Copy files of directory into another using system calls on linux - c

Question

Im trying to copy the files from a directory into another using system calls but i get a "violation of segment core" and I don't know why, the first argument is the origin directory, the second the destiny directory, the third is not used and the fourth is the bytes position where I start to copy every file of the first directory with this I mean for example if Pos = 4 and the file is helloo the copied file content would be o because I use lseek to move to pointer to the position 4 and start to copy from there, this is my code:
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#define BS 512
#define error(a) {perror(a); exit(1);};
int main(int argc, char *argv[]) //argv1 Dir1 argv2 Dir2 argv3 Fich argv4 Pos
{
DIR *dir1;
DIR *dir2;
struct dirent *lectura1;
struct dirent *lectura2;
struct stat st;
int datos1;
int datos2;
int size;
char path[256] = "";
char path2[256] = "";
char temp[256];
char buf[BS];
int j;
int i;
if(argc != 5)
{
error("Numero de argumentos incorrecto");
}
int Pos = atoi(argv[4]);
if(Pos < 0)
{
error("Pos must be 0 or greater")
}
if((dir1 = opendir(argv[1])) == NULL){error("Failed to open origin dir");}
if((dir2 = opendir(argv[2])) == NULL){error("Failed to open destiny dir");}
while((lectura1 = readdir(dir1)) != NULL)
{
sprintf(path, "%s/%s", argv[1], lectura1->d_name);
lectura2 = readdir(dir2);
sprintf(path2, "%s/%s", argv[2], lectura2->d_name);
if (strcmp(lectura1->d_name, "..") != 0 && strcmp(lectura1->d_name, ".") != 0)
{
if (stat(path, &st) == 0)
{
if (S_ISREG(st.st_mode)) //If is a regular file
{
if((datos1 = open(path, O_RDONLY, 00600)) == -1){error("Failed to open file");} //Opens the target file of Dir1 to copy inside Dir2
size = lseek(datos1,0,SEEK_END);
if (size > Pos) //Check if the size of the file is bigger than the position that indicates the point from which to start copying the file
{
lseek(datos1,Pos,SEEK_SET); //Moves the pointer to the start position of the file1
if((datos2 = open(path2, O_CREAT|O_WRONLY, 00200)) == -1){error("Error al abrir archivo copia");}
lseek(datos2,0,SEEK_SET);
j = BS;
i = 0;
int n = 0;
if ((size - i) < BS)
{
j = size - i;
}
while ((n = read(datos1, buf, BS)) > 0)
{
n = write(datos2, buf, j);
i = i + n;
if ((size - i) < BS)
{
j = size - i;
}
}
close(datos1);
close(datos2);
}
}
}
}
}
close(dir1);
close(dir2);
return 0;
}

Answer 1

Yep, it seems to work like this:
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#define BS 512
#define error(a) {perror(a); exit(1);};
int main(int argc, char *argv[]) //argv1 Dir1 argv2 Dir2 argv3 Fich argv4 Pos
{
DIR *dir1;
DIR *dir2;
struct dirent *lectura1;
struct dirent *lectura2;
struct stat st;
int datos1;
int datos2;
int size;
char path[256] = "";
char path2[256] = "";
char temp[256];
char buf[BS];
int j;
int i;
if(argc != 5)
{
error("Numero de argumentos incorrecto");
}
int Pos = atoi(argv[4]);
if(Pos < 0)
{
error("Pos must be 0 or greater")
}
if((dir1 = opendir(argv[1])) == NULL){error("Failed to open origin dir");}
if((dir2 = opendir(argv[2])) == NULL){error("Failed to open destiny dir");}
while((lectura1 = readdir(dir1)) != NULL)
{
sprintf(path, "%s/%s", argv[1], lectura1->d_name);
sprintf(path2, "%s/%s", argv[2], lectura1->d_name); //<-- changed param
if (strcmp(lectura1->d_name, "..") != 0 && strcmp(lectura1->d_name, ".") != 0)
{
if (stat(path, &st) == 0)
{
if (S_ISREG(st.st_mode)) //If is a regular file
{
if((datos1 = open(path, O_RDONLY, 00600)) == -1){error("Failed to open file");} //Opens the target file of Dir1 to copy inside Dir2
size = lseek(datos1,0,SEEK_END);
if (size > Pos) //Check if the size of the file is bigger than the position that indicates the point from which to start copying the file
{
lseek(datos1,Pos,SEEK_SET); //Moves the pointer to the start position of the file1
if((datos2 = open(path2, O_CREAT|O_WRONLY, 00200)) == -1){error("Error al abrir archivo copia");}
lseek(datos2,0,SEEK_SET);
j = BS;
i = 0;
int n = 0;
if ((size - i) < BS)
{
j = size - i;
}
while ((n = read(datos1, buf, BS)) > 0)
{
n = write(datos2, buf, j);
i = i + n;
if ((size - i) < BS)
{
j = size - i;
}
}
close(datos1);
close(datos2);
}
}
}
}
}
closedir(dir1);
closedir(dir2); // <-- changed call
return 0;
}