbuf) {
-                       printf("[%s] ", tbuf);
-               }
-
-               safe_fwrite(rec.mesg, rec.mesg_size, stdout);
+       while (get_next_syslog_record(ctl, &rec) == 0)
+               print_record(ctl, &rec);
+}
 
-               if (*(rec.mesg + rec.mesg_size - 1) != '\n')
-                       putchar('\n');
-       }
+static int init_kmsg(struct dmesg_control *ctl)
+{
+       ctl->kmsg = open("/dev/kmsg", O_RDONLY|O_NONBLOCK);
+       return ctl->kmsg < 0 ? -1 : 0;
 }
 
 int main(int argc, char *argv[])
@@ -699,7 +716,8 @@ int main(int argc, char *argv[])
        static struct dmesg_control ctl = {
                .filename = NULL,
                .action = SYSLOG_ACTION_READ_ALL,
-               .method = DMESG_METHOD_SYSLOG
+               .method = DMESG_METHOD_SYSLOG,
+               .kmsg = -1,
        };
 
        enum {
@@ -841,10 +859,12 @@ int main(int argc, char *argv[])
        switch (ctl.action) {
        case SYSLOG_ACTION_READ_ALL:
        case SYSLOG_ACTION_READ_CLEAR:
+               if (ctl.method == DMESG_METHOD_KMSG && init_kmsg(&ctl) != 0)
+                       ctl.method = DMESG_METHOD_SYSLOG;
+
                n = read_buffer(&ctl, &buf);
                if (n > 0)
                        print_buffer(&ctl, buf, n);
-
                if (!ctl.mmap_buff)
                        free(buf);
                break;
@@ -861,6 +881,9 @@ int main(int argc, char *argv[])
                break;
        }
 
+       if (ctl.kmsg >= 0)
+               close(ctl.kmsg);
+
        if (n < 0 && ctl.method == DMESG_METHOD_SYSLOG)
                err(EXIT_FAILURE, _("klogctl failed"));