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49 lines
1.5 KiB
Nim
49 lines
1.5 KiB
Nim
# Small test program to test for mmap() weirdnesses
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include "lib/system/ansi_c"
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const
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PageSize = 4096
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PROT_READ = 1 # page can be read
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PROT_WRITE = 2 # page can be written
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MAP_PRIVATE = 2 # Changes are private
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when defined(macosx) or defined(bsd):
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const MAP_ANONYMOUS = 0x1000
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elif defined(solaris):
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const MAP_ANONYMOUS = 0x100
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else:
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var
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MAP_ANONYMOUS {.importc: "MAP_ANONYMOUS", header: "<sys/mman.h>".}: cint
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proc mmap(adr: pointer, len: int, prot, flags, fildes: cint,
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off: int): pointer {.header: "<sys/mman.h>".}
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proc munmap(adr: pointer, len: int) {.header: "<sys/mman.h>".}
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proc osAllocPages(size: int): pointer {.inline.} =
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result = mmap(nil, size, PROT_READ or PROT_WRITE,
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MAP_PRIVATE or MAP_ANONYMOUS, -1, 0)
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if result == nil or result == cast[pointer](-1):
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quit 1
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cfprintf(c_stdout, "allocated pages %p..%p\n", result,
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cast[int](result) + size)
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proc osDeallocPages(p: pointer, size: int) {.inline} =
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cfprintf(c_stdout, "freed pages %p..%p\n", p, cast[int](p) + size)
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munmap(p, size-1)
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proc `+!!`(p: pointer, size: int): pointer {.inline.} =
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result = cast[pointer](cast[int](p) + size)
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var p = osAllocPages(3 * PageSize)
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osDeallocPages(p, PageSize)
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# If this fails the OS has freed the whole block starting at 'p':
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echo(cast[ptr int](p +!! (pageSize*2))[])
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osDeallocPages(p +!! PageSize*2, PageSize)
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osDeallocPages(p +!! PageSize, PageSize)
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