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From: Bart Schaefer <schaefer@brasslantern.com>
To: Zsh hackers list <zsh-workers@zsh.org>
Subject: Re: ZSH performance regression in 5.8.1.2-test
Date: Tue, 26 Apr 2022 17:55:31 -0700	[thread overview]
Message-ID: <CAH+w=7aL--jF69z=0kpSeswjQ1SZxdtMA9=Srp6YCbxjneVJZg@mail.gmail.com> (raw)
In-Reply-To: <875081227.118208.1650986156051@mail2.virginmedia.com>

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On Tue, Apr 26, 2022 at 8:16 AM Peter Stephenson
<p.w.stephenson@ntlworld.com> wrote:
>
> We could use some variant of the following as a configure test for safety.

I will be happiest if someone else plugs that in to configure.ac.

Here's the patch again, replacing fstat with lseek.

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diff --git a/Src/input.c b/Src/input.c
index c59232681..8e0a24f92 100644
--- a/Src/input.c
+++ b/Src/input.c
@@ -217,12 +217,31 @@ shinbufrestore(void)
 static int
 shingetchar(void)
 {
-    int nread;
+    int nread, rsize = isset(SHINSTDIN) ? 1 : SHINBUFSIZE;
 
     if (shinbufptr < shinbufendptr)
 	return STOUC(*shinbufptr++);
-
+    else if (rsize == 1 && lseek(SHIN, 0, SEEK_CUR) == 0)
+	rsize = SHINBUFSIZE;
     shinbufreset();
+    if (rsize > 1) {
+	do {
+	    errno = 0;
+	    nread = read(SHIN, shinbuffer, rsize);
+	} while (nread < 0 && errno == EINTR);
+	if (nread <= 0)
+	    return -1;
+	if (isset(SHINSTDIN) &&
+	    (shinbufendptr = memchr(shinbuffer, '\n', nread))) {
+	    shinbufendptr++;
+	    rsize = (shinbufendptr - shinbuffer);
+	    if (nread > rsize &&
+		lseek(SHIN, -(nread - rsize), SEEK_CUR) < 0)
+		zerr("lseek(%d, %d): %e", SHIN, -(nread - rsize), errno);
+	} else
+	    shinbufendptr = shinbuffer + nread;
+	return STOUC(*shinbufptr++);
+    }
     for (;;) {
        errno = 0;
        nread = read(SHIN, shinbufendptr, 1);

  reply	other threads:[~2022-04-27  0:56 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-25 18:16 Jordan Patterson
2022-04-25 18:56 ` Bart Schaefer
2022-04-25 19:20   ` Stephane Chazelas
2022-04-25 21:27     ` Bart Schaefer
2022-04-26  7:01       ` Bart Schaefer
2022-04-26  8:31         ` Peter Stephenson
2022-04-27  0:33           ` Bart Schaefer
2022-04-27 14:11           ` Stephane Chazelas
2022-04-27 15:02             ` Bart Schaefer
2022-04-27 15:07               ` Peter Stephenson
2022-04-27 15:17                 ` Bart Schaefer
2022-04-26 14:31         ` Jun. T
2022-04-26 15:15           ` Peter Stephenson
2022-04-27  0:55             ` Bart Schaefer [this message]
2022-04-27  9:16               ` Jun T
2022-04-27  0:38           ` Bart Schaefer
2022-04-27  9:34             ` Peter Stephenson
2022-04-27 10:28               ` Jun T
2022-04-27 12:42                 ` Jun T
2022-04-27 13:58                 ` Jun T
2022-04-27 15:25                   ` Bart Schaefer
2022-04-27 16:18                     ` Jun. T
2022-04-27 19:54         ` Jordan Patterson
2022-04-28  9:53           ` Jun T
2022-04-28 14:56             ` Bart Schaefer
2022-04-28 18:51           ` Jun. T
2022-04-29  0:28             ` Bart Schaefer
2022-04-29  2:25               ` Jun. T
2022-04-26  1:08 ` Bart Schaefer
2022-04-26  3:03   ` Jordan Patterson

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