Create mycp.c

Solution program for APUE exercise 4.6

mycp.c

@@ -0,0 +1,78 @@
+#include <stdio.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <assert.h>
+
+#define BUFSIZE  1024
+
+int copy(const char *file1, const char *file2){
+    /*copy contents of file1 to file2, ignore the hole*/
+    int fd1, fd2, num, i;
+    int base, probe;
+    char buf[BUFSIZE];
+    /*open the source and target files*/
+    if((fd1 = open(file1, O_RDWR)) == -1){
+        printf("Error opening %s for copying\n", file1);
+        return -1;
+    }
+    if((fd2 = open(file2, O_RDWR|O_APPEND|O_CREAT|O_TRUNC)) == -1){
+        printf("Error creating %s to copy\n", file2);
+        return -1;
+    }
+
+    do{
+        memset(buf, '\0', BUFSIZE);
+
+        if((num = read(fd1, buf, BUFSIZE)) == -1){
+            printf("Error reading %s for copying\n", file1);
+            return -1;
+        }
+        /*clear all "holes"('\0') in the buf array*/
+        base =0;
+        for(i=0; i<num; i++){
+            if(buf[i] != '\0'){
+                base++;
+            }
+            else{
+                probe = i+1;
+                while(probe < num){
+                    if(buf[probe] != '\0'){
+                        buf[base] = buf[probe];
+                        i = probe;
+                        base++;
+                        break;
+                    }
+                    probe++;
+                }
+                if(probe == num){
+                     break;
+                }
+            }
+        }
+        /*write the buf into file2*/
+        if((num = write(fd2, buf, base)) == -1){
+            printf("Error writing %s to copy\n", file2);
+            return -1;
+        }
+    }
+    while(num >0);
+
+    close(fd1);
+    close(fd2);
+
+    return 0;
+}
+
+int main(int argc, char *argv[]){
+    char *file1, *file2;
+
+    if(argc != 3){
+        printf("parameter error!\n");
+        return -1;
+    }
+
+    file1 = argv[1];
+    file2 = argv[2];
+    return copy(file1, file2);
+}