On Sun, Dec 04, 2016 at 09:55:07PM -0800, Michael Forney wrote:
> The FILE streams are buffered, so the end result is essentially the
> same, except now lines are printed as they are read since we don't wait
> until the entire buffer is filled.
>
> This also fixes an issue where only part of the lines during the follow
> were printed if they contained NUL bytes.
> ---
> tail.c | 22 +++++++++++++---------
> 1 file changed, 13 insertions(+), 9 deletions(-)
>
> diff --git a/tail.c b/tail.c
> index 711707f..ad97308 100644
> --- a/tail.c
> +++ b/tail.c
> _AT_@ -20,6 +20,7 @@ dropinit(FILE *fp, const char *str, size_t n)
> char *buf = NULL;
> size_t size = 0, i = 1;
> ssize_t len;
> + int c;
>
> if (mode == 'n') {
> while (i < n && (len = getline(&buf, &size, fp)) > 0)
> _AT_@ -30,7 +31,10 @@ dropinit(FILE *fp, const char *str, size_t n)
> i++;
> }
> free(buf);
> - concat(fp, str, stdout, "<stdout>");
> + while ((c = fgetc(fp)) != EOF) {
> + if (fputc(c, stdout) == EOF)
> + break;
> + }
> }
>
> static void
> _AT_@ -88,9 +92,9 @@ main(int argc, char *argv[])
> {
> struct stat st1, st2;
> FILE *fp;
> - size_t tmpsize, n = 10;
> - int fflag = 0, ret = 0, newline = 0, many = 0;
> - char *numstr, *tmp;
> + size_t n = 10;
> + int fflag = 0, ret = 0, newline = 0, many = 0, c;
> + char *numstr;
> void (*tail)(FILE *, const char *, size_t) = taketail;
>
> ARGBEGIN {
> _AT_@ -141,13 +145,13 @@ main(int argc, char *argv[])
> ret = 1;
> continue;
> }
> - for (tmp = NULL, tmpsize = 0;;) {
> - while (getline(&tmp, &tmpsize, fp) > 0) {
> - fputs(tmp, stdout);
> - fflush(stdout);
> + for (;;) {
> + while ((c = fgetc(fp)) != EOF) {
> + if (fputc(c, stdout) == EOF)
> + eprintf("fputc <stdout>:");
> }
> if (ferror(fp))
> - eprintf("readline %s:", *argv);
> + eprintf("fgetc %s:", *argv);
> clearerr(fp);
> /* ignore error in case file was removed, we continue
> * tracking the existing open file descriptor */
> --
> 2.11.0
>
>
Hey Michael,
Just wondering: did you test if this will be much slower? Ideally test with
both musl and glibc.
--
Kind regards,
Hiltjo
Received on Mon Dec 05 2016 - 10:30:04 CET