ash: [REDIR] Replace GPL noclobberopen code with the FreeBSD version

Upstream commit:

    Date: Thu, 10 Mar 2011 16:52:13 +0800
    [REDIR] Replace GPL noclobberopen code with the FreeBSD version

    Replace noclobberopen() from bash with the FreeBSD code for noclobber
    opens.

    This also reduces code size by eliminating an unnecessary check.

    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

function                                             old     new   delta
changepath                                           192     194      +2
localcmd                                             366     364      -2
expmeta                                              521     517      -4
redirect                                            1210    1135     -75
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/3 up/down: 2/-81)             Total: -79 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 17 insertions, 64 deletions

diff --git a/shell/ash.c b/shell/ash.c
index c353834a4..b4b0d5253 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -5175,68 +5175,6 @@ stoppedjobs(void)
 #define CLOSED -3               /* marks a slot of previously-closed fd */
 
 /*
- * Open a file in noclobber mode.
- * The code was copied from bash.
- */
-static int
-noclobberopen(const char *fname)
-{
-        int r, fd;
-        struct stat finfo, finfo2;
-
-        /*
-         * If the file exists and is a regular file, return an error
-         * immediately.
-         */
-        r = stat(fname, &finfo);
-        if (r == 0 && S_ISREG(finfo.st_mode)) {
-                errno = EEXIST;
-                return -1;
-        }
-
-        /*
-         * If the file was not present (r != 0), make sure we open it
-         * exclusively so that if it is created before we open it, our open
-         * will fail.  Make sure that we do not truncate an existing file.
-         * Note that we don't turn on O_EXCL unless the stat failed -- if the
-         * file was not a regular file, we leave O_EXCL off.
-         */
-        if (r != 0)
-                return open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666);
-        fd = open(fname, O_WRONLY|O_CREAT, 0666);
-
-        /* If the open failed, return the file descriptor right away. */
-        if (fd < 0)
-                return fd;
-
-        /*
-         * OK, the open succeeded, but the file may have been changed from a
-         * non-regular file to a regular file between the stat and the open.
-         * We are assuming that the O_EXCL open handles the case where FILENAME
-         * did not exist and is symlinked to an existing file between the stat
-         * and open.
-         */
-
-        /*
-         * If we can open it and fstat the file descriptor, and neither check
-         * revealed that it was a regular file, and the file has not been
-         * replaced, return the file descriptor.
-         */
-        if (fstat(fd, &finfo2) == 0
-         && !S_ISREG(finfo2.st_mode)
-         && finfo.st_dev == finfo2.st_dev
-         && finfo.st_ino == finfo2.st_ino
-        ) {
-                return fd;
-        }
-
-        /* The file has been replaced.  badness. */
-        close(fd);
-        errno = EEXIST;
-        return -1;
-}
-
-/*
  * Handle here documents.  Normally we fork off a process to write the
  * data to a pipe.  If the document is short, we can stuff the data in
  * the pipe without forking.
@@ -5280,6 +5218,7 @@ openhere(union node *redir)
 static int
 openredirect(union node *redir)
 {
+        struct stat sb;
         char *fname;
         int f;
 
@@ -5319,9 +5258,23 @@ openredirect(union node *redir)
 #endif
                 /* Take care of noclobber mode. */
                 if (Cflag) {
-                        f = noclobberopen(fname);
-                        if (f < 0)
+                        if (stat(fname, &sb) < 0) {
+                                f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666);
+                                if (f < 0)
+                                        goto ecreate;
+                        } else if (!S_ISREG(sb.st_mode)) {
+                                f = open(fname, O_WRONLY, 0666);
+                                if (f < 0)
+                                        goto ecreate;
+                                if (fstat(f, &sb) < 0 && S_ISREG(sb.st_mode)) {
+                                        close(f);
+                                        errno = EEXIST;
+                                        goto ecreate;
+                                }
+                        } else {
+                                errno = EEXIST;
                                 goto ecreate;
+                        }
                         break;
                 }
                 /* FALLTHROUGH */