Implement the <> redirection operator.

7 files changed, 34 insertions, 3 deletions

diff --git a/bin/sh/eval.c b/bin/sh/eval.c
index dabc7e63dec9..8bf2d84522d6 100644
--- a/bin/sh/eval.c
+++ b/bin/sh/eval.c
@@ -442,6 +442,7 @@ expredir(n)
 		switch (redir->type) {
 		case NFROM:
 		case NTO:
+		case NFROMTO:
 		case NAPPEND:
 			expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
 			redir->nfile.expfname = fn.list->text;
diff --git a/bin/sh/jobs.c b/bin/sh/jobs.c
index 5e6b3e7e7f0f..e4374412b170 100644
--- a/bin/sh/jobs.c
+++ b/bin/sh/jobs.c
@@ -1085,6 +1085,8 @@ until:
 		p = ">&";  i = 1;  goto redir;
 	case NFROM:
 		p = "<";  i = 0;  goto redir;
+	case NFROMTO:
+		p = "<>";  i = 0;  goto redir;
 	case NFROMFD:
 		p = "<&";  i = 0;  goto redir;
 redir:
diff --git a/bin/sh/nodetypes b/bin/sh/nodetypes
index ce82a35d266f..53dd18f40845 100644
--- a/bin/sh/nodetypes
+++ b/bin/sh/nodetypes
@@ -118,6 +118,7 @@ NARG narg			# represents a word
 
 NTO nfile			# fd> fname
 NFROM nfile			# fd< fname
+NFROMTO nfile			# fd<> fname
 NAPPEND nfile			# fd>> fname
 	type	  int
 	next	  nodeptr		# next redirection in list
diff --git a/bin/sh/parser.c b/bin/sh/parser.c
index a65dfb3b4253..08d25696ffc2 100644
--- a/bin/sh/parser.c
+++ b/bin/sh/parser.c
@@ -1138,6 +1138,8 @@ parseredir: {
 			}
 		} else if (c == '&')
 			np->type = NFROMFD;
+		else if (c == '>')
+			np->type = NFROMTO;
 		else {
 			np->type = NFROM;
 			pungetc();
diff --git a/bin/sh/redir.c b/bin/sh/redir.c
index 3ef30d0e0151..ee893f40bef2 100644
--- a/bin/sh/redir.c
+++ b/bin/sh/redir.c
@@ -190,6 +190,27 @@ movefd:
 			close(f);
 		}
 		break;
+	case NFROMTO:
+		fname = redir->nfile.expfname;
+#ifdef O_CREAT
+		if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0)
+			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
+#else
+		if ((f = open(fname, O_RDWR, 0666)) < 0) {
+			if (errno != ENOENT)
+				error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
+			else if ((f = creat(fname, 0666)) < 0)
+				error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
+			else {
+				close(f);
+				if ((f = open(fname, O_RDWR)) < 0) {
+					error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
+					remove(fname);
+				}
+			}
+		}
+#endif
+		goto movefd;
 	case NTO:
 		fname = redir->nfile.expfname;
 #ifdef O_CREAT
diff --git a/bin/sh/sh.1 b/bin/sh/sh.1
index 6e1bf1fcf479..8277ddb5da24 100644
--- a/bin/sh/sh.1
+++ b/bin/sh/sh.1
@@ -331,13 +331,14 @@ The following is a list of valid operators:
 .Xc Xc Xc Xc
 .El
 .It Redirection operators:
-.Bl -column "XXX" "XXX" "XXX" "XXX" -offset center -compact
+.Bl -column "XXX" "XXX" "XXX" "XXX" "XXX" -offset center -compact
 .It Xo
 .Li < Ta Xo
 .Li > Ta Xo
 .Li << Ta Xo
-.Li >>
-.Xc Xc Xc Xc
+.Li >> Ta Xo
+.Li <>
+.Xc Xc Xc Xc Xc
 .It Xo
 .Li <& Ta Xo
 .Li >& Ta Xo
@@ -497,6 +498,8 @@ option
 append stdout (or file descriptor n) to file
 .It Li [n]< file
 redirect stdin (or file descriptor n) from file
+.It Li [n]<> file
+redirect stdin (or file descriptor n) to and from file
 .It Li [n1]<&n2
 duplicate stdin (or file descriptor n1) from file descriptor n2
 .It Li [n]<&-
diff --git a/bin/sh/show.c b/bin/sh/show.c
index 4abc4c084e99..0183e6b701e2 100644
--- a/bin/sh/show.c
+++ b/bin/sh/show.c
@@ -157,6 +157,7 @@ shcmd(cmd, fp)
 			case NAPPEND:	s = ">>"; dftfd = 1; break;
 			case NTOFD:	s = ">&"; dftfd = 1; break;
 			case NFROM:	s = "<";  dftfd = 0; break;
+			case NFROMTO:	s = "<>"; dftfd = 0; break;
 			case NFROMFD:	s = "<&"; dftfd = 0; break;
 			default:  	s = "*error*"; dftfd = 0; break;
 		}