libluna: Do not sort empty arrays; avoids a segfault

apps/init.cpp

@@ -149,10 +149,28 @@ static Result<void> load_service(const os::Path& path)
 
         if (parts[0].view() == "Command")
         {
+            if (!service.command.is_empty())
+            {
+                fprintf(g_init_log, "[init] 'Command' cannot be specified after 'Script' has already been set! (%s)\n",
+                        line.chars());
+                return {};
+            }
             service.command = move(parts[1]);
             continue;
         }
 
+        if (parts[0].view() == "Script")
+        {
+            if (!service.command.is_empty())
+            {
+                fprintf(g_init_log, "[init] 'Script' cannot be specified after 'Command' has already been set! (%s)\n",
+                        line.chars());
+                return {};
+            }
+            service.command = TRY(String::format("/bin/sh -- %s"_sv, parts[1].chars()));
+            continue;
+        }
+
         if (parts[0].view() == "Restart")
         {
             if (parts[1].view() == "true" || parts[1].view().to_uint().value_or(0) == 1)
@@ -210,7 +228,7 @@ static Result<void> load_service(const os::Path& path)
 
     if (service.command.is_empty())
     {
-        fprintf(g_init_log, "[init] service file is missing 'Command' entry, aborting!\n");
+        fprintf(g_init_log, "[init] service file is missing 'Command' or 'Script' entry, aborting!\n");
         return {};
     }
 

initrd/etc/init/00-tmpfs

@@ -0,0 +1,3 @@
+Name=tmpfs
+Script=/sbin/mount-tmpfs
+Wait=true

initrd/sbin/mount-tmpfs

@@ -0,0 +1,3 @@
+mkdir -p /tmp
+mount -t tmpfs /tmp
+chmod 1777 /tmp

kernel/src/fs/VFS.cpp

@@ -168,6 +168,11 @@ namespace VFS
         return inode->mode() & S_ISGID;
     }
 
+    bool is_sticky(SharedPtr<Inode> inode)
+    {
+        return inode->mode() & S_ISVTX;
+    }
+
     bool is_seekable(SharedPtr<Inode> inode)
     {
         return inode->type() != InodeType::FIFO && inode->type() != InodeType::CharacterDevice;

kernel/src/fs/VFS.h

@@ -290,6 +290,7 @@ namespace VFS
     bool can_write(SharedPtr<Inode> inode, Credentials auth);
     bool is_setuid(SharedPtr<Inode> inode);
     bool is_setgid(SharedPtr<Inode> inode);
+    bool is_sticky(SharedPtr<Inode> inode);
 
     bool is_seekable(SharedPtr<Inode> inode);
 

kernel/src/sys/link.cpp

@@ -25,11 +25,12 @@ Result<u64> sys_unlinkat(Registers*, SyscallArgs args)
     auto inode = TRY(current->resolve_atfile(dirfd, dirname, false, false));
     if (!VFS::can_write(inode, current->auth)) return err(EACCES);
 
-    if (flags > 0)
-    {
     auto child = TRY(inode->find(basename.chars()));
-        if (child->type() != VFS::InodeType::Directory) return err(ENOTDIR);
+    if (flags == AT_REMOVEDIR && child->type() != VFS::InodeType::Directory) return err(ENOTDIR);
-    }
+
+    if (current->auth.euid != 0 && VFS::is_sticky(inode) && current->auth.euid != inode->uid() &&
+        current->auth.euid != child->uid())
+        return err(EACCES);
 
     TRY(inode->remove_entry(basename.chars()));
 

libluna/src/Sort.cpp

@@ -50,5 +50,6 @@ static void quicksort_impl(void* base, usize start, usize end, usize size, compa
 
 void c_quicksort(void* base, usize nmemb, usize size, compar_t compar)
 {
+    if (nmemb == 0) return;
     quicksort_impl(base, 0, nmemb - 1, size, compar);
 }

libos/src/Mode.cpp

@@ -27,8 +27,7 @@ namespace os
         out[6] = (mode & S_ISGID) ? ((mode & S_IXGRP) ? 's' : 'S') : ((mode & S_IXGRP) ? 'x' : '-');
         out[7] = (mode & S_IROTH) ? 'r' : '-';
         out[8] = (mode & S_IWOTH) ? 'w' : '-';
-        // FIXME: Support the sticky bit.
+        out[9] = (mode & S_ISVTX) ? ((mode & S_IXOTH) ? 't' : 'T') : ((mode & S_IXOTH) ? 'x' : '-');
-        out[9] = (mode & S_IXOTH) ? 'x' : '-';
         out[10] = '\0';
     }
 }