apps: Add cat and edit

apps/CMakeLists.txt

@@ -7,4 +7,6 @@ function(luna_app SOURCE_FILE APP_NAME)
 endfunction()
 
 luna_app(init.c init)
+luna_app(cat.c cat)
+luna_app(edit.c edit)
 luna_app(sh.c sh)

apps/cat.c

@@ -0,0 +1,41 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static void do_cat(FILE* f)
+{
+    char buffer[4096];
+
+    while (1)
+    {
+        size_t nread = fread(buffer, 1, sizeof(buffer), f);
+        if (nread == 0) return;
+        fwrite(buffer, 1, nread, stdout);
+    }
+}
+
+int main(int argc, char** argv)
+{
+    FILE* f;
+
+    if (argc < 2) { do_cat(stdin); }
+    else
+    {
+        for (int i = 1; i < argc; i++)
+        {
+            if (!strcmp(argv[i], "-")) f = stdin;
+            else
+            {
+                f = fopen(argv[i], "r");
+                if (!f)
+                {
+                    perror(argv[i]);
+                    return 1;
+                }
+            }
+
+            do_cat(f);
+            if (f != stdin) fclose(f);
+        }
+    }
+}

apps/edit.c

@@ -0,0 +1,35 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int main(int argc, char** argv)
+{
+    FILE* f;
+
+    if (argc < 2)
+    {
+        fprintf(stderr, "usage: %s [file]", argv[0]);
+        return 1;
+    }
+
+    f = fopen(argv[1], "w");
+    if (!f)
+    {
+        perror(argv[1]);
+        return 1;
+    }
+
+    char buffer[4096];
+
+    while (1)
+    {
+        char* rc = fgets(buffer, sizeof(buffer), stdin);
+        if (rc == 0) break;
+        if (!strcmp(rc, "EOF\n")) break;
+        fputs(buffer, f);
+    }
+
+    fclose(f);
+
+    return 0;
+}

apps/sh.c

@@ -90,6 +90,7 @@ int main()
         if (child == 0)
         {
             char** argv = split_command_into_argv(command);
+            if (argv[0] == NULL) return 0;
             sh_execvp(argv);
             perror(argv[0]);
             return 1;

kernel/src/arch/x86_64/CPU.cpp

@@ -71,7 +71,10 @@ void decode_page_fault_error_code(u64 code)
     {
         // FIXME: Kill this process with SIGSEGV once we have signals and all that.
         kerrorln("Current task %zu was terminated because of a page fault", Scheduler::current()->id);
-        kernel_exit();
+        Scheduler::current()->state = ThreadState::Exited;
+        Scheduler::current()->status = 127;
+        kernel_yield();
+        unreachable();
     }
 
     CPU::print_stack_trace_at(regs);