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authordavid@fubar.dk <david@fubar.dk>2004-09-10 21:04:13 -0700
committerGreg KH <gregkh@suse.de>2005-04-26 21:37:00 -0700
commit0a8dd7f37c6f788c74aa528949c45aca66638e5a (patch)
tree3d329ed3bf9daf1c30d19a41c4de381bc09f7b75
parent3e4414508b409a21b023b9ca4532f62003e0db97 (diff)
[PATCH] compatibility symlinks for udev
On Mon, 2004-09-06 at 17:45 +0200, Kay Sievers wrote: > On Mon, 2004-09-06 at 16:46 +0200, David Zeuthen wrote: > > Nice, I like it. It's a easy way to group device nodes of the same type, > but coming from different kernel subsystems. > That's a good way of putting it, yeah. > > Here's a patch against udev-030 that can help create compatibility > > symlinks like /dev/cdrom, /dev/cdrom1 etc. The patch introduces a new > > substitution type %C (for Compatibility) that can be used as follows > > I suggest using %e for enumeration here, cause "compatibility" can > easily be misunderstood. > Good point, I've changed that. > And we need a few lines added to the man page at udev.8.in :) > Done. I've also added an example. Also, Kay pointed out offlist that the rules can be written to not require a shell script; this actually works KERNEL="sr*", NAME="%k", SYMLINK="cdrom%e" KERNEL="scd*", NAME="%k", SYMLINK="cdrom%e" KERNEL="pcd*", NAME="%k", SYMLINK="cdrom%e" KERNEL="hd[a-z]", PROGRAM="/bin/cat /proc/ide/%k/media", RESULT="cdrom", NAME="\%k", SYMLINK="cdrom%e" KERNEL="fd[0-9]", NAME="%k", SYMLINK="floppy%e" KERNEL="hd[a-z]", PROGRAM="/bin/cat /proc/ide/%k/media", RESULT="floppy", NAME=\"%k", SYMLINK="floppy%e" New patch is attached. David
-rw-r--r--namedev.c40
-rw-r--r--udev.8.in15
2 files changed, 55 insertions, 0 deletions
diff --git a/namedev.c b/namedev.c
index 52417e3793..466016c297 100644
--- a/namedev.c
+++ b/namedev.c
@@ -42,6 +42,7 @@
#include "logging.h"
#include "namedev.h"
#include "klibc_fixups.h"
+#include "udevdb.h"
static struct sysfs_attribute *find_sysfs_attribute(struct sysfs_class_device *class_dev, struct sysfs_device *sysfs_device, char *attr);
@@ -179,6 +180,37 @@ static int get_format_len(char **str)
return -1;
}
+/** Finds the lowest positive N such that <name>N isn't present in
+ * $(udevroot) either as a file or a symlink.
+ *
+ * @param name Name to check for
+ * @return 0 if <name> didn't exist and N otherwise.
+ */
+static unsigned int find_free_number (struct udevice *udev, char *name)
+{
+ char temp[NAME_SIZE];
+ char path[NAME_SIZE];
+ struct udevice dev;
+ int result;
+
+ /* have to sweep the database for each lookup */
+ result = 0;
+ strncpy(temp, name, sizeof (temp));
+ while (1) {
+ if (udevdb_get_dev_byname(temp, path, &dev) != 0)
+ goto found;
+ /* symlink might be stale if $(udevroot) isn't cleaned; check
+ * on major/minor to see if it's the same device
+ */
+ if (dev.major == udev->major && dev.minor == udev->minor)
+ goto found;
+ snprintf (temp, sizeof(temp), "%s%d", name, ++result);
+ }
+
+found:
+ return result;
+}
+
static void apply_format(struct udevice *udev, char *string, size_t maxsize,
struct sysfs_class_device *class_dev,
struct sysfs_device *sysfs_device)
@@ -195,6 +227,7 @@ static void apply_format(struct udevice *udev, char *string, size_t maxsize,
char *rest;
int slen;
struct sysfs_attribute *tmpattr;
+ unsigned int next_free_number;
pos = string;
while (1) {
@@ -284,6 +317,13 @@ static void apply_format(struct udevice *udev, char *string, size_t maxsize,
strfieldcatmax(string, "%", maxsize);
pos++;
break;
+ case 'e':
+ next_free_number = find_free_number(udev, string);
+ if (next_free_number > 0) {
+ snprintf(temp2, sizeof(temp2), "%d", next_free_number);
+ strfieldcatmax(string, temp2, maxsize);
+ }
+ break;
default:
dbg("unknown substitution type '%%%c'", c);
break;
diff --git a/udev.8.in b/udev.8.in
index 6d1dfd9d18..9c22f8aa63 100644
--- a/udev.8.in
+++ b/udev.8.in
@@ -272,6 +272,13 @@ all remaining parts of the result string are substituted:
.BI %s{ filename }
The content of a sysfs attribute.
.TP
+.B %e
+If a device node already exists with the name, the smallest positive
+decimal integer N is substituted such that the resulting name doesn't
+match an existing device node. Otherwise nothing is substituted. This
+can be used to create compatibility symlinks and enumerate devices of
+the same type originating from different kernel subsystems.
+.TP
.B %%
The '%' character itself.
.P
@@ -302,6 +309,14 @@ KERNEL="ttyUSB1", NAME="pda", SYMLINK="palmtop handheld"
# multiple USB webcams with symlinks to be called webcam0, webcam1, ...
BUS="usb", SYSFS{model}="XV3", NAME="video%n", SYMLINK="webcam%n"
+
+# grouping of optical drives from multiple kernel subsystems
+KERNEL="sr*", NAME="%k", SYMLINK="cdrom%e"
+KERNEL="scd*", NAME="%k", SYMLINK="cdrom%e"
+KERNEL="pcd*", NAME="%k", SYMLINK="cdrom%e"
+KERNEL="hd[a-z]", PROGRAM="/bin/cat /proc/ide/%k/media", RESULT="cdrom",
+ NAME="%k", SYMLINK="cdrom%e"
+
.fi
.P
The permissions and ownership of the created device file is read from