Date: Mon, 27 Apr 2026 03:21:34 +0000 From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: d7338bb4914d - main - bin/sh: make it possible to use as interactive init Message-ID: <69eed63e.3af1e.59d3cfe4@gitrepo.freebsd.org>
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The branch main has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=d7338bb4914d120e5719d3216b23a509c49ed3be commit d7338bb4914d120e5719d3216b23a509c49ed3be Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2026-04-20 18:03:39 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2026-04-27 01:45:12 +0000 bin/sh: make it possible to use as interactive init If the /sbin/init binary is broken somehow, the way out is to set the loader environment variable init_path to something else. The most natural choice would be either /bin/sh or /rescue/sh. Unfortunately, this does not work because the init process starts withoud stdin/out descriptors. Make it nicer to users by teaching /bin/sh startup code to open standard descriptors on /dev/console if the shell is run as init. Reviewed by: imp, jilles, zlei Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D56536 --- bin/sh/main.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/bin/sh/main.c b/bin/sh/main.c index 94e8da6b4921..0ca2d4942426 100644 --- a/bin/sh/main.c +++ b/bin/sh/main.c @@ -39,6 +39,9 @@ #include <fcntl.h> #include <locale.h> #include <errno.h> +#include <termios.h> +#include <paths.h> +#include <unistd.h> #include "shell.h" #include "main.h" @@ -124,6 +127,22 @@ main(int argc, char *argv[]) trputs("Shell args: "); trargs(argv); #endif rootpid = getpid(); + if (rootpid == 1) { + /* + * Make sh usable for invocation as interactive init + * substitute with init_path=/bin/sh, by opening + * file descriptors 0, 1, and 2 on /dev/console. + */ + if (fcntl(STDIN_FILENO, F_GETFL, NULL) == -1 && errno == EBADF) { + (void)open(_PATH_CONSOLE, O_RDWR); + (void)setsid(); + (void)tcsetsid(STDIN_FILENO, rootpid); + } + if (fcntl(STDOUT_FILENO, F_GETFL, NULL) == -1 && errno == EBADF) + (void)dup2(STDIN_FILENO, STDOUT_FILENO); + if (fcntl(STDERR_FILENO, F_GETFL, NULL) == -1 && errno == EBADF) + (void)dup2(STDIN_FILENO, STDERR_FILENO); + } rootshell = 1; INTOFF; initvar();home | help
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