Karel Zak wrote:
> This patch:
> - clean up tailf(1) code
> - remove stupid "for() { malloc() }" array allocation in the tailf() function
> - add inotify(7) support
>
> Signed-off-by: Karel Zak <kzak@xxxxxxxxxx>
> ---
> configure.ac | 1 +
> text-utils/tailf.1 | 4 +-
> text-utils/tailf.c | 240 ++++++++++++++++++++++++++++++++++------------------
> 3 files changed, 161 insertions(+), 84 deletions(-)
>
Good job. :)
> diff --git a/text-utils/tailf.c b/text-utils/tailf.c
> index f4616cc..8898574 100644
> --- a/text-utils/tailf.c
> +++ b/text-utils/tailf.c
> @@ -19,7 +19,7 @@
> * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
> * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
> * OTHER DEALINGS IN THE SOFTWARE.
> - *
> + *
> * less -F and tail -f cause a disk access every five seconds. This
> * program avoids this problem by waiting for the file size to change.
> * Hence, the file is not accessed, and the access time does not need to be
> @@ -31,111 +31,185 @@
> #include <unistd.h>
> #include <malloc.h>
> #include <string.h>
> +#include <sys/types.h>
> #include <sys/stat.h>
> +#include <unistd.h>
> +#include <fcntl.h>
> #include <ctype.h>
> +#include <errno.h>
> #include <err.h>
> +#include <sys/inotify.h>
> #include "nls.h"
>
> #define DEFAULT_LINES 10
>
> -static size_t filesize(const char *filename)
> +static void
> +tailf(const char *filename, int lines)
> {
> - struct stat sb;
> + char *buf, *p;
> + int head = 0;
> + int tail = 0;
> + FILE *str;
> + int i;
> +
> + if (!(str = fopen(filename, "r")))
> + err(EXIT_FAILURE, _("cannot open \"%s\" for read"), filename);
> +
> + buf = malloc(lines * BUFSIZ);
> + p = buf;
> + while(fgets(p, BUFSIZ, str)) {
need a space:
while (
> + if (++tail >= lines) {
> + tail = 0;
> + head = 1;
> + }
> + p = buf + (tail * BUFSIZ);
> + }
> +
> + if (head) {
> + for (i = tail; i < lines; i++)
> + fputs(buf + (i * BUFSIZ), stdout);
> + for (i = 0; i < tail; i++)
> + fputs(buf + (i * BUFSIZ), stdout);
> + } else {
> + for (i = head; i < tail; i++)
> + fputs(buf + (i * BUFSIZ), stdout);
> + }
>
> - if (!stat(filename, &sb)) return sb.st_size;
> - return 0;
> + fflush(stdout);
> + free(buf);
> + fclose(str);
> }
>
> -static void tailf(const char *filename, int lines)
> +static void
> +roll_file(const char *filename, off_t *size)
> {
> - char **buffer;
> - int head = 0;
> - int tail = 0;
> - FILE *str;
> - int i;
> -
> - if (!(str = fopen(filename, "r")))
> - err(1, _("cannot open \"%s\" for read"), filename);
> -
> - buffer = malloc(lines * sizeof(*buffer));
> - for (i = 0; i < lines; i++) buffer[i] = malloc(BUFSIZ + 1);
> -
> - while (fgets(buffer[tail], BUFSIZ, str)) {
> - if (++tail >= lines) {
> - tail = 0;
> - head = 1;
> + char buf[BUFSIZ];
> + int fd;
> + struct stat st;
> +
> + if (!(fd = open(filename, O_RDONLY)))
> + err(EXIT_FAILURE, _("cannot open \"%s\" for read"), filename);
> +
> + if (fstat(fd, &st) == -1)
> + err(EXIT_FAILURE, _("cannot stat \"%s\""), filename);
> +
> + if (st.st_size == *size) {
> + close(fd);
> + return;
> }
> - }
>
> - if (head) {
> - for (i = tail; i < lines; i++) fputs(buffer[i], stdout);
> - for (i = 0; i < tail; i++) fputs(buffer[i], stdout);
> - } else {
> - for (i = head; i < tail; i++) fputs(buffer[i], stdout);
> - }
> - fflush(stdout);
> + if (!lseek(fd, *size, SEEK_SET) != (off_t)-1) {
I think this should be:
if (lseek(fd, *size, SEEK_SET) != (off_t)-1)
Otherwise the if statement will be always true.
I don't see any other problems in the patch.
-
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