Restore stdin after a pipe - c

Question

I made a pipe using stdin and stdout to communicate but I can't figure out how to restore stdin after closing it in my father process.
Here is an example :
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
void readPBM(char *output)
{
char tmp[1024];
int fd[2] = {0,0};
int pid;
//Open the pipe for inter-process communication
pipe(&fd[0]);
//Fork and test if we are child or parent process
pid = fork();
if(pid) //Parent process
{
wait(NULL); //Wait for child's end
close(fd[1]);//Close pipe's write stream
close(0);//Close stdin
dup(fd[0]);
close(fd[0]);
strcpy(output, "");// Init output at 0
while(fgets(tmp, 1024, stdin) != NULL) //Put remainings entry in output
{
strcat(output, tmp);
}
strcat(output, "It works\n");
}
else if(pid == 0) //Child process
{
close(fd[0]);//Close pipe's read stream
close(1);//Close stdout
dup(fd[1]);//Duplicate stdin
close(fd[1]);
printf("A random string ...\n");
exit(0);
}
else //Print error if fork failed
{
printf("Error creating a new process");
exit(EXIT_FAILURE);
}
}
int main(int argc, char *argv[])
{
int i, j;
char *str = NULL;
char c;
str = malloc(512 * sizeof(char*));
readPBM(str);
printf("%s", str);
c = getchar();
}
I tried to save stdin using : int stdin_copy = dup(0) then restoring it but my getchar is not working.
I also tried to use freopen("/dev/stdin", "a", stdin) but it still doesn't wait for an input

Answer 1

Using fdopen seems to work well so here is the fixed code :
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
void readPBM(char *output)
{
FILE* fp;
char tmp[1024];
int fd[2] = {0,0};
int pid;
//Open the pipe for inter-process communication
pipe(&fd[0]);
//Fork and test if we are child or parent process
pid = fork();
if(pid) //Parent process
{
wait(NULL); //Wait for child's end
close(fd[1]);//Close pipe's write stream
fp = fdopen(fd[0], "r");
strcpy(output, "");// Init output at 0
while(fgets(tmp, 1024, fp) != NULL) //Put remainings entry in output
{
strcat(output, tmp);
}
strcat(output, "It works\n");
fclose(fp);
}
else if(pid == 0) //Child process
{
close(fd[0]);//Close pipe's read stream
close(1);//Close stdout
dup(fd[1]);//Duplicate stdin
close(fd[1]);
printf("A random string ...\n");
exit(0);
}
else //Print error if fork failed
{
printf("Error creating a new process");
exit(EXIT_FAILURE);
}
}
int main(int argc, char *argv[])
{
int i, j;
char *str = NULL;
char c;
str = malloc(512 * sizeof(char*));
readPBM(str);
printf("%s", str);
c = getchar();
}