svn commit: r217206 - in head: bin/sh tools/regression/bin/sh/execution

[Jilles Tjoelker]

Author: jilles
Date: Sun Jan  9 21:07:30 2011
New Revision: 217206
URL: http://svn.freebsd.org/changeset/base/217206

Log:
  sh: Remove special %builtin PATH entry.
  All builtins are now always found before a PATH search.
  
  Most ash derivatives have an undocumented feature where the presence of an
  entry "%builtin" in $PATH will cause builtins to be checked at that point of
  the PATH search, rather than before looking at any directories as documented
  in the man page (very old versions do document this feature).
  
  I am removing this feature from sh, as it complicates the code, may violate
  expectations (for example, /usr/bin/alias is very close to a forkbomb with
  PATH=/usr/bin:%builtin, only /usr/bin/builtin not being another link saves
  it) and appears to be unused (all the %builtin google code search finds is
  in some sort of ash source code).
  
  Note that aliases and functions took and take precedence above builtins.
  Because aliases work on a lexical level they can only ever be overridden on
  a lexical level (quoting or preceding 'builtin' or 'command'). Allowing
  override of functions via PATH does not really fit in the model of sh and it
  would work differently from %builtin if implemented.
  
  Note: POSIX says special builtins are found before functions. We comply to
  this because we do not allow functions with the same name as a special
  builtin.
  
  Silence from:	freebsd-hackers@ (message sent 20101225)
  Discussed with:	dougb

Added:
  head/tools/regression/bin/sh/execution/path1.0   (contents, props changed)
Modified:
  head/bin/sh/exec.c

Modified: head/bin/sh/exec.c
==============================================================================
--- head/bin/sh/exec.c	Sun Jan  9 21:02:11 2011	(r217205)
+++ head/bin/sh/exec.c	Sun Jan  9 21:07:30 2011	(r217206)
@@ -92,7 +92,6 @@ struct tblentry {
 
 
 static struct tblentry *cmdtable[CMDTABLESIZE];
-static int builtinloc = -1;		/* index in path of %builtin, or -1 */
 int exerrno = 0;			/* Last exec error */
 
 
@@ -244,8 +243,7 @@ hashcmd(int argc __unused, char **argv _
 	}
 	while ((name = *argptr) != NULL) {
 		if ((cmdp = cmdlookup(name, 0)) != NULL
-		 && (cmdp->cmdtype == CMDNORMAL
-		     || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)))
+		 && cmdp->cmdtype == CMDNORMAL)
 			delete_cmd_entry();
 		find_command(name, &entry, DO_ERR, pathval());
 		if (verbose) {
@@ -336,8 +334,8 @@ find_command(const char *name, struct cm
 			goto success;
 	}
 
-	/* If %builtin not in path, check for builtin next */
-	if (builtinloc < 0 && (i = find_builtin(name, &spec)) >= 0) {
+	/* Check for builtin next */
+	if ((i = find_builtin(name, &spec)) >= 0) {
 		INTOFF;
 		cmdp = cmdlookup(name, 1);
 		if (cmdp->cmdtype == CMDFUNCTION)
@@ -353,7 +351,7 @@ find_command(const char *name, struct cm
 	prev = -1;		/* where to start */
 	if (cmdp) {		/* doing a rehash */
 		if (cmdp->cmdtype == CMDBUILTIN)
-			prev = builtinloc;
+			prev = -1;
 		else
 			prev = cmdp->param.index;
 	}
@@ -365,19 +363,7 @@ loop:
 		stunalloc(fullname);
 		idx++;
 		if (pathopt) {
-			if (prefix("builtin", pathopt)) {
-				if ((i = find_builtin(name, &spec)) < 0)
-					goto loop;
-				INTOFF;
-				cmdp = cmdlookup(name, 1);
-				if (cmdp->cmdtype == CMDFUNCTION)
-					cmdp = &loc_cmd;
-				cmdp->cmdtype = CMDBUILTIN;
-				cmdp->param.index = i;
-				cmdp->special = spec;
-				INTON;
-				goto success;
-			} else if (prefix("func", pathopt)) {
+			if (prefix("func", pathopt)) {
 				/* handled below */
 			} else {
 				goto loop;	/* ignore unimplemented options */
@@ -484,8 +470,7 @@ hashcd(void)
 
 	for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
 		for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
-			if (cmdp->cmdtype == CMDNORMAL
-			 || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))
+			if (cmdp->cmdtype == CMDNORMAL)
 				cmdp->rehash = 1;
 		}
 	}
@@ -505,13 +490,11 @@ changepath(const char *newval)
 	const char *old, *new;
 	int idx;
 	int firstchange;
-	int bltin;
 
 	old = pathval();
 	new = newval;
 	firstchange = 9999;	/* assume no change */
 	idx = 0;
-	bltin = -1;
 	for (;;) {
 		if (*old != *new) {
 			firstchange = idx;
@@ -522,19 +505,12 @@ changepath(const char *newval)
 		}
 		if (*new == '\0')
 			break;
-		if (*new == '%' && bltin < 0 && prefix("builtin", new + 1))
-			bltin = idx;
 		if (*new == ':') {
 			idx++;
 		}
 		new++, old++;
 	}
-	if (builtinloc < 0 && bltin >= 0)
-		builtinloc = bltin;		/* zap builtins */
-	if (builtinloc >= 0 && bltin < 0)
-		firstchange = 0;
 	clearcmdentry(firstchange);
-	builtinloc = bltin;
 }
 
 
@@ -555,9 +531,7 @@ clearcmdentry(int firstchange)
 		pp = tblp;
 		while ((cmdp = *pp) != NULL) {
 			if ((cmdp->cmdtype == CMDNORMAL &&
-			     cmdp->param.index >= firstchange)
-			 || (cmdp->cmdtype == CMDBUILTIN &&
-			     builtinloc >= firstchange)) {
+			     cmdp->param.index >= firstchange)) {
 				*pp = cmdp->next;
 				ckfree(cmdp);
 			} else {

Added: head/tools/regression/bin/sh/execution/path1.0
==============================================================================
--- /dev/null	00:00:00 1970	(empty, because file is newly added)
+++ head/tools/regression/bin/sh/execution/path1.0	Sun Jan  9 21:07:30 2011	(r217206)
@@ -0,0 +1,15 @@
+# $FreeBSD$
+# Some builtins should not be overridable via PATH.
+
+set -e
+T=$(mktemp -d ${TMPDIR:-/tmp}/sh-test.XXXXXX)
+trap 'rm -rf ${T}' 0
+echo '#!/bin/sh
+echo bad' >"$T/cd"
+chmod 755 "$T/cd"
+cd /bin
+oPATH=$PATH
+PATH=$T:$PATH:%builtin
+cd /
+PATH=$oPATH
+[ "$(pwd)" = / ]