inotail.c: Prepare for follow file by name

1 files changed, 81 insertions, 7 deletions

diff --git a/inotail.c b/inotail.c
index 4195e13..8c161e9 100644
--- a/inotail.c
+++ b/inotail.c
@@ -30,19 +30,31 @@
 #include <fcntl.h>
 #include <errno.h>
 #include <getopt.h>
+#include <libgen.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 
 #include "inotify.h"
 #include "inotify-syscalls.h"
+
 #include "inotail.h"
 
 #define PROGRAM_NAME "inotail"
+/* inotify event buffer length for one file */
+#define INOTIFY_BUFLEN (4 * sizeof(struct inotify_event))
 
 /* Print header with filename before tailing the file? */
 static char verbose = 0;
+
 /* Tailing relative to begin or end of file */
 static char from_begin = 0;
+
+/* Follow the file by name or by fd */
+static enum follow_mode follow = FOLLOW_DESCRIPTOR;
+
+/* Retry accessing the file if it got lost (e.g. deleted, moved) */
+static char retry = 0;
+
 /* Number of ignored files */
 static int n_ignored = 0;
 
@@ -73,7 +85,9 @@ static void usage(const int status)
 {
 	fprintf(stdout, "Usage: %s [OPTION]... [FILE]...\n\n"
 			"  -c N, --bytes=N    output the last N bytes\n"
-			"  -f,   --follow     output as the file grows\n"
+			"  -f,   --follow[={descriptor|name}]\n"
+			"                     output as the file grows (default: descriptor)\n"
+			"  -F                 same as --follow=name\n"
 			"  -n N, --lines=N    output the last N lines (default: %d)\n"
 			"  -v,   --verbose    print headers with file names\n"
 			"  -h,   --help       show this help and exit\n"
@@ -87,7 +101,7 @@ static void usage(const int status)
 
 static inline void setup_file(struct file_struct *f)
 {
-	f->fd = f->i_watch = -1;
+	f->fd = f->i_watch = f->i_d_watch = -1;
 	f->size = 0;
 	f->blksize = BUFSIZ;
 	f->ignore = 0;
@@ -95,6 +109,7 @@ static inline void setup_file(struct file_struct *f)
 
 static void ignore_file(struct file_struct *f)
 {
+	dprintf("File '%s' ignored\n", f->name);
 	if (f->fd != -1) {
 		close(f->fd);
 		f->fd = -1;
@@ -567,10 +582,23 @@ static int tail_file(struct file_struct *f, unsigned long n_units, mode_t mode,
 	return 0;
 }
 
+static int follow_file_by_name(struct file_struct *f)
+{
+	inotify_rm_watch(f->fd, INOTAIL_EVENT_MASK);
+	close(f->fd);
+
+	/* TODO: Set up a watch for the directory the file was in and
+	 * wait for the file to be created again.
+	 */
+	return 0;
+}
+
 static int handle_inotify_event(struct inotify_event *inev, struct file_struct *f)
 {
 	int ret = 0;
 
+	ddump(inev);
+
 	if (inev->mask & IN_MODIFY) {
 		char *fbuf;
 		ssize_t bytes_read;
@@ -607,11 +635,22 @@ static int handle_inotify_event(struct inotify_event *inev, struct file_struct *
 		return ret;
 	} else if (inev->mask & IN_DELETE_SELF) {
 		fprintf(stderr, "File '%s' deleted.\n", f->name);
+
+		if (retry && follow == FOLLOW_NAME) {
+			follow_file_by_name(f);
+		}
 	} else if (inev->mask & IN_MOVE_SELF) {
 		fprintf(stderr, "File '%s' moved.\n", f->name);
+
+		if (follow == FOLLOW_NAME) {
+			follow_file_by_name(f);
+		}
+
 		return 0;
 	} else if (inev->mask & IN_UNMOUNT) {
 		fprintf(stderr, "Device containing file '%s' unmounted.\n", f->name);
+	} else if (f->dir && (inev->mask & (IN_CREATE | IN_MOVED_TO))) {
+		/* File was moved/deleted and became available again */
 	} else if (inev->mask & IN_IGNORED) {
 		return 0;
 	}
@@ -637,14 +676,24 @@ static int watch_files(struct file_struct *files, int n_files)
 
 	for (i = 0; i < n_files; i++) {
 		if (!files[i].ignore) {
-			files[i].i_watch = inotify_add_watch(ifd, files[i].name,
-						IN_MODIFY|IN_DELETE_SELF|IN_MOVE_SELF|IN_UNMOUNT);
+			files[i].i_watch = inotify_add_watch(ifd, files[i].name, INOTAIL_EVENT_MASK);
 
 			if (files[i].i_watch < 0) {
 				fprintf(stderr, "Error: Could not create inotify watch on file '%s' (%s)\n",
 						files[i].name, strerror(errno));
 				ignore_file(&files[i]);
 			}
+
+			if (files[i].dir) {
+				files[i].i_d_watch = inotify_add_watch(ifd, files[i].dir,
+						IN_CREATE | IN_MOVED_TO | IN_DELETE | IN_ONLYDIR);
+
+				if (files[i].i_d_watch < 0) {
+					fprintf(stderr, "Error: Could not create inotify watch on directory '%s' (%s)\n",
+							files[i].dir, strerror(errno));
+					files[i].dir = NULL;
+				}
+			}
 		}
 	}
 
@@ -698,12 +747,12 @@ int main(int argc, char **argv)
 	int i, c, ret = 0;
 	int n_files;
 	unsigned long n_units = DEFAULT_N_LINES;
-	mode_t mode = M_LINES;
+	enum tail_mode mode = M_LINES;
 	char forever = 0;
 	char **filenames;
 	struct file_struct *files = NULL;
 
-	while ((c = getopt_long(argc, argv, "c:n:fvVh", long_opts, NULL)) != -1) {
+	while ((c = getopt_long(argc, argv, "c:n:fFvVh", long_opts, NULL)) != -1) {
 		switch (c) {
 		case 'c':
 			mode = M_BYTES;
@@ -721,8 +770,23 @@ int main(int argc, char **argv)
 			}
 			n_units = strtoul(optarg, NULL, 0);
 			break;
-                case 'f':
+		case 'f':
 			forever = 1;
+			if (!optarg || strncmp(optarg, "descriptor", 11) == 0)
+				follow = FOLLOW_DESCRIPTOR;
+			else if (strncmp(optarg, "name", 5) == 0)
+				follow = FOLLOW_NAME;
+			else {
+				fprintf(stderr,
+					"Error: Invalid follow mode: %s\nSee %s --help for valid options\n",
+					optarg, PROGRAM_NAME);
+				exit(EXIT_FAILURE);
+			}
+			break;
+		case 'F':
+			forever = 1;
+			follow = FOLLOW_NAME;
+			retry = 1;
 			break;
 		case 'v':
 			verbose = 1;
@@ -767,6 +831,16 @@ int main(int argc, char **argv)
 
 	for (i = 0; i < n_files; i++) {
 		files[i].name = filenames[i];
+
+		dprintf("basename: %s\n", basename(files[i].name));
+		dprintf("dirname: %s\n", dirname(files[i].name));
+
+		if (follow == FOLLOW_NAME) {
+			/* TODO: Set dir member of file_struct */
+		} else {
+			files[i].dir = NULL;
+		}
+
 		setup_file(&files[i]);
 		ret = tail_file(&files[i], n_units, mode, forever);
 		if (ret < 0)