#include "unpipc.h" int main(int argc, char **argv) { int fd, i; char *ptr; size_t filesize, mmapsize, pagesize; if (argc != 4) err_quit("usage: test1 "); filesize = atoi(argv[2]); mmapsize = atoi(argv[3]); /* 4open file: create or truncate; set file size */ fd = Open(argv[1], O_RDWR | O_CREAT | O_TRUNC, FILE_MODE); Lseek(fd, filesize-1, SEEK_SET); Write(fd, "", 1); ptr = Mmap(NULL, mmapsize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); Close(fd); pagesize = Sysconf(_SC_PAGESIZE); printf("PAGESIZE = %ld\n", (long) pagesize); for (i = 0; i < max(filesize, mmapsize); i += pagesize) { printf("ptr[%d] = %d\n", i, ptr[i]); ptr[i] = 1; printf("ptr[%d] = %d\n", i + pagesize - 1, ptr[i + pagesize - 1]); ptr[i + pagesize - 1] = 1; } printf("ptr[%d] = %d\n", i, ptr[i]); exit(0); }