From 8220399173cf8d25e37059cadac96ac30f94e82a Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Sat, 2 Apr 2016 18:06:24 +0200 Subject: [PATCH] nsenter,unshare: share common code; fix a bug of not closing all fds function old new delta xvfork_parent_waits_and_exits - 64 +64 exec_prog_or_SHELL - 39 +39 unshare_main 873 810 -63 nsenter_main 663 596 -67 ------------------------------------------------------------------------------ (add/remove: 2/0 grow/shrink: 0/2 up/down: 106/-130) Total: -27 bytes Signed-off-by: Denys Vlasenko --- include/libbb.h | 6 ++++-- libbb/executable.c | 11 ++++++++++- libbb/xfuncs_printf.c | 16 ++++++++++++++++ util-linux/nsenter.c | 21 +++++---------------- util-linux/unshare.c | 19 +++---------------- 5 files changed, 38 insertions(+), 35 deletions(-) diff --git a/include/libbb.h b/include/libbb.h index 5b4280e34..64e61cd26 100644 --- a/include/libbb.h +++ b/include/libbb.h @@ -992,9 +992,10 @@ int BB_EXECVP(const char *file, char *const argv[]) FAST_FUNC; #define BB_EXECVP(prog,cmd) execvp(prog,cmd) #define BB_EXECLP(prog,cmd,...) execlp(prog,cmd,__VA_ARGS__) #endif -int BB_EXECVP_or_die(char **argv) NORETURN FAST_FUNC; +void BB_EXECVP_or_die(char **argv) NORETURN FAST_FUNC; +void exec_prog_or_SHELL(char **argv) NORETURN FAST_FUNC; -/* xvfork() can't be a _function_, return after vfork mangles stack +/* xvfork() can't be a _function_, return after vfork in child mangles stack * in the parent. It must be a macro. */ #define xvfork() \ ({ \ @@ -1006,6 +1007,7 @@ int BB_EXECVP_or_die(char **argv) NORETURN FAST_FUNC; #if BB_MMU pid_t xfork(void) FAST_FUNC; #endif +void xvfork_parent_waits_and_exits(void) FAST_FUNC; /* NOMMU friendy fork+exec: */ pid_t spawn(char **argv) FAST_FUNC; diff --git a/libbb/executable.c b/libbb/executable.c index 85ecc3e6c..05e70312f 100644 --- a/libbb/executable.c +++ b/libbb/executable.c @@ -83,10 +83,19 @@ int FAST_FUNC BB_EXECVP(const char *file, char *const argv[]) } #endif -int FAST_FUNC BB_EXECVP_or_die(char **argv) +void FAST_FUNC BB_EXECVP_or_die(char **argv) { BB_EXECVP(argv[0], argv); /* SUSv3-mandated exit codes */ xfunc_error_retval = (errno == ENOENT) ? 127 : 126; bb_perror_msg_and_die("can't execute '%s'", argv[0]); } + +/* Typical idiom for applets which exec *optional* PROG [ARGS] */ +void FAST_FUNC exec_prog_or_SHELL(char **argv) +{ + if (argv[0]) { + BB_EXECVP_or_die(argv); + } + run_shell(getenv("SHELL"), /*login:*/ 1, NULL, NULL); +} diff --git a/libbb/xfuncs_printf.c b/libbb/xfuncs_printf.c index 4aa1b5ce2..e9222f690 100644 --- a/libbb/xfuncs_printf.c +++ b/libbb/xfuncs_printf.c @@ -659,3 +659,19 @@ pid_t FAST_FUNC xfork(void) return pid; } #endif + +void FAST_FUNC xvfork_parent_waits_and_exits(void) +{ + pid_t pid; + + fflush_all(); + pid = xvfork(); + if (pid > 0) { + /* Parent */ + int exit_status = wait_for_exitstatus(pid); + if (WIFSIGNALED(exit_status)) + kill_myself_with_sig(WTERMSIG(exit_status)); + _exit(WEXITSTATUS(exit_status)); + } + /* Child continues */ +} diff --git a/util-linux/nsenter.c b/util-linux/nsenter.c index 9c1dabaa8..0dad595cd 100644 --- a/util-linux/nsenter.c +++ b/util-linux/nsenter.c @@ -230,7 +230,7 @@ int nsenter_main(int argc UNUSED_PARAM, char **argv) ns->ns_nsfile8 + 3 /* skip over "ns/" */ ); } - /*close(ns_ctx->fd);*/ + close(ns_ctx->fd); /* should close fds, to not confuse exec'ed PROG */ /*ns_ctx->fd = -1;*/ } @@ -244,13 +244,13 @@ int nsenter_main(int argc UNUSED_PARAM, char **argv) } xfchdir(root_fd); xchroot("."); - /*close(root_fd);*/ + close(root_fd); /*root_fd = -1;*/ } if (wd_fd >= 0) { xfchdir(wd_fd); - /*close(wd_fd);*/ + close(wd_fd); /*wd_fd = -1;*/ } @@ -259,14 +259,7 @@ int nsenter_main(int argc UNUSED_PARAM, char **argv) * explicitly requested by the user not to. */ if (!(opts & OPT_nofork) && (opts & OPT_pid)) { - pid_t pid = xvfork(); - if (pid > 0) { - /* Parent */ - int exit_status = wait_for_exitstatus(pid); - if (WIFSIGNALED(exit_status)) - kill_myself_with_sig(WTERMSIG(exit_status)); - return WEXITSTATUS(exit_status); - } + xvfork_parent_waits_and_exits(); /* Child continues */ } @@ -278,9 +271,5 @@ int nsenter_main(int argc UNUSED_PARAM, char **argv) if (opts & OPT_setuid) xsetuid(uid); - if (*argv) { - BB_EXECVP_or_die(argv); - } - - run_shell(getenv("SHELL"), /*login:*/ 1, NULL, NULL); + exec_prog_or_SHELL(argv); } diff --git a/util-linux/unshare.c b/util-linux/unshare.c index 2a5bea5a6..95a7cb647 100644 --- a/util-linux/unshare.c +++ b/util-linux/unshare.c @@ -281,7 +281,7 @@ int unshare_main(int argc UNUSED_PARAM, char **argv) if (fdp.wr >= 0) { close(fdp.wr); /* Release child */ - /*close(fdp.rd);*/ + close(fdp.rd); /* should close fd, to not confuse exec'ed PROG */ } if (need_mount) { @@ -307,14 +307,7 @@ int unshare_main(int argc UNUSED_PARAM, char **argv) * that'll become PID 1 in this new namespace. */ if (opts & OPT_fork) { - pid_t pid = xfork(); - if (pid > 0) { - /* Parent */ - int exit_status = wait_for_exitstatus(pid); - if (WIFSIGNALED(exit_status)) - kill_myself_with_sig(WTERMSIG(exit_status)); - return WEXITSTATUS(exit_status); - } + xvfork_parent_waits_and_exits(); /* Child continues */ } @@ -354,11 +347,5 @@ int unshare_main(int argc UNUSED_PARAM, char **argv) mount_or_die("proc", proc_mnt_target, "proc", MS_NOSUID | MS_NOEXEC | MS_NODEV); } - if (argv[0]) { - BB_EXECVP_or_die(argv); - } - /* unshare from util-linux 2.27.1, despite not documenting it, - * runs a login shell (argv0="-sh") if no PROG is given - */ - run_shell(getenv("SHELL"), /*login:*/ 1, NULL, NULL); + exec_prog_or_SHELL(argv); }