386BSD 0.1 development

Work on file usr/othersrc/public/fileutils-3.2/fileutils-3.2/lib/ftruncate.c

Co-Authored-By: Lynne Greer Jolitz <ljolitz@cardio.ucsf.edu>
Synthesized-from: 386BSD-0.1

diff --git a/usr/othersrc/public/fileutils-3.2/fileutils-3.2/lib/ftruncate.c b/usr/othersrc/public/fileutils-3.2/fileutils-3.2/lib/ftruncate.c
new file mode 100644 (file)
index 0000000..17d263d
--- /dev/null
+++ b/usr/othersrc/public/fileutils-3.2/fileutils-3.2/lib/ftruncate.c
@@ -0,0 +1,72 @@
+/* ftruncate emulations that work on some System V's.
+   This file is in the public domain. */
+
+#include <sys/types.h>
+#include <fcntl.h>
+
+#ifdef F_CHSIZE
+int
+ftruncate (fd, length)
+     int fd;
+     off_t length;
+{
+  return fcntl (fd, F_CHSIZE, length);
+}
+#else
+#ifdef F_FREESP
+/* The following function was written by
+   kucharsk@Solbourne.com (William Kucharski) */
+
+#include <sys/stat.h>
+#include <errno.h>
+#include <unistd.h>
+
+int
+ftruncate (fd, length)
+     int fd;
+     off_t length;
+{
+  struct flock fl;
+  struct stat filebuf;
+
+  if (fstat (fd, &filebuf) < 0)
+    return -1;
+
+  if (filebuf.st_size < length)
+    {
+      /* Extend file length. */
+      if (lseek (fd, (length - 1), SEEK_SET) < 0)
+       return -1;
+
+      /* Write a "0" byte. */
+      if (write (fd, "", 1) != 1)
+       return -1;
+    }
+  else
+    {
+      /* Truncate length. */
+      fl.l_whence = 0;
+      fl.l_len = 0;
+      fl.l_start = length;
+      fl.l_type = F_WRLCK;     /* Write lock on file space. */
+
+      /* This relies on the UNDOCUMENTED F_FREESP argument to
+        fcntl, which truncates the file so that it ends at the
+        position indicated by fl.l_start.
+        Will minor miracles never cease? */
+      if (fcntl (fd, F_FREESP, &fl) < 0)
+       return -1;
+    }
+
+  return 0;
+}
+#else
+int
+ftruncate (fd, length)
+     int fd;
+     off_t length;
+{
+  return chsize (fd, length);
+}
+#endif
+#endif