Merge branch 'pipe'

Conflicts:

	inotail.c

2 files changed, 260 insertions, 19 deletions

diff --git a/inotail.c b/inotail.c
index c19ed4f..7e2b6ac 100644
--- a/inotail.c
+++ b/inotail.c
@@ -89,7 +89,7 @@ static inline void setup_file(struct file_struct *f)
 {
 	f->fd = f->i_watch = -1;
 	f->size = 0;
-	f->blksize = DEFAULT_BUFFER_SIZE;
+	f->blksize = BUFSIZ;
 	f->ignore = 0;
 }
 
@@ -236,24 +236,244 @@ 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)
+static int tail_pipe_from_begin(struct file_struct *f, unsigned long n_units, const char mode)
 {
-	ssize_t rc;
-	char *buf = emalloc(f->blksize);
+	int bytes_read = 0;
+	char buf[BUFSIZ];
 
-	if (verbose)
-		write_header(f->name);
+	if (n_units)
+		n_units--;
+
+	while (n_units > 0) {
+		if ((bytes_read = read(f->fd, buf, BUFSIZ)) <= 0) {
+			if (bytes_read < 0 && (errno == EINTR || errno == EAGAIN))
+				continue;
+			else
+				return bytes_read;
+		}
+
+		if (mode == M_LINES) {
+			int i;
+			ssize_t block_size = BUFSIZ;
+
+			if (bytes_read < BUFSIZ)
+				block_size = bytes_read;
+
+			for (i = 0; i < block_size; i++) {
+				if (buf[i] == '\n') {
+					if (--n_units == 0)
+						break;
+				}
+			}
+
+			if (++i < block_size)
+				write(STDOUT_FILENO, &buf[i], bytes_read - i);
+		} else {
+			if ((unsigned long) bytes_read > n_units) {
+				write(STDOUT_FILENO, &buf[n_units], bytes_read - n_units);
+				bytes_read = n_units;
+			}
+
+			n_units -= bytes_read;
+		}
+	}
+
+	while ((bytes_read = read(f->fd, buf, BUFSIZ)) > 0)
+		write(STDOUT_FILENO, buf, (size_t) bytes_read);
+
+	return 0;
+}
+
+static int tail_pipe_lines(struct file_struct *f, unsigned long n_lines)
+{
+	struct line_buf *first, *last, *tmp;
+	int rc;
+	unsigned long total_lines = 0;
+	const char *p;
 
-	/* We will just tail everything here */
-	while ((rc = read(f->fd, buf, f->blksize)) > 0) {
-		if ((rc = write(STDOUT_FILENO, buf, (size_t) rc)) <= 0) {
-			/* e.g. when writing to a pipe which gets closed */
+	if (from_begin)
+		return tail_pipe_from_begin(f, n_lines, M_LINES);
+
+	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, BUFSIZ)) <= 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 < BUFSIZ) {
+			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) {
+		unsigned long j;
+		for (j = total_lines - n_lines; j; --j) {
+			p = memchr(p, '\n', tmp->buf + tmp->n_bytes - p);
+			p++;
+		}
+	}
+
+	if ((rc = write(STDOUT_FILENO, p, tmp->buf + tmp->n_bytes - p)) <= 0) {
+		/* e.g. when writing to a pipe which gets closed */
+		fprintf(stderr, "Error: Could not write to stdout (%s)\n", strerror(errno));
+		goto out;
+	}
+
+	for (tmp = tmp->next; tmp; tmp = tmp->next)
+		if ((rc = write(STDOUT_FILENO, tmp->buf, tmp->n_bytes)) <= 0) {
 			fprintf(stderr, "Error: Could not write to stdout (%s)\n", strerror(errno));
-			break;
+			goto out;
 		}
+
+	rc = 0;
+out:
+	while (first) {
+		tmp = first->next;
+		free(first);
+		first = tmp;
+	}
+
+	return rc;
+}
+
+static int tail_pipe_bytes(struct file_struct *f, unsigned long n_bytes)
+{
+	struct char_buf *first, *last, *tmp;
+	int rc;
+	unsigned long total_bytes = 0;
+	unsigned long i = 0;		/* Index into buffer */
+
+	if (from_begin)
+		return tail_pipe_from_begin(f, n_bytes, M_BYTES);
+
+	/* XXX: Needed? */
+	if (n_bytes == 0)
+		return 0;
+
+	first = last = emalloc(sizeof(struct char_buf));
+	first->n_bytes = 0;
+	first->next = NULL;
+	tmp = emalloc(sizeof(struct char_buf));
+
+	while(1) {
+		if ((rc = read(f->fd, tmp->buf, BUFSIZ)) <= 0) {
+			if (rc < 0 && (errno == EINTR || errno == EAGAIN))
+				continue;
+			else
+				break;
+		}
+		total_bytes += rc;
+		tmp->n_bytes = rc;
+		tmp->next = NULL;
+
+		/* Try to append to the previous buffer if there's enough free
+		 * space
+		 */
+		if (tmp->n_bytes + last->n_bytes < BUFSIZ) {
+			memcpy(&last->buf[last->n_bytes], tmp->buf, tmp->n_bytes);
+			last->n_bytes += tmp->n_bytes;
+		} else {
+			last = last->next = tmp;
+			if (total_bytes - first->n_bytes > n_bytes) {
+				tmp = first;
+				total_bytes -= first->n_bytes;
+				first = first->next;
+			} else
+				tmp = emalloc(sizeof(struct char_buf));
+		}
+	}
+
+	free(tmp);
+
+	if (rc < 0) {
+		fprintf(stderr, "Error: Could not read from %s\n", pretty_name(f->name));
+		goto out;
+	}
+
+	/* Skip unneeded buffers */
+	for (tmp = first; total_bytes - tmp->n_bytes > n_bytes; tmp = tmp->next)
+		total_bytes -= tmp->n_bytes;
+
+	if (total_bytes > n_bytes)
+		i = total_bytes - n_bytes;
+
+	if ((rc = write(STDOUT_FILENO, &tmp->buf[i], tmp->n_bytes - i)) <= 0) {
+		/* e.g. when writing to a pipe which gets closed */
+		fprintf(stderr, "Error: Could not write to stdout (%s)\n", strerror(errno));
+		goto out;
+	}
+
+	for (tmp = tmp->next; tmp; tmp = tmp->next)
+		if ((rc = write(STDOUT_FILENO, tmp->buf, tmp->n_bytes)) <= 0) {
+			fprintf(stderr, "Error: Could not write to stdout (%s)\n", strerror(errno));
+			goto out;
+		}
+
+
+	rc = 0;
+out:
+	while (first) {
+		tmp = first->next;
+		free(first);
+		first = tmp;
 	}
 
-	free(buf);
 	return rc;
 }
 
@@ -288,8 +508,15 @@ static int tail_file(struct file_struct *f, unsigned long n_units, mode_t mode,
 	}
 
 	/* 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? */
@@ -305,14 +532,14 @@ static int tail_file(struct file_struct *f, unsigned long n_units, mode_t mode,
 		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)
diff --git a/inotail.h b/inotail.h
index ff77b26..ea680cb 100644
--- a/inotail.h
+++ b/inotail.h
@@ -10,8 +10,7 @@
 #include <sys/types.h>
 #include "inotify.h"
 
-/* Number of items to tail. */
-#define DEFAULT_N_LINES 10
+#define DEFAULT_N_LINES 10	/* Number of items to tail. */
 
 #define DEFAULT_BUFFER_SIZE 4096
 /* inotify event buffer length for one file */
@@ -30,6 +29,21 @@ struct file_struct {
 	int i_watch;		/* Inotify watch associated with file_struct */
 };
 
+/* struct for linked list of buffers/lines in tail_pipe_lines */
+struct line_buf {
+	char buf[BUFSIZ];
+	size_t n_lines;
+	size_t n_bytes;
+	struct line_buf *next;
+};
+
+/* struct for linked list of byte buffers in tail_pipe_bytes */
+struct char_buf {
+	char buf[BUFSIZ];
+	size_t n_bytes;
+	struct char_buf *next;
+};
+
 #define IS_PIPELIKE(mode) \
 	(S_ISFIFO(mode) || S_ISSOCK(mode))