From 3efcadf8865efa2e0c5d44606efda87bfd4835fe Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dag-Erling=20Sm=C3=B8rgrav?= <des@des.no>
Date: Mon, 4 Mar 2024 11:37:14 +0100
Subject: [PATCH] zstd: Implement core detection (#2083)

The bsdtar manual page claims that setting zstd:threads to 0 tells zstd
to use as many threads as there are cores in the system, but it actually
disables multi-threading.  Replace 0 with the number of configured
processors.

While here, add a previously missing overflow check.

Co-authored-by: Martin Matuska <martin@matuska.de>
---
 CMakeLists.txt                             |  1 +
 build/cmake/config.h.in                    |  3 +++
 configure.ac                               |  1 +
 libarchive/archive_write_add_filter_zstd.c | 14 +++++++++++++-
 tar/bsdtar.1                               | 15 +++++++--------
 5 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index a953bcea1d..822056b910 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1497,6 +1497,7 @@ CHECK_FUNCTION_EXISTS_GLIBC(strncpy_s HAVE_STRNCPY_S)
 CHECK_FUNCTION_EXISTS_GLIBC(strnlen HAVE_STRNLEN)
 CHECK_FUNCTION_EXISTS_GLIBC(strrchr HAVE_STRRCHR)
 CHECK_FUNCTION_EXISTS_GLIBC(symlink HAVE_SYMLINK)
+CHECK_FUNCTION_EXISTS_GLIBC(sysconf HAVE_SYSCONF)
 CHECK_FUNCTION_EXISTS_GLIBC(timegm HAVE_TIMEGM)
 CHECK_FUNCTION_EXISTS_GLIBC(tzset HAVE_TZSET)
 CHECK_FUNCTION_EXISTS_GLIBC(unlinkat HAVE_UNLINKAT)
diff --git a/build/cmake/config.h.in b/build/cmake/config.h.in
index 045a6b4165..d47694c0c1 100644
--- a/build/cmake/config.h.in
+++ b/build/cmake/config.h.in
@@ -1094,6 +1094,9 @@ typedef uint64_t uintmax_t;
 /* Define to 1 if you have the `symlink' function. */
 #cmakedefine HAVE_SYMLINK 1
 
+/* Define to 1 if you have the `sysconf' function. */
+#cmakedefine HAVE_SYSCONF 1
+
 /* Define to 1 if you have the <sys/acl.h> header file. */
 #cmakedefine HAVE_SYS_ACL_H 1
 
diff --git a/configure.ac b/configure.ac
index 3cf5f50e78..c778c043f0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -804,6 +804,7 @@ AC_CHECK_FUNCS([nl_langinfo openat pipe poll posix_spawnp readlink readlinkat])
 AC_CHECK_FUNCS([readpassphrase])
 AC_CHECK_FUNCS([select setenv setlocale sigaction statfs statvfs])
 AC_CHECK_FUNCS([strchr strdup strerror strncpy_s strnlen strrchr symlink])
+AC_CHECK_FUNCS([sysconf])
 AC_CHECK_FUNCS([timegm tzset unlinkat unsetenv utime utimensat utimes vfork])
 AC_CHECK_FUNCS([wcrtomb wcscmp wcscpy wcslen wctomb wmemcmp wmemcpy wmemmove])
 AC_CHECK_FUNCS([_fseeki64 _get_timezone])
diff --git a/libarchive/archive_write_add_filter_zstd.c b/libarchive/archive_write_add_filter_zstd.c
index df539d326e..b49f453102 100644
--- a/libarchive/archive_write_add_filter_zstd.c
+++ b/libarchive/archive_write_add_filter_zstd.c
@@ -29,6 +29,9 @@
 #ifdef HAVE_ERRNO_H
 #include <errno.h>
 #endif
+#ifdef HAVE_LIMITS_H
+#include <limits.h>
+#endif
 #ifdef HAVE_STDINT_H
 #include <stdint.h>
 #endif
@@ -38,6 +41,9 @@
 #ifdef HAVE_STRING_H
 #include <string.h>
 #endif
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
 #ifdef HAVE_ZSTD_H
 #include <zstd.h>
 #endif
@@ -266,7 +272,13 @@ archive_compressor_zstd_options(struct archive_write_filter *f, const char *key,
 		if (string_to_number(value, &threads) != ARCHIVE_OK) {
 			return (ARCHIVE_WARN);
 		}
-		if (threads < 0) {
+
+#if defined(HAVE_SYSCONF) && defined(_SC_NPROCESSORS_ONLN)
+		if (threads == 0) {
+			threads = sysconf(_SC_NPROCESSORS_ONLN);
+		}
+#endif
+		if (threads < 0 || threads > INT_MAX) {
 			return (ARCHIVE_WARN);
 		}
 		data->threads = (int)threads;
diff --git a/tar/bsdtar.1 b/tar/bsdtar.1
index e570d2a48a..fe9ec95046 100644
--- a/tar/bsdtar.1
+++ b/tar/bsdtar.1
@@ -23,7 +23,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd March 1, 2024
+.Dd April 23, 2024
 .Dt TAR 1
 .Os
 .Sh NAME
@@ -644,14 +644,13 @@ A decimal integer from 4 to 7 specifying the lz4 compression block size
 .It Cm lz4:block-dependence
 Use the previous block of the block being compressed for
 a compression dictionary to improve compression ratio.
-.It Cm zstd:compression-level
-A decimal integer specifying the zstd compression level. Supported values depend
+.It Cm zstd:compression-level Ns = Ns Ar N
+A decimal integer specifying the zstd compression level.
+Supported values depend
 on the library version, common values are from 1 to 22.
-.It Cm zstd:threads
-Specify the number of worker threads to use.
-Setting threads to a special value 0 makes
-.Xr zstd 1
-use as many threads as there are CPU cores on the system.
+.It Cm zstd:threads Ns = Ns Ar N
+Specify the number of worker threads to use, or 0 to use as many
+threads as there are CPU cores in the system.
 .It Cm zstd:frame-per-file
 Start a new compression frame at the beginning of each file in the
 archive.