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giuseppegiuseppe
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syscalls: use gperf for lookup
use gperf to generate a perfect hash to lookup syscall names. It improves significantly the complexity for seccomp_syscall_resolve_name.* since it replaces the expensive strcmp for each syscall in the database, with a lookup table. The complexity for syscall_resolve_num is not changed and it uses the linear search, that is anyway less expensive than seccomp_syscall_resolve_name.* as it uses an index for comparison instead of doing a string comparison. On my machine, calling 1000 seccomp_syscall_resolve_name_arch and seccomp_syscall_resolve_num_arch over the entire syscalls DB passed from ~0.45 sec to ~0.06s. Closes: #207 Signed-off-by: Giuseppe Scrivano <[email protected]>
1 parent 38f04da commit 5e6f2eb

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‎.travis.yml‎

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@@ -32,6 +32,7 @@ addons:
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- valgrind
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- clang
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- lcov
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- gperf
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env:
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global:

‎configure.ac‎

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@@ -119,6 +119,11 @@ AC_DEFINE_UNQUOTED([ENABLE_PYTHON],
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[$(test "$enable_python" = yes && echo 1 || echo 0)],
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[Python bindings build flag.])
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AC_CHECK_TOOL(GPERF, gperf)
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if test -z "$GPERF"; then
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AC_MSG_ERROR([please install gperf])
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fi
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dnl ####
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dnl coverity checks
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dnl ####

‎src/Makefile.am‎

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@@ -31,20 +31,21 @@ SOURCES_ALL = \
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hash.h hash.c \
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db.h db.c \
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arch.c arch.h \
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arch-x86.h arch-x86.c arch-x86-syscalls.c \
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arch-x86_64.h arch-x86_64.c arch-x86_64-syscalls.c \
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arch-x32.h arch-x32.c arch-x32-syscalls.c \
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arch-arm.h arch-arm.c arch-arm-syscalls.c \
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arch-aarch64.h arch-aarch64.c arch-aarch64-syscalls.c \
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arch-mips.h arch-mips.c arch-mips-syscalls.c \
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arch-mips64.h arch-mips64.c arch-mips64-syscalls.c \
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arch-mips64n32.h arch-mips64n32.c arch-mips64n32-syscalls.c \
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arch-parisc.h arch-parisc.c arch-parisc64.c arch-parisc-syscalls.c \
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arch-ppc.h arch-ppc.c arch-ppc-syscalls.c \
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arch-ppc64.h arch-ppc64.c arch-ppc64-syscalls.c \
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arch-riscv64.h arch-riscv64.c arch-riscv64-syscalls.c \
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arch-s390.h arch-s390.c arch-s390-syscalls.c \
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arch-s390x.h arch-s390x.c arch-s390x-syscalls.c
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arch-x86.h arch-x86.c \
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arch-x86_64.h arch-x86_64.c \
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arch-x32.h arch-x32.c \
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arch-arm.h arch-arm.c \
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arch-aarch64.h arch-aarch64.c \
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arch-mips.h arch-mips.c \
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arch-mips64.h arch-mips64.c \
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arch-mips64n32.h arch-mips64n32.c \
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arch-parisc.h arch-parisc.c arch-parisc64.c \
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arch-ppc.h arch-ppc.c \
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arch-ppc64.h arch-ppc64.c \
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arch-riscv64.h arch-riscv64.c \
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arch-s390.h arch-s390.c \
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arch-s390x.h arch-s390x.c\
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syscalls.c syscalls.perf.c
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EXTRA_DIST = arch-syscall-validate
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@@ -68,5 +69,14 @@ libseccomp_la_CFLAGS = ${AM_CFLAGS} ${CODE_COVERAGE_CFLAGS} ${CFLAGS} \
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libseccomp_la_LDFLAGS = ${AM_LDFLAGS} ${CODE_COVERAGE_LDFLAGS} ${LDFLAGS} \
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-version-number ${VERSION_MAJOR}:${VERSION_MINOR}:${VERSION_MICRO}
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EXTRA_DIST += syscalls.perf.c syscalls.perf
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CLEANFILES = syscalls.perf.c syscalls.perf
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syscalls.perf: syscalls.csv syscalls.perf.template
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${AM_V_GEN} ${srcdir}/generate_syscalls_perf.sh ${srcdir}/syscalls.csv ${srcdir}/syscalls.perf.template
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syscalls.perf.c: syscalls.perf
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${GPERF} -m 100 --null-strings --pic -tCEG -T -S1 $< > $@
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check-build:
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${MAKE} ${AM_MAKEFLAGS} ${check_PROGRAMS}

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