Discard too short log lines

[log-plotter] / main.c

diff --git a/main.c b/main.c
index 6189b7be34b7048123c441f8ea1c33e96c258741..8e145218aa4e463c88e5ecbf33914cae58c93655 100644 (file)
--- a/main.c
+++ b/main.c
@@ -1,6 +1,8 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <string.h>
+#include <time.h>
 #include <sys/epoll.h>
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -9,12 +11,68 @@
 #include "baud.h"
 #include "debug.h"
 
-int read_data(int infd, int outfd)
+/**
+ * Read data from a slow device
+ *
+ * return 1 when a complete NULL terminated line has been read
+ *
+ * return 0 when a partial line has been read and appended to the
+ *              buffer at @offset
+ *
+ * return negative on error
+ */
+static int read_log_line(int infd, char *buf, size_t bufsize, int *offset)
+{
+       int ret;
+       int i;
+
+       ret = read(infd, buf + *offset, bufsize - *offset - 1);
+       if (ret < 0) {
+               pr_err("read: %m\n");
+               return -1;
+       }
+
+       if (ret == 0) {
+               pr_err("Read EOF, stopping\n");
+               return -1;
+       }
+       buf[*offset + ret] = 0;
+
+       for (i = 0; i < ret; i++) {
+               if (buf[i + *offset] == '\n' ||
+                   buf[i + *offset] == '\r') {
+                       /*
+                        * Got a complete line when there is a newline
+                        * at the end. Remove the newline and possible
+                        * other junk, such as '\r'
+                        */
+                       buf[i + *offset] = 0;
+                       *offset = 0;
+
+                       return 1;
+               }
+
+               /*
+                * Fixme! Nothing guarantees that there isn't actually
+                * more data (a part of a new log entry perhaps) after
+                * the newline. So in rare cases (we are prevented
+                * from reading the serial line in very long time) we
+                * might lose data from the stream..
+                */
+       }
+
+       *offset += ret;
+       return 0;
+}
+
+static int read_data(int infd, int outfd)
 {
        struct epoll_event ev;
+       time_t start_time = 0, cur_time;
        int epoll_fd;
        int ret;
        char buf[256];
+       int offset;
 
        epoll_fd = epoll_create(1);
        if (epoll_fd < 0) {
@@ -30,6 +88,9 @@ int read_data(int infd, int outfd)
        }
 
        while (1) {
+               char str[320];
+               int len;
+
                ret = epoll_wait(epoll_fd, &ev, 1, -1);
                if (ret == 0)
                        continue;
@@ -39,19 +100,34 @@ int read_data(int infd, int outfd)
                        return -1;
                }
 
-               ret = read(infd, buf, sizeof(buf));
-               if (read < 0) {
-                       pr_err("read: %m\n");
-                       break;
-               }
+               if (!start_time)
+                       start_time = time(NULL);
 
-               if (ret == 0) {
-                       pr_err("Read EOF, stopping\n");
-                       break;
+               ret = read_log_line(infd, buf, sizeof(buf), &offset);
+               if (ret < 0)
+                       return ret;
+
+               if (ret == 0)
+                       continue;
+
+               if (strlen(buf) < 5) {
+                       pr_debug("discarding truncated log entry\n");
+                       offset = 0;
+                       continue;
                }
 
-               ret = write(outfd, buf, ret);
-               if (read < 0) {
+               cur_time = time(NULL);
+
+               pr_info("%s\n", buf);
+
+               if (!outfd)
+                       continue;
+
+               len = snprintf(str, sizeof(str),
+                       "%ld;%s\n", cur_time - start_time, buf);
+
+               ret = write(outfd, str, len);
+               if (ret < 0) {
                        pr_err("write: %m\n");
                        break;
                }
@@ -63,7 +139,7 @@ int read_data(int infd, int outfd)
 int main(int argc, char *argv[])
 {
        struct plotter_options options;
-       int fd, baud, ret = 0, out_fd = STDOUT_FILENO;
+       int fd, baud, ret = 0, out_fd = 0;
 
        if (read_args(argc, argv, &options))
                return 1;