libctf/ctf-subr.c

   1 /* Simple subrs.
   2    Copyright (C) 2019 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 const char *
 130 ctf_strerror (int err)
 131 {
 132   return (const char *) (strerror (err));
 133 }
 134
 135 /* Set the CTF library client version to the specified version.  If version is
 136    zero, we just return the default library version number.  */
 137 int
 138 ctf_version (int version)
 139 {
 140   if (version < 0)
 141     {
 142       errno = EINVAL;
 143       return -1;
 144     }
 145
 146   if (version > 0)
 147     {
 148       /*  Dynamic version switching is not presently supported. */
 149       if (version != CTF_VERSION)
 150         {
 151           errno = ENOTSUP;
 152           return -1;
 153         }
 154       ctf_dprintf ("ctf_version: client using version %d\n", version);
 155       _libctf_version = version;
 156     }
 157
 158   return _libctf_version;
 159 }
 160
 161 void
 162 libctf_init_debug (void)
 163 {
 164   static int inited;
 165   if (!inited)
 166     {
 167       _libctf_debug = getenv ("LIBCTF_DEBUG") != NULL;
 168       inited = 1;
 169     }
 170 }
 171
 172 void ctf_setdebug (int debug)
 173 {
 174   /* Ensure that libctf_init_debug() has been called, so that we don't get our
 175      debugging-on-or-off smashed by the next call.  */
 176
 177   libctf_init_debug();
 178   _libctf_debug = debug;
 179   ctf_dprintf ("CTF debugging set to %i\n", debug);
 180 }
 181
 182 int ctf_getdebug (void)
 183 {
 184   return _libctf_debug;
 185 }
 186
 187 _libctf_printflike_ (1, 2)
 188 void ctf_dprintf (const char *format, ...)
 189 {
 190   if (_libctf_debug)
 191     {
 192       va_list alist;
 193
 194       va_start (alist, format);
 195       fflush (stdout);
 196       (void) fputs ("libctf DEBUG: ", stderr);
 197       (void) vfprintf (stderr, format, alist);
 198       va_end (alist);
 199     }
 200 }