dist/ntp/ElectricFence/page.c

   1 /*      $NetBSD$        */
   2
   3 #ifdef HAVE_CONFIG_H
   4 # include <config.h>
   5 #endif
   6 #include "efence.h"
   7 #include <stdlib.h>
   8 #include <unistd.h>
   9 #include <fcntl.h>
  10 #include <sys/mman.h>
  11 #include <stdio.h>
  12 #include <errno.h>
  13 #include <string.h>
  14
  15 /*
  16  * Lots of systems are missing the definition of PROT_NONE.
  17  */
  18 #ifndef PROT_NONE
  19 #define PROT_NONE       0
  20 #endif
  21
  22 /*
  23  * 386 BSD has MAP_ANON instead of MAP_ANONYMOUS.
  24  */
  25 #if ( !defined(MAP_ANONYMOUS) && defined(MAP_ANON) )
  26 #define MAP_ANONYMOUS   MAP_ANON
  27 #endif
  28
  29 /*
  30  * For some reason, I can't find mprotect() in any of the headers on
  31  * IRIX or SunOS 4.1.2
  32  */
  33 /* extern C_LINKAGE int mprotect(void * addr, size_t len, int prot); */
  34
  35 static caddr_t  startAddr = (caddr_t) 0;
  36
  37 static const char *
  38 stringErrorReport(void)
  39 {
  40         return strerror(errno);
  41 }
  42
  43 /*
  44  * Create memory.
  45  */
  46 #if defined(MAP_ANONYMOUS)
  47 void *
  48 Page_Create(size_t size)
  49 {
  50         caddr_t         allocation;
  51
  52         /*
  53          * In this version, "startAddr" is a _hint_, not a demand.
  54          * When the memory I map here is contiguous with other
  55          * mappings, the allocator can coalesce the memory from two
  56          * or more mappings into one large contiguous chunk, and thus
  57          * might be able to find a fit that would not otherwise have
  58          * been possible. I could _force_ it to be contiguous by using
  59          * the MMAP_FIXED flag, but I don't want to stomp on memory mappings
  60          * generated by other software, etc.
  61          */
  62         allocation = (caddr_t) mmap(
  63          startAddr
  64         ,(int)size
  65         ,PROT_READ|PROT_WRITE
  66         ,MAP_PRIVATE|MAP_ANONYMOUS
  67         ,-1
  68         ,0);
  69
  70 #ifndef __hpux
  71         /*
  72          * Set the "address hint" for the next mmap() so that it will abut
  73          * the mapping we just created.
  74          *
  75          * HP/UX 9.01 has a kernel bug that makes mmap() fail sometimes
  76          * when given a non-zero address hint, so we'll leave the hint set
  77          * to zero on that system. HP recently told me this is now fixed.
  78          * Someone please tell me when it is probable to assume that most
  79          * of those systems that were running 9.01 have been upgraded.
  80          */
  81         startAddr = allocation + size;
  82 #endif
  83
  84         if ( allocation == (caddr_t)-1 )
  85                 EF_Exit("mmap() failed: %s", stringErrorReport());
  86
  87         return (void *)allocation;
  88 }
  89 #else
  90 void *
  91 Page_Create(size_t size)
  92 {
  93         static int      devZeroFd = -1;
  94         caddr_t         allocation;
  95
  96         if ( devZeroFd == -1 ) {
  97                 devZeroFd = open("/dev/zero", O_RDWR);
  98                 if ( devZeroFd < 0 )
  99                         EF_Exit(
 100                          "open() on /dev/zero failed: %s"
 101                         ,stringErrorReport());
 102         }
 103
 104         /*
 105          * In this version, "startAddr" is a _hint_, not a demand.
 106          * When the memory I map here is contiguous with other
 107          * mappings, the allocator can coalesce the memory from two
 108          * or more mappings into one large contiguous chunk, and thus
 109          * might be able to find a fit that would not otherwise have
 110          * been possible. I could _force_ it to be contiguous by using
 111          * the MMAP_FIXED flag, but I don't want to stomp on memory mappings
 112          * generated by other software, etc.
 113          */
 114         allocation = (caddr_t) mmap(
 115          startAddr
 116         ,(int)size
 117         ,PROT_READ|PROT_WRITE
 118         ,MAP_PRIVATE
 119         ,devZeroFd
 120         ,0);
 121
 122         startAddr = allocation + size;
 123
 124         if ( allocation == (caddr_t)-1 )
 125                 EF_Exit("mmap() failed: %s", stringErrorReport());
 126
 127         return (void *)allocation;
 128 }
 129 #endif
 130
 131 static void
 132 mprotectFailed(void)
 133 {
 134         EF_Exit("mprotect() failed: %s", stringErrorReport());
 135 }
 136
 137 void
 138 Page_AllowAccess(void * address, size_t size)
 139 {
 140         if ( mprotect((caddr_t)address, size, PROT_READ|PROT_WRITE) < 0 )
 141                 mprotectFailed();
 142 }
 143
 144 void
 145 Page_DenyAccess(void * address, size_t size)
 146 {
 147         if ( mprotect((caddr_t)address, size, PROT_NONE) < 0 )
 148                 mprotectFailed();
 149 }
 150
 151 void
 152 Page_Delete(void * address, size_t size)
 153 {
 154         if ( munmap((caddr_t)address, size) < 0 )
 155                 Page_DenyAccess(address, size);
 156 }
 157
 158 #if defined(_SC_PAGESIZE)
 159 size_t
 160 Page_Size(void)
 161 {
 162         return (size_t)sysconf(_SC_PAGESIZE);
 163 }
 164 #elif defined(_SC_PAGE_SIZE)
 165 size_t
 166 Page_Size(void)
 167 {
 168         return (size_t)sysconf(_SC_PAGE_SIZE);
 169 }
 170 #else
 171 /* extern int   getpagesize(); */
 172 size_t
 173 Page_Size(void)
 174 {
 175         return getpagesize();
 176 }
 177 #endif