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-rw-r--r--bin/sh/eval.c933
1 files changed, 933 insertions, 0 deletions
diff --git a/bin/sh/eval.c b/bin/sh/eval.c
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index 0000000..48a9f99
--- /dev/null
+++ b/bin/sh/eval.c
@@ -0,0 +1,933 @@
+/*-
+ * Copyright (c) 1993
+ * The Regents of the University of California. All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Kenneth Almquist.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the University of
+ * California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef lint
+static char sccsid[] = "@(#)eval.c 8.1 (Berkeley) 5/31/93";
+#endif /* not lint */
+
+/*
+ * Evaluate a command.
+ */
+
+#include "shell.h"
+#include "nodes.h"
+#include "syntax.h"
+#include "expand.h"
+#include "parser.h"
+#include "jobs.h"
+#include "eval.h"
+#include "builtins.h"
+#include "options.h"
+#include "exec.h"
+#include "redir.h"
+#include "input.h"
+#include "output.h"
+#include "trap.h"
+#include "var.h"
+#include "memalloc.h"
+#include "error.h"
+#include "mystring.h"
+#include "myhistedit.h"
+#include <signal.h>
+
+
+/* flags in argument to evaltree */
+#define EV_EXIT 01 /* exit after evaluating tree */
+#define EV_TESTED 02 /* exit status is checked; ignore -e flag */
+#define EV_BACKCMD 04 /* command executing within back quotes */
+
+
+/* reasons for skipping commands (see comment on breakcmd routine) */
+#define SKIPBREAK 1
+#define SKIPCONT 2
+#define SKIPFUNC 3
+
+MKINIT int evalskip; /* set if we are skipping commands */
+STATIC int skipcount; /* number of levels to skip */
+MKINIT int loopnest; /* current loop nesting level */
+int funcnest; /* depth of function calls */
+
+
+char *commandname;
+struct strlist *cmdenviron;
+int exitstatus; /* exit status of last command */
+
+
+#ifdef __STDC__
+STATIC void evalloop(union node *);
+STATIC void evalfor(union node *);
+STATIC void evalcase(union node *, int);
+STATIC void evalsubshell(union node *, int);
+STATIC void expredir(union node *);
+STATIC void evalpipe(union node *);
+STATIC void evalcommand(union node *, int, struct backcmd *);
+STATIC void prehash(union node *);
+#else
+STATIC void evalloop();
+STATIC void evalfor();
+STATIC void evalcase();
+STATIC void evalsubshell();
+STATIC void expredir();
+STATIC void evalpipe();
+STATIC void evalcommand();
+STATIC void prehash();
+#endif
+
+
+
+/*
+ * Called to reset things after an exception.
+ */
+
+#ifdef mkinit
+INCLUDE "eval.h"
+
+RESET {
+ evalskip = 0;
+ loopnest = 0;
+ funcnest = 0;
+}
+
+SHELLPROC {
+ exitstatus = 0;
+}
+#endif
+
+
+
+/*
+ * The eval commmand.
+ */
+
+evalcmd(argc, argv)
+ char **argv;
+{
+ char *p;
+ char *concat;
+ char **ap;
+
+ if (argc > 1) {
+ p = argv[1];
+ if (argc > 2) {
+ STARTSTACKSTR(concat);
+ ap = argv + 2;
+ for (;;) {
+ while (*p)
+ STPUTC(*p++, concat);
+ if ((p = *ap++) == NULL)
+ break;
+ STPUTC(' ', concat);
+ }
+ STPUTC('\0', concat);
+ p = grabstackstr(concat);
+ }
+ evalstring(p);
+ }
+ return exitstatus;
+}
+
+
+/*
+ * Execute a command or commands contained in a string.
+ */
+
+void
+evalstring(s)
+ char *s;
+ {
+ union node *n;
+ struct stackmark smark;
+
+ setstackmark(&smark);
+ setinputstring(s, 1);
+ while ((n = parsecmd(0)) != NEOF) {
+ evaltree(n, 0);
+ popstackmark(&smark);
+ }
+ popfile();
+ popstackmark(&smark);
+}
+
+
+
+/*
+ * Evaluate a parse tree. The value is left in the global variable
+ * exitstatus.
+ */
+
+void
+evaltree(n, flags)
+ union node *n;
+ {
+ if (n == NULL) {
+ TRACE(("evaltree(NULL) called\n"));
+ exitstatus = 0;
+ goto out;
+ }
+ displayhist = 1; /* show history substitutions done with fc */
+ TRACE(("evaltree(0x%x: %d) called\n", (int)n, n->type));
+ switch (n->type) {
+ case NSEMI:
+ evaltree(n->nbinary.ch1, 0);
+ if (evalskip)
+ goto out;
+ evaltree(n->nbinary.ch2, flags);
+ break;
+ case NAND:
+ evaltree(n->nbinary.ch1, EV_TESTED);
+ if (evalskip || exitstatus != 0)
+ goto out;
+ evaltree(n->nbinary.ch2, flags);
+ break;
+ case NOR:
+ evaltree(n->nbinary.ch1, EV_TESTED);
+ if (evalskip || exitstatus == 0)
+ goto out;
+ evaltree(n->nbinary.ch2, flags);
+ break;
+ case NREDIR:
+ expredir(n->nredir.redirect);
+ redirect(n->nredir.redirect, REDIR_PUSH);
+ evaltree(n->nredir.n, flags);
+ popredir();
+ break;
+ case NSUBSHELL:
+ evalsubshell(n, flags);
+ break;
+ case NBACKGND:
+ evalsubshell(n, flags);
+ break;
+ case NIF: {
+ int status = 0;
+
+ evaltree(n->nif.test, EV_TESTED);
+ if (evalskip)
+ goto out;
+ if (exitstatus == 0) {
+ evaltree(n->nif.ifpart, flags);
+ status = exitstatus;
+ } else if (n->nif.elsepart) {
+ evaltree(n->nif.elsepart, flags);
+ status = exitstatus;
+ }
+ exitstatus = status;
+ break;
+ }
+ case NWHILE:
+ case NUNTIL:
+ evalloop(n);
+ break;
+ case NFOR:
+ evalfor(n);
+ break;
+ case NCASE:
+ evalcase(n, flags);
+ break;
+ case NDEFUN:
+ defun(n->narg.text, n->narg.next);
+ exitstatus = 0;
+ break;
+ case NNOT:
+ evaltree(n->nnot.com, EV_TESTED);
+ exitstatus = !exitstatus;
+ break;
+
+ case NPIPE:
+ evalpipe(n);
+ break;
+ case NCMD:
+ evalcommand(n, flags, (struct backcmd *)NULL);
+ break;
+ default:
+ out1fmt("Node type = %d\n", n->type);
+ flushout(&output);
+ break;
+ }
+out:
+ if (pendingsigs)
+ dotrap();
+ if ((flags & EV_EXIT) || (eflag && exitstatus && !(flags & EV_TESTED)))
+ exitshell(exitstatus);
+}
+
+
+STATIC void
+evalloop(n)
+ union node *n;
+ {
+ int status;
+
+ loopnest++;
+ status = 0;
+ for (;;) {
+ evaltree(n->nbinary.ch1, EV_TESTED);
+ if (evalskip) {
+skipping: if (evalskip == SKIPCONT && --skipcount <= 0) {
+ evalskip = 0;
+ continue;
+ }
+ if (evalskip == SKIPBREAK && --skipcount <= 0)
+ evalskip = 0;
+ break;
+ }
+ if (n->type == NWHILE) {
+ if (exitstatus != 0)
+ break;
+ } else {
+ if (exitstatus == 0)
+ break;
+ }
+ evaltree(n->nbinary.ch2, 0);
+ status = exitstatus;
+ if (evalskip)
+ goto skipping;
+ }
+ loopnest--;
+ exitstatus = status;
+}
+
+
+
+STATIC void
+evalfor(n)
+ union node *n;
+ {
+ struct arglist arglist;
+ union node *argp;
+ struct strlist *sp;
+ struct stackmark smark;
+
+ setstackmark(&smark);
+ arglist.lastp = &arglist.list;
+ for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
+ expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
+ if (evalskip)
+ goto out;
+ }
+ *arglist.lastp = NULL;
+
+ exitstatus = 0;
+ loopnest++;
+ for (sp = arglist.list ; sp ; sp = sp->next) {
+ setvar(n->nfor.var, sp->text, 0);
+ evaltree(n->nfor.body, 0);
+ if (evalskip) {
+ if (evalskip == SKIPCONT && --skipcount <= 0) {
+ evalskip = 0;
+ continue;
+ }
+ if (evalskip == SKIPBREAK && --skipcount <= 0)
+ evalskip = 0;
+ break;
+ }
+ }
+ loopnest--;
+out:
+ popstackmark(&smark);
+}
+
+
+
+STATIC void
+evalcase(n, flags)
+ union node *n;
+ {
+ union node *cp;
+ union node *patp;
+ struct arglist arglist;
+ struct stackmark smark;
+
+ setstackmark(&smark);
+ arglist.lastp = &arglist.list;
+ expandarg(n->ncase.expr, &arglist, EXP_TILDE);
+ for (cp = n->ncase.cases ; cp && evalskip == 0 ; cp = cp->nclist.next) {
+ for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
+ if (casematch(patp, arglist.list->text)) {
+ if (evalskip == 0) {
+ evaltree(cp->nclist.body, flags);
+ }
+ goto out;
+ }
+ }
+ }
+out:
+ popstackmark(&smark);
+}
+
+
+
+/*
+ * Kick off a subshell to evaluate a tree.
+ */
+
+STATIC void
+evalsubshell(n, flags)
+ union node *n;
+ {
+ struct job *jp;
+ int backgnd = (n->type == NBACKGND);
+
+ expredir(n->nredir.redirect);
+ jp = makejob(n, 1);
+ if (forkshell(jp, n, backgnd) == 0) {
+ if (backgnd)
+ flags &=~ EV_TESTED;
+ redirect(n->nredir.redirect, 0);
+ evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
+ }
+ if (! backgnd) {
+ INTOFF;
+ exitstatus = waitforjob(jp);
+ INTON;
+ }
+}
+
+
+
+/*
+ * Compute the names of the files in a redirection list.
+ */
+
+STATIC void
+expredir(n)
+ union node *n;
+ {
+ register union node *redir;
+
+ for (redir = n ; redir ; redir = redir->nfile.next) {
+ if (redir->type == NFROM
+ || redir->type == NTO
+ || redir->type == NAPPEND) {
+ struct arglist fn;
+ fn.lastp = &fn.list;
+ expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
+ redir->nfile.expfname = fn.list->text;
+ }
+ }
+}
+
+
+
+/*
+ * Evaluate a pipeline. All the processes in the pipeline are children
+ * of the process creating the pipeline. (This differs from some versions
+ * of the shell, which make the last process in a pipeline the parent
+ * of all the rest.)
+ */
+
+STATIC void
+evalpipe(n)
+ union node *n;
+ {
+ struct job *jp;
+ struct nodelist *lp;
+ int pipelen;
+ int prevfd;
+ int pip[2];
+
+ TRACE(("evalpipe(0x%x) called\n", (int)n));
+ pipelen = 0;
+ for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
+ pipelen++;
+ INTOFF;
+ jp = makejob(n, pipelen);
+ prevfd = -1;
+ for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
+ prehash(lp->n);
+ pip[1] = -1;
+ if (lp->next) {
+ if (pipe(pip) < 0) {
+ close(prevfd);
+ error("Pipe call failed");
+ }
+ }
+ if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
+ INTON;
+ if (prevfd > 0) {
+ close(0);
+ copyfd(prevfd, 0);
+ close(prevfd);
+ }
+ if (pip[1] >= 0) {
+ close(pip[0]);
+ if (pip[1] != 1) {
+ close(1);
+ copyfd(pip[1], 1);
+ close(pip[1]);
+ }
+ }
+ evaltree(lp->n, EV_EXIT);
+ }
+ if (prevfd >= 0)
+ close(prevfd);
+ prevfd = pip[0];
+ close(pip[1]);
+ }
+ INTON;
+ if (n->npipe.backgnd == 0) {
+ INTOFF;
+ exitstatus = waitforjob(jp);
+ TRACE(("evalpipe: job done exit status %d\n", exitstatus));
+ INTON;
+ }
+}
+
+
+
+/*
+ * Execute a command inside back quotes. If it's a builtin command, we
+ * want to save its output in a block obtained from malloc. Otherwise
+ * we fork off a subprocess and get the output of the command via a pipe.
+ * Should be called with interrupts off.
+ */
+
+void
+evalbackcmd(n, result)
+ union node *n;
+ struct backcmd *result;
+ {
+ int pip[2];
+ struct job *jp;
+ struct stackmark smark; /* unnecessary */
+
+ setstackmark(&smark);
+ result->fd = -1;
+ result->buf = NULL;
+ result->nleft = 0;
+ result->jp = NULL;
+ exitstatus = 0;
+ if (n == NULL)
+ goto out;
+ if (n->type == NCMD) {
+ evalcommand(n, EV_BACKCMD, result);
+ } else {
+ if (pipe(pip) < 0)
+ error("Pipe call failed");
+ jp = makejob(n, 1);
+ if (forkshell(jp, n, FORK_NOJOB) == 0) {
+ FORCEINTON;
+ close(pip[0]);
+ if (pip[1] != 1) {
+ close(1);
+ copyfd(pip[1], 1);
+ close(pip[1]);
+ }
+ evaltree(n, EV_EXIT);
+ }
+ close(pip[1]);
+ result->fd = pip[0];
+ result->jp = jp;
+ }
+out:
+ popstackmark(&smark);
+ TRACE(("evalbackcmd done: fd=%d buf=0x%x nleft=%d jp=0x%x\n",
+ result->fd, result->buf, result->nleft, result->jp));
+}
+
+
+
+/*
+ * Execute a simple command.
+ */
+
+STATIC void
+evalcommand(cmd, flags, backcmd)
+ union node *cmd;
+ struct backcmd *backcmd;
+ {
+ struct stackmark smark;
+ union node *argp;
+ struct arglist arglist;
+ struct arglist varlist;
+ char **argv;
+ int argc;
+ char **envp;
+ int varflag;
+ struct strlist *sp;
+ register char *p;
+ int mode;
+ int pip[2];
+ struct cmdentry cmdentry;
+ struct job *jp;
+ struct jmploc jmploc;
+ struct jmploc *volatile savehandler;
+ char *volatile savecmdname;
+ volatile struct shparam saveparam;
+ struct localvar *volatile savelocalvars;
+ volatile int e;
+ char *lastarg;
+
+ /* First expand the arguments. */
+ TRACE(("evalcommand(0x%x, %d) called\n", (int)cmd, flags));
+ setstackmark(&smark);
+ arglist.lastp = &arglist.list;
+ varlist.lastp = &varlist.list;
+ varflag = 1;
+ for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
+ p = argp->narg.text;
+ if (varflag && is_name(*p)) {
+ do {
+ p++;
+ } while (is_in_name(*p));
+ if (*p == '=') {
+ expandarg(argp, &varlist, EXP_VARTILDE);
+ continue;
+ }
+ }
+ expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
+ varflag = 0;
+ }
+ *arglist.lastp = NULL;
+ *varlist.lastp = NULL;
+ expredir(cmd->ncmd.redirect);
+ argc = 0;
+ for (sp = arglist.list ; sp ; sp = sp->next)
+ argc++;
+ argv = stalloc(sizeof (char *) * (argc + 1));
+
+ for (sp = arglist.list ; sp ; sp = sp->next) {
+ TRACE(("evalcommand arg: %s\n", sp->text));
+ *argv++ = sp->text;
+ }
+ *argv = NULL;
+ lastarg = NULL;
+ if (iflag && funcnest == 0 && argc > 0)
+ lastarg = argv[-1];
+ argv -= argc;
+
+ /* Print the command if xflag is set. */
+ if (xflag) {
+ outc('+', &errout);
+ for (sp = varlist.list ; sp ; sp = sp->next) {
+ outc(' ', &errout);
+ out2str(sp->text);
+ }
+ for (sp = arglist.list ; sp ; sp = sp->next) {
+ outc(' ', &errout);
+ out2str(sp->text);
+ }
+ outc('\n', &errout);
+ flushout(&errout);
+ }
+
+ /* Now locate the command. */
+ if (argc == 0) {
+ cmdentry.cmdtype = CMDBUILTIN;
+ cmdentry.u.index = BLTINCMD;
+ } else {
+ find_command(argv[0], &cmdentry, 1);
+ if (cmdentry.cmdtype == CMDUNKNOWN) { /* command not found */
+ exitstatus = 2;
+ flushout(&errout);
+ return;
+ }
+ /* implement the bltin builtin here */
+ if (cmdentry.cmdtype == CMDBUILTIN && cmdentry.u.index == BLTINCMD) {
+ for (;;) {
+ argv++;
+ if (--argc == 0)
+ break;
+ if ((cmdentry.u.index = find_builtin(*argv)) < 0) {
+ outfmt(&errout, "%s: not found\n", *argv);
+ exitstatus = 2;
+ flushout(&errout);
+ return;
+ }
+ if (cmdentry.u.index != BLTINCMD)
+ break;
+ }
+ }
+ }
+
+ /* Fork off a child process if necessary. */
+ if (cmd->ncmd.backgnd
+ || cmdentry.cmdtype == CMDNORMAL && (flags & EV_EXIT) == 0
+ || (flags & EV_BACKCMD) != 0
+ && (cmdentry.cmdtype != CMDBUILTIN
+ || cmdentry.u.index == DOTCMD
+ || cmdentry.u.index == EVALCMD)) {
+ jp = makejob(cmd, 1);
+ mode = cmd->ncmd.backgnd;
+ if (flags & EV_BACKCMD) {
+ mode = FORK_NOJOB;
+ if (pipe(pip) < 0)
+ error("Pipe call failed");
+ }
+ if (forkshell(jp, cmd, mode) != 0)
+ goto parent; /* at end of routine */
+ if (flags & EV_BACKCMD) {
+ FORCEINTON;
+ close(pip[0]);
+ if (pip[1] != 1) {
+ close(1);
+ copyfd(pip[1], 1);
+ close(pip[1]);
+ }
+ }
+ flags |= EV_EXIT;
+ }
+
+ /* This is the child process if a fork occurred. */
+ /* Execute the command. */
+ if (cmdentry.cmdtype == CMDFUNCTION) {
+ trputs("Shell function: "); trargs(argv);
+ redirect(cmd->ncmd.redirect, REDIR_PUSH);
+ saveparam = shellparam;
+ shellparam.malloc = 0;
+ shellparam.nparam = argc - 1;
+ shellparam.p = argv + 1;
+ shellparam.optnext = NULL;
+ INTOFF;
+ savelocalvars = localvars;
+ localvars = NULL;
+ INTON;
+ if (setjmp(jmploc.loc)) {
+ if (exception == EXSHELLPROC)
+ freeparam((struct shparam *)&saveparam);
+ else {
+ freeparam(&shellparam);
+ shellparam = saveparam;
+ }
+ poplocalvars();
+ localvars = savelocalvars;
+ handler = savehandler;
+ longjmp(handler->loc, 1);
+ }
+ savehandler = handler;
+ handler = &jmploc;
+ for (sp = varlist.list ; sp ; sp = sp->next)
+ mklocal(sp->text);
+ funcnest++;
+ evaltree(cmdentry.u.func, 0);
+ funcnest--;
+ INTOFF;
+ poplocalvars();
+ localvars = savelocalvars;
+ freeparam(&shellparam);
+ shellparam = saveparam;
+ handler = savehandler;
+ popredir();
+ INTON;
+ if (evalskip == SKIPFUNC) {
+ evalskip = 0;
+ skipcount = 0;
+ }
+ if (flags & EV_EXIT)
+ exitshell(exitstatus);
+ } else if (cmdentry.cmdtype == CMDBUILTIN) {
+ trputs("builtin command: "); trargs(argv);
+ mode = (cmdentry.u.index == EXECCMD)? 0 : REDIR_PUSH;
+ if (flags == EV_BACKCMD) {
+ memout.nleft = 0;
+ memout.nextc = memout.buf;
+ memout.bufsize = 64;
+ mode |= REDIR_BACKQ;
+ }
+ redirect(cmd->ncmd.redirect, mode);
+ savecmdname = commandname;
+ cmdenviron = varlist.list;
+ e = -1;
+ if (setjmp(jmploc.loc)) {
+ e = exception;
+ exitstatus = (e == EXINT)? SIGINT+128 : 2;
+ goto cmddone;
+ }
+ savehandler = handler;
+ handler = &jmploc;
+ commandname = argv[0];
+ argptr = argv + 1;
+ optptr = NULL; /* initialize nextopt */
+ exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
+ flushall();
+cmddone:
+ out1 = &output;
+ out2 = &errout;
+ freestdout();
+ if (e != EXSHELLPROC) {
+ commandname = savecmdname;
+ if (flags & EV_EXIT) {
+ exitshell(exitstatus);
+ }
+ }
+ handler = savehandler;
+ if (e != -1) {
+ if (e != EXERROR || cmdentry.u.index == BLTINCMD
+ || cmdentry.u.index == DOTCMD
+ || cmdentry.u.index == EVALCMD
+ || cmdentry.u.index == HISTCMD
+ || cmdentry.u.index == EXECCMD)
+ exraise(e);
+ FORCEINTON;
+ }
+ if (cmdentry.u.index != EXECCMD)
+ popredir();
+ if (flags == EV_BACKCMD) {
+ backcmd->buf = memout.buf;
+ backcmd->nleft = memout.nextc - memout.buf;
+ memout.buf = NULL;
+ }
+ } else {
+ trputs("normal command: "); trargs(argv);
+ clearredir();
+ redirect(cmd->ncmd.redirect, 0);
+ if (varlist.list) {
+ p = stalloc(strlen(pathval()) + 1);
+ scopy(pathval(), p);
+ } else {
+ p = pathval();
+ }
+ for (sp = varlist.list ; sp ; sp = sp->next)
+ setvareq(sp->text, VEXPORT|VSTACK);
+ envp = environment();
+ shellexec(argv, envp, p, cmdentry.u.index);
+ /*NOTREACHED*/
+ }
+ goto out;
+
+parent: /* parent process gets here (if we forked) */
+ if (mode == 0) { /* argument to fork */
+ INTOFF;
+ exitstatus = waitforjob(jp);
+ INTON;
+ } else if (mode == 2) {
+ backcmd->fd = pip[0];
+ close(pip[1]);
+ backcmd->jp = jp;
+ }
+
+out:
+ if (lastarg)
+ setvar("_", lastarg, 0);
+ popstackmark(&smark);
+}
+
+
+
+/*
+ * Search for a command. This is called before we fork so that the
+ * location of the command will be available in the parent as well as
+ * the child. The check for "goodname" is an overly conservative
+ * check that the name will not be subject to expansion.
+ */
+
+STATIC void
+prehash(n)
+ union node *n;
+ {
+ struct cmdentry entry;
+
+ if (n->type == NCMD && goodname(n->ncmd.args->narg.text))
+ find_command(n->ncmd.args->narg.text, &entry, 0);
+}
+
+
+
+/*
+ * Builtin commands. Builtin commands whose functions are closely
+ * tied to evaluation are implemented here.
+ */
+
+/*
+ * No command given, or a bltin command with no arguments. Set the
+ * specified variables.
+ */
+
+bltincmd(argc, argv) char **argv; {
+ listsetvar(cmdenviron);
+ return exitstatus;
+}
+
+
+/*
+ * Handle break and continue commands. Break, continue, and return are
+ * all handled by setting the evalskip flag. The evaluation routines
+ * above all check this flag, and if it is set they start skipping
+ * commands rather than executing them. The variable skipcount is
+ * the number of loops to break/continue, or the number of function
+ * levels to return. (The latter is always 1.) It should probably
+ * be an error to break out of more loops than exist, but it isn't
+ * in the standard shell so we don't make it one here.
+ */
+
+breakcmd(argc, argv) char **argv; {
+ int n;
+
+ n = 1;
+ if (argc > 1)
+ n = number(argv[1]);
+ if (n > loopnest)
+ n = loopnest;
+ if (n > 0) {
+ evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
+ skipcount = n;
+ }
+ return 0;
+}
+
+
+/*
+ * The return command.
+ */
+
+returncmd(argc, argv) char **argv; {
+ int ret;
+
+ ret = exitstatus;
+ if (argc > 1)
+ ret = number(argv[1]);
+ if (funcnest) {
+ evalskip = SKIPFUNC;
+ skipcount = 1;
+ }
+ return ret;
+}
+
+
+truecmd(argc, argv) char **argv; {
+ return 0;
+}
+
+
+execcmd(argc, argv) char **argv; {
+ if (argc > 1) {
+ iflag = 0; /* exit on error */
+ mflag = 0;
+ optschanged();
+ shellexec(argv + 1, environment(), pathval(), 0);
+
+ }
+ return 0;
+}
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