Make fixes and improvements

- Fix handling of precision in hex float formatting
- Enhance the cocmd interpreter for system() and popen()
- Manually ran the Lua unit tests, which are now passing
- Let stdio i/o operations happen when file is in error state
- We're now saving and restoring xmm in ftrace out of paranoia

libc/stdio/ftw.h

@@ -0,0 +1,90 @@
+#ifndef COSMOPOLITAN_THIRD_PARTY_MUSL_FTW_H_
+#define COSMOPOLITAN_THIRD_PARTY_MUSL_FTW_H_
+#include "libc/calls/struct/stat.h"
+#if !(__ASSEMBLER__ + __LINKER__ + 0)
+COSMOPOLITAN_C_START_
+
+/**
+ * Type for file.
+ */
+#define FTW_F 1
+
+/**
+ * Type for directory.
+ */
+#define FTW_D 2
+
+/**
+ * Type for directory that cannot be read.
+ */
+#define FTW_DNR 3
+
+/**
+ * Type for stat() failed and not a symbolic link.
+ */
+#define FTW_NS 4
+
+/**
+ * Type for symbolic link when `FTW_PHYS` is in flags.
+ */
+#define FTW_SL 5
+
+/**
+ * Directory and `FTW_DEPTH` in flags.
+ */
+#define FTW_DP 6
+
+/**
+ * Type for broken symbolic link when `FTW_PHYS` is not in flags.
+ */
+#define FTW_SLN 7
+
+/**
+ * Flag to prevent following symbolic links (recommended).
+ * @see nftw() flags
+ */
+#define FTW_PHYS 1
+
+/**
+ * Flag to prevent crossing mount points.
+ * @see nftw() flags
+ */
+#define FTW_MOUNT 2
+
+/**
+ * Unsupported.
+ * @see nftw() flags
+ */
+#define FTW_CHDIR 4
+
+/**
+ * Flag for post-order traversal.
+ *
+ * 1. Will use `FTW_DP` instead of `FTW_D` as type.
+ * 2. Directory callback happens *after* rather than before.
+ *
+ * @see nftw() flags
+ */
+#define FTW_DEPTH 8
+
+struct FTW {
+
+  /**
+   * Byte offset of basename component in `fpath` passed to callback.
+   */
+  int base;
+
+  /**
+   * Depth relative to `dirpath` whose level is zero.
+   */
+  int level;
+};
+
+int ftw(const char *, int (*)(const char *, const struct stat *, int), int);
+int nftw(const char *,
+         int (*)(const char *, const struct stat *, int, struct FTW *), int,
+         int);
+
+COSMOPOLITAN_C_END_
+#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
+#endif /* COSMOPOLITAN_THIRD_PARTY_MUSL_FTW_H_ */