Add files to Arena lab

.github/labeler.yml

@@ -2,7 +2,7 @@ topic/software-stack:
   - 'chapters/software-stack/**/*'
 
 topic/data:
-  - 'content/chapters/data/**/*'
+  - 'chapters/data/**/*'
 
 topic/compute:
   - 'content/chapters/compute/**/*'

chapters/data/.gitignore

@@ -0,0 +1,2 @@
+/_site
+/slides.md

chapters/data/Makefile

@@ -0,0 +1,33 @@
+RVMD = reveal-md
+MDPP = markdown-pp
+FFMPEG = ffmpeg
+
+SLIDES ?= slides.mdpp
+SLIDES_OUT ?= slides.md
+MEDIA_DIR ?= media
+SITE ?= _site
+OPEN ?= xdg-open
+
+.PHONY: all html clean videos
+
+all: videos html
+
+html: $(SITE)
+
+$(SITE): $(SLIDES)
+	$(MDPP) $< -o $(SLIDES_OUT)
+	$(RVMD) $(SLIDES_OUT) --static $@
+
+videos:
+	for TARGET in $(TARGETS); do \
+		$(FFMPEG) -framerate 0.5 -f image2 -y \
+			-i "$(MEDIA_DIR)/$$TARGET/$$TARGET-%d.svg" -vf format=yuv420p $(MEDIA_DIR)/$$TARGET-generated.gif; \
+	done
+
+open: $(SITE)
+	$(OPEN) $</index.html
+
+clean:
+	-rm -f $(MEDIA_DIR)/*-generated.gif
+	-rm -f *~
+	-rm -fr $(SITE) $(SLIDES_OUT)

chapters/data/arena/drills/questions/operators.md

@@ -0,0 +1,37 @@
+# Operator Overloading
+
+## Question Text
+
+How many constructor calls, copy constructor calls, assignment operator calls and destructor calls does the following program issue?
+
+```d
+Obj quiz(Obj o1, Obj o2)
+{
+    o2 = o1;
+    return o2;
+}
+void main()
+{
+    Obj b = quiz(o1, o2);
+}
+```
+
+## Question Answers
+
++ constructor calls = 0, copy constructor calls = 3, assignment operator calls = 1, destructor calls = 3
+
+- constructor calls = 1, copy constructor calls = 2, assignment operator calls = 1, destructor calls = 2
+
+- constructor calls = 0, copy constructor calls = 2, assignment operator calls = 1, destructor calls = 2
+
+- constructor calls = 0, copy constructor calls = 3, assignment operator calls = 1, destructor calls = 1
+
+## Feedback
+
+- There are no constructor calls because there is no object construction when using `int`.
+
+- There are 3 copy constructor calls: for passing `o1`, for passing `o2`, and for returning `o2`.
+
+- There is 1 assignment operator call for `o2 = o1`.
+
+- There are 3 destructor calls, because each constructed object needs to be destroyed.

chapters/data/arena/drills/tasks/access-counter/README.md

@@ -0,0 +1,45 @@
+## Access Counter
+
+Navigate to the `support/access-counter/` directory.
+
+Your goal is to update the `src/access_counter.c` source code file to capture memory access exceptions (i.e. the `SIGSEGV` signal) and to update page permissions in order for the access to eventually succeed.
+Use `mprotect` to update the protection of the pages in stages: read, write and then exec.
+Each time an update is made, the `counter` variable is increased;
+this is used for testing.
+
+The signal handler is already in place as the `access_handler()` function.
+It is called any time a `SIGSEGV` signal is being sent out to the current process.
+You will update the handler by following the `TODO` comments and instructions here.
+
+The `pages` array stores information about accessed pages.
+Assume the `MAX_PAGES` size of the array is enough to store information.
+When an existing page is accessed and causes a memory exception, the permission is update, in the stages mentioned above: read, write, and then exec.
+When a new page is accessed, a new entry is filled in the `pages` array, initialized with read protection.
+Use `mmap()` to reserve virtual pages.
+Use anonymous mapping (i.e. the `MAP_ANONYMOUS`) flag.
+Use any permissions required.
+
+To test it, enter the `tests/` directory and run:
+
+```console
+make check
+```
+
+In case of a correct solution, you will get an output such as:
+
+```text
+./run_all_tests.sh
+test_acess_read                  ........................ passed ...   9
+test_acess_write                 ........................ passed ...   9
+test_acess_exec                  ........................ passed ...  10
+test_acess_read_write            ........................ passed ...  12
+test_acess_read_exec             ........................ passed ...  12
+test_acess_write_exec            ........................ passed ...  12
+test_acess_exec_read             ........................ passed ...  12
+test_acess_exec_write            ........................ passed ...  12
+test_acess_write_read            ........................ passed ...  12
+
+Total:                                                           100/100
+```
+
+If you're having difficulties solving this exercise, go through [this](../../../reading/arena.md) reading material.

chapters/data/arena/drills/tasks/access-counter/solution/src/Makefile

@@ -0,0 +1,14 @@
+CFLAGS ?= -Wall -Wextra
+CPPFLAGS ?= -I../utils
+
+.PHONY: all clean
+
+all: access_counter.o ../utils/log/log.o
+
+access_counter.o: access_counter.c ../utils/utils.h ../utils/log/log.h
+
+../utils/log/log.o: ../utils/log/log.c ../utils/log/log.h
+
+clean:
+	-rm -f access_counter.o ../utils/log/log.o
+	-rm -f *~

chapters/data/arena/drills/tasks/access-counter/solution/src/access_counter.c

@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: BSD-3-Clause
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <signal.h>
+#include <sys/mman.h>
+
+#include "utils.h"
+#include "access_counter.h"
+
+struct page_info {
+	int prot;
+	void *start;
+};
+
+unsigned long counter;
+
+#define MAX_PAGES	16
+static struct page_info pages[MAX_PAGES];
+static size_t num_pages;
+
+/* This is useful for filling the contents when execution rights are provided. */
+static void do_nothing(void)
+{
+}
+
+/*
+ * The actual SIGSEVG handler.
+ */
+static void access_handler(int signum, siginfo_t *si, void *arg)
+{
+	long page_size = sysconf(_SC_PAGESIZE);
+	void *start;
+	int rc;
+	unsigned int i;
+
+	log_debug("Enter handler");
+
+	counter++;
+
+	if (signum != SIGSEGV) {
+		fprintf(stderr, "Unable to handle signal %d (%s)\n", signum, strsignal(signum));
+		return;
+	}
+
+	/* TODO 2: Obtain page strart address in start variable. */
+	start = (void *) ((unsigned long) si->si_addr & ~0xFFFUL);
+	log_debug("start: %p", start);
+
+	for (i = 0; i < num_pages; i++)
+		if (pages[i].start == start)
+			break;
+
+	if (i >= num_pages && i < MAX_PAGES) {
+		pages[i].start = start;
+		pages[i].prot = PROT_NONE;
+		num_pages += 1;
+	}
+
+	log_debug("i = %u", i);
+
+	/* TODO 21: Update page proctections with mprotect(). */
+	switch (pages[i].prot) {
+	case PROT_NONE:
+		rc = mprotect(start, page_size, PROT_READ);
+		DIE(rc < 0, "mprotect");
+		pages[i].prot = PROT_READ;
+		break;
+	case PROT_READ:
+		rc = mprotect(start, page_size, PROT_READ | PROT_WRITE);
+		DIE(rc < 0, "mprotect");
+		pages[i].prot = PROT_WRITE;
+		break;
+	case PROT_WRITE:
+		rc = mprotect(start, page_size, PROT_READ | PROT_WRITE | PROT_EXEC);
+		DIE(rc < 0, "mprotect");
+		/* Optimistically copy 64 bytes of code. Should be more than enough. */
+		memcpy(start, do_nothing, 64);
+		pages[i].prot = PROT_EXEC;
+		break;
+	default:
+		break;
+	}
+}
+
+void register_sigsegv_handler(void)
+{
+	struct sigaction sa;
+	int rc;
+
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = access_handler;
+	sa.sa_flags = SA_SIGINFO;
+
+	rc = sigaction(SIGSEGV, &sa, NULL);
+	DIE(rc < 0, "sigaction");
+}

chapters/data/arena/drills/tasks/access-counter/solution/src/access_counter.h

@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+
+#ifndef ACCESS_PRINTER_H_
+#define ACCESS_PRINTER_H_	1
+
+extern unsigned long counter;
+void register_sigsegv_handler(void);
+
+#endif

chapters/data/arena/drills/tasks/access-counter/solution/utils/log/CPPLINT.cfg

@@ -0,0 +1 @@
+exclude_files=log\.c