Initial commit

Author: tniessen

.editorconfig

@@ -0,0 +1,7 @@
+
+root = true
+
+[**.{c,h,sh}]
+indent_style = space
+indent_size  = 2
+

.gitignore

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+*.o
+memfs

Makefile

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+
+CC=gcc
+CFLAGS=-g -Wall -D_FILE_OFFSET_BITS=64
+LDFLAGS=-L~/fuse-2.9.5/lib/ -lfuse
+
+OBJ=memfs.o node.o dir.o
+
+%.o: %.c
+	$(CC) -c $(CFLAGS) $< -o $@
+
+memfs: $(OBJ)
+	$(CC) $(OBJ) $(LDFLAGS) -o memfs
+
+.PHONY: clean
+clean:
+	rm -f *.o memfs
+

debug.sh

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+#!/bin/bash
+set -e
+make
+gdb --args ./memfs -d -s -o default_permissions -o auto_unmount testmount

dir.c

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+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "dir.h"
+
+int dir_add(struct node *dirnode, struct direntry *entry, int replace, int *added) {
+  struct direntry **dir = (struct direntry **) &dirnode->data;
+  struct direntry *existing_entry;
+
+  if(dir_find(dirnode, entry->name, strlen(entry->name), &existing_entry)) {
+    if(replace) {
+      *added = 0;
+      existing_entry->node = entry->node;
+      return 1;
+    } else {
+      errno = EEXIST;
+      return 0;
+    }
+  }
+
+  *added = 1;
+
+  if(*dir == NULL) {
+    *dir = entry;
+    entry->next = NULL;
+  } else {
+    entry->next = *dir;
+    *dir = entry;
+  }
+
+  // The entry is now linked in the directory
+  entry->node->vstat.st_nlink++;
+
+  // If the entry is a directory, .. is an implicit hardlink to the parent
+  // directory.
+  if(S_ISDIR(entry->node->vstat.st_mode)) {
+    dirnode->vstat.st_nlink++;
+  }
+
+  return 1;
+}
+
+int dir_add_alloc(struct node *dirnode, const char *name, struct node *node, int replace) {
+  struct direntry *entry = malloc(sizeof(struct direntry));
+  int added;
+
+  if(!entry) {
+    errno = ENOMEM;
+    return 0;
+  }
+
+  strcpy(entry->name, name);
+  entry->node = node;
+
+  if(!dir_add(dirnode, entry, replace, &added)) {
+    free(entry);
+    return 0;
+  }
+
+  if(!added) free(entry);
+
+  return 1;
+}
+
+int dir_remove(struct node *dirnode, const char *name) {
+  struct direntry **dir = (struct direntry **) &dirnode->data;
+
+  struct direntry *ent = *dir;
+  struct direntry **ptr = dir;
+
+  while(ent != NULL) {
+    if(strcmp(ent->name, name) == 0) {
+      *ptr = ent->next;
+
+      // See dir_add for details
+      if(S_ISDIR(ent->node->vstat.st_mode)) {
+        dirnode->vstat.st_nlink--;
+      }
+
+      free(ent);
+
+      return 1;
+    }
+
+    ptr = &ent->next;
+    ent = ent->next;
+  }
+
+  errno = ENOENT;
+
+  return 0;
+}
+
+int dir_find(struct node *dirnode, const char *name, int namelen, struct direntry **entry) {
+  struct direntry *ent = (struct direntry *) dirnode->data;
+
+  while(ent != NULL) {
+    if(strlen(ent->name) == namelen) {
+      if(strncmp(ent->name, name, namelen) == 0) {
+        if(entry != NULL) *entry = ent;
+        return 1;
+      }
+    }
+    ent = ent->next;
+  }
+
+  errno = ENOENT;
+
+  return 0;
+}
+

dir.h

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+
+#include <linux/limits.h>
+#include "node.h"
+
+#ifndef _DIR_H
+#define _DIR_H
+
+struct direntry {
+  char             name[PATH_MAX];
+  struct node     *node;
+  struct direntry *next;
+};
+
+int dir_add(struct node *dir, struct direntry *entry, int replace, int *added);
+
+int dir_add_alloc(struct node *dir, const char *name, struct node *node, int replace);
+
+int dir_remove(struct node *dir, const char *name);
+
+int dir_find(struct node *dir, const char *name, int namelen, struct direntry **entry);
+
+#endif
+