Added userland/testbin

userland/testbin/forktest/forktest.c

@@ -37,10 +37,16 @@
  */
 
 #include <unistd.h>
+#include <fcntl.h>
 #include <string.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <err.h>
+#include <test161/test161.h>
+
+#define FORKTEST_FILENAME_BASE "forktest"
+
+static char filename[32];
 
 /*
  * This is used by all processes, to try to help make sure all
@@ -48,6 +54,18 @@
  */
 static volatile int mypid;
 
+/*
+ * Helper function to do pow()
+ */
+static
+int pow_int(int x, int y) {
+	int i;
+	int result = 1;
+	for(i = 0; i < y; i++)
+		result *= x;
+	return result;
+}
+
 /*
  * Helper function for fork that prints a warning on error.
  */
@@ -141,17 +159,38 @@ test(int nowait)
 	 * to prevent wait/exit problems if fork corrupts memory.
 	 */
 
+	/*
+	 * Guru: We have a problem here.
+	 * We need to write the output to a file since test161 is
+	 * supposed to be as simple as possible. This requires the
+	 * test to tell test161 whether it passed or succeeded.
+	 * We cannot lseek and read stdout, to check the output,
+	 * so we need to write the output to a file and then check it later.
+	 *
+	 * So far so good. However, if in the future, forktest is
+	 * going to be combined with triple/quint/etc, then the filename
+	 * cannot be the same across multiple copies. So we need a
+	 * unique filename per instance of forktest.
+	 * So...
+	 */
+	snprintf(filename, 32, "%s-%d.bin", FORKTEST_FILENAME_BASE, getpid());
+	int fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC);
+	if(fd < 3) {
+		// 0, 1, 2 are stdin, stdout, stderr
+		err(1, "Failed to open file to write data into\n");
+	}
+
 	pid0 = dofork();
-	putchar('A');
+	write(fd, "A", 1);
 	check();
 	pid1 = dofork();
-	putchar('B');
+	write(fd, "B", 1);
 	check();
 	pid2 = dofork();
-	putchar('C');
+	write(fd, "C", 1);
 	check();
 	pid3 = dofork();
-	putchar('D');
+	write(fd, "D", 1);
 	check();
 
 	/*
@@ -163,7 +202,44 @@ test(int nowait)
 	dowait(nowait, pid1);
 	dowait(nowait, pid0);
 
-	putchar('\n');
+	// Check if file contents are correct
+	// lseek may not be implemented..so close and reopen
+	close(fd);
+	fd = open(filename, O_RDONLY);
+	if(fd < 3) {
+		err(1, "Failed to open file for verification\n");
+	}
+	char buffer[30];
+	int len;
+	int char_idx, i;
+	int observed, expected;
+	char character = 'A';
+
+	memset(buffer, 0, 30);
+	len = read(fd, buffer, 30);
+	printf("%s\n", buffer);
+	if(len != 30) {
+		err(1, "Did not get expected number of characters\n");
+	}
+	// Check if number of instances of each character is correct
+	// 2As; 4Bs; 8Cs; 16Ds
+	for(char_idx = 0; char_idx < 4; char_idx++) {
+		observed = 0;
+		expected = pow_int(2, char_idx + 1);
+		for(i = 0; i < 30; i++) {
+			// In C, char can be directly converted to an ASCII index
+			// So, A is 65, B is 66, ...
+			if(buffer[i] == character + char_idx) {
+				observed++;
+			}
+		}
+		if(observed != expected) {
+			// Failed
+			err(1, "Failed! Expected %d%cs..observed: %d\n", expected, character + char_idx, observed);
+		}
+	}
+	success(TEST161_SUCCESS, SECRET, "/testbin/forktest");
+	close(fd);
 }
 
 int