none/tests/linux/mremap2.c

   1 #define _GNU_SOURCE
   2
   3 #include <stdio.h>
   4
   5 #include "tests/sys_mman.h"
   6 #include <assert.h>
   7 #include <stdlib.h>
   8 #include <sys/types.h>
   9 #include <unistd.h>
  10 #include <errno.h>
  11 #include <syscall.h>
  12
  13
  14 #ifndef REMAP_FIXED
  15 #define MREMAP_FIXED 2
  16 #endif
  17
  18
  19 static int PAGE;
  20
  21 void mapanon_fixed ( void* start, size_t length )
  22 {
  23   void* r = mmap(start, length, PROT_NONE,
  24                  MAP_FIXED|MAP_PRIVATE|MAP_ANONYMOUS, 0,0);
  25   assert(r != MAP_FAILED);
  26   assert(r == start);
  27 }
  28
  29 void unmap_and_check ( void* start, size_t length )
  30 {
  31    int r = munmap( start, length );
  32    assert(r == 0);
  33 }
  34
  35 char* workingarea = NULL;
  36 char* try_dst     = NULL;
  37
  38 // set up working area so expansion limit is 20*PAGE
  39 //
  40 //   |   10   |   20   |   10   |   60   |
  41 //   |  pre   |  src   |  FREE  |  post  |
  42 //
  43 //  A suitable attempted fixed dst is workingarea + 150*PAGE.
  44
  45 char* setup ( void* other_stuff, int other_len )
  46 {
  47   if (!workingarea) {
  48      workingarea = mmap(0, 200*PAGE, PROT_NONE,
  49                            MAP_ANONYMOUS|MAP_PRIVATE, 0,0);
  50      assert(workingarea);
  51      try_dst = workingarea + 150*PAGE;
  52      unmap_and_check(workingarea, 200*PAGE);
  53   }
  54
  55   if (other_stuff) {
  56     unmap_and_check(other_stuff, other_len);
  57   }
  58
  59   // get rid of the old working area
  60   unmap_and_check( workingarea, 200*PAGE);
  61
  62   // pre block
  63   mapanon_fixed( workingarea + 0*PAGE, 9*PAGE);
  64
  65   // the area
  66   mapanon_fixed( workingarea + 10*PAGE, 20*PAGE );
  67
  68   // upper half
  69   mapanon_fixed( workingarea + 40*PAGE, 60*PAGE );
  70
  71   return workingarea + 10*PAGE;
  72 }
  73
  74 /* show the working area */
  75 void show ( void )
  76 {
  77   int i,r __attribute__((unused));
  78   for (i = 0; i < 200; i++) {
  79     r = mprotect( workingarea + i * PAGE, PAGE, PROT_NONE );
  80     // We used to print 'X' or '.' according to the mprotect result, but the
  81     // results are too variable and the test was never reliable.  So now we
  82     // just always print '.'.  At least this test gives mremap a thorough
  83     // working out and so will detect egregious problems like crashes.
  84     //printf("%c", r == 0 ? 'X' : '.');
  85     printf(".");
  86     if (i == 49 || i == 99 || i == 149) printf("\n");
  87   }
  88   printf("\n");
  89 }
  90
  91
  92 char* dst = NULL;
  93 char* src = NULL;
  94 char* dst_impossible = NULL;
  95
  96
  97 char* identify ( char* p )
  98 {
  99   if (p == dst)            return "dst";
 100   if (p == src)            return "src";
 101   if (p == dst_impossible) return "dst_imp!";
 102   if (p == try_dst)        return "dst_poss";
 103   return "other";
 104 }
 105
 106 int main ( void )
 107 {
 108   int alocal, maymove, fixed, nsi, dstpossible;
 109   int newsizes[6] = { 19, 20, 21, 29, 30, 31 };
 110
 111   char* tidythis = NULL;
 112   int  tidylen = 0;
 113   int firsttime = 1;
 114   char buf[100];
 115
 116   dst_impossible = (char*)(&alocal) + 500 * 1000 * 1000;
 117
 118   PAGE = sysconf(_SC_PAGESIZE);
 119
 120   for (maymove = 0; maymove <= 1 ; maymove++) {
 121   for (fixed = 0; fixed <= 1; fixed++) {
 122     printf("\n");
 123   for (nsi = 0; nsi < 6; nsi++) {
 124   for (dstpossible = 0; dstpossible <= 1; dstpossible++) {
 125
 126     char* r;
 127     int newsize = newsizes[nsi] * PAGE;
 128     int flags = (maymove ? MREMAP_MAYMOVE : 0)  |
 129                 (fixed ? MREMAP_FIXED : 0);
 130     dst = dstpossible ? try_dst : dst_impossible;
 131     src = setup( tidythis, tidylen );
 132
 133     if (firsttime) {
 134        printf("dst_possible   = %p\n", try_dst );
 135        printf("dst_impossible = %p\n", dst_impossible );
 136        printf("           src = %p\n", src);
 137        printf("\n");
 138        sprintf(buf, "cat /proc/%d/maps", getpid());
 139        if (0) system(buf);
 140        firsttime = 0;
 141     }
 142
 143     printf("maymv %d   fixed %d   newsz %2d   dstpo %d  dst %p ->  ",
 144            maymove, fixed, newsizes[nsi], dstpossible, dst );
 145     r = (char*)
 146         syscall(__NR_mremap, src, 20*PAGE, newsize, flags, dst, 0 );
 147     // We used to print the address or error, but that was also unreliable.
 148     //if (r == MAP_FAILED)
 149     //  printf("error %d\n", errno);
 150     //else
 151     //  printf("%p (== %s)\n", r, identify(r));
 152     printf("\n");
 153
 154     if (1) {
 155        show();
 156        printf("\n");
 157     }
 158
 159     if (r != MAP_FAILED) {
 160       if (r != src && r != try_dst && r != dst_impossible) {
 161         tidythis = r;
 162         tidylen = newsize;
 163       }
 164     }
 165
 166   }
 167   }
 168   }
 169   }
 170   return 0;
 171 }