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-rw-r--r--inotail.c139
1 files changed, 131 insertions, 8 deletions
diff --git a/inotail.c b/inotail.c
index 0b77deb..228a6e9 100644
--- a/inotail.c
+++ b/inotail.c
@@ -31,6 +31,7 @@
#include <errno.h>
#include <getopt.h>
#include <ctype.h>
+#include <assert.h>
#include <sys/types.h>
#include <sys/stat.h>
@@ -64,6 +65,18 @@ static const struct option long_opts[] = {
{ NULL, 0, NULL, 0 }
};
+static char *emalloc(size_t size)
+{
+ char *ret = malloc(size);
+
+ if (unlikely(!ret)) {
+ fprintf(stderr, "Error: Failed to allocate %d bytes of memory (%s)\n", size, strerror(errno));
+ exit(EXIT_FAILURE);
+ }
+
+ return ret;
+}
+
static void usage(const int status)
{
fprintf(stdout, "Usage: %s [OPTION]... [FILE]...\n\n"
@@ -218,8 +231,123 @@ static off_t bytes_to_offset(struct file_struct *f, unsigned long n_bytes)
return offset;
}
+/* 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 {
+ char buf[BUFFER_SIZE];
+ size_t n_lines;
+ size_t n_bytes;
+ struct line_buf *next;
+ };
+ struct line_buf *first, *last, *tmp;
+ ssize_t rc;
+ unsigned long total_lines = 0;
+
+ dprintf("in tail_pipe_lines (%d)\n");
+
+ 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) {
+ const char *p;
+
+ if ((rc = read(f->fd, tmp->buf, BUFFER_SIZE)) <= 0)
+ 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);
+
+ /* XXX: Even necessary? */
+ if (rc < 0) {
+ fprintf(stderr, "Error: Could not read from %s\n", pretty_name(f->name));
+ rc = -1;
+ goto err_out;
+ }
+
+ if (last->n_bytes == 0)
+ goto err_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;
+
+ {
+ char const *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);
+ assert(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;
+
+err_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];
@@ -234,11 +362,6 @@ static ssize_t tail_pipe_lines(struct file_struct *f, unsigned long n_lines)
return rc;
}
-static ssize_t tail_pipe_bytes(struct file_struct *f, unsigned long n_bytes) {
- /* TODO: Implement me :) */
- return 0;
-}
-
static int tail_file(struct file_struct *f, unsigned long n_units, char mode, char forever)
{
ssize_t bytes_read = 0;
@@ -293,14 +416,14 @@ 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);
+
while ((bytes_read = read(f->fd, buf, BUFFER_SIZE)) > 0)
write(STDOUT_FILENO, buf, (size_t) bytes_read);