Initial commit

build/fs/api_file.js

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+let File = {
+  // **`File.read(name)`**
+  // Read the whole file into a string variable.
+  //
+  // Return value: a string contents of the file.
+  // If file does not exist, an empty string is returned.
+  //
+  // Example: read a .json configuration file into a config object:
+  // ```javascript
+  // let obj = JSON.parse(File.read('settings.json')); 
+  // ```
+  read: function(path) {
+    let n = 0; let res = ''; let buf = 'xxxxxxxxxx'; // Should be > 5
+    let fp = File.fopen(path, 'r');
+    if (fp === null) return null;
+    while ((n = File.fread(buf, 1, buf.length, fp)) > 0) {
+      res += buf.slice(0, n);
+    }
+    File.fclose(fp);
+    return res;
+  },
+
+  // **`File.remove(name)`**
+  // Delete file with a given name. Return value: 0
+  // on success, non-0 on failure.
+  remove: ffi('int remove(char *)'),
+
+  // **`File.rename(old, new)`**
+  // Rename file `old` to `new`. Return 0 on success, non-0 on failure.
+  rename: ffi('int rename(char *, char *)'),
+
+  // **`File.write(str, name, mode)`**
+  // Write string `str` into file `name`.
+  //
+  // If file does not exist, it is created. `mode` is an optional file open
+  // mode argument, `'w'` by default, which means that previous content is
+  // deleted. Set `mode` to `'a'` in order to append to the existing content.
+  // Return value: number of bytes written.
+  //
+  // Example - write a configuration object into a file:
+  // ```javascript
+  // File.write(JSON.stringify(obj, 'settings.json'));
+  // ```
+  write: function(str, path, oMode) {
+    let fp = File.fopen(path, oMode || 'w');
+    if (fp === null) return 0;
+    let off = 0; let tot = str.length;
+    while (off < tot) {
+      let len = 5;  // Use light 5-byte strings for writing
+      if (off + len > tot) len = tot - off;
+      let n = File.fwrite(str.slice(off, off + len), 1, len, fp);
+      // if (n <= 0) break;
+      off += n;
+    }
+    File.fclose(fp);
+    return off;
+  },
+
+  fopen: ffi('void *fopen(char *, char *)'),
+  fclose: ffi('void fclose(void *)'),
+  fread: ffi('int fread(char *, int, int, void *)'),
+  fwrite: ffi('int fwrite(char *, int, int, void *)'),
+};