Someone can help me with my code in c? - c

Question

Iam trying to create a code with 1 parent and 2 childrens. The method recive 3 parameters:
original_file word1 word2
The parent read a file line by line:
If the line is pair, send the line to method proccess_pair and the word1.
If the line contains the word1, save the lines in the file_1.txt
If the line is odd, send the line to method proccess_odd and the word2.
If the line contains the word1, save the lines in the file_2.txt
Im beginner in c, and i trying with this:
int p_h1[2] // pipe from parent to child1
int p_h2[2];// pipe from parent to child2
int main(int argc, char **argv){
pid_t pdi1, pdi2;
FILE *fd; // for original file
FILE *p_h1f, *p_h2f; //file create for child1 and child2 respectively
char buffer[1024];//buffer
if (pid1<0){
fprintf(stderr,"Error fork \n %s \n",strerror(errno));
exit(EXIT_FAILURE);
}
else if (pid1==0){//Im the child1
//proccess for child 1
proccess_pair(arg[2]);
exit(EXIT_SUCCESS);
}
pid2 = fork();
if (pid2<0){
fprintf(stderr,"Error fork \n %s \n",strerror(errno));
exit(EXIT_FAILURE);
}
else if (pid2==0){//Im the child2
//proccess for child 2
proccess_odd(arg[2]);
exit(EXIT_SUCCESS);
}
//Parent dont read from pipe
close(p_h1[0]);
close(p_h2[0]);
fd = fopen(argv[1],"r"); //I openthe file for read it;
p_h1f = fdopen(p_h1[1],"w")
p_h2f = fdopen(p_h2[1],"w")
int i = 1;
while(fgets(buffer,1024,fd) != NULL){
if (i % 2 ==0){ //check if the lines is pairs
fputs(buffer,p_h1f);
fflush(p_h1f);
}else{
fputs(buffer,p_h2f);
fflush(p_h2f);
}
i++;
}
close(p_h1[1]);
close(p_h2[1]);
fclose(fd);
wait(NULL);
wait(NULL);
}
Both methods(for chil1 and chil2) will be the same(but closing the correct sides of pipes), for this reason i only implement one of them:
void proccess_pair(char *word1){
FILE *fd;
fd = fopen("file_1.txt","w");
//closing the not used
close(p_h1[1]);
close(p_h2[1]);
close(p_h2[0]);
int nsto = dup(1)//duplicate the stdout
dup2(fd,1);//changing stdout->file_1.txt
execlp("grep","grep",word1,NULL);//execution of grep
exit(EXIT_SUCCESS);
}
Im learning and i know that i have many many error, for this reason i need help.
Regards

Answer 1

How i can create many pipes in an array in c?
On a POSIX-conformant system, you can do that by calling pipe() many times on elements of a 2D array of int, as you presented.
¿I can use two different pipes(parent-child1,parent-child2)? I can use an array of pipes?
A pipe itself lives only in the kernel. There is no userspace data
structure representing a pipe, so you cannot have an array of pipes.
The file descriptors for the pipe ends, however, are just ints. The pipe() function takes as its argument a pointer to the first element of an array of at least two int, and (on success) it writes the appropriate file descriptors into the array.
From a C perspective, there is nothing special about the array in which the pipe ends are to be returned. In particular, it can be an element of a multi-dimensional array if you so desire. Or it can be a local variable. Or it can be a member of a struct or a union. Or it can be a large enough block of dynamically-allocated space. It's not special.

Answer 2

Something like this should work:
int new_process(char *word){ // return the writing part of a pipe to a newly created child
int p[2];
pipe( p ); // get a new pipe
if (fork()==0) { // create a new child
dup2(p[0],0); // child's in is pipe's entry
close(p[1]); // close writing part
execlp("grep","grep",word,NULL); // exec
}
close(p[0]); // parent don't need the reading part
return p[1]; // send back the writing part to caller
}
int main(int argc, char **argv) {
int f1 = new_process(argv[1]); // get the pipe to first child
int f2 = new_process(argv[1]); // ...second...
char buffer[1024];//buffer
FILE *fd = fopen(argv[1],"r"); // open the file for reading;
while(fgets(buffer,1024,fd) != NULL) { // read aline
if (i % 2 ==0) { //check if the line no is pair
fputs(buffer,f1); // send it to first child
fflush(f1);
} else{
fputs(buffer,f2); // send it to second child
fflush(f2);
}
i++;
}
close(f1);
close(f2);
fclose(fd);
wait(NULL);
wait(NULL);
}
Don't forget to add necessary controls on failures.