+ return len ? xmemdup0(file_name, len) : all_slashes_name(file_name);
+}
+
+/* Returns the file name portion of 'file_name' as a malloc()'d string,
+ * similar to the POSIX basename() function but thread-safe. */
+char *
+base_name(const char *file_name)
+{
+ size_t end, start;
+
+ end = strlen(file_name);
+ while (end > 0 && file_name[end - 1] == '/') {
+ end--;
+ }
+
+ if (!end) {
+ return all_slashes_name(file_name);
+ }
+
+ start = end;
+ while (start > 0 && file_name[start - 1] != '/') {
+ start--;
+ }
+
+ return xmemdup0(file_name + start, end - start);
+}
+
+/* If 'file_name' starts with '/', returns a copy of 'file_name'. Otherwise,
+ * returns an absolute path to 'file_name' considering it relative to 'dir',
+ * which itself must be absolute. 'dir' may be null or the empty string, in
+ * which case the current working directory is used.
+ *
+ * Returns a null pointer if 'dir' is null and getcwd() fails. */
+char *
+abs_file_name(const char *dir, const char *file_name)
+{
+ if (file_name[0] == '/') {
+ return xstrdup(file_name);
+ } else if (dir && dir[0]) {
+ char *separator = dir[strlen(dir) - 1] == '/' ? "" : "/";
+ return xasprintf("%s%s%s", dir, separator, file_name);
+ } else {
+ char *cwd = get_cwd();
+ if (cwd) {
+ char *abs_name = xasprintf("%s/%s", cwd, file_name);
+ free(cwd);
+ return abs_name;
+ } else {
+ return NULL;
+ }
+ }
+}
+
+
+/* Pass a value to this function if it is marked with
+ * __attribute__((warn_unused_result)) and you genuinely want to ignore
+ * its return value. (Note that every scalar type can be implicitly
+ * converted to bool.) */
+void ignore(bool x OVS_UNUSED) { }
+
+/* Returns an appropriate delimiter for inserting just before the 0-based item
+ * 'index' in a list that has 'total' items in it. */
+const char *
+english_list_delimiter(size_t index, size_t total)
+{
+ return (index == 0 ? ""
+ : index < total - 1 ? ", "
+ : total > 2 ? ", and "
+ : " and ");
+}
+
+/* Given a 32 bit word 'n', calculates floor(log_2('n')). This is equivalent
+ * to finding the bit position of the most significant one bit in 'n'. It is
+ * an error to call this function with 'n' == 0. */
+int
+log_2_floor(uint32_t n)
+{
+ assert(n);
+
+#if !defined(UINT_MAX) || !defined(UINT32_MAX)
+#error "Someone screwed up the #includes."
+#elif __GNUC__ >= 4 && UINT_MAX == UINT32_MAX
+ return 31 - __builtin_clz(n);
+#else
+ {
+ int log = 0;
+
+#define BIN_SEARCH_STEP(BITS) \
+ if (n >= (1 << BITS)) { \
+ log += BITS; \
+ n >>= BITS; \
+ }
+ BIN_SEARCH_STEP(16);
+ BIN_SEARCH_STEP(8);
+ BIN_SEARCH_STEP(4);
+ BIN_SEARCH_STEP(2);
+ BIN_SEARCH_STEP(1);
+#undef BIN_SEARCH_STEP
+ return log;
+ }
+#endif
+}
+
+/* Given a 32 bit word 'n', calculates ceil(log_2('n')). It is an error to
+ * call this function with 'n' == 0. */
+int
+log_2_ceil(uint32_t n)
+{
+ return log_2_floor(n) + !IS_POW2(n);
+}
+
+/* Returns the number of trailing 0-bits in 'n', or 32 if 'n' is 0. */
+int
+ctz(uint32_t n)
+{
+ if (!n) {
+ return 32;
+ } else {
+#if !defined(UINT_MAX) || !defined(UINT32_MAX)
+#error "Someone screwed up the #includes."
+#elif __GNUC__ >= 4 && UINT_MAX == UINT32_MAX
+ return __builtin_ctz(n);
+#else
+ unsigned int k;
+ int count = 31;
+
+#define CTZ_STEP(X) \
+ k = n << (X); \
+ if (k) { \
+ count -= X; \
+ n = k; \
+ }
+ CTZ_STEP(16);
+ CTZ_STEP(8);
+ CTZ_STEP(4);
+ CTZ_STEP(2);
+ CTZ_STEP(1);
+#undef CTZ_STEP
+
+ return count;
+#endif
+ }
+}
+
+/* Returns true if the 'n' bytes starting at 'p' are zeros. */
+bool
+is_all_zeros(const uint8_t *p, size_t n)
+{
+ size_t i;
+
+ for (i = 0; i < n; i++) {
+ if (p[i] != 0x00) {
+ return false;
+ }
+ }
+ return true;
+}
+
+/* Returns true if the 'n' bytes starting at 'p' are 0xff. */
+bool
+is_all_ones(const uint8_t *p, size_t n)
+{
+ size_t i;
+
+ for (i = 0; i < n; i++) {
+ if (p[i] != 0xff) {
+ return false;
+ }
+ }
+ return true;
+}
+
+/* Copies 'n_bits' bits starting from bit 'src_ofs' in 'src' to the 'n_bits'
+ * starting from bit 'dst_ofs' in 'dst'. 'src' is 'src_len' bytes long and
+ * 'dst' is 'dst_len' bytes long.
+ *
+ * If you consider all of 'src' to be a single unsigned integer in network byte
+ * order, then bit N is the bit with value 2**N. That is, bit 0 is the bit
+ * with value 1 in src[src_len - 1], bit 1 is the bit with value 2, bit 2 is
+ * the bit with value 4, ..., bit 8 is the bit with value 1 in src[src_len -
+ * 2], and so on. Similarly for 'dst'.
+ *
+ * Required invariants:
+ * src_ofs + n_bits <= src_len * 8
+ * dst_ofs + n_bits <= dst_len * 8
+ * 'src' and 'dst' must not overlap.
+ */
+void
+bitwise_copy(const void *src_, unsigned int src_len, unsigned int src_ofs,
+ void *dst_, unsigned int dst_len, unsigned int dst_ofs,
+ unsigned int n_bits)
+{
+ const uint8_t *src = src_;
+ uint8_t *dst = dst_;
+
+ src += src_len - (src_ofs / 8 + 1);
+ src_ofs %= 8;
+
+ dst += dst_len - (dst_ofs / 8 + 1);
+ dst_ofs %= 8;
+
+ if (src_ofs == 0 && dst_ofs == 0) {
+ unsigned int n_bytes = n_bits / 8;
+ if (n_bytes) {
+ dst -= n_bytes - 1;
+ src -= n_bytes - 1;
+ memcpy(dst, src, n_bytes);
+
+ n_bits %= 8;
+ src--;
+ dst--;
+ }
+ if (n_bits) {
+ uint8_t mask = (1 << n_bits) - 1;
+ *dst = (*dst & ~mask) | (*src & mask);
+ }