Initial revision

1 files changed, 72 insertions, 0 deletions

diff --git a/lib/ftruncate.c b/lib/ftruncate.c
new file mode 100644
index 000000000..17d263d51
--- /dev/null
+++ b/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