On 05.07.22 13:59, Sascha Hauer wrote:
> On Tue, Jul 05, 2022 at 01:55:37PM +0200, Ahmad Fatoum wrote:
>> For OF-enabled platforms with aliases, device file naming is pretty much
>> solved: If there is mmc2 = &something, then we have a mmc2 device and
>> a /dev/mmc2 device file. For other platforms like x86, EFI-provided
>> devices are harder to get ahold of. Add a command to make this
>> straight-forward to do in scripts. The main use of this is probably to
>> access parameters like nt_signature or guid:
>>
>> devlookup /dev/disk0 guid
>>
>> This would print to console, but we have no output capture yet, so add
>> an optional -v VARIABLE parameter as well to allow easy use from
>> scripts.
>>
>> Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
>> ---
>> v1 -> v2:
>> - fix typo in commit message (Michael)
>> - accept cdev without /dev/ prefix (Sascha)
>> - early exit on cdev without dev, e.g. /dev/zero
>> ---
>> commands/Kconfig | 13 ++++++++
>> commands/Makefile | 1 +
>> commands/devlookup.c | 78 ++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 92 insertions(+)
>> create mode 100644 commands/devlookup.c
>>
>> diff --git a/commands/Kconfig b/commands/Kconfig
>> index c5505321cfd9..037b41155695 100644
>> --- a/commands/Kconfig
>> +++ b/commands/Kconfig
>> @@ -75,6 +75,19 @@ config CMD_DEVINFO
>> If called with a device path being the argument, devinfo shows more
>> default information about this device and its parameters.
>>
>> +config CMD_DEVLOOKUP
>> + tristate
>> + prompt "devlookup"
>> + help
>> + Look up device behind device file and its parameters
>> +
>> + devlookup [-v VAR] /dev/DEVICE [parameter]
>> +
>> + Detects the device behind a device file and outputs it,
>> + unless a second argument is given. In that case the device
>> + parameter with that name is looked up. Specifying -v VARIABLE
>> + will write output to VARIABLE instead of printing it.
>> +
>> config CMD_DEVUNBIND
>> tristate
>> prompt "devunbind"
>> diff --git a/commands/Makefile b/commands/Makefile
>> index b3b7bafe6b64..0aae8893d696 100644
>> --- a/commands/Makefile
>> +++ b/commands/Makefile
>> @@ -110,6 +110,7 @@ obj-$(CONFIG_CMD_DETECT) += detect.o
>> obj-$(CONFIG_CMD_BOOT) += boot.o
>> obj-$(CONFIG_CMD_DEVINFO) += devinfo.o
>> obj-$(CONFIG_CMD_DEVUNBIND) += devunbind.o
>> +obj-$(CONFIG_CMD_DEVLOOKUP) += devlookup.o
>> obj-$(CONFIG_CMD_DRVINFO) += drvinfo.o
>> obj-$(CONFIG_CMD_READF) += readf.o
>> obj-$(CONFIG_CMD_MENUTREE) += menutree.o
>> diff --git a/commands/devlookup.c b/commands/devlookup.c
>> new file mode 100644
>> index 000000000000..c361d5b58860
>> --- /dev/null
>> +++ b/commands/devlookup.c
>> @@ -0,0 +1,78 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +
>> +#include <common.h>
>> +#include <command.h>
>> +#include <fs.h>
>> +#include <getopt.h>
>> +#include <malloc.h>
>> +#include <linux/stat.h>
>> +#include <linux/ctype.h>
>> +#include <environment.h>
>> +
>> +static int report(const char *variable, const char *val)
>> +{
>> + if (!val)
>> + return -(errno ?: EINVAL);
>> +
>> + if (variable)
>> + return setenv(variable, val);
>> +
>> + printf("%s\n", val);
>> + return 0;
>> +}
>> +
>> +static int do_devlookup(int argc, char *argv[])
>> +{
>> + const char *variable = NULL, *devicefile, *paramname;
>> + struct cdev *cdev;
>> + int opt;
>> +
>> + while ((opt = getopt(argc, argv, "v:")) > 0) {
>> + switch(opt) {
>> + case 'v':
>> + variable = optarg;
>> + break;
>> + }
>> + }
>> +
>> + if (argc - optind == 0 || argc - optind > 2)
>> + return COMMAND_ERROR_USAGE;
>> +
>> + devicefile = argv[optind];
>> + paramname = argv[optind+1];
>> +
>> + if (strstarts(devicefile, "/dev/"))
>> + devicefile += sizeof("/dev/") - 1;
>
> Forgot to mention: We have devpath_to_name() which does exactly that.
> Also I merged your last series with that change, so unless you have
> made other changes we should be fine.
Yes, I added a check below for deviceless cdevs, which otherwise
would crash on devlookup /dev/full
Do you need me to create a v3 or will you fix this up?
Cheers,
Ahmad
>
> Sascha
>
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