gods

commit ba7e5a3e9562ba1df4047996c14c8f425d43ede5
parent ab58abffb9808ad1b65cc09e9656699e6fcececc
Author: Naveen Narayanan <zerous@nocebo.space>
Date:   Sat,  9 Oct 2021 18:57:45 +0200

Implement readline()

The function readline() uses read() to check if there
is new data; if it finds new data it returns the same
otherwise NULL is returned. main() uses this function
to process new data if found or usleep() otherwise.

Diffstat:
M
main.c
 | 
62
++++++++++++++++++++++++++++++++++++++++++--------------------

1 file changed, 42 insertions(+), 20 deletions(-)
diff --git a/main.c b/main.c
@@ -1,8 +1,10 @@
 #include <err.h>
 #include <errno.h>
+#include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 
 #include "attack.h"
 #include "config.h"
@@ -10,7 +12,7 @@
 #include "parser.h"
 #include "queue.h"
 
-#define BUFSZ 256
+#define BUFSZ 512
 
 static char buf[BUFSZ];
 SLIST_HEAD(lhead, attacker) head = SLIST_HEAD_INITIALIZER(head);
@@ -47,35 +49,55 @@ init(struct attacker *a)
 	a->last = attack;
 }
 
+/*
+ * XXX readline relies upon the assumption
+ * that a line can be atmost BUFSZ long
+ */
+char *
+readline(int fd)
+{
+	static char *next;
+	static int rem;
+	int n;
+
+	if (rem)
+		for (int i = 0; i < rem; ++i)
+			buf[i] = next[i];
+
+	if ((n = read(fd, buf+rem, BUFSZ-rem)) == -1)
+		err(1, "read failed");
+
+	rem += n;
+	for (int i = 0; i < rem; ++i)
+		if (buf[i] == '\n') {
+			buf[i] = '\0';
+			rem -= i+1;
+			next = (rem == 0) ? NULL : &buf[i+1];
+			return buf;
+		}
+
+	return NULL;
+}
+
 int
 main(int argc, char **argv)
 {
-	FILE *fp;
 	char *line;
-	int c, found;
+	int fd, found;
 	struct attacker *a;
 
-	fp = fopen(sshlog, "r");
-	if (!fp)
-		err(1, "fopen failed: %s", sshlog);
+	fd = open(sshlog, O_RDONLY);
+	if (fd == -1)
+		err(1, "open failed: %s", sshlog);
 
-	c = 0;
 	for ( ; ; ) {
-		if (c == EOF)
-			break;
-
-		line = buf;
-		memset(buf, 0, BUFSZ);
-
-		while ((c = fgetc(fp)) != EOF) {
-			if (c == '\n') {
-				*line = '\0';
-				break;
-			}
-			*line++ = c;
+		while ((line = readline(fd)) == NULL) {
+			usleep(500000);
+			continue;
 		}
 
-		if (parse(buf) == -1) {
+
+		if (parse(line) == -1) {
 			fprintf(stderr, "parse failed\n");
 			continue;
 		}