From 50281d1db5768a38bafed8dc28956e71075c0f60 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ciro=20Santilli=20=E5=85=AD=E5=9B=9B=E4=BA=8B=E4=BB=B6=20?=
 =?UTF-8?q?=E6=B3=95=E8=BD=AE=E5=8A=9F?= <ciro.santilli@gmail.com>
Date: Tue, 8 Oct 2019 00:00:01 +0000
Subject: [PATCH] nodejs: file io

---
 README.adoc                                   |  4 +++-
 .../lkmc/nodejs/command_line_arguments.js     |  2 ++
 rootfs_overlay/lkmc/nodejs/file_write_read.js | 20 +++++++++++++++++++
 userland/c/file_write_read.c                  |  8 ++++----
 4 files changed, 29 insertions(+), 5 deletions(-)
 create mode 100755 rootfs_overlay/lkmc/nodejs/file_write_read.js

diff --git a/README.adoc b/README.adoc
index ca7f0f5..3f5c3e8 100644
--- a/README.adoc
+++ b/README.adoc
@@ -13188,8 +13188,10 @@ ERROR: package host-nodejs installs executables without proper RPATH
 
 Examples:
 
-* process
+* `process`
 ** link:rootfs_overlay/lkmc/nodejs/command_line_arguments.js[]
+* `fs`
+** link:rootfs_overlay/lkmc/nodejs/file_write_read.js[]
 
 === Userland content bibliography
 
diff --git a/rootfs_overlay/lkmc/nodejs/command_line_arguments.js b/rootfs_overlay/lkmc/nodejs/command_line_arguments.js
index da9651e..6d51fbd 100755
--- a/rootfs_overlay/lkmc/nodejs/command_line_arguments.js
+++ b/rootfs_overlay/lkmc/nodejs/command_line_arguments.js
@@ -1,5 +1,7 @@
 #!/usr/bin/env node
 
+// https://cirosantilli.com/linux-kernel-module-cheat#node-js
+
 for (const arg of process.argv) {
   console.log(arg);
 }
diff --git a/rootfs_overlay/lkmc/nodejs/file_write_read.js b/rootfs_overlay/lkmc/nodejs/file_write_read.js
new file mode 100755
index 0000000..98a222b
--- /dev/null
+++ b/rootfs_overlay/lkmc/nodejs/file_write_read.js
@@ -0,0 +1,20 @@
+#!/usr/bin/env node
+
+// https://cirosantilli.com/linux-kernel-module-cheat#node-js
+
+const assert = require('assert');
+const fs = require('fs');
+const path = require('path');
+
+const file_path = path.basename(__filename) + '.tmp';
+const data = 'asdf\nqwer\n';
+const encoding = 'utf8';
+
+// Write to file.
+//
+// Error handling through exceptions:
+// https://stackoverflow.com/questions/15543235/checking-if-writefilesync-successfully-wrote-the-file
+fs.writeFileSync(file_path, data, encoding);
+
+// Read from file.
+assert.strictEqual(fs.readFileSync(file_path, encoding), data);
diff --git a/userland/c/file_write_read.c b/userland/c/file_write_read.c
index 6c1ae4e..08560f2 100644
--- a/userland/c/file_write_read.c
+++ b/userland/c/file_write_read.c
@@ -108,10 +108,10 @@ int file_write(char *path, char *write_string) {
 
 int main(void) {
     char *path = LKMC_TMP_FILE;
-    char *input = "asdf\nqwer\n";
+    char *data = "asdf\nqwer\n";
 
     /* Write entire string to file at once. */
-    if (file_write(path, input) == -1) {
+    if (file_write(path, data) == -1) {
         LKMC_IO_ERROR("file_write", path);
     }
 
@@ -121,7 +121,7 @@ int main(void) {
         if (output == NULL) {
             LKMC_IO_ERROR("file_read", path);
         }
-        assert(strcmp(input, output) == 0);
+        assert(strcmp(data, output) == 0);
         free(output);
     }
 
@@ -131,7 +131,7 @@ int main(void) {
         if (size == -1) {
             LKMC_IO_ERROR("file_size", path);
         }
-        assert((size_t)size == strlen(input));
+        assert((size_t)size == strlen(data));
     }
 
     return EXIT_SUCCESS;