Add file removal, rm

src/kernel/fat16.c

@@ -42,21 +42,20 @@ typedef struct {
   uint32_t size;
   uint16_t dir_cluster;
   uint16_t dir_index;
-  uint8_t valid;
+  uint8_t removed;
 } fat16_inode_t;
 
 static fat16_inode_t inodes[MAX_INODES];
 
 static fat16_inode_t *inode_create(uint16_t first_cluster, uint32_t size, uint16_t dir_cluster, uint16_t dir_index) {
   for (uint64_t i = 0; i < MAX_INODES; i++) {
-    if (!inodes[i].valid) {
+    if (!inodes[i].refs) {
       inodes[i] = (fat16_inode_t){
           .refs = 1,
           .first_cluster = first_cluster,
           .size = size,
           .dir_cluster = dir_cluster,
           .dir_index = dir_index,
-          .valid = 1,
       };
       return &inodes[i];
     }
@@ -66,7 +65,7 @@ static fat16_inode_t *inode_create(uint16_t first_cluster, uint32_t size, uint16
 
 static fat16_inode_t *inode_get(uint32_t dir_cluster, uint16_t dir_index) {
   for (uint64_t i = 0; i < MAX_INODES; i++) {
-    if (inodes[i].valid && inodes[i].dir_cluster == dir_cluster && inodes[i].dir_index == dir_index) {
+    if (inodes[i].refs && inodes[i].dir_cluster == dir_cluster && inodes[i].dir_index == dir_index) {
       return &inodes[i];
     }
   }
@@ -84,14 +83,8 @@ static fat16_inode_t *inode_use(uint16_t first_cluster, uint32_t size, uint16_t
 }
 
 static void inode_free(fat16_inode_t *inode) {
-  inode->refs--;
-  if (!inode->refs) {
-    for (uint64_t i = 0; i < MAX_INODES; i++) {
-      if (&inodes[i] == inode) {
-        inodes[i].valid = 0;
-        break;
-      }
-    }
+  if (inode->refs) {
+    inode->refs--;
   }
 }
 
@@ -263,6 +256,10 @@ fs_node_t *fat16_open_by(const fs_node_t *directory, const char *name, uint64_t
     return NUL;
   }
 
+  if (((fat16_node_t *)directory)->inode->removed) {
+    return NUL;
+  }
+
   uint16_t dir_cluster = ((fat16_node_t *)directory)->inode->first_cluster;
 
   char name_8_3[12];
@@ -350,6 +347,10 @@ fs_node_t *fat16_open_at(const fs_node_t *directory, uint16_t index, uint64_t fl
     return NUL;
   }
 
+  if (((fat16_node_t *)directory)->inode->removed) {
+    return NUL;
+  }
+
   uint16_t dir_cluster = ((fat16_node_t *)directory)->inode->first_cluster;
 
   fat16_dir_entry_t *entries;
@@ -403,6 +404,10 @@ uint64_t fat16_read(const fs_node_t *file, uint32_t offset, uint32_t bytes, void
     return (uint64_t)-1;
   }
 
+  if (fat_file->inode->removed) {
+    return 0;
+  }
+
   if (offset >= fat_file->inode->size) {
     return 0;
   }
@@ -460,6 +465,10 @@ uint64_t fat16_write(fs_node_t *file, uint32_t offset, const void *from, uint32_
     return (uint64_t)-1;
   }
 
+  if (fat_file->inode->removed) {
+    return 0;
+  }
+
   ensure_fat();
 
   if (!fat_file->inode->first_cluster) {
@@ -540,6 +549,10 @@ uint64_t fat16_truncate(fs_node_t *file, uint32_t size) {
     return (uint64_t)-1;
   }
 
+  if (fat_file->inode->removed) {
+    return 0;
+  }
+
   if (file->size == size) {
     return size;
   } else if (file->size < size) {
@@ -585,6 +598,57 @@ uint64_t fat16_truncate(fs_node_t *file, uint32_t size) {
   return (uint64_t)-1;
 }
 
+uint64_t fat16_remove(fs_node_t *file) {
+  fat16_node_t *fat_file = (fat16_node_t *)file;
+
+  if (fat_file->base.type != FAT16) {
+    return (uint64_t)-1;
+  }
+
+  if (fat_file->inode->removed) {
+    return 0;
+  }
+
+  if (file->is_dir) {
+    fat16_dir_entry_t *subentries;
+    uint16_t subentries_count = read_directory(fat_file->inode->first_cluster, &subentries);
+    uint16_t ei = 0, vi = 0;
+    while (ei < subentries_count && subentries[ei].name[0]) {
+      if ((uint8_t)subentries[ei].name[0] != 0xE5 && (uint8_t)subentries[ei].attributes != 0x0F) {
+        vi++;
+      }
+      ei++;
+    }
+    memory_free(subentries);
+    if (vi > 2) {
+      return (uint64_t)-1;
+    }
+  }
+
+  fat_file->inode->removed = 1;
+
+  if (fat_file->inode->first_cluster) {
+    ensure_fat();
+    uint64_t next_cluster = fat_file->inode->first_cluster;
+    do {
+      uint32_t swap = fat[next_cluster];
+      fat[next_cluster] = 0;
+      next_cluster = swap;
+    } while (next_cluster < 0xFFF8);
+    flush_fat();
+  }
+
+  fat16_dir_entry_t *entries;
+  uint16_t entries_count = read_directory(fat_file->inode->dir_cluster, &entries);
+  entries[fat_file->inode->dir_index].name[0] = 0xE5;
+  entries[fat_file->inode->dir_index].first_cluster = 0;
+  entries[fat_file->inode->dir_index].size = 0;
+  write_directory(fat_file->inode->dir_cluster, entries, entries_count);
+  memory_free(entries);
+
+  return 1;
+}
+
 typedef struct {
   stream_t stream;
   fs_node_t *node;