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#ifdef __linux__
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>
#ifndef O_DIRECT
#define O_DIRECT 00040000 /* direct disk access hint */
#endif
int main(int argc, char** argv) {
if (argc != 2) {
fprintf(stderr, "Expected 1 argument: the file to read.\n");
return 1;
}
int fd = open(argv[1], O_RDONLY | O_DIRECT);
if (fd == -1) {
perror("failed to open file");
return 1;
}
const size_t buf_size = 4096;
unsigned char* buf = mmap(NULL, buf_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
if (buf == MAP_FAILED) {
perror("mmap failed");
return 1;
}
while (1) {
ssize_t amt_read = read(fd, buf, buf_size);
if (amt_read == 0) {
break;
}
if (amt_read == -1) {
perror("failed to read file");
return 1;
}
fwrite(buf, 1, amt_read, stdout);
fflush(stdout);
}
return 0;
}
#else // __linux__
#include <stdio.h>
int main(void) {
fprintf(stderr, "Not supported on this platform.\n");
return 1;
}
#endif // __linux__
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