initial commit

2 files changed, 307 insertions, 0 deletions

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..93ef656
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,10 @@
+CFLAGS=-O2 -Wall -Wno-unused-parameter -Wextra -Wwrite-strings
+
+ALL=mlog
+
+all: $(ALL)
+
+clean: FRC
+	rm -f $(ALL)
+
+FRC:
diff --git a/mlog.c b/mlog.c
new file mode 100644
index 0000000..566d5d4
--- /dev/null
+++ b/mlog.c
@@ -0,0 +1,297 @@
+/* mlog - merge log files by timestamp */
+
+#ifdef __linux__
+#define USE_INOTIFY
+#endif
+
+#include <sys/stat.h>
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#ifdef USE_INOTIFY
+#include <sys/poll.h>
+#include <sys/inotify.h>
+#endif
+
+int uflag;			/* remove duplicates */
+int fflag;			/* -f follow / -ff tail+follow */
+int sflag;			/* strip socklog prefix */
+
+struct logfile {
+	char *path;
+	FILE *file;
+	char *line;
+	size_t linelen;
+	size_t linealloc;
+	dev_t st_dev;
+	ino_t st_ino;
+#ifdef USE_INOTIFY
+	int wd;
+#endif
+};
+
+struct logfile *logs;
+int logcnt;
+int ifd;
+
+int spacestrcmp(const char *a, const char *b)
+{
+        for (; *a==*b && *a && *a != ' '; a++, b++);
+        return *(unsigned char *)a - *(unsigned char *)b;
+}
+
+void
+reopen(int i)
+{
+	logs[i].file = fopen(logs[i].path, "r");
+	if (!logs[i].file)
+		return;
+
+	struct stat st;
+	fstat(fileno(logs[i].file), &st);
+
+	if (S_ISDIR(st.st_mode)) {
+		fclose(logs[i].file);
+		logs[i].file = 0;
+		errno = EISDIR;
+		return;
+	}
+
+	logs[i].st_dev = st.st_dev;
+	logs[i].st_ino = st.st_ino;
+
+#ifdef USE_INOTIFY
+	if (logs[i].wd)
+		inotify_rm_watch(ifd, logs[i].wd);
+
+	// note that IN_DELETE_SELF doesn't work as we keep the file open
+	logs[i].wd = inotify_add_watch(ifd, logs[i].path, IN_MODIFY | IN_ATTRIB | IN_MOVE_SELF /* ? | IN_CLOSE_WRITE */);
+#endif
+}
+
+void
+wait_inotify()
+{
+#ifdef USE_INOTIFY
+	struct pollfd fds[1];
+	fds[0].fd = ifd;
+	fds[0].events = POLLIN;
+
+	int timeout = -1;
+	for (int i = 0; i < logcnt; i++)
+		if (!logs[i].file)
+			timeout = 3000; /* missing file, need to wait if it appears */
+
+	int r = poll(fds, 1, timeout);
+	if (r == 1) {
+		char ibuf[255];
+		while (read(ifd, ibuf, sizeof ibuf) == sizeof ibuf)
+			;
+	}
+	if (r != 0)
+		usleep(25000);	/* 25ms, debounce quick subsequent writes */
+#else
+	sleep(3);
+#endif
+}
+
+void
+strip(int i)
+{
+	char *s = logs[i].line;
+	char *z = s + logs[i].linelen;
+
+	int d = 0;
+	int m = 0;
+	int t = 0;
+	int c = 0;
+	int p = 0;
+	int e = 0;
+
+	while (s < z && *s != ' ') {
+		switch (*s++) {
+		case '-': m++; break;
+		case 'T': t++; break;
+		case ':': c++; break;
+		case '.': p++; break;
+		case '0':
+		case '1':
+		case '2':
+		case '3':
+		case '4':
+		case '5':
+		case '6':
+		case '7':
+		case '8':
+		case '9': d++; break;
+		default: e++;
+		}
+	}
+
+	// 2024-01-10T17:57:34.40282
+	if (!(d == 19 && m == 2 && t == 1 && c == 2 && e == 0))
+		return;
+
+	char *b = s;
+
+	// skip "daemon.notice:"
+	while (s < z && *++s != ' ')
+		;
+	if (s[-1] != ':')
+		return;
+
+	// skip " Jan 10 19:17:56"
+	if (s + 16 < z && s[10] == ':' && s[13] == ':')
+		s += 16;
+
+	if (s >= z)
+		return;
+
+	size_t shrink = s - b;
+	size_t rest = logs[i].linelen - shrink - (b - logs[i].line);
+	memmove(b, s, rest);
+	logs[i].linelen -= shrink;
+}
+
+int
+nextline(int i)
+{
+	if (!logs[i].file) {
+		if (fflag)
+			reopen(i);
+		else
+			return 0;
+		if (!logs[i].file)
+			return 0;
+	}
+
+	errno = 0;
+	ssize_t r = getline(&(logs[i].line), &(logs[i].linealloc), logs[i].file);
+	if (r >= 0) {		/* successful read */
+		logs[i].linelen = r;
+		if (sflag)
+			strip(i);
+		return 1;
+	}
+
+	int e = errno;
+	free(logs[i].line);
+	logs[i].line = 0;
+	logs[i].linealloc = 0;
+
+	if (e == 0 && fflag) { /* hit EOF */
+		clearerr(logs[i].file);
+
+		struct stat st;
+		r = stat(logs[i].path, &st);
+		if (r < 0 ||
+		    st.st_dev != logs[i].st_dev ||
+		    st.st_ino != logs[i].st_ino ||
+		    ftell(logs[i].file) > st.st_size) {
+			fprintf(stderr, "stat failed, file vanished?\n");
+			fclose(logs[i].file);
+			logs[i].file = 0;
+			if (r == 0 && fflag)
+				return nextline(i);
+			return 0;
+		}
+
+		return 1;
+	}
+
+	if (e != 0)
+		fprintf(stderr, "error reading '%s': %s\n",
+		    logs[i].path, strerror(e));
+	fclose(logs[i].file);
+	logs[i].file = 0;
+	return 0;
+}
+
+int
+main(int argc, char *argv[])
+{
+	int opt;
+
+	while ((opt = getopt(argc, argv, "fsu")) != -1) {
+                switch (opt) {
+                case 'f': fflag++; break;
+                case 's': sflag++; break;
+                case 'u': uflag++; break;
+                default:
+		usage:
+                        fputs("usage: mlog [-fu] FILES...\n", stderr);
+                        exit(2);
+                }
+        }
+
+	logcnt = argc - optind;
+	if (logcnt == 0)
+		goto usage;
+	logs = calloc(logcnt, sizeof logs[0]);
+	if (!logs)
+		exit(111);
+
+#ifdef USE_INOTIFY
+        ifd = inotify_init();
+        if (ifd < 0)
+                exit(111);
+#endif
+
+	for (int i = 0; i < logcnt; i++) {
+		logs[i].path = argv[optind+i];
+		reopen(i);
+		if (!logs[i].file)
+			fprintf(stderr, "mlog: can't open log '%s': %s\n",
+			    logs[i].path,
+			    strerror(errno));
+		if (fflag > 1 && logs[i].file)
+			fseek(logs[i].file, 0L, SEEK_END);
+	}
+
+	while (1) {
+		for (int i = 0; i < logcnt; i++)
+			if (!logs[i].line)
+				nextline(i);
+
+		int minidx = -1;
+		for (int i = 0; i < logcnt; i++) {
+			if (logs[i].line) {
+				minidx = i;
+				break;
+			}
+		}
+		if (minidx < 0) {
+			if (fflag) {
+				wait_inotify();
+				continue;
+			} else {
+				break;
+			}
+		}
+		for (int i = minidx + 1; i < logcnt; i++) {
+			if (!logs[i].line)
+				continue;
+			if (spacestrcmp(logs[minidx].line, logs[i].line) > 0)
+				minidx = i;
+		}
+
+		fwrite(logs[minidx].line, logs[minidx].linelen, 1, stdout);
+		if (logs[minidx].line[logs[minidx].linelen - 1] != '\n')
+			fputc('\n', stdout);
+
+		if (uflag) {
+			for (int i = 0; i < logcnt; i++) {
+				if (i != minidx &&
+				    logs[i].line &&
+				    strcmp(logs[i].line, logs[minidx].line) == 0)
+					nextline(i);
+			}
+		}
+
+		nextline(minidx);
+	}
+}