wrapper.c

   1 /*
   2  * Various trivial helper wrappers around standard functions
   3  */
   4 #include "cache.h"
   5 #include "config.h"
   6
   7 static int memory_limit_check(size_t size, int gentle)
   8 {
   9         static size_t limit = 0;
  10         if (!limit) {
  11                 limit = git_env_ulong("GIT_ALLOC_LIMIT", 0);
  12                 if (!limit)
  13                         limit = SIZE_MAX;
  14         }
  15         if (size > limit) {
  16                 if (gentle) {
  17                         error("attempting to allocate %"PRIuMAX" over limit %"PRIuMAX,
  18                               (uintmax_t)size, (uintmax_t)limit);
  19                         return -1;
  20                 } else
  21                         die("attempting to allocate %"PRIuMAX" over limit %"PRIuMAX,
  22                             (uintmax_t)size, (uintmax_t)limit);
  23         }
  24         return 0;
  25 }
  26
  27 char *xstrdup(const char *str)
  28 {
  29         char *ret = strdup(str);
  30         if (!ret)
  31                 die("Out of memory, strdup failed");
  32         return ret;
  33 }
  34
  35 static void *do_xmalloc(size_t size, int gentle)
  36 {
  37         void *ret;
  38
  39         if (memory_limit_check(size, gentle))
  40                 return NULL;
  41         ret = malloc(size);
  42         if (!ret && !size)
  43                 ret = malloc(1);
  44         if (!ret) {
  45                 if (!gentle)
  46                         die("Out of memory, malloc failed (tried to allocate %lu bytes)",
  47                             (unsigned long)size);
  48                 else {
  49                         error("Out of memory, malloc failed (tried to allocate %lu bytes)",
  50                               (unsigned long)size);
  51                         return NULL;
  52                 }
  53         }
  54 #ifdef XMALLOC_POISON
  55         memset(ret, 0xA5, size);
  56 #endif
  57         return ret;
  58 }
  59
  60 void *xmalloc(size_t size)
  61 {
  62         return do_xmalloc(size, 0);
  63 }
  64
  65 static void *do_xmallocz(size_t size, int gentle)
  66 {
  67         void *ret;
  68         if (unsigned_add_overflows(size, 1)) {
  69                 if (gentle) {
  70                         error("Data too large to fit into virtual memory space.");
  71                         return NULL;
  72                 } else
  73                         die("Data too large to fit into virtual memory space.");
  74         }
  75         ret = do_xmalloc(size + 1, gentle);
  76         if (ret)
  77                 ((char*)ret)[size] = 0;
  78         return ret;
  79 }
  80
  81 void *xmallocz(size_t size)
  82 {
  83         return do_xmallocz(size, 0);
  84 }
  85
  86 void *xmallocz_gently(size_t size)
  87 {
  88         return do_xmallocz(size, 1);
  89 }
  90
  91 /*
  92  * xmemdupz() allocates (len + 1) bytes of memory, duplicates "len" bytes of
  93  * "data" to the allocated memory, zero terminates the allocated memory,
  94  * and returns a pointer to the allocated memory. If the allocation fails,
  95  * the program dies.
  96  */
  97 void *xmemdupz(const void *data, size_t len)
  98 {
  99         return memcpy(xmallocz(len), data, len);
 100 }
 101
 102 char *xstrndup(const char *str, size_t len)
 103 {
 104         char *p = memchr(str, '\0', len);
 105         return xmemdupz(str, p ? p - str : len);
 106 }
 107
 108 int xstrncmpz(const char *s, const char *t, size_t len)
 109 {
 110         int res = strncmp(s, t, len);
 111         if (res)
 112                 return res;
 113         return s[len] == '\0' ? 0 : 1;
 114 }
 115
 116 void *xrealloc(void *ptr, size_t size)
 117 {
 118         void *ret;
 119
 120         if (!size) {
 121                 free(ptr);
 122                 return xmalloc(0);
 123         }
 124
 125         memory_limit_check(size, 0);
 126         ret = realloc(ptr, size);
 127         if (!ret)
 128                 die("Out of memory, realloc failed");
 129         return ret;
 130 }
 131
 132 void *xcalloc(size_t nmemb, size_t size)
 133 {
 134         void *ret;
 135
 136         if (unsigned_mult_overflows(nmemb, size))
 137                 die("data too large to fit into virtual memory space");
 138
 139         memory_limit_check(size * nmemb, 0);
 140         ret = calloc(nmemb, size);
 141         if (!ret && (!nmemb || !size))
 142                 ret = calloc(1, 1);
 143         if (!ret)
 144                 die("Out of memory, calloc failed");
 145         return ret;
 146 }
 147
 148 void xsetenv(const char *name, const char *value, int overwrite)
 149 {
 150         if (setenv(name, value, overwrite))
 151                 die_errno(_("could not setenv '%s'"), name ? name : "(null)");
 152 }
 153
 154 /*
 155  * Limit size of IO chunks, because huge chunks only cause pain.  OS X
 156  * 64-bit is buggy, returning EINVAL if len >= INT_MAX; and even in
 157  * the absence of bugs, large chunks can result in bad latencies when
 158  * you decide to kill the process.
 159  *
 160  * We pick 8 MiB as our default, but if the platform defines SSIZE_MAX
 161  * that is smaller than that, clip it to SSIZE_MAX, as a call to
 162  * read(2) or write(2) larger than that is allowed to fail.  As the last
 163  * resort, we allow a port to pass via CFLAGS e.g. "-DMAX_IO_SIZE=value"
 164  * to override this, if the definition of SSIZE_MAX given by the platform
 165  * is broken.
 166  */
 167 #ifndef MAX_IO_SIZE
 168 # define MAX_IO_SIZE_DEFAULT (8*1024*1024)
 169 # if defined(SSIZE_MAX) && (SSIZE_MAX < MAX_IO_SIZE_DEFAULT)
 170 #  define MAX_IO_SIZE SSIZE_MAX
 171 # else
 172 #  define MAX_IO_SIZE MAX_IO_SIZE_DEFAULT
 173 # endif
 174 #endif
 175
 176 /**
 177  * xopen() is the same as open(), but it die()s if the open() fails.
 178  */
 179 int xopen(const char *path, int oflag, ...)
 180 {
 181         mode_t mode = 0;
 182         va_list ap;
 183
 184         /*
 185          * va_arg() will have undefined behavior if the specified type is not
 186          * compatible with the argument type. Since integers are promoted to
 187          * ints, we fetch the next argument as an int, and then cast it to a
 188          * mode_t to avoid undefined behavior.
 189          */
 190         va_start(ap, oflag);
 191         if (oflag & O_CREAT)
 192                 mode = va_arg(ap, int);
 193         va_end(ap);
 194
 195         for (;;) {
 196                 int fd = open(path, oflag, mode);
 197                 if (fd >= 0)
 198                         return fd;
 199                 if (errno == EINTR)
 200                         continue;
 201
 202                 if ((oflag & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
 203                         die_errno(_("unable to create '%s'"), path);
 204                 else if ((oflag & O_RDWR) == O_RDWR)
 205                         die_errno(_("could not open '%s' for reading and writing"), path);
 206                 else if ((oflag & O_WRONLY) == O_WRONLY)
 207                         die_errno(_("could not open '%s' for writing"), path);
 208                 else
 209                         die_errno(_("could not open '%s' for reading"), path);
 210         }
 211 }
 212
 213 static int handle_nonblock(int fd, short poll_events, int err)
 214 {
 215         struct pollfd pfd;
 216
 217         if (err != EAGAIN && err != EWOULDBLOCK)
 218                 return 0;
 219
 220         pfd.fd = fd;
 221         pfd.events = poll_events;
 222
 223         /*
 224          * no need to check for errors, here;
 225          * a subsequent read/write will detect unrecoverable errors
 226          */
 227         poll(&pfd, 1, -1);
 228         return 1;
 229 }
 230
 231 /*
 232  * xread() is the same a read(), but it automatically restarts read()
 233  * operations with a recoverable error (EAGAIN and EINTR). xread()
 234  * DOES NOT GUARANTEE that "len" bytes is read even if the data is available.
 235  */
 236 ssize_t xread(int fd, void *buf, size_t len)
 237 {
 238         ssize_t nr;
 239         if (len > MAX_IO_SIZE)
 240                 len = MAX_IO_SIZE;
 241         while (1) {
 242                 nr = read(fd, buf, len);
 243                 if (nr < 0) {
 244                         if (errno == EINTR)
 245                                 continue;
 246                         if (handle_nonblock(fd, POLLIN, errno))
 247                                 continue;
 248                 }
 249                 return nr;
 250         }
 251 }
 252
 253 /*
 254  * xwrite() is the same a write(), but it automatically restarts write()
 255  * operations with a recoverable error (EAGAIN and EINTR). xwrite() DOES NOT
 256  * GUARANTEE that "len" bytes is written even if the operation is successful.
 257  */
 258 ssize_t xwrite(int fd, const void *buf, size_t len)
 259 {
 260         ssize_t nr;
 261         if (len > MAX_IO_SIZE)
 262                 len = MAX_IO_SIZE;
 263         while (1) {
 264                 nr = write(fd, buf, len);
 265                 if (nr < 0) {
 266                         if (errno == EINTR)
 267                                 continue;
 268                         if (handle_nonblock(fd, POLLOUT, errno))
 269                                 continue;
 270                 }
 271
 272                 return nr;
 273         }
 274 }
 275
 276 /*
 277  * xpread() is the same as pread(), but it automatically restarts pread()
 278  * operations with a recoverable error (EAGAIN and EINTR). xpread() DOES
 279  * NOT GUARANTEE that "len" bytes is read even if the data is available.
 280  */
 281 ssize_t xpread(int fd, void *buf, size_t len, off_t offset)
 282 {
 283         ssize_t nr;
 284         if (len > MAX_IO_SIZE)
 285                 len = MAX_IO_SIZE;
 286         while (1) {
 287                 nr = pread(fd, buf, len, offset);
 288                 if ((nr < 0) && (errno == EAGAIN || errno == EINTR))
 289                         continue;
 290                 return nr;
 291         }
 292 }
 293
 294 ssize_t read_in_full(int fd, void *buf, size_t count)
 295 {
 296         char *p = buf;
 297         ssize_t total = 0;
 298
 299         while (count > 0) {
 300                 ssize_t loaded = xread(fd, p, count);
 301                 if (loaded < 0)
 302                         return -1;
 303                 if (loaded == 0)
 304                         return total;
 305                 count -= loaded;
 306                 p += loaded;
 307                 total += loaded;
 308         }
 309
 310         return total;
 311 }
 312
 313 ssize_t write_in_full(int fd, const void *buf, size_t count)
 314 {
 315         const char *p = buf;
 316         ssize_t total = 0;
 317
 318         while (count > 0) {
 319                 ssize_t written = xwrite(fd, p, count);
 320                 if (written < 0)
 321                         return -1;
 322                 if (!written) {
 323                         errno = ENOSPC;
 324                         return -1;
 325                 }
 326                 count -= written;
 327                 p += written;
 328                 total += written;
 329         }
 330
 331         return total;
 332 }
 333
 334 ssize_t pread_in_full(int fd, void *buf, size_t count, off_t offset)
 335 {
 336         char *p = buf;
 337         ssize_t total = 0;
 338
 339         while (count > 0) {
 340                 ssize_t loaded = xpread(fd, p, count, offset);
 341                 if (loaded < 0)
 342                         return -1;
 343                 if (loaded == 0)
 344                         return total;
 345                 count -= loaded;
 346                 p += loaded;
 347                 total += loaded;
 348                 offset += loaded;
 349         }
 350
 351         return total;
 352 }
 353
 354 int xdup(int fd)
 355 {
 356         int ret = dup(fd);
 357         if (ret < 0)
 358                 die_errno("dup failed");
 359         return ret;
 360 }
 361
 362 /**
 363  * xfopen() is the same as fopen(), but it die()s if the fopen() fails.
 364  */
 365 FILE *xfopen(const char *path, const char *mode)
 366 {
 367         for (;;) {
 368                 FILE *fp = fopen(path, mode);
 369                 if (fp)
 370                         return fp;
 371                 if (errno == EINTR)
 372                         continue;
 373
 374                 if (*mode && mode[1] == '+')
 375                         die_errno(_("could not open '%s' for reading and writing"), path);
 376                 else if (*mode == 'w' || *mode == 'a')
 377                         die_errno(_("could not open '%s' for writing"), path);
 378                 else
 379                         die_errno(_("could not open '%s' for reading"), path);
 380         }
 381 }
 382
 383 FILE *xfdopen(int fd, const char *mode)
 384 {
 385         FILE *stream = fdopen(fd, mode);
 386         if (stream == NULL)
 387                 die_errno("Out of memory? fdopen failed");
 388         return stream;
 389 }
 390
 391 FILE *fopen_for_writing(const char *path)
 392 {
 393         FILE *ret = fopen(path, "w");
 394
 395         if (!ret && errno == EPERM) {
 396                 if (!unlink(path))
 397                         ret = fopen(path, "w");
 398                 else
 399                         errno = EPERM;
 400         }
 401         return ret;
 402 }
 403
 404 static void warn_on_inaccessible(const char *path)
 405 {
 406         warning_errno(_("unable to access '%s'"), path);
 407 }
 408
 409 int warn_on_fopen_errors(const char *path)
 410 {
 411         if (errno != ENOENT && errno != ENOTDIR) {
 412                 warn_on_inaccessible(path);
 413                 return -1;
 414         }
 415
 416         return 0;
 417 }
 418
 419 FILE *fopen_or_warn(const char *path, const char *mode)
 420 {
 421         FILE *fp = fopen(path, mode);
 422
 423         if (fp)
 424                 return fp;
 425
 426         warn_on_fopen_errors(path);
 427         return NULL;
 428 }
 429
 430 int xmkstemp(char *filename_template)
 431 {
 432         int fd;
 433         char origtemplate[PATH_MAX];
 434         strlcpy(origtemplate, filename_template, sizeof(origtemplate));
 435
 436         fd = mkstemp(filename_template);
 437         if (fd < 0) {
 438                 int saved_errno = errno;
 439                 const char *nonrelative_template;
 440
 441                 if (strlen(filename_template) != strlen(origtemplate))
 442                         filename_template = origtemplate;
 443
 444                 nonrelative_template = absolute_path(filename_template);
 445                 errno = saved_errno;
 446                 die_errno("Unable to create temporary file '%s'",
 447                         nonrelative_template);
 448         }
 449         return fd;
 450 }
 451
 452 /* Adapted from libiberty's mkstemp.c. */
 453
 454 #undef TMP_MAX
 455 #define TMP_MAX 16384
 456
 457 int git_mkstemps_mode(char *pattern, int suffix_len, int mode)
 458 {
 459         static const char letters[] =
 460                 "abcdefghijklmnopqrstuvwxyz"
 461                 "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
 462                 "0123456789";
 463         static const int num_letters = ARRAY_SIZE(letters) - 1;
 464         static const char x_pattern[] = "XXXXXX";
 465         static const int num_x = ARRAY_SIZE(x_pattern) - 1;
 466         char *filename_template;
 467         size_t len;
 468         int fd, count;
 469
 470         len = strlen(pattern);
 471
 472         if (len < num_x + suffix_len) {
 473                 errno = EINVAL;
 474                 return -1;
 475         }
 476
 477         if (strncmp(&pattern[len - num_x - suffix_len], x_pattern, num_x)) {
 478                 errno = EINVAL;
 479                 return -1;
 480         }
 481
 482         /*
 483          * Replace pattern's XXXXXX characters with randomness.
 484          * Try TMP_MAX different filenames.
 485          */
 486         filename_template = &pattern[len - num_x - suffix_len];
 487         for (count = 0; count < TMP_MAX; ++count) {
 488                 int i;
 489                 uint64_t v;
 490                 if (csprng_bytes(&v, sizeof(v)) < 0)
 491                         return error_errno("unable to get random bytes for temporary file");
 492
 493                 /* Fill in the random bits. */
 494                 for (i = 0; i < num_x; i++) {
 495                         filename_template[i] = letters[v % num_letters];
 496                         v /= num_letters;
 497                 }
 498
 499                 fd = open(pattern, O_CREAT | O_EXCL | O_RDWR, mode);
 500                 if (fd >= 0)
 501                         return fd;
 502                 /*
 503                  * Fatal error (EPERM, ENOSPC etc).
 504                  * It doesn't make sense to loop.
 505                  */
 506                 if (errno != EEXIST)
 507                         break;
 508         }
 509         /* We return the null string if we can't find a unique file name.  */
 510         pattern[0] = '\0';
 511         return -1;
 512 }
 513
 514 int git_mkstemp_mode(char *pattern, int mode)
 515 {
 516         /* mkstemp is just mkstemps with no suffix */
 517         return git_mkstemps_mode(pattern, 0, mode);
 518 }
 519
 520 int xmkstemp_mode(char *filename_template, int mode)
 521 {
 522         int fd;
 523         char origtemplate[PATH_MAX];
 524         strlcpy(origtemplate, filename_template, sizeof(origtemplate));
 525
 526         fd = git_mkstemp_mode(filename_template, mode);
 527         if (fd < 0) {
 528                 int saved_errno = errno;
 529                 const char *nonrelative_template;
 530
 531                 if (!filename_template[0])
 532                         filename_template = origtemplate;
 533
 534                 nonrelative_template = absolute_path(filename_template);
 535                 errno = saved_errno;
 536                 die_errno("Unable to create temporary file '%s'",
 537                         nonrelative_template);
 538         }
 539         return fd;
 540 }
 541
 542 static int warn_if_unremovable(const char *op, const char *file, int rc)
 543 {
 544         int err;
 545         if (!rc || errno == ENOENT)
 546                 return 0;
 547         err = errno;
 548         warning_errno("unable to %s '%s'", op, file);
 549         errno = err;
 550         return rc;
 551 }
 552
 553 int unlink_or_msg(const char *file, struct strbuf *err)
 554 {
 555         int rc = unlink(file);
 556
 557         assert(err);
 558
 559         if (!rc || errno == ENOENT)
 560                 return 0;
 561
 562         strbuf_addf(err, "unable to unlink '%s': %s",
 563                     file, strerror(errno));
 564         return -1;
 565 }
 566
 567 int unlink_or_warn(const char *file)
 568 {
 569         return warn_if_unremovable("unlink", file, unlink(file));
 570 }
 571
 572 int rmdir_or_warn(const char *file)
 573 {
 574         return warn_if_unremovable("rmdir", file, rmdir(file));
 575 }
 576
 577 int remove_or_warn(unsigned int mode, const char *file)
 578 {
 579         return S_ISGITLINK(mode) ? rmdir_or_warn(file) : unlink_or_warn(file);
 580 }
 581
 582 static int access_error_is_ok(int err, unsigned flag)
 583 {
 584         return (is_missing_file_error(err) ||
 585                 ((flag & ACCESS_EACCES_OK) && err == EACCES));
 586 }
 587
 588 int access_or_warn(const char *path, int mode, unsigned flag)
 589 {
 590         int ret = access(path, mode);
 591         if (ret && !access_error_is_ok(errno, flag))
 592                 warn_on_inaccessible(path);
 593         return ret;
 594 }
 595
 596 int access_or_die(const char *path, int mode, unsigned flag)
 597 {
 598         int ret = access(path, mode);
 599         if (ret && !access_error_is_ok(errno, flag))
 600                 die_errno(_("unable to access '%s'"), path);
 601         return ret;
 602 }
 603
 604 char *xgetcwd(void)
 605 {
 606         struct strbuf sb = STRBUF_INIT;
 607         if (strbuf_getcwd(&sb))
 608                 die_errno(_("unable to get current working directory"));
 609         return strbuf_detach(&sb, NULL);
 610 }
 611
 612 int xsnprintf(char *dst, size_t max, const char *fmt, ...)
 613 {
 614         va_list ap;
 615         int len;
 616
 617         va_start(ap, fmt);
 618         len = vsnprintf(dst, max, fmt, ap);
 619         va_end(ap);
 620
 621         if (len < 0)
 622                 BUG("your snprintf is broken");
 623         if (len >= max)
 624                 BUG("attempt to snprintf into too-small buffer");
 625         return len;
 626 }
 627
 628 void write_file_buf(const char *path, const char *buf, size_t len)
 629 {
 630         int fd = xopen(path, O_WRONLY | O_CREAT | O_TRUNC, 0666);
 631         if (write_in_full(fd, buf, len) < 0)
 632                 die_errno(_("could not write to '%s'"), path);
 633         if (close(fd))
 634                 die_errno(_("could not close '%s'"), path);
 635 }
 636
 637 void write_file(const char *path, const char *fmt, ...)
 638 {
 639         va_list params;
 640         struct strbuf sb = STRBUF_INIT;
 641
 642         va_start(params, fmt);
 643         strbuf_vaddf(&sb, fmt, params);
 644         va_end(params);
 645
 646         strbuf_complete_line(&sb);
 647
 648         write_file_buf(path, sb.buf, sb.len);
 649         strbuf_release(&sb);
 650 }
 651
 652 void sleep_millisec(int millisec)
 653 {
 654         poll(NULL, 0, millisec);
 655 }
 656
 657 int xgethostname(char *buf, size_t len)
 658 {
 659         /*
 660          * If the full hostname doesn't fit in buf, POSIX does not
 661          * specify whether the buffer will be null-terminated, so to
 662          * be safe, do it ourselves.
 663          */
 664         int ret = gethostname(buf, len);
 665         if (!ret)
 666                 buf[len - 1] = 0;
 667         return ret;
 668 }
 669
 670 int is_empty_or_missing_file(const char *filename)
 671 {
 672         struct stat st;
 673
 674         if (stat(filename, &st) < 0) {
 675                 if (errno == ENOENT)
 676                         return 1;
 677                 die_errno(_("could not stat %s"), filename);
 678         }
 679
 680         return !st.st_size;
 681 }
 682
 683 int open_nofollow(const char *path, int flags)
 684 {
 685 #ifdef O_NOFOLLOW
 686         return open(path, flags | O_NOFOLLOW);
 687 #else
 688         struct stat st;
 689         if (lstat(path, &st) < 0)
 690                 return -1;
 691         if (S_ISLNK(st.st_mode)) {
 692                 errno = ELOOP;
 693                 return -1;
 694         }
 695         return open(path, flags);
 696 #endif
 697 }
 698
 699 int csprng_bytes(void *buf, size_t len)
 700 {
 701 #if defined(HAVE_ARC4RANDOM) || defined(HAVE_ARC4RANDOM_LIBBSD)
 702         /* This function never returns an error. */
 703         arc4random_buf(buf, len);
 704         return 0;
 705 #elif defined(HAVE_GETRANDOM)
 706         ssize_t res;
 707         char *p = buf;
 708         while (len) {
 709                 res = getrandom(p, len, 0);
 710                 if (res < 0)
 711                         return -1;
 712                 len -= res;
 713                 p += res;
 714         }
 715         return 0;
 716 #elif defined(HAVE_GETENTROPY)
 717         int res;
 718         char *p = buf;
 719         while (len) {
 720                 /* getentropy has a maximum size of 256 bytes. */
 721                 size_t chunk = len < 256 ? len : 256;
 722                 res = getentropy(p, chunk);
 723                 if (res < 0)
 724                         return -1;
 725                 len -= chunk;
 726                 p += chunk;
 727         }
 728         return 0;
 729 #elif defined(HAVE_RTLGENRANDOM)
 730         if (!RtlGenRandom(buf, len))
 731                 return -1;
 732         return 0;
 733 #elif defined(HAVE_OPENSSL_CSPRNG)
 734         int res = RAND_bytes(buf, len);
 735         if (res == 1)
 736                 return 0;
 737         if (res == -1)
 738                 errno = ENOTSUP;
 739         else
 740                 errno = EIO;
 741         return -1;
 742 #else
 743         ssize_t res;
 744         char *p = buf;
 745         int fd, err;
 746         fd = open("/dev/urandom", O_RDONLY);
 747         if (fd < 0)
 748                 return -1;
 749         while (len) {
 750                 res = xread(fd, p, len);
 751                 if (res < 0) {
 752                         err = errno;
 753                         close(fd);
 754                         errno = err;
 755                         return -1;
 756                 }
 757                 len -= res;
 758                 p += res;
 759         }
 760         close(fd);
 761         return 0;
 762 #endif
 763 }