[PATCH #2] lib: create blkdevsize.c, linux_version.c, blockdev.h

[Stefan Krah <stefan@xxxxxxxxxxxx>]

Karel Zak <kzak@xxxxxxxxxx> wrote:
>  What about a new file lib/linux_version.c ?
> 
>  See linux_version_code() in mkswap. I think it's more generic
>  implementation.


yes, that's nicer. Somehow I prefer get_linux_version() and kernel_version()
from gpt.c, so I used that.


Stefan Krah


remarks:

  - changed (%u -> %d) in sscanf() of get_linux_version()

  - added blkdev_get_sector_size()

  - took over the kernel < 2.3.3 workaround from fdisk.c, but
    could not find the reason for the workaround.


========================================================================

diff --git a/lib/blkdevsize.c b/lib/blkdevsize.c
new file mode 100644
index 0000000..834b00c
--- /dev/null
+++ b/lib/blkdevsize.c
@@ -0,0 +1,95 @@
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#include "blockdev.h"
+
+
+#define BLKSSZGET _IO(0x12,104)    /* hardware sector size (int *arg) */
+#define BLKGETSIZE _IO(0x12,96)    /* size in 512-byte sectors (ulong *arg) */
+#define BLKGETSIZE64 _IOR(0x12,114,size_t)	/* size in bytes (u64 *arg) */
+
+
+/* get size in bytes */
+int
+blkdev_get_size(int fd, unsigned long long *bytes)
+{
+	unsigned long size;
+
+	/* kernels 2.4.15-2.4.17 had a broken BLKGETSIZE64 */
+	if (get_linux_version() >= kernel_version(2,6,0))
+		if (ioctl(fd, BLKGETSIZE64, bytes) >= 0)
+			return 0;
+
+	if (ioctl(fd, BLKGETSIZE, &size) >= 0) {
+		*bytes = ((unsigned long long)size << 9);
+		return 0;
+	}
+
+	return -1;
+}
+
+/* get 512-byte sector count */
+int
+blkdev_get_sectors(int fd, unsigned long long *sectors)
+{
+	unsigned long long bytes;
+
+	if (blkdev_get_size(fd, &bytes) == 0) {
+		*sectors = (bytes >> 9);
+		return 0;
+	}
+
+	return -1;
+}
+
+/* get hardware sector size */
+int
+blkdev_get_sector_size(int fd, int *sector_size)
+{
+	/* FIXME: supply reason for this */
+	if (get_linux_version() < kernel_version(2,3,3)) {
+		*sector_size = 512;
+		return 0;
+	}
+	if (ioctl(fd, BLKSSZGET, sector_size) >= 0)
+		return 0;
+
+	return -1;
+}
+
+
+#ifdef TEST_PROGRAM
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <err.h>
+int
+main(int argc, char **argv)
+{
+	unsigned long long bytes;
+	unsigned long long sectors;
+	int sector_size;
+	int fd;
+
+
+	if (argc != 2) {
+		fprintf(stderr, "usage: %s device\n", argv[0]);
+		exit(1);
+	}
+
+	if ((fd = open(argv[1], O_RDONLY)) < 0)
+		err(1, "error");
+
+	if (blkdev_get_size(fd, &bytes) < 0)
+		err(1, "error");
+	if (blkdev_get_sectors(fd, &sectors) < 0)
+		err(1, "error");
+	if (blkdev_get_sector_size(fd, &sector_size) < 0)
+		err(1, "error");
+
+
+	printf("bytes: %llu	sectors: %llu	sector size: %d\n", bytes, sectors, sector_size);
+
+	return 0;
+}
+#endif /* TEST_PROGRAM */
+


========================================================================

diff --git a/lib/blockdev.h b/lib/blockdev.h
new file mode 100644
index 0000000..2d6e6c0
--- /dev/null
+++ b/lib/blockdev.h
@@ -0,0 +1,17 @@
+#ifndef BLOCKDEV_H
+#define BLOCKDEV_H
+
+
+int kernel_version(int p, int q, int r);
+int get_linux_version(void);
+
+
+/* get size in bytes */
+int blkdev_get_size(int fd, unsigned long long *bytes);
+/* get 512-byte sector count */
+int blkdev_get_sectors(int fd, unsigned long long *sectors);
+/* get hardware sector size */
+int blkdev_get_sector_size(int fd, int *sector_size);
+
+
+#endif /* BLOCKDEV_H */


========================================================================

diff --git a/lib/linux_version.c b/lib/linux_version.c
new file mode 100644
index 0000000..5b40bc3
--- /dev/null
+++ b/lib/linux_version.c
@@ -0,0 +1,30 @@
+#include <stdio.h>
+#include <sys/utsname.h>
+#include "blockdev.h"
+
+
+int
+kernel_version (int p, int q, int r)
+{
+	return 65536*p + 256*q + r;
+}
+
+int
+get_linux_version (void)
+{
+	static int kver = -1;
+	struct utsname uts;
+	int major;
+	int minor;
+	int teeny;
+
+	if (kver != -1)
+		return kver;
+	if (uname (&uts))
+		return kver = 0;
+	if (sscanf (uts.release, "%d.%d.%d", &major, &minor, &teeny) != 3)
+		return kver = 0;
+	return kver = kernel_version (major, minor, teeny);
+}
+
+

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