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+dnl Check for mmap() |
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+dnl AC_FUNC_MMAP checks for private fixed mappings, we don't need |
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+dnl fixed mappings, so check only wether private mappings work. |
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+dnl AC_FUNC_MMAP would fail on HP-UX for example. |
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+AC_DEFUN([AC_C_FUNC_MMAP_PRIVATE], |
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+[ |
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+ AC_CACHE_CHECK([for working mmap], [ac_cv_c_mmap_private], |
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+ [ |
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+ AC_RUN_IFELSE([AC_LANG_SOURCE([ |
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+#include <unistd.h> |
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+#include <stdlib.h> |
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+#include <sys/mman.h> |
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+#ifdef HAVE_SYS_TYPES_H |
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+#include <sys/types.h> |
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+#endif |
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+#ifdef HAVE_SYS_STAT_H |
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+#include <sys/stat.h> |
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+#endif |
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+#include <fcntl.h> |
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+int main(void) |
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+{
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+ char *data, *data2, *data3; |
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+ unsigned i, datasize = 1024; |
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+ int fd; |
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+ |
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+ /* First, make a file with some known garbage in it. */ |
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+ data = (char*) malloc(datasize); |
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+ if(!data) |
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+ return 1; |
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+ for(i=0;i<datasize;i++) |
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+ *(data + i) = rand(); |
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+ umask(0); |
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+ fd = creat("conftest.mmap", 0600);
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+ if(fd < 0) |
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+ return 1; |
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+ if(write (fd, data, datasize) != datasize) |
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+ return 1; |
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+ close(fd); |
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+ fd = open("conftest.mmap", O_RDWR);
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+ if (fd < 0) |
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+ return 1; |
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+ /* Next, try to mmap the file at a fixed address which already has |
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+ something else allocated at it. If we can, also make sure that |
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+ we see the same garbage. */ |
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+ data2 = mmap(NULL, sizeof(data), PROT_READ | PROT_WRITE, |
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+ MAP_PRIVATE, fd, 0L); |
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+ if(data2 == MAP_FAILED) |
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+ return 2; |
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+ for(i=0;i<sizeof(data);i++) |
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+ if(*(data + i) != *(data2+ i)) |
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+ return 3; |
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+ /* Finally, make sure that changes to the mapped area do not |
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+ percolate back to the file as seen by read(). (This is a bug on |
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+ some variants of i386 svr4.0.) */ |
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+ for (i = 0; i < datasize; ++i) |
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+ *(data2 + i) = *(data2 + i) + 1; |
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+ data3 = (char*) malloc(datasize); |
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+ if(!data3) |
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+ return 1; |
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+ if(read (fd, data3, datasize) != datasize) |
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+ return 1; |
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+ for(i=0;i<sizeof(data);i++) |
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+ if(*(data + i) != *(data3 + i)) |
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+ return 3; |
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+ close(fd); |
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+ return 0; |
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+}])], |
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+ [ac_cv_c_mmap_private=yes], |
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+ [ac_cv_c_mmap_private=no], |
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+ [ac_cv_c_mmap_private=no])]) |
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+if test $ac_cv_c_mmap_private = yes; then |
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+ AC_DEFINE(HAVE_MMAP, 1, |
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+ [Define to 1 if you have a working `mmap' system call that supports MAP_PRIVATE.]) |
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+fi |
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+rm -f conftest.mmap |
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+]) |
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+ |
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+ |
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+ |