Implementation of simple cp commands in linux

Implementation of simple cp commands in linux: $./cp ~ /Filename ~ /OtherName // copy the file to the file $./cp ~ /Directory/filename. // copy the file to the current directory $./cp ~ /Directory/... implementation of simple cp commands in linux: $./cp ~ /Filename ~ /OtherName // copy the file to the file $./cp ~ /Directory/filename. // copy the file to the current directory $./cp ~ /Directory/filename ~ /Directory // copying a file to a directory is not in vain. directly uploading the code is King! 001 # include 002 # include 003 # include 004 # include 005 # include 006 # include 007 # include 008 # include 009 www.2cto.com 010 # define BUF_SIZE 1024011 # define PATH_LEN 128012 013 void my_err (char * err_string, int line) 014 {015 fprintf (stderr, "line: % d", line ); 016 perror (err_string); 017 exit (1); 018} 019 020 void copy_data (const int frd, const int fwd) 021 {022 int read_len = 0, write_len = 0; 023 unsigned char buf [BUF_SIZE], * p_buf; 024 025 while (read_len = read (frd, buf, BUF_SIZE) {026 027 if (-1 = read_len) {028 my_err ("Read error", _ LINE _); 029} 030 else if (read_len> 0) {// write the Read part to the target file 031 p_buf = buf; www.2cto.com 032 while (write_len = write (fwd, p_buf, read_len) {033 if (write_len = read_len) {034 break; 035} 036 else if (write_len> 0) {// only Write part 037 p_buf + = write_len; 038 read_len-= write_len; 039} 040 else if (-1 = write_len) {041 my_err ("Write error ", _ LINE _); 042} 043} 044 if (-1 = write_len) break; 045} 046} 047} 048 049int main (int argc, char ** argv) 050 {051 052 int frd, fwd; // Read/Write file descriptor 053 int len = 0; 054 char * pSrc, * pDes; // point to the source file path and target file path 055 struct stat src_st, des_st; 056 057 if (argc <3) {058 printf ("usage. /MyCp <源文件路径> <目标文件路径> \ N "); 059 my_err (" arguments error ", _ LINE _); 060} 061 062 frd = open (argv [1], O_RDONLY ); 063 if (frd =-1) {064 my_err ("Can not opne file", _ LINE _); 065} 066 067 if (fstat (frd, & src_st) =-1) {068 my_err ("stat error" ,__ LINE __); 069} www.2cto.com 070/* check whether the source file path is a directory */071 if (S_ISDIR (src_st.st_mode) {072 my_err ("skipping directories" ,__ LINE __); 073} 074 075 pDes = argv [2]; 076 stat (argv [2], & des_st); 077 if (S_ISDIR (de S_st.st_mode) {// if the target path is a directory, use the source file name 078 079 len = strlen (argv [1]); 080 pSrc = argv [1] + (len-1 ); // point to the last character 081/* First find the source file name */082 while (pSrc> = argv [1] & * pSrc! = '/') {083 pSrc --; 084} 085 pSrc ++; // point to the source file name 086 087 len = strlen (argv [2]); 088 //. indicates copying to the current working directory 089 if (1 = len &&'. '= * (argv [2]) {090 len = 0; // if no space is requested, the 091 pDes = pSrc will not be released later; 092} 093 else {// copy to a directory and use the source file name 094 pDes = (char *) malloc (sizeof (char) * PATH_LEN ); 095 www.2cto.com if (NULL = pDes) {096 my_err ("malloc error", _ LINE _); 097} 098 099 strcpy (pDes, argv [2]); 100 101 if (* (pDes + (len-1 ))! = '/') {// If the last '/' is missing from the directory, add '/' 102 strcat (pDes, "/"); 103} 104 strcat (pDes + len, pSrc); 105} 106} 107 108/* open the target file with the same permissions as the source file */109 fwd = open (pDes, O_WRONLY | O_CREAT | O_TRUNC, src_st.st_mode ); 110 if (fwd =-1) {111 my_err ("Can not creat file", _ LINE _); 112} 113 copy_data (frd, fwd ); 114 // puts ("end of copy"); 115 if (len> 0 & pDes! = NULL) 116 www.2cto.com free (pDes); 117 118 close (frd); 119 close (fwd); 120 121 return 0; 122}
Author: bo