Replace safe FD fix with Solaris/ksh2020 version (re: 045fe6a)

McDutchie · McDutchie · commit ab98ec65e4ce · 2021-01-08T16:35:26.000Z
This pulls a new version of sh_iosafefd() from: https://github.com/oracle/solaris-userland/blob/master/components/ksh93/patches/285-30771135.patch It was written by Kurtis Rader for ksh2020: att#198 att#199 It is presumably better than the Red Hat version and also comes with more regression test cases (although it still doesn't fix modernish BUG_CSUBSTDO, which remains in the TODO file). This commit does not go along with other peripheral changes from that patch, i.e. a different name and location of this function. src/cmd/ksh93/sh/io.c: - Replace sh_iosafefd() as above. src/cmd/ksh93/tests/subshell.sh: - Add and tweak tests from the patch.
diff --git a/src/cmd/ksh93/sh/io.c b/src/cmd/ksh93/sh/io.c
@@ -436,22 +436,28 @@ int  sh_iovalidfd(Shell_t *shp, int fd)
 	return(1);
 }
 
-int  sh_iosafefd(Shell_t* shp, int sfd)
+/*
+ * Return the lowest numbered fd that is equal to or greater than
+ * the requested 'min_fd' and which is not currently in use.
+ */
+int  sh_iosafefd(Shell_t* shp, int min_fd)
 {
 	register int	fd;
 	while(1)
 	{
-		for(fd=0; fd < shp->topfd; fd++)
+		if(fcntl(min_fd, F_GETFD) == -1)
 		{
-			if (filemap[fd].save_fd==sfd || filemap[fd].orig_fd==sfd || (fcntl(sfd, F_GETFD) != -1 || errno != EBADF))
+			for(fd = 0; fd < shp->topfd; fd++)
 			{
-				sfd++;
-				continue;
+				if (filemap[fd].save_fd == min_fd || filemap[fd].orig_fd == min_fd)
+					break;
 			}
+			if(fd == shp->topfd)
+				break;
 		}
-		break;
+		min_fd++;
 	}
-	return(sfd);
+	return(min_fd);
 }
 
 int  sh_inuse(Shell_t *shp, int fd)
diff --git a/src/cmd/ksh93/tests/subshell.sh b/src/cmd/ksh93/tests/subshell.sh
@@ -854,6 +854,32 @@ actual=${ get_value; }
 actual=`get_value`
 [[ $actual == "$expect" ]] || err_exit "\`Comsub\` failed to return output (expected '$expect', got '$actual')"
 
+# more tests from https://github.com/oracle/solaris-userland/blob/master/components/ksh93/patches/285-30771135.patch
+tmpfile=$tmp/1116072.dummy
+touch "$tmpfile"
+exp='return value'
+function get_value
+{
+	case=$1
+	(( case >= 1 )) && exec 3< $tmpfile
+	(( case >= 2 )) && exec 4< $tmpfile
+	(( case >= 3 )) && exec 6< $tmpfile
+	# To trigger the bug we have to spawn an external command.
+	$(whence -p true)
+	(( case >= 1 )) && exec 3<&-
+	(( case >= 2 )) && exec 4<&-
+	(( case >= 3 )) && exec 6<&-
+	print "$exp"
+}
+got=$(get_value 0)
+[[ $got == "$exp" ]] || err_exit "failed to capture subshell output when closing fd: case 0"
+got=$(get_value 1)
+[[ $got == "$exp" ]] || err_exit "failed to capture subshell output when closing fd: case 1"
+got=$(get_value 2)
+[[ $got == "$exp" ]] || err_exit "failed to capture subshell output when closing fd: case 2"
+got=$(get_value 3)
+[[ $got == "$exp" ]] || err_exit "failed to capture subshell output when closing fd: case 3"
+
 # ======
 # https://bugzilla.redhat.com/1117404
 

Original file line number	Diff line number	Diff line change
`@@ -436,22 +436,28 @@ int sh_iovalidfd(Shell_t *shp, int fd)`
`436`	`436`	`return(1);`
`437`	`437`	`}`
`438`	`438`
`439`		`-int sh_iosafefd(Shell_t* shp, int sfd)`
	`439`	`+/*`
	`440`	`+ * Return the lowest numbered fd that is equal to or greater than`
	`441`	`+ * the requested 'min_fd' and which is not currently in use.`
	`442`	`+ */`
	`443`	`+int sh_iosafefd(Shell_t* shp, int min_fd)`
`440`	`444`	`{`
`441`	`445`	`register int fd;`
`442`	`446`	`while(1)`
`443`	`447`	`{`
`444`		`- for(fd=0; fd < shp->topfd; fd++)`
	`448`	`+ if(fcntl(min_fd, F_GETFD) == -1)`
`445`	`449`	`{`
`446`		`- if (filemap[fd].save_fd==sfd \|\| filemap[fd].orig_fd==sfd \|\| (fcntl(sfd, F_GETFD) != -1 \|\| errno != EBADF))`
	`450`	`+ for(fd = 0; fd < shp->topfd; fd++)`
`447`	`451`	`{`
`448`		`- sfd++;`
`449`		`- continue;`
	`452`	`+ if (filemap[fd].save_fd == min_fd \|\| filemap[fd].orig_fd == min_fd)`
	`453`	`+ break;`
`450`	`454`	`}`
	`455`	`+ if(fd == shp->topfd)`
	`456`	`+ break;`
`451`	`457`	`}`
`452`		`- break;`
	`458`	`+ min_fd++;`
`453`	`459`	`}`
`454`		`- return(sfd);`
	`460`	`+ return(min_fd);`
`455`	`461`	`}`
`456`	`462`
`457`	`463`	`int sh_inuse(Shell_t *shp, int fd)`