Date: Wed, 25 Feb 2026 21:12:56 +0000 From: Dag-Erling=?utf-8?Q? Sm=C3=B8rg?=rav <des@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 8ae3f4499194 - main - system(3): Fix null case Message-ID: <699f65d8.30799.72e465a3@gitrepo.freebsd.org>
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The branch main has been updated by des: URL: https://cgit.FreeBSD.org/src/commit/?id=8ae3f44991948cc97b09adc248a9a46db71bf9e0 commit 8ae3f44991948cc97b09adc248a9a46db71bf9e0 Author: Dag-Erling Smørgrav <des@FreeBSD.org> AuthorDate: 2026-02-25 21:12:42 +0000 Commit: Dag-Erling Smørgrav <des@FreeBSD.org> CommitDate: 2026-02-25 21:12:42 +0000 system(3): Fix null case Our manual page states that if given a null pointer, system() returns non-zero if the shell is available and zero if it is not. This is consistent with the C standard's description of system(), but it is not what we actually do. What we actually do is always return non-zero, as required by POSIX. As the POSIX rationale explains, implementing the logic required by the C standard does not violate POSIX, since a conforming system always has a shell, therefore the logic will always return non-zero. Since our libc is commonly used in non-conforming situations such as chroots or thin jails, we should implement the full logic required by the C standard. MFC after: 1 week Sponsored by: Klara, Inc. Reviewed by: obiwac, bnovkov, kevans Differential Revision: https://reviews.freebsd.org/D55484 --- lib/libc/stdlib/system.c | 2 +- lib/libc/tests/stdlib/system_test.c | 10 ++++++++++ 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/lib/libc/stdlib/system.c b/lib/libc/stdlib/system.c index 17dd63eb52f9..94f7460c9b68 100644 --- a/lib/libc/stdlib/system.c +++ b/lib/libc/stdlib/system.c @@ -64,7 +64,7 @@ __libc_system(const char *command) pid_t pid; if (command == NULL) /* just checking... */ - return (1); + return (eaccess(_PATH_BSHELL, X_OK) == 0); /* * If we are the first concurrent instance, ignore SIGINT and diff --git a/lib/libc/tests/stdlib/system_test.c b/lib/libc/tests/stdlib/system_test.c index 713e4bb0f87a..b6a31583d52d 100644 --- a/lib/libc/tests/stdlib/system_test.c +++ b/lib/libc/tests/stdlib/system_test.c @@ -57,10 +57,20 @@ ATF_TC(system_null); ATF_TC_HEAD(system_null, tc) { atf_tc_set_md_var(tc, "descr", "system(NULL)"); + atf_tc_set_md_var(tc, "require.user", "root"); } ATF_TC_BODY(system_null, tc) { + /* First, test in a normal environment */ ATF_REQUIRE_EQ(1, system(NULL)); + + /* Now enter an empty chroot */ + ATF_REQUIRE_EQ(0, chroot(".")); + ATF_REQUIRE_EQ(0, chdir("/")); + + /* Test again with no shell available */ + ATF_REQUIRE_EQ(0, system(NULL)); + ATF_REQUIRE_EQ(W_EXITCODE(127, 0), system("true")); } /*home | help
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