banan-os/userspace/cat-mmap/main.cpp

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#include <fcntl.h>
#include <stdio.h>
#include <sys/mman.h>
#include <sys/stat.h>
bool cat_file(int fd)
{
struct stat st;
if (fstat(fd, &st) == -1)
{
perror("stat");
return false;
}
void* addr = mmap(nullptr, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
if (addr == MAP_FAILED)
{
perror("mmap");
return false;
}
ssize_t nwrite = write(STDOUT_FILENO, addr, st.st_size);
if (nwrite == -1)
perror("write");
if (munmap(addr, st.st_size) == -1)
{
perror("munmap");
return false;
}
return true;
}
int main(int argc, char** argv)
{
int ret = 0;
if (argc > 1)
{
for (int i = 1; i < argc; i++)
{
int fd = open(argv[i], O_RDONLY);
if (fd == -1)
{
perror(argv[i]);
ret = 1;
continue;
}
if (!cat_file(fd))
ret = 1;
close(fd);
}
}
else
{
if (!cat_file(STDIN_FILENO))
ret = 1;
}
return ret;
}