On 07/03/15 12:10, Pádraig Brady wrote:
> BTW I noticed tee uses stdio calls which is redundant overhead currently.
> It wouldn't if we added a --buffered call to tee so that it might
> honor stdbuf(1), though I'm not sure it's worth that flexibility in tee.
I've attached this change, though I'm 50:50 about applying it,
since it's only a micro optimization.
cheers,
Pádraig.
>From f5d31e13265fda65017145f9206d634d6715cded Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C3=A1draig=20Brady?= <p...@draigbrady.com>
Date: Mon, 9 Mar 2015 23:58:25 +0000
Subject: [PATCH] tee: avoid using stdio as tee doesn't buffer
* src/tee.c (tee_files): Since tee doesn't buffer, avoid using
stdio streams and just the lower level fd interface.
Since we'd disabled buffering in stdio, this is
not a significant optimization.
---
src/tee.c | 37 ++++++++++++++++---------------------
1 file changed, 16 insertions(+), 21 deletions(-)
diff --git a/src/tee.c b/src/tee.c
index 3c39a4a..a0ed3c2 100644
--- a/src/tee.c
+++ b/src/tee.c
@@ -25,7 +25,7 @@
#include "argmatch.h"
#include "error.h"
#include "fadvise.h"
-#include "stdio--.h"
+#include "full-write.h"
#include "xfreopen.h"
/* The official name of this program (e.g., no 'g' prefix). */
@@ -182,15 +182,16 @@ static bool
tee_files (int nfiles, const char **files)
{
size_t n_outputs = 0;
- FILE **descriptors;
+ int *descriptors;
char buffer[BUFSIZ];
ssize_t bytes_read = 0;
int i;
bool ok = true;
- char const *mode_string =
- (O_BINARY
- ? (append ? "ab" : "wb")
- : (append ? "a" : "w"));
+ int mode = O_WRONLY | O_CREAT | O_BINARY;
+ if (append)
+ mode |= O_APPEND;
+ else
+ mode |= O_TRUNC;
descriptors = xnmalloc (nfiles + 1, sizeof *descriptors);
@@ -208,16 +209,15 @@ tee_files (int nfiles, const char **files)
/* In the array of NFILES + 1 descriptors, make
the first one correspond to standard output. */
- descriptors[0] = stdout;
+ descriptors[0] = STDOUT_FILENO;
files[0] = _("standard output");
- setvbuf (stdout, NULL, _IONBF, 0);
n_outputs++;
for (i = 1; i <= nfiles; i++)
{
/* Do not treat "-" specially - as mandated by POSIX. */
- descriptors[i] = fopen (files[i], mode_string);
- if (descriptors[i] == NULL)
+ descriptors[i] = open (files[i], mode, 0666);
+ if (descriptors[i] == -1)
{
error (output_error == output_error_exit
|| output_error == output_error_exit_nopipe,
@@ -225,15 +225,12 @@ tee_files (int nfiles, const char **files)
ok = false;
}
else
- {
- setvbuf (descriptors[i], NULL, _IONBF, 0);
- n_outputs++;
- }
+ n_outputs++;
}
while (n_outputs)
{
- bytes_read = read (0, buffer, sizeof buffer);
+ bytes_read = read (STDIN_FILENO, buffer, sizeof buffer);
if (bytes_read < 0 && errno == EINTR)
continue;
if (bytes_read <= 0)
@@ -242,21 +239,19 @@ tee_files (int nfiles, const char **files)
/* Write to all NFILES + 1 descriptors.
Standard output is the first one. */
for (i = 0; i <= nfiles; i++)
- if (descriptors[i]
- && fwrite (buffer, bytes_read, 1, descriptors[i]) != 1)
+ if (descriptors[i] != -1
+ && full_write (descriptors[i], buffer, bytes_read) != bytes_read)
{
int w_errno = errno;
bool fail = errno != EPIPE || (output_error == output_error_exit
|| output_error == output_error_warn);
- if (descriptors[i] == stdout)
- clearerr (stdout); /* Avoid redundant close_stdout diagnostic. */
if (fail)
{
error (output_error == output_error_exit
|| output_error == output_error_exit_nopipe,
w_errno, "%s", files[i]);
}
- descriptors[i] = NULL;
+ descriptors[i] = -1;
if (fail)
ok = false;
n_outputs--;
@@ -271,7 +266,7 @@ tee_files (int nfiles, const char **files)
/* Close the files, but not standard output. */
for (i = 1; i <= nfiles; i++)
- if (descriptors[i] && fclose (descriptors[i]) != 0)
+ if (descriptors[i] != -1 && close (descriptors[i]) != 0)
{
error (0, errno, "%s", files[i]);
ok = false;
--
2.1.0
