Sub filter: eliminate unnecessary buffering. Previously, when a buffer was processed by the sub filter, its final bytes could be buffered by the filter even if they don't match any pattern. This happened because the Boyer-Moore algorithm, employed by the sub filter since b9447fc457b4 (1.9.4), matches the last characters of patterns prior to checking other characters. If the last character is out of scope, initial bytes of a potential match are buffered until the last character is available. Now, after receiving a flush or recycled buffer, the filter performs additional checks to reduce the number of buffered bytes. The potential match is checked against the initial parts of all patterns. Non-matching bytes are not buffered. This improves processing of a chunked response from upstream by sending the entire chunks without buffering unless a partial match is found at the end of a chunk.

# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


NGX_MAKEFILE=$NGX_OBJS/Makefile
NGX_MODULES_C=$NGX_OBJS/ngx_modules.c

NGX_AUTO_HEADERS_H=$NGX_OBJS/ngx_auto_headers.h
NGX_AUTO_CONFIG_H=$NGX_OBJS/ngx_auto_config.h

NGX_AUTOTEST=$NGX_OBJS/autotest
NGX_AUTOCONF_ERR=$NGX_OBJS/autoconf.err

# STUBs
NGX_ERR=$NGX_OBJS/autoconf.err
MAKEFILE=$NGX_OBJS/Makefile


NGX_PCH=
NGX_USE_PCH=


# check the echo's "-n" option and "\c" capability

if echo "test\c" | grep c >/dev/null; then

    if echo -n test | grep n >/dev/null; then
        ngx_n=
        ngx_c=

    else
        ngx_n=-n
        ngx_c=
    fi

else
    ngx_n=
    ngx_c='\c'
fi


# create Makefile

cat << END > Makefile

default:	build

clean:
	rm -rf Makefile $NGX_OBJS
END