Date: Sat, 25 Apr 2026 13:04:53 +0000 From: Jilles Tjoelker <jilles@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 7262e60119b8 - main - sh: Allow vfork on redirected simple commands Message-ID: <69ecbbf5.27f24.19123d52@gitrepo.freebsd.org>
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The branch main has been updated by jilles: URL: https://cgit.FreeBSD.org/src/commit/?id=7262e60119b8840ee400d281421b8e65d8af9d84 commit 7262e60119b8840ee400d281421b8e65d8af9d84 Author: Jilles Tjoelker <jilles@FreeBSD.org> AuthorDate: 2026-04-25 13:03:29 +0000 Commit: Jilles Tjoelker <jilles@FreeBSD.org> CommitDate: 2026-04-25 13:04:10 +0000 sh: Allow vfork on redirected simple commands Things like `{ some_program; } >/dev/null` use vfork, so use vfork similarly for things like `some_program >/dev/null`. This cannot be done for command substitutions, because of two problems: * Redirections might cause the error message for later redirections or for an unknown command to be sent to the pipe (to be substituted), and this might cause a deadlock if the message is too long. * The assignment of the pipe needs to come before instead of after the redirections. Reviewed by: bdrewery Differential Revision: https://reviews.freebsd.org/D55190 --- bin/sh/eval.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 58 insertions(+), 3 deletions(-) diff --git a/bin/sh/eval.c b/bin/sh/eval.c index d0fddf160771..0c41c5e69eea 100644 --- a/bin/sh/eval.c +++ b/bin/sh/eval.c @@ -34,6 +34,7 @@ #include <paths.h> #include <signal.h> +#include <stdbool.h> #include <stdlib.h> #include <unistd.h> #include <sys/resource.h> @@ -803,6 +804,50 @@ safe_builtin(int idx, int argc, char **argv) return (0); } +/* + * Perform redirections, then execute a simple command with vfork. + * This cannot be used for command substitutions for two reasons: + * - Redirections might cause the error message for later redirections or for + * an unknown command to be sent to the pipe (to be substituted), and this + * might cause a deadlock if the message is too long. + * - The assignment of the pipe needs to come before instead of after the + * redirections. + */ +static bool +redirected_vforkexecshell(struct job *jp, union node *redir, char **argv, + char **envp, const char *path, int idx) +{ + struct jmploc jmploc; + struct jmploc *savehandler; + volatile int in_redirect = 1; + + savehandler = handler; + if (setjmp(jmploc.loc)) { + int e; + + handler = savehandler; + e = exception; + popredir(); + if (e == EXERROR && in_redirect) { + FORCEINTON; + return false; + } + longjmp(handler->loc, 1); + } else { + INTOFF; + handler = &jmploc; + redirect(redir, REDIR_PUSH); + in_redirect = 0; + INTON; + vforkexecshell(jp, argv, envp, path, idx, NULL); + } + INTOFF; + handler = savehandler; + popredir(); + INTON; + return true; +} + /* * Execute a simple command. * Note: This may or may not return if (flags & EV_EXIT). @@ -986,12 +1031,22 @@ evalcommand(union node *cmd, int flags, struct backcmd *backcmd) error("Pipe call failed: %s", strerror(errno)); } if (cmdentry.cmdtype == CMDNORMAL && - cmd->ncmd.redirect == NULL && + (cmd->ncmd.redirect == NULL || (flags & EV_BACKCMD) == 0) && varlist.count == 0 && (mode == FORK_FG || mode == FORK_NOJOB) && !disvforkset() && !iflag && !mflag) { - vforkexecshell(jp, argv, environment(), path, - cmdentry.u.index, flags & EV_BACKCMD ? pip : NULL); + if (cmd->ncmd.redirect != NULL) { + if (redirected_vforkexecshell(jp, + cmd->ncmd.redirect, + argv, environment(), path, + cmdentry.u.index)) + goto parent; + else + goto out; + } else + vforkexecshell(jp, argv, environment(), path, + cmdentry.u.index, + flags & EV_BACKCMD ? pip : NULL); goto parent; } if (forkshell(jp, cmd, mode) != 0)home | help
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