From: Advaith Menon <noreply-git@bp4k.net>
Date: Thu, 15 Jan 2026 14:08:38 +0000 (+0530)
Subject: EC part 5
X-Git-Url: https://git.devinivas.org/?a=commitdiff_plain;h=675067e5249390205ae453ac0d5d01299c6435c1;p=cs3210-lab0.git

EC part 5
---

diff --git a/user/src/lab0/limits.c b/user/src/lab0/limits.c
index 745f205..837b00d 100644
--- a/user/src/lab0/limits.c
+++ b/user/src/lab0/limits.c
@@ -22,5 +22,30 @@ main(int argc, char *argv[])
 
     printf(STDOUT_FD, "Maximum Memory Size: 0x%x\n", memsz);
 
+    /* Extra Credit: Max no of file descriptors */
+    /* Game Plan: File descriptors are allocated sequentially, as we know this
+     * from the xv6 book's explanation on replacing stdin/stdout. We shall keep
+     * track of the current and last file descriptor and keep on duplicating an
+     * existing file until dup returns -1.
+     *
+     * To prove that this works, I'll also keep a manual file counter and ensure
+     * they match.
+     */
+    int curfd, prevfd;
+    // int manual_tally;
+
+    // POC verified
+    // manual_tally = 3;
+
+    curfd = 2; /* because stderr. Only used if first dup fails. */
+
+    while ((prevfd = curfd) && (curfd = dup(0)) >= 0);
+        // ++manual_tally;
+
+    printf(STDOUT_FD, "Maximum Number of Files Open at Once: %d\n",
+            prevfd + 1); // remember first valid descriptor is 0
+    // poc validated
+    // printf(STDOUT_FD, "Maximum Number of Files Open at Once: %d\n",
+    //         manual_tally);
     exit();
 }