part 4 IO

assignment1/part1.c

@@ -60,6 +60,46 @@ void funcCd(char *fpath){
     free(temp);
 }
 
+
+void ioRedirect(char **tokens,int n){
+    FILE *fp;
+    char **arglist = (char **)malloc(MAX_NUM_TOKENS * sizeof(char *));
+    int j=0;
+
+    for(int i=0;strcmp(tokens[i],">>") && strcmp(tokens[i],">") && strcmp(tokens[i],"<");i++){
+            arglist[j] = (char*)malloc(MAX_TOKEN_SIZE*sizeof(char));
+            strcpy(arglist[j++],tokens[i]);
+        }
+        arglist[j]=NULL;
+        char *temp = (char *)malloc(sizeof(char)*150);
+
+        switch (fork()) {
+            case -1:
+                break;
+            case 0: 
+                if(!strcmp(tokens[n-2],">>"))
+                    fp = freopen(tokens[n-1],"a",stdout);
+                else if(!strcmp(tokens[n-2],">"))
+                    fp = freopen(tokens[n-1],"w",stdout);
+                else
+                    fp = freopen(tokens[n-1],"r",stdin);
+                strcpy(temp,"/bin/");
+                strcat(temp,arglist[0]);
+                if(execv(temp,arglist)==-1){
+                    strcpy(temp,"/usr/bin/");
+                    strcat(temp,arglist[0]);
+                    execv(temp,arglist);
+                }
+                free(temp);
+        }
+    wait(NULL);
+
+    for(int i=0;arglist[i]!=NULL;i++)
+        free(arglist[i]);
+    
+    free(arglist);
+}
+
 void exBackground(char **tokens,int n){
     char **arglist = (char **)malloc(MAX_NUM_TOKENS * sizeof(char *));
     int j=0,forkcalls=0;
@@ -100,13 +140,17 @@ void exSerial(char **tokens,int n){
     int j=0;
 
     for(int i=0;i<n;i++){
+        int ioFlag = 0;
         while(tokens[i]!=NULL && strcmp(tokens[i],"&&")!=0 ){
+            if(!ioFlag)
+                ioFlag=strcmp(tokens[i],">>")==0 || strcmp(tokens[i],">")==0 || strcmp(tokens[i],"<")==0;
             arglist[j] = (char*)malloc(MAX_TOKEN_SIZE*sizeof(char));
             strcpy(arglist[j++],tokens[i++]);
         }
         arglist[j]=NULL;
         char *temp = (char *)malloc(sizeof(char)*150);
         
+        if(!ioFlag){
             switch (fork()) {
                 case -1:
                     break;
@@ -120,6 +164,10 @@ void exSerial(char **tokens,int n){
                     }
                     free(temp);
             }
+        }
+        else {
+            ioRedirect(arglist,j);
+        }
         wait(NULL);
         j=0;
     }
@@ -135,14 +183,18 @@ void exParallel(char **tokens,int n){
     int j=0,forkcalls=0;
 
     for(int i=0;i<n;i++){
+        int ioFlag = 0;
         while(tokens[i]!=NULL && strcmp(tokens[i],"&&&")!=0 ){
+            if(!ioFlag)
+                ioFlag=strcmp(tokens[i],">>")==0 || strcmp(tokens[i],">")==0 || strcmp(tokens[i],"<")==0;
             arglist[j] = (char*)malloc(MAX_TOKEN_SIZE*sizeof(char));
             strcpy(arglist[j++],tokens[i++]);
         }
-        forkcalls++;
         arglist[j]=NULL;
         char *temp = (char *)malloc(sizeof(char)*150);
 
+        if(!ioFlag){
+            forkcalls++;
             switch (fork()) {
                 case -1:
                     break;       
@@ -155,7 +207,10 @@ void exParallel(char **tokens,int n){
                         execv(temp,arglist);
                     }
                     free(temp);    
-                
+            }
+        }
+        else {
+            ioRedirect(arglist,j);
         }
         j=0;
     }
@@ -169,6 +224,7 @@ void exParallel(char **tokens,int n){
     free(arglist);
 }
 
+
 /* Splits the string by space and returns the array of tokens
 */
 
@@ -216,7 +272,7 @@ int main(int argc, char* argv[]) {
 	}
 
 	while(1) {			
-        int parallel=0,serial=0,background=0,internal=0,cdir=0;
+        int parallel=0,serial=0,background=0,io=0,cdir=0;
 
 		/* BEGIN: TAKING INPUT */
 		bzero(line, sizeof(line));
@@ -250,6 +306,9 @@ int main(int argc, char* argv[]) {
             if(!background)
                 background=strcmp(tokens[i],"&")==0;
 
+            if(!io)
+                io=strcmp(tokens[i],">>")==0 || strcmp(tokens[i],">")==0 || strcmp(tokens[i],"<")==0;
+
 			// printf("found token %s\n", tokens[i]);
 		}
         t1 = clock(); 
@@ -259,6 +318,8 @@ int main(int argc, char* argv[]) {
             exSerial(tokens,i);
         else if(background)
             exBackground(tokens,i);
+        else if(io)
+            ioRedirect(tokens,i);
         else {
             if(!strcmp(tokens[0],"dir")){
                 funcDir(tokens);