sha1sum: use AF_ALG when available Linux supports accessing kernel crypto API via AF_ALG since version 2.6.38. Coreutils uses libcrypto when available and fallbacks to generic C implementation of various hashing functions. Add a generic afalg_stream() function which uses AF_ALG to calculate the hash of a stream and use sendfile() when possible (regular file with size less or equal than 0x7ffff000 (2,147,479,552) bytes, AKA MAX_RW_COUNT). Use afalg_stream() only in sha1sum for now, but other hashes are possible. The speed gain really depends on the CPU type, on systems which doesn't use libcrypto ranges from ~10% to 320%. This is a test on a Intel(R) Xeon(R) CPU E3-1265L V2 and Debian stretch: $ truncate -s 2GB 2g.bin $ time sha1sum 2g.bin 752ef2367f479e79e4f0cded9c270c2890506ab0 2g.bin real 0m4.829s user 0m4.437s sys 0m0.391s $ time ./sha1sum-afalg 2g.bin 752ef2367f479e79e4f0cded9c270c2890506ab0 2g.bin real 0m3.164s user 0m0.000s sys 0m3.162s Signed-off-by: Matteo Croce <mcroce@redhat.com>

Description:
Compute SHA1 checksum.

Files:
lib/gl_openssl.h
lib/sha1.h
lib/sha1.c
lib/af_alg.h
lib/af_alg.c
m4/gl-openssl.m4
m4/sha1.m4
m4/linux-if-alg.m4

Depends-on:
extern-inline
stdalign
stdint

configure.ac:
gl_SHA1
gl_LINUX_IF_ALG_H

Makefile.am:
lib_SOURCES += sha1.c af_alg.c

Include:
"sha1.h"

Link:
$(LIB_CRYPTO)

License:
LGPLv2+

Maintainer:
Jim Meyering