libctf/ctf-subr.c

   1 /* Simple subrs.
   2    Copyright (C) 2019-2020 Free Software Foundation, Inc.
   3
   4    This file is part of libctf.
   5
   6    libctf is free software; you can redistribute it and/or modify it under
   7    the terms of the GNU General Public License as published by the Free
   8    Software Foundation; either version 3, or (at your option) any later
   9    version.
  10
  11    This program is distributed in the hope that it will be useful, but
  12    WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  14    See the GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; see the file COPYING.  If not see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <ctf-impl.h>
  21 #ifdef HAVE_MMAP
  22 #include <sys/mman.h>
  23 #endif
  24 #include <sys/types.h>
  25 #include <stdarg.h>
  26 #include <string.h>
  27 #include <unistd.h>
  28
  29 #ifndef ENOTSUP
  30 #define ENOTSUP ENOSYS
  31 #endif
  32
  33 int _libctf_version = CTF_VERSION;            /* Library client version.  */
  34 int _libctf_debug = 0;                        /* Debugging messages enabled.  */
  35
  36 /* Private, read-only mmap from a file, with fallback to copying.
  37
  38    No handling of page-offset issues at all: the caller must allow for that. */
  39
  40 _libctf_malloc_ void *
  41 ctf_mmap (size_t length, size_t offset, int fd)
  42 {
  43   void *data;
  44
  45 #ifdef HAVE_MMAP
  46   data = mmap (NULL, length, PROT_READ, MAP_PRIVATE, fd, offset);
  47   if (data == MAP_FAILED)
  48     data = NULL;
  49 #else
  50   if ((data = malloc (length)) != NULL)
  51     {
  52       if (ctf_pread (fd, data, length, offset) <= 0)
  53         {
  54           free (data);
  55           data = NULL;
  56         }
  57     }
  58 #endif
  59   return data;
  60 }
  61
  62 void
  63 ctf_munmap (void *buf, size_t length _libctf_unused_)
  64 {
  65 #ifdef HAVE_MMAP
  66   (void) munmap (buf, length);
  67 #else
  68   free (buf);
  69 #endif
  70 }
  71
  72 ssize_t
  73 ctf_pread (int fd, void *buf, ssize_t count, off_t offset)
  74 {
  75   ssize_t len;
  76   size_t acc = 0;
  77   char *data = (char *) buf;
  78
  79 #ifdef HAVE_PREAD
  80   while (count > 0)
  81     {
  82       errno = 0;
  83       if (((len = pread (fd, data, count, offset)) < 0) &&
  84           errno != EINTR)
  85           return len;
  86       if (errno == EINTR)
  87         continue;
  88
  89       acc += len;
  90       if (len == 0)                             /* EOF.  */
  91         return acc;
  92
  93       count -= len;
  94       offset += len;
  95       data += len;
  96     }
  97   return acc;
  98 #else
  99   off_t orig_off;
 100
 101   if ((orig_off = lseek (fd, 0, SEEK_CUR)) < 0)
 102     return -1;
 103   if ((lseek (fd, offset, SEEK_SET)) < 0)
 104     return -1;
 105
 106   while (count > 0)
 107     {
 108       errno = 0;
 109       if (((len = read (fd, data, count)) < 0) &&
 110           errno != EINTR)
 111           return len;
 112       if (errno == EINTR)
 113         continue;
 114
 115       acc += len;
 116       if (len == 0)                             /* EOF.  */
 117         break;
 118
 119       count -= len;
 120       data += len;
 121     }
 122   if ((lseek (fd, orig_off, SEEK_SET)) < 0)
 123     return -1;                                  /* offset is smashed.  */
 124 #endif
 125
 126   return acc;
 127 }
 128
 129 /* Set the CTF library client version to the specified version.  If version is
 130    zero, we just return the default library version number.  */
 131 int
 132 ctf_version (int version)
 133 {
 134   if (version < 0)
 135     {
 136       errno = EINVAL;
 137       return -1;
 138     }
 139
 140   if (version > 0)
 141     {
 142       /*  Dynamic version switching is not presently supported. */
 143       if (version != CTF_VERSION)
 144         {
 145           errno = ENOTSUP;
 146           return -1;
 147         }
 148       ctf_dprintf ("ctf_version: client using version %d\n", version);
 149       _libctf_version = version;
 150     }
 151
 152   return _libctf_version;
 153 }
 154
 155 void
 156 libctf_init_debug (void)
 157 {
 158   static int inited;
 159   if (!inited)
 160     {
 161       _libctf_debug = getenv ("LIBCTF_DEBUG") != NULL;
 162       inited = 1;
 163     }
 164 }
 165
 166 void ctf_setdebug (int debug)
 167 {
 168   /* Ensure that libctf_init_debug() has been called, so that we don't get our
 169      debugging-on-or-off smashed by the next call.  */
 170
 171   libctf_init_debug();
 172   _libctf_debug = debug;
 173   ctf_dprintf ("CTF debugging set to %i\n", debug);
 174 }
 175
 176 int ctf_getdebug (void)
 177 {
 178   return _libctf_debug;
 179 }
 180
 181 _libctf_printflike_ (1, 2)
 182 void ctf_dprintf (const char *format, ...)
 183 {
 184   if (_libctf_unlikely_ (_libctf_debug))
 185     {
 186       va_list alist;
 187
 188       va_start (alist, format);
 189       fflush (stdout);
 190       (void) fputs ("libctf DEBUG: ", stderr);
 191       (void) vfprintf (stderr, format, alist);
 192       va_end (alist);
 193     }
 194 }
 195
 196 /* This needs more attention to thread-safety later on.  */
 197 static ctf_list_t open_errors;
 198
 199 /* Errors and warnings.  Report the warning or error to the list in FP (or the
 200    open errors list if NULL): if ERR is nonzero it is the errno to report to the
 201    debug stream instead of that recorded on fp.  */
 202 _libctf_printflike_ (4, 5)
 203 extern void
 204 ctf_err_warn (ctf_file_t *fp, int is_warning, int err,
 205               const char *format, ...)
 206 {
 207   va_list alist;
 208   ctf_err_warning_t *cew;
 209
 210   /* Don't bother reporting errors here: we can't do much about them if they
 211      happen.  If we're so short of memory that a tiny malloc doesn't work, a
 212      vfprintf isn't going to work either and the caller will have to rely on the
 213      ENOMEM return they'll be getting in short order anyway.  */
 214
 215   if ((cew = malloc (sizeof (ctf_err_warning_t))) == NULL)
 216     return;
 217
 218   cew->cew_is_warning = is_warning;
 219   va_start (alist, format);
 220   if (vasprintf (&cew->cew_text, format, alist) < 0)
 221     {
 222       free (cew);
 223       va_end (alist);
 224       return;
 225     }
 226   va_end (alist);
 227
 228   /* Include the error code only if there is one, and if this is not a warning.
 229      (Warnings may not have a meaningful error code, since the warning may not
 230      lead to unwinding up to the user.)  */
 231   if (!is_warning && (err != 0 || (fp && ctf_errno (fp) != 0)))
 232     ctf_dprintf ("%s: %s (%s)\n", is_warning ? _("error") : _("warning"),
 233                  cew->cew_text, err != 0 ? ctf_errmsg (err)
 234                  : ctf_errmsg (ctf_errno (fp)));
 235   else
 236     ctf_dprintf ("%s: %s\n", is_warning ? _("error") : _("warning"),
 237                  cew->cew_text);
 238
 239   if (fp != NULL)
 240     ctf_list_append (&fp->ctf_errs_warnings, cew);
 241   else
 242     ctf_list_append (&open_errors, cew);
 243 }
 244
 245 /* Move all the errors/warnings from an fp into the open_errors.  */
 246 void
 247 ctf_err_warn_to_open (ctf_file_t *fp)
 248 {
 249   ctf_list_splice (&open_errors, &fp->ctf_errs_warnings);
 250 }
 251
 252 /* Error-warning reporting: an 'iterator' that returns errors and warnings from
 253    the error/warning list, in order of emission.  Errors and warnings are popped
 254    after return: the caller must free the returned error-text pointer.
 255
 256    An fp of NULL returns CTF-open-time errors from the open_errors variable
 257    above.
 258
 259    The treatment of errors from this function itself is somewhat unusual: it
 260    will often be called on an error path, so we don't want to overwrite the
 261    ctf_errno unless we have no choice.  So, like ctf_bufopen et al, this
 262    function takes an errp pointer where errors are reported.  The pointer is
 263    optional: if not set, errors are reported via the fp (if non-NULL).  Calls
 264    with neither fp nor errp set are mildly problematic because there is no clear
 265    way to report end-of-iteration: you just have to assume that a NULL return
 266    means the end, and not an iterator error.  */
 267
 268 char *
 269 ctf_errwarning_next (ctf_file_t *fp, ctf_next_t **it, int *is_warning,
 270                      int *errp)
 271 {
 272   ctf_next_t *i = *it;
 273   char *ret;
 274   ctf_list_t *errlist;
 275   ctf_err_warning_t *cew;
 276
 277   if (fp)
 278     errlist = &fp->ctf_errs_warnings;
 279   else
 280     errlist = &open_errors;
 281
 282   if (!i)
 283     {
 284       if ((i = ctf_next_create ()) == NULL)
 285         {
 286           if (errp)
 287             *errp = ENOMEM;
 288           else if (fp)
 289             ctf_set_errno (fp, ENOMEM);
 290           return NULL;
 291         }
 292
 293       i->cu.ctn_fp = fp;
 294       i->ctn_iter_fun = (void (*) (void)) ctf_errwarning_next;
 295       *it = i;
 296     }
 297
 298   if ((void (*) (void)) ctf_errwarning_next != i->ctn_iter_fun)
 299     {
 300       if (errp)
 301         *errp = ECTF_NEXT_WRONGFUN;
 302       else if (fp)
 303         ctf_set_errno (fp, ECTF_NEXT_WRONGFUN);
 304       return NULL;
 305     }
 306
 307   if (fp != i->cu.ctn_fp)
 308     {
 309       if (errp)
 310         *errp = ECTF_NEXT_WRONGFP;
 311       else if (fp)
 312         ctf_set_errno (fp, ECTF_NEXT_WRONGFP);
 313       return NULL;
 314     }
 315
 316   cew = ctf_list_next (errlist);
 317
 318   if (!cew)
 319     {
 320       ctf_next_destroy (i);
 321       *it = NULL;
 322       if (errp)
 323         *errp = ECTF_NEXT_END;
 324       else if (fp)
 325         ctf_set_errno (fp, ECTF_NEXT_END);
 326       return NULL;
 327     }
 328
 329   if (is_warning)
 330     *is_warning = cew->cew_is_warning;
 331   ret = cew->cew_text;
 332   ctf_list_delete (errlist, cew);
 333   free (cew);
 334   return ret;
 335 }
 336
 337 void
 338 ctf_assert_fail_internal (ctf_file_t *fp, const char *file, size_t line,
 339                           const char *exprstr)
 340 {
 341   ctf_err_warn (fp, 0, ECTF_INTERNAL, _("%s: %lu: libctf assertion failed: %s"),
 342                 file, (long unsigned int) line, exprstr);
 343   ctf_set_errno (fp, ECTF_INTERNAL);
 344 }