From 38c4c82aaa32e89c54c3adfb4245217557dd0740 Mon Sep 17 00:00:00 2001
From: Matt Strapp <strap012@umn.edu>
Date: Mon, 5 Oct 2020 22:54:37 -0500
Subject: Add error handling (Fixing #4 again)

---
 P1/src/mapreduce.c | 27 +++++++++++++++++++++++----
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/P1/src/mapreduce.c b/P1/src/mapreduce.c
index 2428f75..19cf937 100644
--- a/P1/src/mapreduce.c
+++ b/P1/src/mapreduce.c
@@ -38,14 +38,24 @@ int main(int argc, char *argv[]) {
 			char numMap[10];
 			sprintf(numMap, "%d", i);
 			execl("./mapper", "./mapper", &numMap, NULL);
+			printf("Mapper execution failed! Make sure \"mapper\" exists in the directory.\n");
+			return 4;
+		} else if (mapperPid == -1) {
+			printf("Fork failed!\n");
+			return 1;
 		}
 	}
 	
     for (int i = 0; i <= nMappers; i++) {
 		//Hopefully this works
-		wait(NULL);
+		int waitError = wait(NULL);
+		if (waitError == -1)
+		{
+			printf("Wait failed!\n");
+			return 5;
+		}
 	}
-
+printf("Not stuck here.\n");
 
 	// ###### DO NOT REMOVE ######
     // shuffle sends the word.txt files generated by mapper 
@@ -57,7 +67,7 @@ int main(int argc, char *argv[]) {
 	}
 	sleep(1);
 
-
+printf("Not stuck here.\n");
 
 	pid_t reducerPid;
 	for (int i = 1; i <= nReducers; i++) {
@@ -66,12 +76,21 @@ int main(int argc, char *argv[]) {
 			char numRed[10];
 			sprintf(numRed, "%d", i);
 			execl("./reducer", "./reducer", &numRed, NULL);
+			printf("Reducer execution failed! Make sure \"reducer\" exists in the directory.\n");
+			return 3;
+		} else if (reducerPid == -1) {
+			printf("Fork failed!\n");
+			return 2;
 		}
 	}
 
 	for (int i = 0; i <= nReducers; i++) {
 		//Maybe this works too?
-		wait(NULL);
+		int waitError = wait(NULL);
+		if (waitError == -1) {
+			printf("Wait failed!\n");
+			return 5;
+		}
 	}
 
 	return 0;
-- 
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