1 files changed, 119 insertions, 10 deletions

diff --git a/inotail.c b/inotail.c
index 920d5a5..e6ad90d 100644
--- a/inotail.c
+++ b/inotail.c
@@ -39,7 +39,6 @@
 #include "inotail.h"
 
 #define PROGRAM_NAME "inotail"
-#define DEFAULT_BUFFER_SIZE 4096
 /* inotify event buffer length for one file */
 #define INOTIFY_BUFLEN (4 * sizeof(struct inotify_event))
 
@@ -240,13 +239,116 @@ static off_t bytes_to_offset(struct file_struct *f, unsigned long n_bytes)
 	return offset;
 }
 
-static ssize_t tail_pipe(struct file_struct *f)
+/* For now more or less a copy of pipe_lines() from coreutils tail */
+static ssize_t tail_pipe_lines(struct file_struct *f, unsigned long n_lines)
 {
+	struct line_buf *first, *last, *tmp;
 	ssize_t rc;
-	char *buf = emalloc(f->blksize);
+	unsigned long total_lines = 0;
+	const char *p;
 
-	if (verbose)
-		write_header(f->name);
+	if (n_lines == 0)
+		return 0;
+
+	first = last = emalloc(sizeof(struct line_buf));
+	first->n_bytes = first->n_lines = 0;
+	first->next = NULL;
+	tmp = emalloc(sizeof(struct line_buf));
+
+	while (1) {
+		if ((rc = read(f->fd, tmp->buf, BUFFER_SIZE)) <= 0) {
+			if (rc < 0 && (errno == EINTR || errno == EAGAIN))
+				continue;
+			else
+				break;
+		}
+		tmp->n_bytes = rc;
+		tmp->n_lines = 0;
+		tmp->next = NULL;
+		p = tmp->buf;
+
+		/* Count the lines in the current buffer */
+		while ((p = memchr(p, '\n', tmp->buf + rc - p))) {
+			++p;
+			++tmp->n_lines;
+		}
+		total_lines += tmp->n_lines;
+
+		/* Try to append to the previous buffer if there's enough free
+		 * space
+		 */
+		if (tmp->n_bytes + last->n_bytes < BUFFER_SIZE) {
+			memcpy(&last->buf[last->n_bytes], tmp->buf, tmp->n_bytes);
+			last->n_bytes += tmp->n_bytes;
+			last->n_lines += tmp->n_lines;
+		} else {
+			last = last->next = tmp;
+			if (total_lines - first->n_lines > n_lines) {
+				tmp = first;
+				total_lines -= first->n_lines;
+				first = first->next;
+			} else
+				tmp = emalloc(sizeof(struct line_buf));
+		}
+	}
+
+	free(tmp);
+
+	if (rc < 0) {
+		fprintf(stderr, "Error: Could not read from %s\n", pretty_name(f->name));
+		goto out;
+	}
+
+	if (last->n_bytes == 0)
+		goto out;
+
+	/* Count incomplete lines */
+	if (last->buf[last->n_bytes - 1] != '\n') {
+		++last->n_lines;
+		++total_lines;
+	}
+
+	/* Skip unneeded buffers */
+	for (tmp = first; total_lines - tmp->n_lines > n_lines; tmp = tmp->next)
+		total_lines -= tmp->n_lines;
+
+	p = tmp->buf;
+
+	if (total_lines > n_lines) {
+		size_t j;
+		for (j = total_lines - n_lines; j; --j) {
+			p = memchr(p, '\n', tmp->buf + tmp->n_bytes - p);
+			++p;
+		}
+	}
+
+	write(STDOUT_FILENO, p, tmp->buf + tmp->n_bytes - p);
+
+	for (tmp = tmp->next; tmp; tmp = tmp->next)
+		if (write(STDOUT_FILENO, tmp->buf, tmp->n_bytes) <= 0) {
+			/* e.g. when writing to a pipe which gets closed */
+			fprintf(stderr, "Error: Could not write to stdout (%s)\n", strerror(errno));
+			rc = -1;
+			break;
+		}
+
+	rc = 0;
+
+out:
+	while (first) {
+		tmp = first->next;
+		free(first);
+		first = tmp;
+	}
+
+	return rc;
+}
+
+/* TODO: Implement me :) */
+static ssize_t tail_pipe_bytes(struct file_struct *f, unsigned long n_bytes)
+{
+	ssize_t rc;
+	char buf[BUFFER_SIZE];
 
 	/* We will just tail everything here */
 	while ((rc = read(f->fd, buf, f->blksize)) > 0) {
@@ -293,8 +395,15 @@ static int tail_file(struct file_struct *f, unsigned long n_units, char mode, ch
 	}
 
 	/* Cannot seek on these */
-	if (IS_PIPELIKE(finfo.st_mode) || f->fd == STDIN_FILENO)
-		return tail_pipe(f);
+	if (IS_PIPELIKE(finfo.st_mode) || f->fd == STDIN_FILENO) {
+		if (verbose)
+			write_header(f->name);
+
+		if (mode == M_LINES)
+			return tail_pipe_lines(f, n_units);
+		else
+			return tail_pipe_bytes(f, n_units);
+	}
 
 	f->size = finfo.st_size;
 	f->blksize = finfo.st_blksize;	/* TODO: Can this value be 0? */
@@ -310,14 +419,14 @@ static int tail_file(struct file_struct *f, unsigned long n_units, char mode, ch
 		return -1;
 	}
 
-	if (verbose)
-		write_header(f->name);
-
 	if (lseek(f->fd, offset, SEEK_SET) == (off_t) -1) {
 		fprintf(stderr, "Error: Could not seek in file '%s' (%s)\n", f->name, strerror(errno));
 		return -1;
 	}
 
+	if (verbose)
+		write_header(f->name);
+
 	buf = emalloc(f->blksize);
 
 	while ((bytes_read = read(f->fd, buf, f->blksize)) > 0)