util/cutils.c

   1 /*
   2  * Simple C functions to supplement the C library
   3  *
   4  * Copyright (c) 2006 Fabrice Bellard
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "qemu/osdep.h"
  26 #include "qemu/host-utils.h"
  27 #include <math.h>
  28
  29 #include "qemu-common.h"
  30 #include "qemu/sockets.h"
  31 #include "qemu/iov.h"
  32 #include "net/net.h"
  33 #include "qemu/ctype.h"
  34 #include "qemu/cutils.h"
  35 #include "qemu/error-report.h"
  36
  37 void strpadcpy(char *buf, int buf_size, const char *str, char pad)
  38 {
  39     int len = qemu_strnlen(str, buf_size);
  40     memcpy(buf, str, len);
  41     memset(buf + len, pad, buf_size - len);
  42 }
  43
  44 void pstrcpy(char *buf, int buf_size, const char *str)
  45 {
  46     int c;
  47     char *q = buf;
  48
  49     if (buf_size <= 0)
  50         return;
  51
  52     for(;;) {
  53         c = *str++;
  54         if (c == 0 || q >= buf + buf_size - 1)
  55             break;
  56         *q++ = c;
  57     }
  58     *q = '\0';
  59 }
  60
  61 /* strcat and truncate. */
  62 char *pstrcat(char *buf, int buf_size, const char *s)
  63 {
  64     int len;
  65     len = strlen(buf);
  66     if (len < buf_size)
  67         pstrcpy(buf + len, buf_size - len, s);
  68     return buf;
  69 }
  70
  71 int strstart(const char *str, const char *val, const char **ptr)
  72 {
  73     const char *p, *q;
  74     p = str;
  75     q = val;
  76     while (*q != '\0') {
  77         if (*p != *q)
  78             return 0;
  79         p++;
  80         q++;
  81     }
  82     if (ptr)
  83         *ptr = p;
  84     return 1;
  85 }
  86
  87 int stristart(const char *str, const char *val, const char **ptr)
  88 {
  89     const char *p, *q;
  90     p = str;
  91     q = val;
  92     while (*q != '\0') {
  93         if (qemu_toupper(*p) != qemu_toupper(*q))
  94             return 0;
  95         p++;
  96         q++;
  97     }
  98     if (ptr)
  99         *ptr = p;
 100     return 1;
 101 }
 102
 103 /* XXX: use host strnlen if available ? */
 104 int qemu_strnlen(const char *s, int max_len)
 105 {
 106     int i;
 107
 108     for(i = 0; i < max_len; i++) {
 109         if (s[i] == '\0') {
 110             break;
 111         }
 112     }
 113     return i;
 114 }
 115
 116 char *qemu_strsep(char **input, const char *delim)
 117 {
 118     char *result = *input;
 119     if (result != NULL) {
 120         char *p;
 121
 122         for (p = result; *p != '\0'; p++) {
 123             if (strchr(delim, *p)) {
 124                 break;
 125             }
 126         }
 127         if (*p == '\0') {
 128             *input = NULL;
 129         } else {
 130             *p = '\0';
 131             *input = p + 1;
 132         }
 133     }
 134     return result;
 135 }
 136
 137 time_t mktimegm(struct tm *tm)
 138 {
 139     time_t t;
 140     int y = tm->tm_year + 1900, m = tm->tm_mon + 1, d = tm->tm_mday;
 141     if (m < 3) {
 142         m += 12;
 143         y--;
 144     }
 145     t = 86400ULL * (d + (153 * m - 457) / 5 + 365 * y + y / 4 - y / 100 +
 146                  y / 400 - 719469);
 147     t += 3600 * tm->tm_hour + 60 * tm->tm_min + tm->tm_sec;
 148     return t;
 149 }
 150
 151 /*
 152  * Make sure data goes on disk, but if possible do not bother to
 153  * write out the inode just for timestamp updates.
 154  *
 155  * Unfortunately even in 2009 many operating systems do not support
 156  * fdatasync and have to fall back to fsync.
 157  */
 158 int qemu_fdatasync(int fd)
 159 {
 160 #ifdef CONFIG_FDATASYNC
 161     return fdatasync(fd);
 162 #else
 163     return fsync(fd);
 164 #endif
 165 }
 166
 167 #ifndef _WIN32
 168 /* Sets a specific flag */
 169 int fcntl_setfl(int fd, int flag)
 170 {
 171     int flags;
 172
 173     flags = fcntl(fd, F_GETFL);
 174     if (flags == -1)
 175         return -errno;
 176
 177     if (fcntl(fd, F_SETFL, flags | flag) == -1)
 178         return -errno;
 179
 180     return 0;
 181 }
 182 #endif
 183
 184 static int64_t suffix_mul(char suffix, int64_t unit)
 185 {
 186     switch (qemu_toupper(suffix)) {
 187     case 'B':
 188         return 1;
 189     case 'K':
 190         return unit;
 191     case 'M':
 192         return unit * unit;
 193     case 'G':
 194         return unit * unit * unit;
 195     case 'T':
 196         return unit * unit * unit * unit;
 197     case 'P':
 198         return unit * unit * unit * unit * unit;
 199     case 'E':
 200         return unit * unit * unit * unit * unit * unit;
 201     }
 202     return -1;
 203 }
 204
 205 /*
 206  * Convert string to bytes, allowing either B/b for bytes, K/k for KB,
 207  * M/m for MB, G/g for GB or T/t for TB. End pointer will be returned
 208  * in *end, if not NULL. Return -ERANGE on overflow, and -EINVAL on
 209  * other error.
 210  */
 211 static int do_strtosz(const char *nptr, const char **end,
 212                       const char default_suffix, int64_t unit,
 213                       uint64_t *result)
 214 {
 215     int retval;
 216     const char *endptr;
 217     unsigned char c;
 218     int mul_required = 0;
 219     double val, mul, integral, fraction;
 220
 221     retval = qemu_strtod_finite(nptr, &endptr, &val);
 222     if (retval) {
 223         goto out;
 224     }
 225     fraction = modf(val, &integral);
 226     if (fraction != 0) {
 227         mul_required = 1;
 228     }
 229     c = *endptr;
 230     mul = suffix_mul(c, unit);
 231     if (mul >= 0) {
 232         endptr++;
 233     } else {
 234         mul = suffix_mul(default_suffix, unit);
 235         assert(mul >= 0);
 236     }
 237     if (mul == 1 && mul_required) {
 238         retval = -EINVAL;
 239         goto out;
 240     }
 241     /*
 242      * Values >= 0xfffffffffffffc00 overflow uint64_t after their trip
 243      * through double (53 bits of precision).
 244      */
 245     if ((val * mul >= 0xfffffffffffffc00) || val < 0) {
 246         retval = -ERANGE;
 247         goto out;
 248     }
 249     *result = val * mul;
 250     retval = 0;
 251
 252 out:
 253     if (end) {
 254         *end = endptr;
 255     } else if (*endptr) {
 256         retval = -EINVAL;
 257     }
 258
 259     return retval;
 260 }
 261
 262 int qemu_strtosz(const char *nptr, const char **end, uint64_t *result)
 263 {
 264     return do_strtosz(nptr, end, 'B', 1024, result);
 265 }
 266
 267 int qemu_strtosz_MiB(const char *nptr, const char **end, uint64_t *result)
 268 {
 269     return do_strtosz(nptr, end, 'M', 1024, result);
 270 }
 271
 272 int qemu_strtosz_metric(const char *nptr, const char **end, uint64_t *result)
 273 {
 274     return do_strtosz(nptr, end, 'B', 1000, result);
 275 }
 276
 277 /**
 278  * Helper function for error checking after strtol() and the like
 279  */
 280 static int check_strtox_error(const char *nptr, char *ep,
 281                               const char **endptr, int libc_errno)
 282 {
 283     assert(ep >= nptr);
 284     if (endptr) {
 285         *endptr = ep;
 286     }
 287
 288     /* Turn "no conversion" into an error */
 289     if (libc_errno == 0 && ep == nptr) {
 290         return -EINVAL;
 291     }
 292
 293     /* Fail when we're expected to consume the string, but didn't */
 294     if (!endptr && *ep) {
 295         return -EINVAL;
 296     }
 297
 298     return -libc_errno;
 299 }
 300
 301 /**
 302  * Convert string @nptr to an integer, and store it in @result.
 303  *
 304  * This is a wrapper around strtol() that is harder to misuse.
 305  * Semantics of @nptr, @endptr, @base match strtol() with differences
 306  * noted below.
 307  *
 308  * @nptr may be null, and no conversion is performed then.
 309  *
 310  * If no conversion is performed, store @nptr in *@endptr and return
 311  * -EINVAL.
 312  *
 313  * If @endptr is null, and the string isn't fully converted, return
 314  * -EINVAL.  This is the case when the pointer that would be stored in
 315  * a non-null @endptr points to a character other than '\0'.
 316  *
 317  * If the conversion overflows @result, store INT_MAX in @result,
 318  * and return -ERANGE.
 319  *
 320  * If the conversion underflows @result, store INT_MIN in @result,
 321  * and return -ERANGE.
 322  *
 323  * Else store the converted value in @result, and return zero.
 324  */
 325 int qemu_strtoi(const char *nptr, const char **endptr, int base,
 326                 int *result)
 327 {
 328     char *ep;
 329     long long lresult;
 330
 331     assert((unsigned) base <= 36 && base != 1);
 332     if (!nptr) {
 333         if (endptr) {
 334             *endptr = nptr;
 335         }
 336         return -EINVAL;
 337     }
 338
 339     errno = 0;
 340     lresult = strtoll(nptr, &ep, base);
 341     if (lresult < INT_MIN) {
 342         *result = INT_MIN;
 343         errno = ERANGE;
 344     } else if (lresult > INT_MAX) {
 345         *result = INT_MAX;
 346         errno = ERANGE;
 347     } else {
 348         *result = lresult;
 349     }
 350     return check_strtox_error(nptr, ep, endptr, errno);
 351 }
 352
 353 /**
 354  * Convert string @nptr to an unsigned integer, and store it in @result.
 355  *
 356  * This is a wrapper around strtoul() that is harder to misuse.
 357  * Semantics of @nptr, @endptr, @base match strtoul() with differences
 358  * noted below.
 359  *
 360  * @nptr may be null, and no conversion is performed then.
 361  *
 362  * If no conversion is performed, store @nptr in *@endptr and return
 363  * -EINVAL.
 364  *
 365  * If @endptr is null, and the string isn't fully converted, return
 366  * -EINVAL.  This is the case when the pointer that would be stored in
 367  * a non-null @endptr points to a character other than '\0'.
 368  *
 369  * If the conversion overflows @result, store UINT_MAX in @result,
 370  * and return -ERANGE.
 371  *
 372  * Else store the converted value in @result, and return zero.
 373  *
 374  * Note that a number with a leading minus sign gets converted without
 375  * the minus sign, checked for overflow (see above), then negated (in
 376  * @result's type).  This is exactly how strtoul() works.
 377  */
 378 int qemu_strtoui(const char *nptr, const char **endptr, int base,
 379                  unsigned int *result)
 380 {
 381     char *ep;
 382     long long lresult;
 383
 384     assert((unsigned) base <= 36 && base != 1);
 385     if (!nptr) {
 386         if (endptr) {
 387             *endptr = nptr;
 388         }
 389         return -EINVAL;
 390     }
 391
 392     errno = 0;
 393     lresult = strtoull(nptr, &ep, base);
 394
 395     /* Windows returns 1 for negative out-of-range values.  */
 396     if (errno == ERANGE) {
 397         *result = -1;
 398     } else {
 399         if (lresult > UINT_MAX) {
 400             *result = UINT_MAX;
 401             errno = ERANGE;
 402         } else if (lresult < INT_MIN) {
 403             *result = UINT_MAX;
 404             errno = ERANGE;
 405         } else {
 406             *result = lresult;
 407         }
 408     }
 409     return check_strtox_error(nptr, ep, endptr, errno);
 410 }
 411
 412 /**
 413  * Convert string @nptr to a long integer, and store it in @result.
 414  *
 415  * This is a wrapper around strtol() that is harder to misuse.
 416  * Semantics of @nptr, @endptr, @base match strtol() with differences
 417  * noted below.
 418  *
 419  * @nptr may be null, and no conversion is performed then.
 420  *
 421  * If no conversion is performed, store @nptr in *@endptr and return
 422  * -EINVAL.
 423  *
 424  * If @endptr is null, and the string isn't fully converted, return
 425  * -EINVAL.  This is the case when the pointer that would be stored in
 426  * a non-null @endptr points to a character other than '\0'.
 427  *
 428  * If the conversion overflows @result, store LONG_MAX in @result,
 429  * and return -ERANGE.
 430  *
 431  * If the conversion underflows @result, store LONG_MIN in @result,
 432  * and return -ERANGE.
 433  *
 434  * Else store the converted value in @result, and return zero.
 435  */
 436 int qemu_strtol(const char *nptr, const char **endptr, int base,
 437                 long *result)
 438 {
 439     char *ep;
 440
 441     assert((unsigned) base <= 36 && base != 1);
 442     if (!nptr) {
 443         if (endptr) {
 444             *endptr = nptr;
 445         }
 446         return -EINVAL;
 447     }
 448
 449     errno = 0;
 450     *result = strtol(nptr, &ep, base);
 451     return check_strtox_error(nptr, ep, endptr, errno);
 452 }
 453
 454 /**
 455  * Convert string @nptr to an unsigned long, and store it in @result.
 456  *
 457  * This is a wrapper around strtoul() that is harder to misuse.
 458  * Semantics of @nptr, @endptr, @base match strtoul() with differences
 459  * noted below.
 460  *
 461  * @nptr may be null, and no conversion is performed then.
 462  *
 463  * If no conversion is performed, store @nptr in *@endptr and return
 464  * -EINVAL.
 465  *
 466  * If @endptr is null, and the string isn't fully converted, return
 467  * -EINVAL.  This is the case when the pointer that would be stored in
 468  * a non-null @endptr points to a character other than '\0'.
 469  *
 470  * If the conversion overflows @result, store ULONG_MAX in @result,
 471  * and return -ERANGE.
 472  *
 473  * Else store the converted value in @result, and return zero.
 474  *
 475  * Note that a number with a leading minus sign gets converted without
 476  * the minus sign, checked for overflow (see above), then negated (in
 477  * @result's type).  This is exactly how strtoul() works.
 478  */
 479 int qemu_strtoul(const char *nptr, const char **endptr, int base,
 480                  unsigned long *result)
 481 {
 482     char *ep;
 483
 484     assert((unsigned) base <= 36 && base != 1);
 485     if (!nptr) {
 486         if (endptr) {
 487             *endptr = nptr;
 488         }
 489         return -EINVAL;
 490     }
 491
 492     errno = 0;
 493     *result = strtoul(nptr, &ep, base);
 494     /* Windows returns 1 for negative out-of-range values.  */
 495     if (errno == ERANGE) {
 496         *result = -1;
 497     }
 498     return check_strtox_error(nptr, ep, endptr, errno);
 499 }
 500
 501 /**
 502  * Convert string @nptr to an int64_t.
 503  *
 504  * Works like qemu_strtol(), except it stores INT64_MAX on overflow,
 505  * and INT_MIN on underflow.
 506  */
 507 int qemu_strtoi64(const char *nptr, const char **endptr, int base,
 508                  int64_t *result)
 509 {
 510     char *ep;
 511
 512     assert((unsigned) base <= 36 && base != 1);
 513     if (!nptr) {
 514         if (endptr) {
 515             *endptr = nptr;
 516         }
 517         return -EINVAL;
 518     }
 519
 520     errno = 0;
 521     /* FIXME This assumes int64_t is long long */
 522     *result = strtoll(nptr, &ep, base);
 523     return check_strtox_error(nptr, ep, endptr, errno);
 524 }
 525
 526 /**
 527  * Convert string @nptr to an uint64_t.
 528  *
 529  * Works like qemu_strtoul(), except it stores UINT64_MAX on overflow.
 530  */
 531 int qemu_strtou64(const char *nptr, const char **endptr, int base,
 532                   uint64_t *result)
 533 {
 534     char *ep;
 535
 536     assert((unsigned) base <= 36 && base != 1);
 537     if (!nptr) {
 538         if (endptr) {
 539             *endptr = nptr;
 540         }
 541         return -EINVAL;
 542     }
 543
 544     errno = 0;
 545     /* FIXME This assumes uint64_t is unsigned long long */
 546     *result = strtoull(nptr, &ep, base);
 547     /* Windows returns 1 for negative out-of-range values.  */
 548     if (errno == ERANGE) {
 549         *result = -1;
 550     }
 551     return check_strtox_error(nptr, ep, endptr, errno);
 552 }
 553
 554 /**
 555  * Convert string @nptr to a double.
 556   *
 557  * This is a wrapper around strtod() that is harder to misuse.
 558  * Semantics of @nptr and @endptr match strtod() with differences
 559  * noted below.
 560  *
 561  * @nptr may be null, and no conversion is performed then.
 562  *
 563  * If no conversion is performed, store @nptr in *@endptr and return
 564  * -EINVAL.
 565  *
 566  * If @endptr is null, and the string isn't fully converted, return
 567  * -EINVAL. This is the case when the pointer that would be stored in
 568  * a non-null @endptr points to a character other than '\0'.
 569  *
 570  * If the conversion overflows, store +/-HUGE_VAL in @result, depending
 571  * on the sign, and return -ERANGE.
 572  *
 573  * If the conversion underflows, store +/-0.0 in @result, depending on the
 574  * sign, and return -ERANGE.
 575  *
 576  * Else store the converted value in @result, and return zero.
 577  */
 578 int qemu_strtod(const char *nptr, const char **endptr, double *result)
 579 {
 580     char *ep;
 581
 582     if (!nptr) {
 583         if (endptr) {
 584             *endptr = nptr;
 585         }
 586         return -EINVAL;
 587     }
 588
 589     errno = 0;
 590     *result = strtod(nptr, &ep);
 591     return check_strtox_error(nptr, ep, endptr, errno);
 592 }
 593
 594 /**
 595  * Convert string @nptr to a finite double.
 596  *
 597  * Works like qemu_strtod(), except that "NaN" and "inf" are rejected
 598  * with -EINVAL and no conversion is performed.
 599  */
 600 int qemu_strtod_finite(const char *nptr, const char **endptr, double *result)
 601 {
 602     double tmp;
 603     int ret;
 604
 605     ret = qemu_strtod(nptr, endptr, &tmp);
 606     if (!ret && !isfinite(tmp)) {
 607         if (endptr) {
 608             *endptr = nptr;
 609         }
 610         ret = -EINVAL;
 611     }
 612
 613     if (ret != -EINVAL) {
 614         *result = tmp;
 615     }
 616     return ret;
 617 }
 618
 619 /**
 620  * Searches for the first occurrence of 'c' in 's', and returns a pointer
 621  * to the trailing null byte if none was found.
 622  */
 623 #ifndef HAVE_STRCHRNUL
 624 const char *qemu_strchrnul(const char *s, int c)
 625 {
 626     const char *e = strchr(s, c);
 627     if (!e) {
 628         e = s + strlen(s);
 629     }
 630     return e;
 631 }
 632 #endif
 633
 634 /**
 635  * parse_uint:
 636  *
 637  * @s: String to parse
 638  * @value: Destination for parsed integer value
 639  * @endptr: Destination for pointer to first character not consumed
 640  * @base: integer base, between 2 and 36 inclusive, or 0
 641  *
 642  * Parse unsigned integer
 643  *
 644  * Parsed syntax is like strtoull()'s: arbitrary whitespace, a single optional
 645  * '+' or '-', an optional "0x" if @base is 0 or 16, one or more digits.
 646  *
 647  * If @s is null, or @base is invalid, or @s doesn't start with an
 648  * integer in the syntax above, set *@value to 0, *@endptr to @s, and
 649  * return -EINVAL.
 650  *
 651  * Set *@endptr to point right beyond the parsed integer (even if the integer
 652  * overflows or is negative, all digits will be parsed and *@endptr will
 653  * point right beyond them).
 654  *
 655  * If the integer is negative, set *@value to 0, and return -ERANGE.
 656  *
 657  * If the integer overflows unsigned long long, set *@value to
 658  * ULLONG_MAX, and return -ERANGE.
 659  *
 660  * Else, set *@value to the parsed integer, and return 0.
 661  */
 662 int parse_uint(const char *s, unsigned long long *value, char **endptr,
 663                int base)
 664 {
 665     int r = 0;
 666     char *endp = (char *)s;
 667     unsigned long long val = 0;
 668
 669     assert((unsigned) base <= 36 && base != 1);
 670     if (!s) {
 671         r = -EINVAL;
 672         goto out;
 673     }
 674
 675     errno = 0;
 676     val = strtoull(s, &endp, base);
 677     if (errno) {
 678         r = -errno;
 679         goto out;
 680     }
 681
 682     if (endp == s) {
 683         r = -EINVAL;
 684         goto out;
 685     }
 686
 687     /* make sure we reject negative numbers: */
 688     while (qemu_isspace(*s)) {
 689         s++;
 690     }
 691     if (*s == '-') {
 692         val = 0;
 693         r = -ERANGE;
 694         goto out;
 695     }
 696
 697 out:
 698     *value = val;
 699     *endptr = endp;
 700     return r;
 701 }
 702
 703 /**
 704  * parse_uint_full:
 705  *
 706  * @s: String to parse
 707  * @value: Destination for parsed integer value
 708  * @base: integer base, between 2 and 36 inclusive, or 0
 709  *
 710  * Parse unsigned integer from entire string
 711  *
 712  * Have the same behavior of parse_uint(), but with an additional check
 713  * for additional data after the parsed number. If extra characters are present
 714  * after the parsed number, the function will return -EINVAL, and *@v will
 715  * be set to 0.
 716  */
 717 int parse_uint_full(const char *s, unsigned long long *value, int base)
 718 {
 719     char *endp;
 720     int r;
 721
 722     r = parse_uint(s, value, &endp, base);
 723     if (r < 0) {
 724         return r;
 725     }
 726     if (*endp) {
 727         *value = 0;
 728         return -EINVAL;
 729     }
 730
 731     return 0;
 732 }
 733
 734 int qemu_parse_fd(const char *param)
 735 {
 736     long fd;
 737     char *endptr;
 738
 739     errno = 0;
 740     fd = strtol(param, &endptr, 10);
 741     if (param == endptr /* no conversion performed */                    ||
 742         errno != 0      /* not representable as long; possibly others */ ||
 743         *endptr != '\0' /* final string not empty */                     ||
 744         fd < 0          /* invalid as file descriptor */                 ||
 745         fd > INT_MAX    /* not representable as int */) {
 746         return -1;
 747     }
 748     return fd;
 749 }
 750
 751 /*
 752  * Implementation of  ULEB128 (http://en.wikipedia.org/wiki/LEB128)
 753  * Input is limited to 14-bit numbers
 754  */
 755 int uleb128_encode_small(uint8_t *out, uint32_t n)
 756 {
 757     g_assert(n <= 0x3fff);
 758     if (n < 0x80) {
 759         *out++ = n;
 760         return 1;
 761     } else {
 762         *out++ = (n & 0x7f) | 0x80;
 763         *out++ = n >> 7;
 764         return 2;
 765     }
 766 }
 767
 768 int uleb128_decode_small(const uint8_t *in, uint32_t *n)
 769 {
 770     if (!(*in & 0x80)) {
 771         *n = *in++;
 772         return 1;
 773     } else {
 774         *n = *in++ & 0x7f;
 775         /* we exceed 14 bit number */
 776         if (*in & 0x80) {
 777             return -1;
 778         }
 779         *n |= *in++ << 7;
 780         return 2;
 781     }
 782 }
 783
 784 /*
 785  * helper to parse debug environment variables
 786  */
 787 int parse_debug_env(const char *name, int max, int initial)
 788 {
 789     char *debug_env = getenv(name);
 790     char *inv = NULL;
 791     long debug;
 792
 793     if (!debug_env) {
 794         return initial;
 795     }
 796     errno = 0;
 797     debug = strtol(debug_env, &inv, 10);
 798     if (inv == debug_env) {
 799         return initial;
 800     }
 801     if (debug < 0 || debug > max || errno != 0) {
 802         warn_report("%s not in [0, %d]", name, max);
 803         return initial;
 804     }
 805     return debug;
 806 }
 807
 808 /*
 809  * Helper to print ethernet mac address
 810  */
 811 const char *qemu_ether_ntoa(const MACAddr *mac)
 812 {
 813     static char ret[18];
 814
 815     snprintf(ret, sizeof(ret), "%02x:%02x:%02x:%02x:%02x:%02x",
 816              mac->a[0], mac->a[1], mac->a[2], mac->a[3], mac->a[4], mac->a[5]);
 817
 818     return ret;
 819 }
 820
 821 /*
 822  * Return human readable string for size @val.
 823  * @val can be anything that uint64_t allows (no more than "16 EiB").
 824  * Use IEC binary units like KiB, MiB, and so forth.
 825  * Caller is responsible for passing it to g_free().
 826  */
 827 char *size_to_str(uint64_t val)
 828 {
 829     static const char *suffixes[] = { "", "Ki", "Mi", "Gi", "Ti", "Pi", "Ei" };
 830     uint64_t div;
 831     int i;
 832
 833     /*
 834      * The exponent (returned in i) minus one gives us
 835      * floor(log2(val * 1024 / 1000).  The correction makes us
 836      * switch to the higher power when the integer part is >= 1000.
 837      * (see e41b509d68afb1f for more info)
 838      */
 839     frexp(val / (1000.0 / 1024.0), &i);
 840     i = (i - 1) / 10;
 841     div = 1ULL << (i * 10);
 842
 843     return g_strdup_printf("%0.3g %sB", (double)val / div, suffixes[i]);
 844 }
 845
 846 int qemu_pstrcmp0(const char **str1, const char **str2)
 847 {
 848     return g_strcmp0(*str1, *str2);
 849 }