4 files changed, 110 insertions, 0 deletions
diff --git a/csci5271/hw1/hw1markup.md b/csci5271/hw1/hw1markup.md
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+++ b/csci5271/hw1/hw1markup.md
@@ -0,0 +1,43 @@
+# Homework 1
+## Q1
+
+## Q2
+### A: Perl
+After adding a name to the request, add a semicolon followed by the command. The semicolon is the shell command separator which allows it to parse commands.
+#### Example Request
+```
+"?field-name=;perl+-e+'`command`'"
+```
+### B: C
+
+## Q3
+
+## Q4
+### A
+#### Mistake 1a: Potentially overloading the array
+If the function is called with `to` larger than outer bound of the array, there is a buffer overflow that happens. For example, running it by default with an array of size 10 with a `to` of size 11 on gcc 11.1 causes it to crash because of stack smashing.
+##### Mistake 1b: Underloading the array
+If the function is called with `from` smaller than 0 will cause some values of the array to be replaced with other values from memory. It did not crash, but it is not the intended behavior.
+#### Mistake 2:
+
+#### Mistake 3:
+
+### B: Same Signature
+```c
+    void reverse_range(int *a, int from, int to) {
+        
+```
+### C: Different Signature
+```c
+    int* reverse_range(int arr[], int arrSize, int from, int to) {
+        if (from < 0 || to >= arrSize)
+            return NULL;
+        for (int i = from; i < to; i++) {
+            int temp = arr[i];
+            arr[i] = arr[to];
+            arr[to] = temp;
+            to--;
+        }
+        return arr;
+```
+## Q5
+\ No newline at end of file
diff --git a/csci5271/hw1/hw1p2a.pl b/csci5271/hw1/hw1p2a.pl
new file mode 100755
index 0000000..a8bfe2e
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+++ b/csci5271/hw1/hw1p2a.pl
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+#!/usr/bin/perl
+print "Content-Type: text/html\r\n\r\n";
+print "<HTML><BODY>\n";
+($field_name, $username_to_look_for) = split(/=/, <>);
+chomp $username_to_look_for;
+$result = `last -1000 | grep $username_to_look_for`;
+if ($result) {
+print "$username_to_look_for has logged in recently.\n";
+} else {
+print "$username_to_look_for has NOT logged in recently.\n";
+}
+print "</BODY></HTML>\n";
+\ No newline at end of file
diff --git a/csci5271/hw1/hw1p2b.c b/csci5271/hw1/hw1p2b.c
new file mode 100644
index 0000000..df5ac73
--- /dev/null
+++ b/csci5271/hw1/hw1p2b.c
@@ -0,0 +1,28 @@
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <unistd.h>
+void silly_function(char *pathname) {
+  struct stat f, we;
+  int rfd, wfd;
+  char *buf;
+  stat(pathname, &f);
+  stat("./critical", &we);
+  if (f.st_dev == we.st_dev && f.st_ino == we.st_ino) {
+    return;
+  }
+  rfd = open(pathname, O_RDONLY);
+  buf = malloc(f.st_size - 1);
+  read(rfd, buf, f.st_size - 1);
+  close(rfd);
+  stat(pathname, &f);
+  if (f.st_dev == we.st_dev && f.st_ino == we.st_ino) {
+    return;
+  }
+  wfd = open(pathname, O_WRONLY | O_TRUNC);
+  write(wfd, buf, f.st_size - 1);
+  close(wfd);
+  free(buf);
+}
+
+int main() { silly_function("./not"); }
+\ No newline at end of file
diff --git a/csci5271/hw1/hw1p4.c b/csci5271/hw1/hw1p4.c
new file mode 100644
index 0000000..e449de5
--- /dev/null
+++ b/csci5271/hw1/hw1p4.c
@@ -0,0 +1,27 @@
+#include <stdio.h>
+
+/* Reverse the elements from FROM to TO, inclusive */
+void reverse_range(int *a, int from, int to) {
+  unsigned int *p = &a[from];
+  unsigned int *q = &a[to];
+  /* Until the pointers move past each other: */
+  while (!(p == q + 1 || p == q + 2)) {
+    /* Swap *p with *q, without using a temporary variable */
+    *p += *q;     /* *p == P + Q */
+    *q = *p - *q; /* *q == P + Q - Q = P */
+    *p = *p - *q; /* *p == P + Q - P = Q */
+    /* Advance pointers towards each other */
+    p++;
+    q--;
+  }
+}
+int main() {
+  int a[10] = {255, 0, -65536, 2147483647, -2147483648,
+               -1,  0, 1,      2,          3};
+  reverse_range(a, 0, 9);
+  for (int i = 0; i < 10; i++) {
+    printf("%d ", a[i]);
+  }
+  printf("\n");
+  return 0;
+}
+\ No newline at end of file