X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Futil.c;h=1751c6f418f84e3736a47b25956542f2c7cd8d06;hb=8a8cd0acd09763f5edca6506bb286447c5776778;hp=39ca3b54b73029bb807a50ff73f0ac11bfd29615;hpb=d98e60075528c3065ad453f7add4b30f22edcde3;p=sliver-openvswitch.git diff --git a/lib/util.c b/lib/util.c index 39ca3b54b..1751c6f41 100644 --- a/lib/util.c +++ b/lib/util.c @@ -1,5 +1,5 @@ /* - * Copyright (c) 2008, 2009, 2010 Nicira Networks. + * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -17,22 +17,65 @@ #include #include "util.h" #include +#include +#include #include +#include #include #include #include +#include #include +#include "byte-order.h" #include "coverage.h" +#include "ovs-thread.h" #include "vlog.h" VLOG_DEFINE_THIS_MODULE(util); +COVERAGE_DEFINE(util_xalloc); + +/* argv[0] without directory names. */ const char *program_name; +/* Name for the currently running thread or process, for log messages, process + * listings, and debuggers. */ +DEFINE_PER_THREAD_MALLOCED_DATA(char *, subprogram_name); + +/* --version option output. */ +static char *program_version; + +/* Buffer used by ovs_strerror(). */ +DEFINE_PER_THREAD_DATA(struct { char s[128]; }, strerror_buffer, { "" }); + +void +ovs_assert_failure(const char *where, const char *function, + const char *condition) +{ + /* Prevent an infinite loop (or stack overflow) in case VLOG_ABORT happens + * to trigger an assertion failure of its own. */ + static int reentry = 0; + + switch (reentry++) { + case 0: + VLOG_ABORT("%s: assertion %s failed in %s()", + where, condition, function); + NOT_REACHED(); + + case 1: + fprintf(stderr, "%s: assertion %s failed in %s()", + where, condition, function); + abort(); + + default: + abort(); + } +} + void out_of_memory(void) { - ovs_fatal(0, "virtual memory exhausted"); + ovs_abort(0, "virtual memory exhausted"); } void * @@ -135,68 +178,252 @@ xasprintf(const char *format, ...) return s; } +/* Similar to strlcpy() from OpenBSD, but it never reads more than 'size - 1' + * bytes from 'src' and doesn't return anything. */ void ovs_strlcpy(char *dst, const char *src, size_t size) { if (size > 0) { - size_t n = strlen(src); - size_t n_copy = MIN(n, size - 1); - memcpy(dst, src, n_copy); - dst[n_copy] = '\0'; + size_t len = strnlen(src, size - 1); + memcpy(dst, src, len); + dst[len] = '\0'; + } +} + +/* Copies 'src' to 'dst'. Reads no more than 'size - 1' bytes from 'src'. + * Always null-terminates 'dst' (if 'size' is nonzero), and writes a zero byte + * to every otherwise unused byte in 'dst'. + * + * Except for performance, the following call: + * ovs_strzcpy(dst, src, size); + * is equivalent to these two calls: + * memset(dst, '\0', size); + * ovs_strlcpy(dst, src, size); + * + * (Thus, ovs_strzcpy() is similar to strncpy() without some of the pitfalls.) + */ +void +ovs_strzcpy(char *dst, const char *src, size_t size) +{ + if (size > 0) { + size_t len = strnlen(src, size - 1); + memcpy(dst, src, len); + memset(dst + len, '\0', size - len); } } +/* Prints 'format' on stderr, formatting it like printf() does. If 'err_no' is + * nonzero, then it is formatted with ovs_retval_to_string() and appended to + * the message inside parentheses. Then, terminates with abort(). + * + * This function is preferred to ovs_fatal() in a situation where it would make + * sense for a monitoring process to restart the daemon. + * + * 'format' should not end with a new-line, because this function will add one + * itself. */ +void +ovs_abort(int err_no, const char *format, ...) +{ + va_list args; + + va_start(args, format); + ovs_abort_valist(err_no, format, args); +} + +/* Same as ovs_abort() except that the arguments are supplied as a va_list. */ +void +ovs_abort_valist(int err_no, const char *format, va_list args) +{ + ovs_error_valist(err_no, format, args); + abort(); +} + +/* Prints 'format' on stderr, formatting it like printf() does. If 'err_no' is + * nonzero, then it is formatted with ovs_retval_to_string() and appended to + * the message inside parentheses. Then, terminates with EXIT_FAILURE. + * + * 'format' should not end with a new-line, because this function will add one + * itself. */ void ovs_fatal(int err_no, const char *format, ...) { va_list args; - fprintf(stderr, "%s: ", program_name); va_start(args, format); - vfprintf(stderr, format, args); - va_end(args); - if (err_no != 0) - fprintf(stderr, " (%s)", - err_no == EOF ? "end of file" : strerror(err_no)); - putc('\n', stderr); + ovs_fatal_valist(err_no, format, args); +} +/* Same as ovs_fatal() except that the arguments are supplied as a va_list. */ +void +ovs_fatal_valist(int err_no, const char *format, va_list args) +{ + ovs_error_valist(err_no, format, args); exit(EXIT_FAILURE); } +/* Prints 'format' on stderr, formatting it like printf() does. If 'err_no' is + * nonzero, then it is formatted with ovs_retval_to_string() and appended to + * the message inside parentheses. + * + * 'format' should not end with a new-line, because this function will add one + * itself. */ void ovs_error(int err_no, const char *format, ...) { - int save_errno = errno; va_list args; - fprintf(stderr, "%s: ", program_name); va_start(args, format); - vfprintf(stderr, format, args); + ovs_error_valist(err_no, format, args); va_end(args); +} + +/* Same as ovs_error() except that the arguments are supplied as a va_list. */ +void +ovs_error_valist(int err_no, const char *format, va_list args) +{ + const char *subprogram_name = get_subprogram_name(); + int save_errno = errno; + + if (subprogram_name[0]) { + fprintf(stderr, "%s(%s): ", program_name, subprogram_name); + } else { + fprintf(stderr, "%s: ", program_name); + } + + vfprintf(stderr, format, args); if (err_no != 0) { - fprintf(stderr, " (%s)", - err_no == EOF ? "end of file" : strerror(err_no)); + fprintf(stderr, " (%s)", ovs_retval_to_string(err_no)); } putc('\n', stderr); errno = save_errno; } -/* Sets program_name based on 'argv0'. Should be called at the beginning of - * main(), as "set_program_name(argv[0]);". */ -void set_program_name(const char *argv0) +/* Many OVS functions return an int which is one of: + * - 0: no error yet + * - >0: errno value + * - EOF: end of file (not necessarily an error; depends on the function called) + * + * Returns the appropriate human-readable string. The caller must copy the + * string if it wants to hold onto it, as the storage may be overwritten on + * subsequent function calls. + */ +const char * +ovs_retval_to_string(int retval) +{ + return (!retval ? "" + : retval == EOF ? "End of file" + : ovs_strerror(retval)); +} + +const char * +ovs_strerror(int error) +{ + enum { BUFSIZE = sizeof strerror_buffer_get()->s }; + int save_errno; + char *buffer; + char *s; + + save_errno = errno; + buffer = strerror_buffer_get()->s; + +#if STRERROR_R_CHAR_P + /* GNU style strerror_r() might return an immutable static string, or it + * might write and return 'buffer', but in either case we can pass the + * returned string directly to the caller. */ + s = strerror_r(error, buffer, BUFSIZE); +#else /* strerror_r() returns an int. */ + s = buffer; + if (strerror_r(error, buffer, BUFSIZE)) { + /* strerror_r() is only allowed to fail on ERANGE (because the buffer + * is too short). We don't check the actual failure reason because + * POSIX requires strerror_r() to return the error but old glibc + * (before 2.13) returns -1 and sets errno. */ + snprintf(buffer, BUFSIZE, "Unknown error %d", error); + } +#endif + + errno = save_errno; + + return s; +} + +/* Sets global "program_name" and "program_version" variables. Should + * be called at the beginning of main() with "argv[0]" as the argument + * to 'argv0'. + * + * 'version' should contain the version of the caller's program. If 'version' + * is the same as the VERSION #define, the caller is assumed to be part of Open + * vSwitch. Otherwise, it is assumed to be an external program linking against + * the Open vSwitch libraries. + * + * The 'date' and 'time' arguments should likely be called with + * "__DATE__" and "__TIME__" to use the time the binary was built. + * Alternatively, the "set_program_name" macro may be called to do this + * automatically. + */ +void +set_program_name__(const char *argv0, const char *version, const char *date, + const char *time) { const char *slash = strrchr(argv0, '/'); + + assert_single_threaded(); + program_name = slash ? slash + 1 : argv0; + + free(program_version); + + if (!strcmp(version, VERSION)) { + program_version = xasprintf("%s (Open vSwitch) "VERSION"\n" + "Compiled %s %s\n", + program_name, date, time); + } else { + program_version = xasprintf("%s %s\n" + "Open vSwitch Library "VERSION"\n" + "Compiled %s %s\n", + program_name, version, date, time); + } +} + +/* Returns the name of the currently running thread or process. */ +const char * +get_subprogram_name(void) +{ + const char *name = subprogram_name_get(); + return name ? name : ""; +} + +/* Sets 'name' as the name of the currently running thread or process. (This + * appears in log messages and may also be visible in system process listings + * and debuggers.) */ +void +set_subprogram_name(const char *name) +{ + free(subprogram_name_set(xstrdup(name))); +#if HAVE_GLIBC_PTHREAD_SETNAME_NP + pthread_setname_np(pthread_self(), name); +#elif HAVE_NETBSD_PTHREAD_SETNAME_NP + pthread_setname_np(pthread_self(), "%s", name); +#elif HAVE_PTHREAD_SET_NAME_NP + pthread_set_name_np(pthread_self(), name); +#endif +} + +/* Returns a pointer to a string describing the program version. The + * caller must not modify or free the returned string. + */ +const char * +get_program_version(void) +{ + return program_version; } /* Print the version information for the program. */ void -ovs_print_version(char *date, char *time, - uint8_t min_ofp, uint8_t max_ofp) +ovs_print_version(uint8_t min_ofp, uint8_t max_ofp) { - printf("%s (Open vSwitch) "VERSION BUILDNR"\n", program_name); - printf("Compiled %s %s\n", date, time); + printf("%s", program_version); if (min_ofp || max_ofp) { printf("OpenFlow versions %#x:%#x\n", min_ofp, max_ofp); } @@ -358,9 +585,37 @@ hexit_value(int c) case 'f': case 'F': return 0xf; + + default: + return -1; } +} + +/* Returns the integer value of the 'n' hexadecimal digits starting at 's', or + * UINT_MAX if one of those "digits" is not really a hex digit. If 'ok' is + * nonnull, '*ok' is set to true if the conversion succeeds or to false if a + * non-hex digit is detected. */ +unsigned int +hexits_value(const char *s, size_t n, bool *ok) +{ + unsigned int value; + size_t i; - NOT_REACHED(); + value = 0; + for (i = 0; i < n; i++) { + int hexit = hexit_value(s[i]); + if (hexit < 0) { + if (ok) { + *ok = false; + } + return UINT_MAX; + } + value = (value << 4) + hexit; + } + if (ok) { + *ok = true; + } + return value; } /* Returns the current working directory as a malloc()'d string, or a null @@ -386,7 +641,7 @@ get_cwd(void) int error = errno; free(buf); if (error != ERANGE) { - VLOG_WARN("getcwd failed (%s)", strerror(error)); + VLOG_WARN("getcwd failed (%s)", ovs_strerror(error)); return NULL; } size *= 2; @@ -394,6 +649,14 @@ get_cwd(void) } } +static char * +all_slashes_name(const char *s) +{ + return xstrdup(s[0] == '/' && s[1] == '/' && s[2] != '/' ? "//" + : s[0] == '/' ? "/" + : "."); +} + /* Returns the directory name portion of 'file_name' as a malloc()'d string, * similar to the POSIX dirname() function but thread-safe. */ char * @@ -409,15 +672,31 @@ dir_name(const char *file_name) while (len > 0 && file_name[len - 1] == '/') { len--; } - if (!len) { - return xstrdup((file_name[0] == '/' - && file_name[1] == '/' - && file_name[2] != '/') ? "//" - : file_name[0] == '/' ? "/" - : "."); - } else { - return xmemdup0(file_name, len); + 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, @@ -446,9 +725,505 @@ abs_file_name(const char *dir, const char *file_name) } } +/* Like readlink(), but returns the link name as a null-terminated string in + * allocated memory that the caller must eventually free (with free()). + * Returns NULL on error, in which case errno is set appropriately. */ +char * +xreadlink(const char *filename) +{ + size_t size; + + for (size = 64; ; size *= 2) { + char *buf = xmalloc(size); + ssize_t retval = readlink(filename, buf, size); + int error = errno; + + if (retval >= 0 && retval < size) { + buf[retval] = '\0'; + return buf; + } + + free(buf); + if (retval < 0) { + errno = error; + return NULL; + } + } +} + +/* Returns a version of 'filename' with symlinks in the final component + * dereferenced. This differs from realpath() in that: + * + * - 'filename' need not exist. + * + * - If 'filename' does exist as a symlink, its referent need not exist. + * + * - Only symlinks in the final component of 'filename' are dereferenced. + * + * The caller must eventually free the returned string (with free()). */ +char * +follow_symlinks(const char *filename) +{ + struct stat s; + char *fn; + int i; + + fn = xstrdup(filename); + for (i = 0; i < 10; i++) { + char *linkname; + char *next_fn; + + if (lstat(fn, &s) != 0 || !S_ISLNK(s.st_mode)) { + return fn; + } + + linkname = xreadlink(fn); + if (!linkname) { + VLOG_WARN("%s: readlink failed (%s)", + filename, ovs_strerror(errno)); + return fn; + } + + if (linkname[0] == '/') { + /* Target of symlink is absolute so use it raw. */ + next_fn = linkname; + } else { + /* Target of symlink is relative so add to 'fn''s directory. */ + char *dir = dir_name(fn); + + if (!strcmp(dir, ".")) { + next_fn = linkname; + } else { + char *separator = dir[strlen(dir) - 1] == '/' ? "" : "/"; + next_fn = xasprintf("%s%s%s", dir, separator, linkname); + free(linkname); + } + + free(dir); + } + + free(fn); + fn = next_fn; + } + + VLOG_WARN("%s: too many levels of symlinks", filename); + free(fn); + return xstrdup(filename); +} /* 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) +{ + ovs_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'. Undefined if 'n' == 0. */ +#if !defined(UINT_MAX) || !defined(UINT32_MAX) +#error "Someone screwed up the #includes." +#elif __GNUC__ >= 4 && UINT_MAX == UINT32_MAX +/* Defined inline in util.h. */ +#else +static int +raw_ctz(uint32_t n) +{ + 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 the number of 1-bits in 'x', between 0 and 32 inclusive. */ +unsigned int +popcount(uint32_t x) +{ + /* In my testing, this implementation is over twice as fast as any other + * portable implementation that I tried, including GCC 4.4 + * __builtin_popcount(), although nonportable asm("popcnt") was over 50% + * faster. */ +#define INIT1(X) \ + ((((X) & (1 << 0)) != 0) + \ + (((X) & (1 << 1)) != 0) + \ + (((X) & (1 << 2)) != 0) + \ + (((X) & (1 << 3)) != 0) + \ + (((X) & (1 << 4)) != 0) + \ + (((X) & (1 << 5)) != 0) + \ + (((X) & (1 << 6)) != 0) + \ + (((X) & (1 << 7)) != 0)) +#define INIT2(X) INIT1(X), INIT1((X) + 1) +#define INIT4(X) INIT2(X), INIT2((X) + 2) +#define INIT8(X) INIT4(X), INIT4((X) + 4) +#define INIT16(X) INIT8(X), INIT8((X) + 8) +#define INIT32(X) INIT16(X), INIT16((X) + 16) +#define INIT64(X) INIT32(X), INIT32((X) + 32) + + static const uint8_t popcount8[256] = { + INIT64(0), INIT64(64), INIT64(128), INIT64(192) + }; + + return (popcount8[x & 0xff] + + popcount8[(x >> 8) & 0xff] + + popcount8[(x >> 16) & 0xff] + + popcount8[x >> 24]); +} + +/* 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); + } + } else { + while (n_bits > 0) { + unsigned int max_copy = 8 - MAX(src_ofs, dst_ofs); + unsigned int chunk = MIN(n_bits, max_copy); + uint8_t mask = ((1 << chunk) - 1) << dst_ofs; + + *dst &= ~mask; + *dst |= ((*src >> src_ofs) << dst_ofs) & mask; + + src_ofs += chunk; + if (src_ofs == 8) { + src--; + src_ofs = 0; + } + dst_ofs += chunk; + if (dst_ofs == 8) { + dst--; + dst_ofs = 0; + } + n_bits -= chunk; + } + } +} + +/* Zeros the 'n_bits' bits starting from bit 'dst_ofs' in 'dst'. 'dst' is + * 'dst_len' bytes long. + * + * If you consider all of 'dst' 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 dst[dst_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 dst[dst_len - + * 2], and so on. + * + * Required invariant: + * dst_ofs + n_bits <= dst_len * 8 + */ +void +bitwise_zero(void *dst_, unsigned int dst_len, unsigned dst_ofs, + unsigned int n_bits) +{ + uint8_t *dst = dst_; + + if (!n_bits) { + return; + } + + dst += dst_len - (dst_ofs / 8 + 1); + dst_ofs %= 8; + + if (dst_ofs) { + unsigned int chunk = MIN(n_bits, 8 - dst_ofs); + + *dst &= ~(((1 << chunk) - 1) << dst_ofs); + + n_bits -= chunk; + if (!n_bits) { + return; + } + + dst--; + } + + while (n_bits >= 8) { + *dst-- = 0; + n_bits -= 8; + } + + if (n_bits) { + *dst &= ~((1 << n_bits) - 1); + } +} + +/* Sets to 1 all of the 'n_bits' bits starting from bit 'dst_ofs' in 'dst'. + * 'dst' is 'dst_len' bytes long. + * + * If you consider all of 'dst' 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 dst[dst_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 dst[dst_len - + * 2], and so on. + * + * Required invariant: + * dst_ofs + n_bits <= dst_len * 8 + */ +void +bitwise_one(void *dst_, unsigned int dst_len, unsigned dst_ofs, + unsigned int n_bits) +{ + uint8_t *dst = dst_; + + if (!n_bits) { + return; + } + + dst += dst_len - (dst_ofs / 8 + 1); + dst_ofs %= 8; + + if (dst_ofs) { + unsigned int chunk = MIN(n_bits, 8 - dst_ofs); + + *dst |= ((1 << chunk) - 1) << dst_ofs; + + n_bits -= chunk; + if (!n_bits) { + return; + } + + dst--; + } + + while (n_bits >= 8) { + *dst-- = 0xff; + n_bits -= 8; + } + + if (n_bits) { + *dst |= (1 << n_bits) - 1; + } +} + +/* Scans the 'n_bits' bits starting from bit 'dst_ofs' in 'dst' for 1-bits. + * Returns false if any 1-bits are found, otherwise true. 'dst' is 'dst_len' + * bytes long. + * + * If you consider all of 'dst' 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 dst[dst_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 dst[dst_len - + * 2], and so on. + * + * Required invariant: + * dst_ofs + n_bits <= dst_len * 8 + */ +bool +bitwise_is_all_zeros(const void *p_, unsigned int len, unsigned int ofs, + unsigned int n_bits) +{ + const uint8_t *p = p_; + + if (!n_bits) { + return true; + } + + p += len - (ofs / 8 + 1); + ofs %= 8; + + if (ofs) { + unsigned int chunk = MIN(n_bits, 8 - ofs); + + if (*p & (((1 << chunk) - 1) << ofs)) { + return false; + } + + n_bits -= chunk; + if (!n_bits) { + return true; + } + + p--; + } + + while (n_bits >= 8) { + if (*p) { + return false; + } + n_bits -= 8; + p--; + } + + if (n_bits && *p & ((1 << n_bits) - 1)) { + return false; + } + + return true; +} + +/* Copies the 'n_bits' low-order bits of 'value' into the 'n_bits' bits + * starting at bit 'dst_ofs' in 'dst', which is 'dst_len' bytes long. + * + * If you consider all of 'dst' 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 dst[dst_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 dst[dst_len - + * 2], and so on. + * + * Required invariants: + * dst_ofs + n_bits <= dst_len * 8 + * n_bits <= 64 + */ +void +bitwise_put(uint64_t value, + void *dst, unsigned int dst_len, unsigned int dst_ofs, + unsigned int n_bits) +{ + ovs_be64 n_value = htonll(value); + bitwise_copy(&n_value, sizeof n_value, 0, + dst, dst_len, dst_ofs, + n_bits); +} + +/* Returns the value of the 'n_bits' bits starting at bit 'src_ofs' in 'src', + * which is 'src_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. + * + * Required invariants: + * src_ofs + n_bits <= src_len * 8 + * n_bits <= 64 + */ +uint64_t +bitwise_get(const void *src, unsigned int src_len, + unsigned int src_ofs, unsigned int n_bits) +{ + ovs_be64 value = htonll(0); + + bitwise_copy(src, src_len, src_ofs, + &value, sizeof value, 0, + n_bits); + return ntohll(value); +}