Implement the -C (-o noclobber) option, which prevents existing regular

files from being overwritten by shell redirection.

8 files changed, 19 insertions, 1 deletions

diff --git a/bin/sh/error.c b/bin/sh/error.c
index 0cf20b3..96e6534 100644
--- a/bin/sh/error.c
+++ b/bin/sh/error.c
@@ -247,6 +247,7 @@ STATIC const struct errname errormsg[] = {
 #ifdef ELIBACC
 	{ ELIBACC,	E_EXEC,	"shared library missing" },
 #endif
+	{ EEXIST,	E_CREAT, "file exists" },
 	{ 0,		0,	NULL },
 };
 
diff --git a/bin/sh/eval.c b/bin/sh/eval.c
index 9f65d90..0c3f85b 100644
--- a/bin/sh/eval.c
+++ b/bin/sh/eval.c
@@ -448,6 +448,7 @@ expredir(union node *n)
 		case NTO:
 		case NFROMTO:
 		case NAPPEND:
+		case NCLOBBER:
 			expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
 			redir->nfile.expfname = fn.list->text;
 			break;
diff --git a/bin/sh/jobs.c b/bin/sh/jobs.c
index 14f1909..b1cc2de 100644
--- a/bin/sh/jobs.c
+++ b/bin/sh/jobs.c
@@ -1057,6 +1057,8 @@ until:
 		p = ">>";  i = 1;  goto redir;
 	case NTOFD:
 		p = ">&";  i = 1;  goto redir;
+	case NCLOBBER:
+		p = ">|"; i = 1; goto redir;
 	case NFROM:
 		p = "<";  i = 0;  goto redir;
 	case NFROMTO:
diff --git a/bin/sh/nodetypes b/bin/sh/nodetypes
index 53dd18f..27fbcd1 100644
--- a/bin/sh/nodetypes
+++ b/bin/sh/nodetypes
@@ -120,6 +120,7 @@ NTO nfile			# fd> fname
 NFROM nfile			# fd< fname
 NFROMTO nfile			# fd<> fname
 NAPPEND nfile			# fd>> fname
+NCLOBBER nfile			# fd>| fname
 	type	  int
 	next	  nodeptr		# next redirection in list
 	fd	  int			# file descriptor being redirected
diff --git a/bin/sh/parser.c b/bin/sh/parser.c
index 08cd737..6e0f23b 100644
--- a/bin/sh/parser.c
+++ b/bin/sh/parser.c
@@ -1145,6 +1145,8 @@ parseredir: {
 			np->type = NAPPEND;
 		else if (c == '&')
 			np->type = NTOFD;
+		else if (c == '|')
+			np->type = NCLOBBER;
 		else {
 			np->type = NTO;
 			pungetc();
diff --git a/bin/sh/redir.c b/bin/sh/redir.c
index b596463..60a6151 100644
--- a/bin/sh/redir.c
+++ b/bin/sh/redir.c
@@ -43,6 +43,7 @@ static const char rcsid[] =
 #endif /* not lint */
 
 #include <sys/types.h>
+#include <sys/stat.h>
 #include <signal.h>
 #include <string.h>
 #include <fcntl.h>
@@ -62,6 +63,7 @@ static const char rcsid[] =
 #include "output.h"
 #include "memalloc.h"
 #include "error.h"
+#include "options.h"
 
 
 #define EMPTY -2		/* marks an unused slot in redirtab */
@@ -161,6 +163,7 @@ again:
 STATIC void
 openredirect(union node *redir, char memory[10])
 {
+	struct stat sb;
 	int fd = redir->nfile.fd;
 	char *fname;
 	int f;
@@ -207,6 +210,9 @@ movefd:
 		goto movefd;
 	case NTO:
 		fname = redir->nfile.expfname;
+		if (Cflag && stat(fname, &sb) != -1 && S_ISREG(sb.st_mode))
+			error("cannot create %s: %s", fname,
+			    errmsg(EEXIST, E_CREAT));
 #ifdef O_CREAT
 		if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
@@ -215,6 +221,11 @@ movefd:
 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
 #endif
 		goto movefd;
+	case NCLOBBER:
+		fname = redir->nfile.expfname;
+		if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
+			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
+		goto movefd;
 	case NAPPEND:
 		fname = redir->nfile.expfname;
 #ifdef O_APPEND
diff --git a/bin/sh/sh.1 b/bin/sh/sh.1
index 9c8cc34..e9f5f08 100644
--- a/bin/sh/sh.1
+++ b/bin/sh/sh.1
@@ -195,7 +195,6 @@ completion.
 .It Fl C Li noclobber
 Do not overwrite existing files with
 .Dq Li > .
-(UNIMPLEMENTED)
 .It Fl E Li emacs
 Enable the builtin
 .Xr emacs 1
diff --git a/bin/sh/show.c b/bin/sh/show.c
index 3880d38..0e9a181 100644
--- a/bin/sh/show.c
+++ b/bin/sh/show.c
@@ -142,6 +142,7 @@ shcmd(union node *cmd, FILE *fp)
 			case NTO:	s = ">";  dftfd = 1; break;
 			case NAPPEND:	s = ">>"; dftfd = 1; break;
 			case NTOFD:	s = ">&"; dftfd = 1; break;
+			case NCLOBBER:	s = ">|"; dftfd = 1; break;
 			case NFROM:	s = "<";  dftfd = 0; break;
 			case NFROMTO:	s = "<>"; dftfd = 0; break;
 			case NFROMFD:	s = "<&"; dftfd = 0; break;