Add a simple /bin/df which gathers its info from /proc/df.

Kernel/Ext2FileSystem.cpp

@@ -1359,3 +1359,27 @@ bool Ext2FSInode::chmod(mode_t mode, int& error)
     set_metadata_dirty(true);
     return true;
 }
+
+unsigned Ext2FS::total_block_count() const
+{
+    LOCKER(m_lock);
+    return super_block().s_blocks_count;
+}
+
+unsigned Ext2FS::free_block_count() const
+{
+    LOCKER(m_lock);
+    return super_block().s_free_blocks_count;
+}
+
+unsigned Ext2FS::total_inode_count() const
+{
+    LOCKER(m_lock);
+    return super_block().s_inodes_count;
+}
+
+unsigned Ext2FS::free_inode_count() const
+{
+    LOCKER(m_lock);
+    return super_block().s_free_inodes_count;
+}

Kernel/Ext2FileSystem.h

@@ -62,6 +62,11 @@ public:
     virtual ~Ext2FS() override;
     virtual bool initialize() override;
 
+    virtual unsigned total_block_count() const override;
+    virtual unsigned free_block_count() const override;
+    virtual unsigned total_inode_count() const override;
+    virtual unsigned free_inode_count() const override;
+
 private:
     typedef unsigned BlockIndex;
     typedef unsigned GroupIndex;

Kernel/FileSystem.h

@@ -37,6 +37,11 @@ public:
 
     bool is_readonly() const { return m_readonly; }
 
+    virtual unsigned total_block_count() const { return 0; }
+    virtual unsigned free_block_count() const { return 0; }
+    virtual unsigned total_inode_count() const { return 0; }
+    virtual unsigned free_inode_count() const { return 0; }
+
     struct DirectoryEntry {
         DirectoryEntry(const char* name, InodeIdentifier, byte file_type);
         DirectoryEntry(const char* name, size_t name_length, InodeIdentifier, byte file_type);

Kernel/ProcFS.cpp

@@ -28,6 +28,7 @@ enum ProcFileType {
     __FI_Root_Start,
     FI_Root_mm,
     FI_Root_mounts,
+    FI_Root_df,
     FI_Root_kmalloc,
     FI_Root_all,
     FI_Root_summary,
@@ -399,6 +400,27 @@ ByteBuffer procfs$mounts(InodeIdentifier)
     return builder.to_byte_buffer();
 }
 
+ByteBuffer procfs$df(InodeIdentifier)
+{
+    // FIXME: This is obviously racy against the VFS mounts changing.
+    StringBuilder builder;
+    VFS::the().for_each_mount([&builder] (auto& mount) {
+        auto& fs = mount.guest_fs();
+        builder.appendf("%s,", fs.class_name());
+        builder.appendf("%u,", fs.total_block_count());
+        builder.appendf("%u,", fs.free_block_count());
+        builder.appendf("%u,", fs.total_inode_count());
+        builder.appendf("%u,", fs.free_inode_count());
+        if (!mount.host().is_valid())
+            builder.append("/");
+        else {
+            builder.append(VFS::the().absolute_path(mount.host()));
+        }
+        builder.append('\n');
+    });
+    return builder.to_byte_buffer();
+}
+
 ByteBuffer procfs$cpuinfo(InodeIdentifier)
 {
     StringBuilder builder;
@@ -1076,6 +1098,7 @@ ProcFS::ProcFS()
     m_entries.resize(FI_MaxStaticFileIndex);
     m_entries[FI_Root_mm] = { "mm", FI_Root_mm, procfs$mm };
     m_entries[FI_Root_mounts] = { "mounts", FI_Root_mounts, procfs$mounts };
+    m_entries[FI_Root_df] = { "df", FI_Root_df, procfs$df };
     m_entries[FI_Root_kmalloc] = { "kmalloc", FI_Root_kmalloc, procfs$kmalloc };
     m_entries[FI_Root_all] = { "all", FI_Root_all, procfs$all };
     m_entries[FI_Root_summary] = { "summary", FI_Root_summary, procfs$summary };

Kernel/sync.sh

@@ -64,6 +64,7 @@ cp -v ../Userland/dmesg mnt/bin/dmesg
 cp -v ../Userland/chmod mnt/bin/chmod
 cp -v ../Userland/top mnt/bin/top
 cp -v ../Userland/ln mnt/bin/ln
+cp -v ../Userland/df mnt/bin/df
 cp -v ../Applications/Terminal/Terminal mnt/bin/Terminal
 cp -v ../Applications/FontEditor/FontEditor mnt/bin/FontEditor
 cp -v ../Applications/Launcher/Launcher mnt/bin/Launcher

Userland/.gitignore

@@ -32,3 +32,4 @@ top
 chmod
 pape
 ln
+df

Userland/Makefile

@@ -27,6 +27,7 @@ OBJS = \
        dmesg.o \
        chmod.o \
        top.o \
+       df.o \
        ln.o \
        rm.o
 
@@ -61,6 +62,7 @@ APPS = \
        chmod \
        top \
        ln \
+       df \
        rm
 
 ARCH_FLAGS =
@@ -174,6 +176,9 @@ top: top.o
 ln: ln.o
 	$(LD) -o $@ $(LDFLAGS) $< ../LibC/LibC.a
 
+df: df.o
+	$(LD) -o $@ $(LDFLAGS) $< ../LibC/LibC.a
+
 .cpp.o:
 	@echo "CXX $<"; $(CXX) $(CXXFLAGS) -o $@ -c $<
 

Userland/df.cpp

@@ -0,0 +1,55 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <AK/AKString.h>
+#include <AK/Vector.h>
+
+struct FileSystem {
+    String fs;
+    size_t total_block_count { 0 };
+    size_t free_block_count { 0 };
+    size_t total_inode_count { 0 };
+    size_t free_inode_count { 0 };
+    String mount_point;
+};
+
+int main(int, char**)
+{
+    FILE* fp = fopen("/proc/df", "r");
+    if (!fp) {
+        perror("failed to open /proc/df");
+        return 1;
+    }
+    printf("Filesystem    Blocks        Used    Available   Mount point\n");
+    for (;;) {
+        char buf[4096];
+        char* ptr = fgets(buf, sizeof(buf), fp);
+        if (!ptr)
+            break;
+        auto parts = String(buf, Chomp).split(',');
+        if (parts.size() < 6)
+            break;
+        bool ok;
+        String fs = parts[0];
+        unsigned total_block_count = parts[1].to_uint(ok);
+        ASSERT(ok);
+        unsigned free_block_count = parts[2].to_uint(ok);
+        ASSERT(ok);
+        unsigned total_inode_count = parts[3].to_uint(ok);
+        ASSERT(ok);
+        unsigned free_inode_count = parts[4].to_uint(ok);
+        ASSERT(ok);
+        String mount_point = parts[5];
+
+        printf("% 10s", fs.characters());
+        printf("%10u  ", total_block_count);
+        printf("%10u   ", total_block_count - free_block_count);
+        printf("%10u   ", free_block_count);
+        printf("%s", mount_point.characters());
+        printf("\n");
+    }
+    int rc = fclose(fp);
+    ASSERT(rc == 0);
+    return 0;
+}