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be860ca2a7
freebsd-dev/bin/sh
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Hiroki Sato be860ca2a7 Improve performance of "read" built-in command when using a seekable 
fd.

The read built-in command calls read(2) with a 1-byte buffer because
newline characters need to be detected even on a byte stream which
comes from a non-seekable file descriptor.  Because of this, the
following script calls >6,000 read(2) to show a 6KiB file:

 while read IN; do echo "$IN"; done < /COPYRIGHT

When the input byte stream is seekable, it is possible to read a data
block and then reposition the file pointer to where a newline
character found.  This change adds a small buffer to do this and
reduces the number of read(2) calls.

Theoretically, multiple built-in commands reading the same seekable
byte stream in a single pipe chain can share the buffer.  However,
this change just makes a single invocation of the read built-in
allocate a buffer and deallocate it every time for simplicity.
Although this causes read(2) to read the same regions multiple times,
the performance penalty should be small compared to the reduction of
read(2) calls.

Reviewed by:		jilles
MFC after:		1 week
Differential Revision:	https://reviews.freebsd.org/D23747
2020-02-20 03:01:27 +00:00
..
bltin General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00
funcs Renumber copyright clause 4 2017-02-28 23:42:47 +00:00
tests sh: Test that executing various binary files is rejected 2019-12-30 21:32:55 +00:00
alias.c sh: Fix use after free when resetting an in-use alias. 2017-04-16 22:10:02 +00:00
alias.h Renumber copyright clause 4 2017-02-28 23:42:47 +00:00
arith_yacc.c sh: Restore $((x)) error checking after fix for $((-9223372036854775808)) 2019-02-10 22:23:05 +00:00
arith_yacc.h sh: Restore $((x)) error checking after fix for $((-9223372036854775808)) 2019-02-10 22:23:05 +00:00
arith_yylex.c sh: Restore $((x)) error checking after fix for $((-9223372036854775808)) 2019-02-10 22:23:05 +00:00
arith.h sh: Remove unused function declaration for arith_lex_reset(). 2017-03-18 20:41:07 +00:00
builtins.def Allow defining nofork builtins from builtins.def and move always-safe ones there. 2017-06-04 21:02:48 +00:00
cd.c sh: Fix rare memory leak with SIGINT 2020-01-01 12:06:37 +00:00
cd.h Renumber copyright clause 4 2017-02-28 23:42:47 +00:00
dot.profile Install .shrc for root, and set PS1 for the toor account. 2019-01-24 23:34:51 +00:00
dot.shrc Comment out the default sh(1) aliases for root, introduced in r343416. 2019-01-25 17:09:26 +00:00
error.c sh: Unify EXERROR and EXEXEC 2018-11-09 14:58:24 +00:00
error.h sh: Unify EXERROR and EXEXEC 2018-11-09 14:58:24 +00:00
eval.c sh: Unify EXERROR and EXEXEC 2018-11-09 14:58:24 +00:00
eval.h Renumber copyright clause 4 2017-02-28 23:42:47 +00:00
exec.c sh: Unify EXERROR and EXEXEC 2018-11-09 14:58:24 +00:00
exec.h sh: Use exitstatus instead of exerrno to pass EXEXEC status 2018-10-27 20:17:57 +00:00
expand.c sh: Fix ${param?} default error message 2018-11-28 20:03:53 +00:00
expand.h Renumber copyright clause 4 2017-02-28 23:42:47 +00:00
histedit.c Do not use our custom completion function, it is not needed anymore 2019-09-16 07:31:59 +00:00
input.c sh: Use 126 and 127 exit status for failures opening a script 2018-11-27 21:49:59 +00:00
input.h Renumber copyright clause 4 2017-02-28 23:42:47 +00:00
jobs.c sh: Add set -o pipefail 2019-02-24 21:05:13 +00:00
jobs.h sh: Move various structs from jobs.h to jobs.c 2018-01-01 22:31:52 +00:00
mail.c sh: Don't use padvance() for MAIL/MAILPATH 2018-07-15 09:14:30 +00:00
mail.h General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00
main.c sh: Unify EXERROR and EXEXEC 2018-11-09 14:58:24 +00:00
main.h General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00
Makefile Fix .depend files to work for build tools. 2019-06-15 17:08:13 +00:00
Makefile.depend DIRDEPS_BUILD: Update dependencies. 2017-10-31 00:07:04 +00:00
memalloc.c General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00
memalloc.h General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00
miscbltin.c Improve performance of "read" built-in command when using a seekable 2020-02-20 03:01:27 +00:00
mkbuiltins Don't hardcode /usr/bin as the path for mktemp in build tools 2018-02-06 15:41:35 +00:00
mknodes.c General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00
mksyntax.c sh: Split CNL syntax category to avoid a check on state[level].syntax 2018-05-21 21:52:48 +00:00
mktokens Don't hardcode /usr/bin as the path for mktemp in build tools 2018-02-06 15:41:35 +00:00
myhistedit.h General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00
mystring.c General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00
mystring.h General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00
nodes.c.pat Renumber copyright clause 4 2017-02-28 23:42:47 +00:00
nodetypes Renumber copyright clause 4 2017-02-28 23:42:47 +00:00
options.c General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00
options.h sh: Add set -o pipefail 2019-02-24 21:05:13 +00:00
output.c sh: Send normal output from bind builtin to stdout 2019-02-19 21:27:30 +00:00
output.h sh: Send normal output from bind builtin to stdout 2019-02-19 21:27:30 +00:00
parser.c Make sh(1) support \u in PS1. This removes one fork/exec on interactive 2019-01-24 11:59:46 +00:00
parser.h General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00
profile Don't mess with BLOCKSIZE in shell startup files - it's set by login.conf(5); 2019-01-20 22:08:49 +00:00
redir.c General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00
redir.h General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00
sh.1 sh: Add set -o pipefail 2019-02-24 21:05:13 +00:00
shell.h sh: Restore $((x)) error checking after fix for $((-9223372036854775808)) 2019-02-10 22:23:05 +00:00
show.c General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00
show.h General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00
TOUR sh: Unify EXERROR and EXEXEC 2018-11-09 14:58:24 +00:00
trap.c General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00
trap.h General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00
var.c sh: Do not place exported but unset variables into the environment 2019-01-03 20:22:35 +00:00
var.h General further adoption of SPDX licensing ID tags. 2017-11-20 19:49:47 +00:00