Implement truncate.

diff --git a/toys/truncate.c b/toys/truncate.c
new file mode 100644 (file)
index 0000000..dccd321
--- /dev/null
+++ b/toys/truncate.c
@@ -0,0 +1,47 @@
+/* vi: set sw=4 ts=4:
+ *
+ * truncate.c - set file length, extending sparsely if necessary
+ *
+ * Copyright 2011 Rob Landley <rob@landley.net>
+ *
+ * Not in SUSv4
+
+USE_TRUNCATE(NEWTOY(truncate, "<1s#|c", TOYFLAG_BIN))
+
+config TRUNCATE
+       bool "truncate"
+       default y
+       help
+         usage: truncate [-c] -s file...
+         Set length of file(s), extending sparsely if necessary.
+
+         -c    Don't create file if it doesn't exist.
+         -s    New size
+*/
+
+#include "toys.h"
+
+DEFINE_GLOBALS(
+       long size;
+)
+
+#define TT this.truncate
+
+static void do_truncate(int fd, char *name)
+{
+       if (fd<0) return;
+       if (ftruncate(fd, TT.size)) {
+               perror_msg("failed to set '%s' to '%ld'", name, TT.size);
+               toys.exitval = EXIT_FAILURE;
+       }
+}
+
+void truncate_main(void)
+{
+       int cr = !(toys.optflags&1);
+
+       // Create files with mask rwrwrw.
+       // Nonexistent files are only an error if we're supposed to create them.
+       loopfiles_rw(toys.optargs, O_WRONLY|(cr ? O_CREAT : 0), 0666, cr,
+               do_truncate);
+}