balena-image-fs - npm Package Compare versions

Comparing version 7.4.0-build-get-filesystem-label-dd0cf1da6d688913dbb3a01f372b1df9a2bdf86f-1 to 7.4.0-build-get-filesystem-label-e101822ba5412f3e4c1b9ee09856b35a55497e75-1

build/fsLabel.d.ts

@@ -5,3 +5,3 @@ import { Disk } from 'file-disk';
 /**
- * @summary An error to describe why getLabel() failed to find a filesystem label.
+ * @summary An error to describe why getFsLabel() failed to find a filesystem label.
  */
@@ -24,3 +24,3 @@ export declare class LabelNotFound extends TypedError {
  *     for (const partition of info.partitions) {
- *         const label = await getLabel(disk, partition);
+ *         const label = await getFsLabel(disk, partition);
  *         console.log(`${partition.index}: ${label}`);
@@ -30,2 +30,2 @@ *     }
  */
-export declare function getLabel(disk: Disk, partition: GPTPartition | MBRPartition): Promise<string>;
+export declare function getFsLabel(disk: Disk, partition: GPTPartition | MBRPartition): Promise<string>;

build/fsLabel.js

 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
-exports.getLabel = exports.LabelNotFound = void 0;
+exports.getFsLabel = exports.LabelNotFound = void 0;
 const typed_error_1 = require("typed-error");
@@ -10,4 +10,29 @@ // GPT partition GUIDs
 const GUID_LINUX_NATIVE = '0FC63DAF-8483-4772-8E79-3D69D8477DE4';
+// Maximum length to read among various filesystem metadata. Change as needed
+// to support additional filesystems.
+const FS_METADATA_MAXLEN = 0x100;
+// MBR partition type IDs
+// https://en.wikipedia.org/wiki/Partition_type
+const PARTID_FAT32_CHS = 0xB;
+const PARTID_FAT32_LBA = 0xC;
+const PARTID_FAT16_LBA = 0xE;
+const PARTID_LINUX_NATIVE = 0x83;
+// FAT constants
+// https://en.wikipedia.org/wiki/Design_of_the_FAT_file_system#Extended_BIOS_Parameter_Block
+// https://en.wikipedia.org/wiki/Design_of_the_FAT_file_system#FAT32_Extended_BIOS_Parameter_Block
+const FAT_LABEL_MAXLEN = 11;
+const FAT_MAGIC_VALUE = 0x29;
+const FAT16_MAGIC_OFFSET = 0x26;
+const FAT16_LABEL_OFFSET = 0x2B;
+const FAT32_MAGIC_OFFSET = 0x42;
+const FAT32_LABEL_OFFSET = 0x47;
+// EXT4 constants
+// https://www.kernel.org/doc/html/latest/filesystems/ext4/index.html
+const EXT4_SUPERBLOCK_OFFSET = 0x400;
+const EXT4_MAGIC_OFFSET = 0x38;
+const EXT4_MAGIC_VALUE_LE = 0xEF53;
+const EXT4_LABEL_OFFSET = 0x78;
+const EXT4_LABEL_MAXLEN = 16;
 /**
- * @summary An error to describe why getLabel() failed to find a filesystem label.
+ * @summary An error to describe why getFsLabel() failed to find a filesystem label.
  */
@@ -33,3 +58,3 @@ class LabelNotFound extends typed_error_1.TypedError {
  *     for (const partition of info.partitions) {
- *         const label = await getLabel(disk, partition);
+ *         const label = await getFsLabel(disk, partition);
  *         console.log(`${partition.index}: ${label}`);
@@ -39,74 +64,65 @@ *     }
  */
-async function getLabel(disk, partition) {
-    // If GPT, can we just read the protective MBR?
-    // Is there a more Typescript native way to determine partition table type? 
+async function getFsLabel(disk, partition) {
     const isGpt = 'guid' in partition;
     const isMbr = !isGpt;
-    // Read filesystem metadata. May need further reads depending on filesystem.
-    let buf = Buffer.alloc(0x100);
-    await disk.read(buf, 0, buf.length, partition.offset);
-    let labelOffset = 0;
-    let maxLength = 0;
+    // Use a buffer capable of reading any filesystem metadata. Defer actual
+    // read until select filesystem.
+    const buf = Buffer.alloc(FS_METADATA_MAXLEN);
+    let labelOffset;
+    let maxLength;
     // A filesystem places the label in a certain position in its metadata. So
-    // we must determine the type of filesystem, but there are many possibilities.
-    // We first narrow the possibilities by checking the partition type (MBR) or
-    // GUID (GPT) for the containing partition. There are two broad categories --
-    // FAT types and Linux native types. Finally we confirm the presence of signature
-    // bytes within the filesystem.
-    // https://en.wikipedia.org/wiki/Partition_type
-    const mbrFatTypes = [0xB, 0xC, 0xE];
+    // we must determine the type of filesystem. We first narrow the possibilities
+    // by checking the partition type (MBR) or GUID (GPT) for the containing partition.
+    // There are two broad categories of filesystem -- FAT types and Linux native
+    // types. Finally we confirm the presence of signature bytes within the filesystem
+    // metadata.
+    // FAT types
+    const mbrFatTypes = [PARTID_FAT32_CHS, PARTID_FAT32_LBA, PARTID_FAT16_LBA];
     const gptFatTypes = [GUID_EFI_SYSTEM, GUID_MS_BASIC_DATA];
-    let foundPartType = false;
-    let foundLabel = false;
-    if (isMbr && mbrFatTypes.some(ptype => partition.type === ptype)
-        || isGpt && gptFatTypes.some(ptype => partition.type === ptype)) {
-        foundPartType = true;
-        maxLength = 11;
+    if (isMbr && mbrFatTypes.includes(partition.type)
+        || isGpt && gptFatTypes.includes(partition.type)) {
+        maxLength = FAT_LABEL_MAXLEN;
+        await disk.read(buf, 0, buf.length, partition.offset);
         // FAT16
-        if (buf.readUInt8(0x26) === 0x29) {
-            labelOffset = 0x2B;
-            foundLabel = true;
+        if (buf.readUInt8(FAT16_MAGIC_OFFSET) === FAT_MAGIC_VALUE) {
+            labelOffset = FAT16_LABEL_OFFSET;
             // FAT32
         }
-        else if (buf.readUInt8(0x42) === 0x29) {
-            labelOffset = 0x47;
-            foundLabel = true;
+        else if (buf.readUInt8(FAT32_MAGIC_OFFSET) === FAT_MAGIC_VALUE) {
+            labelOffset = FAT32_LABEL_OFFSET;
         }
     }
-    // Linux filesytem of some kind
+    // Linux filesytem of some kind; expecting ext2+
     const gptLinuxTypes = [GUID_LINUX_NATIVE, GUID_MS_BASIC_DATA];
-    if (!foundLabel
-        && ((isMbr && partition.type === 0x83)
-            || (isGpt && gptLinuxTypes.some(ptype => partition.type === ptype)))) {
-        foundPartType = true;
-        maxLength = 16;
+    if (labelOffset == null && ((isMbr && partition.type === PARTID_LINUX_NATIVE)
+        || (isGpt && gptLinuxTypes.includes(partition.type)))) {
+        maxLength = EXT4_LABEL_MAXLEN;
         // ext2+; reload buffer within superblock
-        await disk.read(buf, 0, buf.length, partition.offset + 0x400);
-        if (buf.readUInt16LE(0x38) === 0xEF53) {
-            labelOffset = 0x78;
-            foundLabel = true;
+        await disk.read(buf, 0, buf.length, partition.offset + EXT4_SUPERBLOCK_OFFSET);
+        if (buf.readUInt16LE(EXT4_MAGIC_OFFSET) === EXT4_MAGIC_VALUE_LE) {
+            labelOffset = EXT4_LABEL_OFFSET;
         }
     }
     // Fail on unexpected partition/filesystem
-    if (!foundPartType) {
+    // If max length for a label not defined, then implicitly we have not even
+    // found a partition type.
+    if (maxLength == null) {
         throw new LabelNotFound(partition.index, 'unexpected partition type');
     }
-    else if (!foundLabel) {
+    if (labelOffset == null) {
         throw new LabelNotFound(partition.index, 'can\'t read filesystem');
     }
     // Exclude trailing /0 bytes to stringify.
-    let i = 0;
-    for (; i <= maxLength; i++) {
-        // If label fills available space, no need to test. We just need i
-        // to have the expected value for Buffer.toString() call below.
-        if (i == maxLength) {
+    let zeroBytePosition;
+    for (let i = 0; i < maxLength; i++) {
+        if (buf.readUInt8(labelOffset + i) === 0) {
+            zeroBytePosition = i;
             break;
         }
-        if (buf.readUInt8(labelOffset + i) == 0) {
-            break;
-        }
     }
-    return buf.toString('utf8', labelOffset, labelOffset + i).trim();
+    // Didn't find a /0 byte; must be max length.
+    zeroBytePosition !== null && zeroBytePosition !== void 0 ? zeroBytePosition : (zeroBytePosition = maxLength);
+    return buf.toString('utf8', labelOffset, labelOffset + zeroBytePosition).trim();
 }
-exports.getLabel = getLabel;
+exports.getFsLabel = getFsLabel;
 //# sourceMappingURL=fsLabel.js.map

build/index.d.ts

 /// <reference types="node" />
 import * as Fs from 'fs';
 import { Disk } from 'file-disk';
-export { getLabel, LabelNotFound } from './fsLabel';
+export { getFsLabel, LabelNotFound } from './fsLabel';
 /**
@@ -6,0 +6,0 @@ * @summary Run a function with a node fs like interface for a partition

build/index.js

@@ -18,3 +18,3 @@ "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
-exports.interact = exports.LabelNotFound = exports.getLabel = void 0;
+exports.interact = exports.LabelNotFound = exports.getFsLabel = void 0;
 /**
@@ -31,3 +31,3 @@ * @module imagefs
 var fsLabel_1 = require("./fsLabel");
-Object.defineProperty(exports, "getLabel", { enumerable: true, get: function () { return fsLabel_1.getLabel; } });
+Object.defineProperty(exports, "getFsLabel", { enumerable: true, get: function () { return fsLabel_1.getFsLabel; } });
 Object.defineProperty(exports, "LabelNotFound", { enumerable: true, get: function () { return fsLabel_1.LabelNotFound; } });
@@ -34,0 +34,0 @@ class MountError extends typed_error_1.TypedError {

CHANGELOG.md

@@ -7,3 +7,3 @@ # Change Log
 
-## 7.4.0 - 2025-01-17
+## 7.4.0 - 2025-01-22
 
@@ -10,0 +10,0 @@ * Add getLabel() to retrieve filesystem label [Ken Bannister]

package.json

 {
   "name": "balena-image-fs",
-  "version": "7.4.0-build-get-filesystem-label-dd0cf1da6d688913dbb3a01f372b1df9a2bdf86f-1",
+  "version": "7.4.0-build-get-filesystem-label-e101822ba5412f3e4c1b9ee09856b35a55497e75-1",
   "description": "Image filesystem manipulation utilities",
@@ -62,4 +62,4 @@ "main": "build/index.js",
   "versionist": {
-    "publishedAt": "2025-01-17T03:40:29.783Z"
+    "publishedAt": "2025-01-22T01:24:43.336Z"
   }
 }

No alert changes

Improved metrics

Total package byte prevSize

38943

increased by3.91%

Lines of code

329

increased by5.11%

No dependency changes