Implementation of linux cp (copy) command in C language
I was just going to post my problem, but then I started programming and could not stop because the issue was bothering me so much that I ended up solving it. But I think people can benefit from this program, especially beginners and intermediate people in C. That is why I decided to post it, hopefully you guys will like it. Of course this command already exists on linux so why would I write such program? Well because I am learning systems programming on my own, and it is important to know how to work with files, directories, etc.
After you compile it, you can do following:
1) ./cp2 file1.txt file2.txt
Simply makes a copy of the file with specified name (in this case file2.txt)
2) ./cp2 file1.txt /someDirInCurrentDir
Copies file1.txt in current directory to a directory which is in current directory (preserves same file name)
3) ./cp2 /someDir /anotherDir
Copies all REGULAR files from someDir to anotherDir (both directories must be in the directory where you are calling the program from, same goes for the previous 2).
Code:
/** cp2.c
* version 1 of cp - uses read and write with tunable buffer size
*
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <dirent.h>
#include <sys/types.h>
#include <sys/stat.h>
#define BUFFERSIZE 1024
#define COPYMORE 0644
void oops(char *, char *);
int copyDir(char *src, char *dest);
int copyFiles(char *src, char *dest);
int dostat(char *filename);
int mode_isReg(struct stat info);
int main(int ac, char *av[])
{
/* checks args */
if(ac != 3)
{
fprintf(stderr, "usage: %s source destination\n", *av);
exit(1);
}
char *src = av[1];
char *dest = av[2];
if( src[0] != '/' && dest[0] != '/' )//cp1 file1.txt file2.txt
{
copyFiles(src, dest);
}
else if( src[0] != '/' && dest[0] == '/' )//cp1 file1.txt /dir
{
int i;
for(i=1; i<=strlen(dest); i++)
{
dest[(i-1)] = dest[i];
}
strcat(dest, "/");
strcat(dest, src);
copyFiles(src, dest);
}
else if( src[0] == '/' && dest[0] == '/' )//cp1 /dir1 /dir2
{ //- copies all regular files from /dir1 to /dir2
int i;
for(i=1; i<=strlen(dest); i++)
{
dest[(i-1)] = dest[i];
}
for(i=1; i<=strlen(src); i++)
{
src[(i-1)] = src[i];
}
//printf("COPYING TWO DIRECTORIES:\n");
//printf("SRC is %s, DEST is %s\n", src, dest);
copyDir(src, dest);
}
else
{
fprintf(stderr, "usage: cp1 source destination\n");
exit(1);
}
}
int copyDir(char *source, char *destination)
{
DIR *dir_ptr = NULL;
struct dirent *direntp;
char tempDest[strlen(destination)+1];
char tempSrc[strlen(source)+1];
strcat(destination, "/");
strcat(source, "/");
strcpy(tempDest, destination);
strcpy(tempSrc, source);
//char *fileN;
struct stat fileinfo;
//printf("RIGHT BEFORE COPYING FILES in copyDir()\n");
//printf("before strcat tempDest=%s\n", tempDest);
if( (dir_ptr = opendir(source)) == NULL )
{
fprintf(stderr, "cp1: cannot open %s for copying\n", source);
return 0;
}
else
{
while( (direntp = readdir(dir_ptr)))
{
//printf("direntp DNAME is %s\n", direntp->d_name);
//fileN = direntp->d_name;
//printf("File name before Reg Check is %s\n", fileN);
if(dostat(direntp->d_name))
{
strcat(tempDest, direntp->d_name);
//printf("after strcat tempDest=%s\n", tempDest);
strcat(tempSrc, direntp->d_name);
copyFiles(tempSrc, tempDest);
strcpy(tempDest, destination);
strcpy(tempSrc, source);
}
}
closedir(dir_ptr);
return 1;
}
}
int dostat(char *filename)
{
struct stat fileInfo;
//printf("Next File %s\n", filename);
if(stat(filename, &fileInfo) >=0)
if(S_ISREG(fileInfo.st_mode))
return 1;
else return 0;
return;
}
int copyFiles(char *source, char *destination)
{
int in_fd, out_fd, n_chars;
char buf[BUFFERSIZE];
/* open files */
if( (in_fd=open(source, O_RDONLY)) == -1 )
{
oops("Cannot open ", source);
}
if( (out_fd=creat(destination, COPYMORE)) == -1 )
{
oops("Cannot creat ", destination);
}
/* copy files */
while( (n_chars = read(in_fd, buf, BUFFERSIZE)) > 0 )
{
if( write(out_fd, buf, n_chars) != n_chars )
{
oops("Write error to ", destination);
}
if( n_chars == -1 )
{
oops("Read error from ", source);
}
}
/* close files */
if( close(in_fd) == -1 || close(out_fd) == -1 )
{
oops("Error closing files", "");
}
return 1;
}
void oops(char *s1, char *s2)
{
fprintf(stderr, "Error: %s ", s1);
perror(s2);
exit(1);
}
Enjoy
