2 * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
29 #include "byte-order.h"
31 #include "ovs-thread.h"
34 VLOG_DEFINE_THIS_MODULE(util);
36 COVERAGE_DEFINE(util_xalloc);
38 /* argv[0] without directory names. */
39 const char *program_name;
41 /* Ordinarily "" but set to "monitor" for a monitor process or "worker" for a
43 const char *subprogram_name = "";
45 /* --version option output. */
46 static char *program_version;
48 /* Buffer used by ovs_strerror(). */
49 DEFINE_PER_THREAD_DATA(struct { char s[128]; }, strerror_buffer, { "" });
52 ovs_assert_failure(const char *where, const char *function,
53 const char *condition)
55 /* Prevent an infinite loop (or stack overflow) in case VLOG_ABORT happens
56 * to trigger an assertion failure of its own. */
57 static int reentry = 0;
61 VLOG_ABORT("%s: assertion %s failed in %s()",
62 where, condition, function);
66 fprintf(stderr, "%s: assertion %s failed in %s()",
67 where, condition, function);
78 ovs_abort(0, "virtual memory exhausted");
82 xcalloc(size_t count, size_t size)
84 void *p = count && size ? calloc(count, size) : malloc(1);
85 COVERAGE_INC(util_xalloc);
95 return xcalloc(1, size);
101 void *p = malloc(size ? size : 1);
102 COVERAGE_INC(util_xalloc);
110 xrealloc(void *p, size_t size)
112 p = realloc(p, size ? size : 1);
113 COVERAGE_INC(util_xalloc);
121 xmemdup(const void *p_, size_t size)
123 void *p = xmalloc(size);
129 xmemdup0(const char *p_, size_t length)
131 char *p = xmalloc(length + 1);
132 memcpy(p, p_, length);
138 xstrdup(const char *s)
140 return xmemdup0(s, strlen(s));
144 xvasprintf(const char *format, va_list args)
150 va_copy(args2, args);
151 needed = vsnprintf(NULL, 0, format, args);
153 s = xmalloc(needed + 1);
155 vsnprintf(s, needed + 1, format, args2);
162 x2nrealloc(void *p, size_t *n, size_t s)
164 *n = *n == 0 ? 1 : 2 * *n;
165 return xrealloc(p, *n * s);
169 xasprintf(const char *format, ...)
174 va_start(args, format);
175 s = xvasprintf(format, args);
181 /* Similar to strlcpy() from OpenBSD, but it never reads more than 'size - 1'
182 * bytes from 'src' and doesn't return anything. */
184 ovs_strlcpy(char *dst, const char *src, size_t size)
187 size_t len = strnlen(src, size - 1);
188 memcpy(dst, src, len);
193 /* Copies 'src' to 'dst'. Reads no more than 'size - 1' bytes from 'src'.
194 * Always null-terminates 'dst' (if 'size' is nonzero), and writes a zero byte
195 * to every otherwise unused byte in 'dst'.
197 * Except for performance, the following call:
198 * ovs_strzcpy(dst, src, size);
199 * is equivalent to these two calls:
200 * memset(dst, '\0', size);
201 * ovs_strlcpy(dst, src, size);
203 * (Thus, ovs_strzcpy() is similar to strncpy() without some of the pitfalls.)
206 ovs_strzcpy(char *dst, const char *src, size_t size)
209 size_t len = strnlen(src, size - 1);
210 memcpy(dst, src, len);
211 memset(dst + len, '\0', size - len);
215 /* Prints 'format' on stderr, formatting it like printf() does. If 'err_no' is
216 * nonzero, then it is formatted with ovs_retval_to_string() and appended to
217 * the message inside parentheses. Then, terminates with abort().
219 * This function is preferred to ovs_fatal() in a situation where it would make
220 * sense for a monitoring process to restart the daemon.
222 * 'format' should not end with a new-line, because this function will add one
225 ovs_abort(int err_no, const char *format, ...)
229 va_start(args, format);
230 ovs_abort_valist(err_no, format, args);
233 /* Same as ovs_abort() except that the arguments are supplied as a va_list. */
235 ovs_abort_valist(int err_no, const char *format, va_list args)
237 ovs_error_valist(err_no, format, args);
241 /* Prints 'format' on stderr, formatting it like printf() does. If 'err_no' is
242 * nonzero, then it is formatted with ovs_retval_to_string() and appended to
243 * the message inside parentheses. Then, terminates with EXIT_FAILURE.
245 * 'format' should not end with a new-line, because this function will add one
248 ovs_fatal(int err_no, const char *format, ...)
252 va_start(args, format);
253 ovs_fatal_valist(err_no, format, args);
256 /* Same as ovs_fatal() except that the arguments are supplied as a va_list. */
258 ovs_fatal_valist(int err_no, const char *format, va_list args)
260 ovs_error_valist(err_no, format, args);
264 /* Prints 'format' on stderr, formatting it like printf() does. If 'err_no' is
265 * nonzero, then it is formatted with ovs_retval_to_string() and appended to
266 * the message inside parentheses.
268 * 'format' should not end with a new-line, because this function will add one
271 ovs_error(int err_no, const char *format, ...)
275 va_start(args, format);
276 ovs_error_valist(err_no, format, args);
280 /* Same as ovs_error() except that the arguments are supplied as a va_list. */
282 ovs_error_valist(int err_no, const char *format, va_list args)
284 int save_errno = errno;
286 if (subprogram_name[0]) {
287 fprintf(stderr, "%s(%s): ", program_name, subprogram_name);
289 fprintf(stderr, "%s: ", program_name);
292 vfprintf(stderr, format, args);
294 fprintf(stderr, " (%s)", ovs_retval_to_string(err_no));
301 /* Many OVS functions return an int which is one of:
304 * - EOF: end of file (not necessarily an error; depends on the function called)
306 * Returns the appropriate human-readable string. The caller must copy the
307 * string if it wants to hold onto it, as the storage may be overwritten on
308 * subsequent function calls.
311 ovs_retval_to_string(int retval)
314 : retval == EOF ? "End of file"
315 : ovs_strerror(retval));
319 ovs_strerror(int error)
321 enum { BUFSIZE = sizeof strerror_buffer_get()->s };
327 buffer = strerror_buffer_get()->s;
329 #if STRERROR_R_CHAR_P
330 /* GNU style strerror_r() might return an immutable static string, or it
331 * might write and return 'buffer', but in either case we can pass the
332 * returned string directly to the caller. */
333 s = strerror_r(error, buffer, BUFSIZE);
334 #else /* strerror_r() returns an int. */
336 if (strerror_r(error, buffer, BUFSIZE)) {
337 /* strerror_r() is only allowed to fail on ERANGE (because the buffer
338 * is too short). We don't check the actual failure reason because
339 * POSIX requires strerror_r() to return the error but old glibc
340 * (before 2.13) returns -1 and sets errno. */
341 snprintf(buffer, BUFSIZE, "Unknown error %d", error);
350 /* Sets global "program_name" and "program_version" variables. Should
351 * be called at the beginning of main() with "argv[0]" as the argument
354 * 'version' should contain the version of the caller's program. If 'version'
355 * is the same as the VERSION #define, the caller is assumed to be part of Open
356 * vSwitch. Otherwise, it is assumed to be an external program linking against
357 * the Open vSwitch libraries.
359 * The 'date' and 'time' arguments should likely be called with
360 * "__DATE__" and "__TIME__" to use the time the binary was built.
361 * Alternatively, the "set_program_name" macro may be called to do this
365 set_program_name__(const char *argv0, const char *version, const char *date,
368 const char *slash = strrchr(argv0, '/');
370 assert_single_threaded();
372 program_name = slash ? slash + 1 : argv0;
374 free(program_version);
376 if (!strcmp(version, VERSION)) {
377 program_version = xasprintf("%s (Open vSwitch) "VERSION"\n"
379 program_name, date, time);
381 program_version = xasprintf("%s %s\n"
382 "Open vSwitch Library "VERSION"\n"
384 program_name, version, date, time);
388 /* Returns a pointer to a string describing the program version. The
389 * caller must not modify or free the returned string.
392 get_program_version(void)
394 return program_version;
397 /* Print the version information for the program. */
399 ovs_print_version(uint8_t min_ofp, uint8_t max_ofp)
401 printf("%s", program_version);
402 if (min_ofp || max_ofp) {
403 printf("OpenFlow versions %#x:%#x\n", min_ofp, max_ofp);
407 /* Writes the 'size' bytes in 'buf' to 'stream' as hex bytes arranged 16 per
408 * line. Numeric offsets are also included, starting at 'ofs' for the first
409 * byte in 'buf'. If 'ascii' is true then the corresponding ASCII characters
410 * are also rendered alongside. */
412 ovs_hex_dump(FILE *stream, const void *buf_, size_t size,
413 uintptr_t ofs, bool ascii)
415 const uint8_t *buf = buf_;
416 const size_t per_line = 16; /* Maximum bytes per line. */
420 size_t start, end, n;
423 /* Number of bytes on this line. */
424 start = ofs % per_line;
426 if (end - start > size)
431 fprintf(stream, "%08jx ", (uintmax_t) ROUND_DOWN(ofs, per_line));
432 for (i = 0; i < start; i++)
433 fprintf(stream, " ");
435 fprintf(stream, "%02hhx%c",
436 buf[i - start], i == per_line / 2 - 1? '-' : ' ');
439 for (; i < per_line; i++)
440 fprintf(stream, " ");
441 fprintf(stream, "|");
442 for (i = 0; i < start; i++)
443 fprintf(stream, " ");
444 for (; i < end; i++) {
445 int c = buf[i - start];
446 putc(c >= 32 && c < 127 ? c : '.', stream);
448 for (; i < per_line; i++)
449 fprintf(stream, " ");
450 fprintf(stream, "|");
452 fprintf(stream, "\n");
461 str_to_int(const char *s, int base, int *i)
464 bool ok = str_to_llong(s, base, &ll);
470 str_to_long(const char *s, int base, long *li)
473 bool ok = str_to_llong(s, base, &ll);
479 str_to_llong(const char *s, int base, long long *x)
481 int save_errno = errno;
484 *x = strtoll(s, &tail, base);
485 if (errno == EINVAL || errno == ERANGE || tail == s || *tail != '\0') {
496 str_to_uint(const char *s, int base, unsigned int *u)
498 return str_to_int(s, base, (int *) u);
502 str_to_ulong(const char *s, int base, unsigned long *ul)
504 return str_to_long(s, base, (long *) ul);
508 str_to_ullong(const char *s, int base, unsigned long long *ull)
510 return str_to_llong(s, base, (long long *) ull);
513 /* Converts floating-point string 's' into a double. If successful, stores
514 * the double in '*d' and returns true; on failure, stores 0 in '*d' and
517 * Underflow (e.g. "1e-9999") is not considered an error, but overflow
518 * (e.g. "1e9999)" is. */
520 str_to_double(const char *s, double *d)
522 int save_errno = errno;
525 *d = strtod(s, &tail);
526 if (errno == EINVAL || (errno == ERANGE && *d != 0)
527 || tail == s || *tail != '\0') {
537 /* Returns the value of 'c' as a hexadecimal digit. */
542 case '0': case '1': case '2': case '3': case '4':
543 case '5': case '6': case '7': case '8': case '9':
569 /* Returns the integer value of the 'n' hexadecimal digits starting at 's', or
570 * UINT_MAX if one of those "digits" is not really a hex digit. If 'ok' is
571 * nonnull, '*ok' is set to true if the conversion succeeds or to false if a
572 * non-hex digit is detected. */
574 hexits_value(const char *s, size_t n, bool *ok)
580 for (i = 0; i < n; i++) {
581 int hexit = hexit_value(s[i]);
588 value = (value << 4) + hexit;
596 /* Returns the current working directory as a malloc()'d string, or a null
597 * pointer if the current working directory cannot be determined. */
604 /* Get maximum path length or at least a reasonable estimate. */
605 path_max = pathconf(".", _PC_PATH_MAX);
606 size = (path_max < 0 ? 1024
607 : path_max > 10240 ? 10240
610 /* Get current working directory. */
612 char *buf = xmalloc(size);
613 if (getcwd(buf, size)) {
614 return xrealloc(buf, strlen(buf) + 1);
618 if (error != ERANGE) {
619 VLOG_WARN("getcwd failed (%s)", ovs_strerror(error));
628 all_slashes_name(const char *s)
630 return xstrdup(s[0] == '/' && s[1] == '/' && s[2] != '/' ? "//"
635 /* Returns the directory name portion of 'file_name' as a malloc()'d string,
636 * similar to the POSIX dirname() function but thread-safe. */
638 dir_name(const char *file_name)
640 size_t len = strlen(file_name);
641 while (len > 0 && file_name[len - 1] == '/') {
644 while (len > 0 && file_name[len - 1] != '/') {
647 while (len > 0 && file_name[len - 1] == '/') {
650 return len ? xmemdup0(file_name, len) : all_slashes_name(file_name);
653 /* Returns the file name portion of 'file_name' as a malloc()'d string,
654 * similar to the POSIX basename() function but thread-safe. */
656 base_name(const char *file_name)
660 end = strlen(file_name);
661 while (end > 0 && file_name[end - 1] == '/') {
666 return all_slashes_name(file_name);
670 while (start > 0 && file_name[start - 1] != '/') {
674 return xmemdup0(file_name + start, end - start);
677 /* If 'file_name' starts with '/', returns a copy of 'file_name'. Otherwise,
678 * returns an absolute path to 'file_name' considering it relative to 'dir',
679 * which itself must be absolute. 'dir' may be null or the empty string, in
680 * which case the current working directory is used.
682 * Returns a null pointer if 'dir' is null and getcwd() fails. */
684 abs_file_name(const char *dir, const char *file_name)
686 if (file_name[0] == '/') {
687 return xstrdup(file_name);
688 } else if (dir && dir[0]) {
689 char *separator = dir[strlen(dir) - 1] == '/' ? "" : "/";
690 return xasprintf("%s%s%s", dir, separator, file_name);
692 char *cwd = get_cwd();
694 char *abs_name = xasprintf("%s/%s", cwd, file_name);
703 /* Like readlink(), but returns the link name as a null-terminated string in
704 * allocated memory that the caller must eventually free (with free()).
705 * Returns NULL on error, in which case errno is set appropriately. */
707 xreadlink(const char *filename)
711 for (size = 64; ; size *= 2) {
712 char *buf = xmalloc(size);
713 ssize_t retval = readlink(filename, buf, size);
716 if (retval >= 0 && retval < size) {
729 /* Returns a version of 'filename' with symlinks in the final component
730 * dereferenced. This differs from realpath() in that:
732 * - 'filename' need not exist.
734 * - If 'filename' does exist as a symlink, its referent need not exist.
736 * - Only symlinks in the final component of 'filename' are dereferenced.
738 * The caller must eventually free the returned string (with free()). */
740 follow_symlinks(const char *filename)
746 fn = xstrdup(filename);
747 for (i = 0; i < 10; i++) {
751 if (lstat(fn, &s) != 0 || !S_ISLNK(s.st_mode)) {
755 linkname = xreadlink(fn);
757 VLOG_WARN("%s: readlink failed (%s)",
758 filename, ovs_strerror(errno));
762 if (linkname[0] == '/') {
763 /* Target of symlink is absolute so use it raw. */
766 /* Target of symlink is relative so add to 'fn''s directory. */
767 char *dir = dir_name(fn);
769 if (!strcmp(dir, ".")) {
772 char *separator = dir[strlen(dir) - 1] == '/' ? "" : "/";
773 next_fn = xasprintf("%s%s%s", dir, separator, linkname);
784 VLOG_WARN("%s: too many levels of symlinks", filename);
786 return xstrdup(filename);
789 /* Pass a value to this function if it is marked with
790 * __attribute__((warn_unused_result)) and you genuinely want to ignore
791 * its return value. (Note that every scalar type can be implicitly
792 * converted to bool.) */
793 void ignore(bool x OVS_UNUSED) { }
795 /* Returns an appropriate delimiter for inserting just before the 0-based item
796 * 'index' in a list that has 'total' items in it. */
798 english_list_delimiter(size_t index, size_t total)
800 return (index == 0 ? ""
801 : index < total - 1 ? ", "
802 : total > 2 ? ", and "
806 /* Given a 32 bit word 'n', calculates floor(log_2('n')). This is equivalent
807 * to finding the bit position of the most significant one bit in 'n'. It is
808 * an error to call this function with 'n' == 0. */
810 log_2_floor(uint32_t n)
814 #if !defined(UINT_MAX) || !defined(UINT32_MAX)
815 #error "Someone screwed up the #includes."
816 #elif __GNUC__ >= 4 && UINT_MAX == UINT32_MAX
817 return 31 - __builtin_clz(n);
822 #define BIN_SEARCH_STEP(BITS) \
823 if (n >= (1 << BITS)) { \
832 #undef BIN_SEARCH_STEP
838 /* Given a 32 bit word 'n', calculates ceil(log_2('n')). It is an error to
839 * call this function with 'n' == 0. */
841 log_2_ceil(uint32_t n)
843 return log_2_floor(n) + !is_pow2(n);
846 /* Returns the number of trailing 0-bits in 'n'. Undefined if 'n' == 0. */
847 #if !defined(UINT_MAX) || !defined(UINT32_MAX)
848 #error "Someone screwed up the #includes."
849 #elif __GNUC__ >= 4 && UINT_MAX == UINT32_MAX
850 /* Defined inline in util.h. */
858 #define CTZ_STEP(X) \
875 /* Returns the number of 1-bits in 'x', between 0 and 32 inclusive. */
879 /* In my testing, this implementation is over twice as fast as any other
880 * portable implementation that I tried, including GCC 4.4
881 * __builtin_popcount(), although nonportable asm("popcnt") was over 50%
884 ((((X) & (1 << 0)) != 0) + \
885 (((X) & (1 << 1)) != 0) + \
886 (((X) & (1 << 2)) != 0) + \
887 (((X) & (1 << 3)) != 0) + \
888 (((X) & (1 << 4)) != 0) + \
889 (((X) & (1 << 5)) != 0) + \
890 (((X) & (1 << 6)) != 0) + \
891 (((X) & (1 << 7)) != 0))
892 #define INIT2(X) INIT1(X), INIT1((X) + 1)
893 #define INIT4(X) INIT2(X), INIT2((X) + 2)
894 #define INIT8(X) INIT4(X), INIT4((X) + 4)
895 #define INIT16(X) INIT8(X), INIT8((X) + 8)
896 #define INIT32(X) INIT16(X), INIT16((X) + 16)
897 #define INIT64(X) INIT32(X), INIT32((X) + 32)
899 static const uint8_t popcount8[256] = {
900 INIT64(0), INIT64(64), INIT64(128), INIT64(192)
903 return (popcount8[x & 0xff] +
904 popcount8[(x >> 8) & 0xff] +
905 popcount8[(x >> 16) & 0xff] +
909 /* Returns true if the 'n' bytes starting at 'p' are zeros. */
911 is_all_zeros(const uint8_t *p, size_t n)
915 for (i = 0; i < n; i++) {
923 /* Returns true if the 'n' bytes starting at 'p' are 0xff. */
925 is_all_ones(const uint8_t *p, size_t n)
929 for (i = 0; i < n; i++) {
937 /* Copies 'n_bits' bits starting from bit 'src_ofs' in 'src' to the 'n_bits'
938 * starting from bit 'dst_ofs' in 'dst'. 'src' is 'src_len' bytes long and
939 * 'dst' is 'dst_len' bytes long.
941 * If you consider all of 'src' to be a single unsigned integer in network byte
942 * order, then bit N is the bit with value 2**N. That is, bit 0 is the bit
943 * with value 1 in src[src_len - 1], bit 1 is the bit with value 2, bit 2 is
944 * the bit with value 4, ..., bit 8 is the bit with value 1 in src[src_len -
945 * 2], and so on. Similarly for 'dst'.
947 * Required invariants:
948 * src_ofs + n_bits <= src_len * 8
949 * dst_ofs + n_bits <= dst_len * 8
950 * 'src' and 'dst' must not overlap.
953 bitwise_copy(const void *src_, unsigned int src_len, unsigned int src_ofs,
954 void *dst_, unsigned int dst_len, unsigned int dst_ofs,
957 const uint8_t *src = src_;
960 src += src_len - (src_ofs / 8 + 1);
963 dst += dst_len - (dst_ofs / 8 + 1);
966 if (src_ofs == 0 && dst_ofs == 0) {
967 unsigned int n_bytes = n_bits / 8;
971 memcpy(dst, src, n_bytes);
978 uint8_t mask = (1 << n_bits) - 1;
979 *dst = (*dst & ~mask) | (*src & mask);
983 unsigned int max_copy = 8 - MAX(src_ofs, dst_ofs);
984 unsigned int chunk = MIN(n_bits, max_copy);
985 uint8_t mask = ((1 << chunk) - 1) << dst_ofs;
988 *dst |= ((*src >> src_ofs) << dst_ofs) & mask;
1005 /* Zeros the 'n_bits' bits starting from bit 'dst_ofs' in 'dst'. 'dst' is
1006 * 'dst_len' bytes long.
1008 * If you consider all of 'dst' to be a single unsigned integer in network byte
1009 * order, then bit N is the bit with value 2**N. That is, bit 0 is the bit
1010 * with value 1 in dst[dst_len - 1], bit 1 is the bit with value 2, bit 2 is
1011 * the bit with value 4, ..., bit 8 is the bit with value 1 in dst[dst_len -
1014 * Required invariant:
1015 * dst_ofs + n_bits <= dst_len * 8
1018 bitwise_zero(void *dst_, unsigned int dst_len, unsigned dst_ofs,
1019 unsigned int n_bits)
1021 uint8_t *dst = dst_;
1027 dst += dst_len - (dst_ofs / 8 + 1);
1031 unsigned int chunk = MIN(n_bits, 8 - dst_ofs);
1033 *dst &= ~(((1 << chunk) - 1) << dst_ofs);
1043 while (n_bits >= 8) {
1049 *dst &= ~((1 << n_bits) - 1);
1053 /* Sets to 1 all of the 'n_bits' bits starting from bit 'dst_ofs' in 'dst'.
1054 * 'dst' is 'dst_len' bytes long.
1056 * If you consider all of 'dst' to be a single unsigned integer in network byte
1057 * order, then bit N is the bit with value 2**N. That is, bit 0 is the bit
1058 * with value 1 in dst[dst_len - 1], bit 1 is the bit with value 2, bit 2 is
1059 * the bit with value 4, ..., bit 8 is the bit with value 1 in dst[dst_len -
1062 * Required invariant:
1063 * dst_ofs + n_bits <= dst_len * 8
1066 bitwise_one(void *dst_, unsigned int dst_len, unsigned dst_ofs,
1067 unsigned int n_bits)
1069 uint8_t *dst = dst_;
1075 dst += dst_len - (dst_ofs / 8 + 1);
1079 unsigned int chunk = MIN(n_bits, 8 - dst_ofs);
1081 *dst |= ((1 << chunk) - 1) << dst_ofs;
1091 while (n_bits >= 8) {
1097 *dst |= (1 << n_bits) - 1;
1101 /* Scans the 'n_bits' bits starting from bit 'dst_ofs' in 'dst' for 1-bits.
1102 * Returns false if any 1-bits are found, otherwise true. 'dst' is 'dst_len'
1105 * If you consider all of 'dst' to be a single unsigned integer in network byte
1106 * order, then bit N is the bit with value 2**N. That is, bit 0 is the bit
1107 * with value 1 in dst[dst_len - 1], bit 1 is the bit with value 2, bit 2 is
1108 * the bit with value 4, ..., bit 8 is the bit with value 1 in dst[dst_len -
1111 * Required invariant:
1112 * dst_ofs + n_bits <= dst_len * 8
1115 bitwise_is_all_zeros(const void *p_, unsigned int len, unsigned int ofs,
1116 unsigned int n_bits)
1118 const uint8_t *p = p_;
1124 p += len - (ofs / 8 + 1);
1128 unsigned int chunk = MIN(n_bits, 8 - ofs);
1130 if (*p & (((1 << chunk) - 1) << ofs)) {
1142 while (n_bits >= 8) {
1150 if (n_bits && *p & ((1 << n_bits) - 1)) {
1157 /* Copies the 'n_bits' low-order bits of 'value' into the 'n_bits' bits
1158 * starting at bit 'dst_ofs' in 'dst', which is 'dst_len' bytes long.
1160 * If you consider all of 'dst' to be a single unsigned integer in network byte
1161 * order, then bit N is the bit with value 2**N. That is, bit 0 is the bit
1162 * with value 1 in dst[dst_len - 1], bit 1 is the bit with value 2, bit 2 is
1163 * the bit with value 4, ..., bit 8 is the bit with value 1 in dst[dst_len -
1166 * Required invariants:
1167 * dst_ofs + n_bits <= dst_len * 8
1171 bitwise_put(uint64_t value,
1172 void *dst, unsigned int dst_len, unsigned int dst_ofs,
1173 unsigned int n_bits)
1175 ovs_be64 n_value = htonll(value);
1176 bitwise_copy(&n_value, sizeof n_value, 0,
1177 dst, dst_len, dst_ofs,
1181 /* Returns the value of the 'n_bits' bits starting at bit 'src_ofs' in 'src',
1182 * which is 'src_len' bytes long.
1184 * If you consider all of 'src' to be a single unsigned integer in network byte
1185 * order, then bit N is the bit with value 2**N. That is, bit 0 is the bit
1186 * with value 1 in src[src_len - 1], bit 1 is the bit with value 2, bit 2 is
1187 * the bit with value 4, ..., bit 8 is the bit with value 1 in src[src_len -
1190 * Required invariants:
1191 * src_ofs + n_bits <= src_len * 8
1195 bitwise_get(const void *src, unsigned int src_len,
1196 unsigned int src_ofs, unsigned int n_bits)
1198 ovs_be64 value = htonll(0);
1200 bitwise_copy(src, src_len, src_ofs,
1201 &value, sizeof value, 0,
1203 return ntohll(value);