mdev-helpers

commit: eb6a25e1ec9c063d1498f7adf9ef01bf8ebd99d4
parent aa5fe6585c792c800eb06b6c945e65b24131bc65
Author: Haelwenn (lanodan) Monnier <contact@hacktivis.me>
Date:   Thu, 19 Feb 2026 15:49:47 +0100

cmd/disk_id.c: Add

Diffstat:
A
cmd/disk_id.c
119
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

1 file changed, 119 insertions(+), 0 deletions(-)
diff --git a/cmd/disk_id.c b/cmd/disk_id.c
@@ -0,0 +1,119 @@
+// mdev-helpers: Collection of helpers for mdev/mdevd
+// SPDX-FileCopyrightText: 2017-2022 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
+// SPDX-License-Identifier: BSD-3-Clause
+
+#define _DEFAULT_SOURCE
+#include <ctype.h> // isalnum
+#include <errno.h>
+#include <fcntl.h>       // open
+#include <linux/hdreg.h> // HDIO_GET_IDENTITY
+#include <stdint.h>      // uint16_t
+#include <stdio.h>
+#include <string.h>  // strerror
+#include <stropts.h> // ioctl
+#include <unistd.h>  // fsync, write
+
+static char *
+strip(char *s, size_t *len)
+{
+	while(*len > 0 && *s == ' ')
+	{
+		s++;
+		(*len)--;
+	}
+
+	while(*len > 0 && s[(*len) - 1] == ' ')
+	{
+		s[(*len) - 1] = '\0';
+		(*len)--;
+	}
+
+	return s;
+}
+
+static size_t
+strncpyalnum(char *dest, char *src, size_t len)
+{
+	size_t i = 0;
+
+	for(; i < len; i++)
+	{
+		if(src[i] == '\0') break;
+
+		dest[i] = isalnum(src[i]) ? src[i] : '_';
+	}
+
+	return i;
+}
+
+int
+main(int argc, char *argv[])
+{
+	if(argc != 2)
+	{
+		fprintf(stderr, "disk_id: error: Need 1 argument, got %d\n", argc - 1);
+		fprintf(stderr, "Usage: disk_id <block_device_path>\n");
+		return 1;
+	}
+
+	const char *dev = argv[1];
+
+	int fd = open(dev, O_RDONLY | O_NONBLOCK | O_LARGEFILE);
+
+	// IDENTITY is 512 bytes
+	static uint16_t identity[256];
+	int ret = ioctl(fd, HDIO_GET_IDENTITY, identity);
+	if(ret < 0)
+	{
+		switch(errno)
+		{
+		case EINVAL:
+			fprintf(stderr,
+			        "disk_id: error: Device '%s' -> ioctl(HDIO_GET_IDENTITY): [EINVAL] Is a partition "
+			        "not a disk\n",
+			        dev);
+			return 1;
+		case ENOMSG:
+			fprintf(stderr,
+			        "disk_id: error: Device '%s' -> ioctl(HDIO_GET_IDENTITY): [ENOMSG] Information not "
+			        "available\n",
+			        dev);
+			return 1;
+		default:
+			fprintf(stderr,
+			        "disk_id: error: Device '%s' -> ioctl(HDIO_GET_IDENTITY): %s\n",
+			        dev,
+			        strerror(errno));
+			return 1;
+		}
+	}
+
+	// TODO: Handle errno
+	close(fd);
+
+	static char serno_buf[20]    = "";
+	static char model_buf[40]    = "";
+	static char disk_id[40 + 20] = "";
+
+	size_t serno_len = 20;
+	memcpy(serno_buf, (char *)&identity[10], serno_len);
+	char *serno = strip(serno_buf, &serno_len);
+	//printf("serno: [%s] (%zd)\n", serno, serno_len);
+
+	size_t model_len = 40;
+	memcpy(model_buf, (char *)&identity[27], model_len);
+	char *model = strip(model_buf, &model_len);
+	//printf("model: [%s] (%zd)\n", model, model_len);
+
+	size_t modelz = strncpyalnum(disk_id, model, model_len);
+	if(modelz == 0) return 1;
+
+	disk_id[modelz++] = '_';
+
+	size_t serialz = strncpyalnum(disk_id + modelz, serno, serno_len);
+	if(serialz == 0) return 1;
+
+	printf("%s\n", disk_id);
+
+	return 0;
+}