Merge 8afbcd491e into 1a4c2e8807

These are extra types needed to distinguish devices by the installed
display panel

man/systemd-analyze.xml

@@ -1091,7 +1091,7 @@ io.systemd.credential:vmm.notify_socket=vsock-stream:2:254570042
     </refsect2>
 
     <refsect2>
-      <title><command>systemd-analyze chid</command></title>
+      <title><command>systemd-analyze chid <optional>/sys/class/drm/&lt;card&gt;/edid</optional></command></title>
 
       <para>Shows a list of Computer Hardware IDs (CHIDs) of the local system. These IDs identify the
       system's computer hardware, based on SMBIOS data. See <ulink

src/analyze/analyze-chid.c

@@ -3,27 +3,42 @@
 #include "analyze.h"
 #include "analyze-chid.h"
 #include "chid-fundamental.h"
+#include "device-util.h"
+#include "dirent-util.h"
+#include "edid-fundamental.h"
 #include "efi-api.h"
 #include "escape.h"
 #include "fd-util.h"
 #include "fileio.h"
 #include "format-table.h"
 #include "parse-util.h"
+#include "sd-device.h"
 #include "strv.h"
 #include "utf8.h"
 #include "virt.h"
 
 static int parse_chid_type(const char *s, size_t *ret) {
+        char *e;
         unsigned u;
         int r;
 
         assert(s);
 
-        r = safe_atou(s, &u);
-        if (r < 0)
-                return r;
-        if (u >= CHID_TYPES_MAX)
-                return -ERANGE;
+        if ((e = startswith(s, "ext"))) {
+                r = safe_atou(e, &u);
+                if (r < 0)
+                        return r;
+                if (u >= CHID_TYPES_MAX - EXTRA_CHID_BASE)
+                        return -ERANGE;
+                u += EXTRA_CHID_BASE;
+        } else {
+                r = safe_atou(s, &u);
+                if (r < 0)
+                        return r;
+                if (u >= EXTRA_CHID_BASE)
+                        return -ERANGE;
+        }
+
 
         if (ret)
                 *ret = u;
@@ -43,6 +58,7 @@ static const char *const chid_smbios_friendly[_CHID_SMBIOS_FIELDS_MAX] = {
         [CHID_SMBIOS_BIOS_MAJOR]             = "bios-major",
         [CHID_SMBIOS_BIOS_MINOR]             = "bios-minor",
         [CHID_SMBIOS_ENCLOSURE_TYPE]         = "enclosure-type",
+        [CHID_EDID_PANEL]                    = "edid-panel",
 };
 
 static const char chid_smbios_fields_char[_CHID_SMBIOS_FIELDS_MAX] = {
@@ -57,6 +73,7 @@ static const char chid_smbios_fields_char[_CHID_SMBIOS_FIELDS_MAX] = {
         [CHID_SMBIOS_BIOS_MAJOR]             = 'R',
         [CHID_SMBIOS_BIOS_MINOR]             = 'r',
         [CHID_SMBIOS_ENCLOSURE_TYPE]         = 'e',
+        [CHID_EDID_PANEL]                    = 'E',
 };
 
 static char *chid_smbios_fields_string(uint32_t combination) {
@@ -90,10 +107,17 @@ static int add_chid(Table *table, const EFI_GUID guids[static CHID_TYPES_MAX], s
         if (!flags)
                 return log_oom();
 
+
+        if (t < EXTRA_CHID_BASE)
+                r = table_add_many(table, TABLE_UINT, (unsigned) t);
+        else
+                r = table_add_cell_stringf(table, NULL, "ext%zu", t - EXTRA_CHID_BASE);
+        if (r < 0)
+                return table_log_add_error(r);
+
         r = table_add_many(table,
-                           TABLE_UINT, (unsigned) t,
-                           TABLE_STRING, flags,
-                           TABLE_UUID, id);
+                            TABLE_STRING, flags,
+                            TABLE_UUID, id);
         if (r < 0)
                 return table_log_add_error(r);
 
@@ -223,6 +247,71 @@ static int smbios_fields_acquire(char16_t *fields[static _CHID_SMBIOS_FIELDS_MAX
         return 0;
 }
 
+static int edid_parse(sd_device *drm_card, char16_t **ret_panel) {
+        assert(drm_card);
+        assert(ret_panel);
+        int r;
+        const char *edid_content = NULL;
+        size_t edid_size = 0;
+        r = sd_device_get_sysattr_value_full(drm_card, "edid", &edid_content, &edid_size);
+        if (r < 0)
+                return r;
+        if (edid_size == 0)
+                return -ENODEV;
+
+        EdidHeader header;
+        if (!edid_parse_blob(edid_content, edid_size, &header))
+                return -EBADMSG;
+
+        _cleanup_free_ char16_t *panel_id = new0(char16_t, 8);
+        if (!panel_id)
+                return log_oom();
+
+        if (!edid_get_panel_id(&header, panel_id))
+                return -EBADMSG;
+
+        *ret_panel = TAKE_PTR(panel_id);
+        return 0;
+}
+
+static int edid_search(char16_t **ret_panel) {
+        assert(ret_panel);
+        _cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
+        int r, n = 0;
+
+        r = sd_device_enumerator_new(&e);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_allow_uninitialized(e);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_add_match_subsystem(e, "drm", true);
+        if (r < 0)
+                return r;
+
+        FOREACH_DEVICE(e, d) {
+                const char *drm_path = NULL;
+                r = edid_parse(d, ret_panel);
+                if (r == -ENOENT)
+                        continue;
+                if (r < 0) {
+                        r = sd_device_get_syspath(d, &drm_path);
+                        if (r < 0)
+                                return log_debug_errno(r, "Failed to get DRM device path: %m");
+                        log_debug("Skipping DRM device with invalid EDID: %s", drm_path);
+                        continue;
+                }
+                n++;
+                if (n > 1)
+                        return -ENOTUNIQ;
+
+        }
+
+        return n = 0 ? -ENODEV : 0;
+}
+
 int verb_chid(int argc, char *argv[], void *userdata) {
 
         _cleanup_(table_unrefp) Table *table = NULL;
@@ -243,6 +332,30 @@ int verb_chid(int argc, char *argv[], void *userdata) {
         if (r < 0)
                 return r;
 
+        if (arg_drm_card_path) {
+                _cleanup_(sd_device_unrefp) sd_device *drm_card = NULL;
+                r = sd_device_new_from_path(&drm_card, arg_drm_card_path);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to open device %s: %m", arg_drm_card_path);
+
+                const char *subsys = NULL;
+                r = sd_device_get_subsystem(drm_card, &subsys);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to get subsystem for device %s: %m", arg_drm_card_path);
+                if (!streq(subsys, "drm"))
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Cannot read EDID from a \"%s\" device", subsys);
+
+                r = edid_parse(drm_card, &smbios_fields[CHID_EDID_PANEL]);
+                if (r < 0)
+                    return log_error_errno(r, "Failed to parse EDID for device %s: %m", arg_drm_card_path);
+        } else {
+                r = edid_search(&smbios_fields[CHID_EDID_PANEL]);
+                if (r == -ENOTUNIQ)
+                        return log_error_errno(r, "Detected multiple monitors, use --drm-card option");
+                else if (r != -ENODEV && r < 0)
+                        return log_error_errno(r, "Failed to find a valid EDID: %m");
+        }
+
         EFI_GUID chids[CHID_TYPES_MAX] = {};
         chid_calculate((const char16_t* const*) smbios_fields, chids);
 
@@ -257,7 +370,7 @@ int verb_chid(int argc, char *argv[], void *userdata) {
                         size_t t;
                         r = parse_chid_type(*as, &t);
                         if (r < 0)
-                                return log_error_errno(r, "Failed to pare CHID type: %s", *as);
+                                return log_error_errno(r, "Failed to parse CHID type: %s", *as);
 
                         r = add_chid(table, chids, t);
                         if (r < 0)

src/analyze/analyze.c

@@ -121,12 +121,14 @@ char *arg_profile = NULL;
 bool arg_legend = true;
 bool arg_table = false;
 ImagePolicy *arg_image_policy = NULL;
+char *arg_drm_card_path = NULL;
 
 STATIC_DESTRUCTOR_REGISTER(arg_dot_from_patterns, strv_freep);
 STATIC_DESTRUCTOR_REGISTER(arg_dot_to_patterns, strv_freep);
 STATIC_DESTRUCTOR_REGISTER(arg_root, freep);
 STATIC_DESTRUCTOR_REGISTER(arg_image, freep);
 STATIC_DESTRUCTOR_REGISTER(arg_security_policy, freep);
+STATIC_DESTRUCTOR_REGISTER(arg_drm_card_path, freep);
 STATIC_DESTRUCTOR_REGISTER(arg_unit, freep);
 STATIC_DESTRUCTOR_REGISTER(arg_profile, freep);
 STATIC_DESTRUCTOR_REGISTER(arg_image_policy, image_policy_freep);
@@ -287,6 +289,8 @@ static int help(int argc, char *argv[], void *userdata) {
                "     --image=PATH            Operate on disk image as filesystem root\n"
                "     --image-policy=POLICY   Specify disk image dissection policy\n"
                "  -m --mask                  Parse parameter as numeric capability mask\n"
+               "     --drm-card=PATH         Use this DRM card to get EDID\n"
+
                "\nSee the %2$s for details.\n",
                program_invocation_short_name,
                link,
@@ -333,6 +337,7 @@ static int parse_argv(int argc, char *argv[]) {
                 ARG_TLDR,
                 ARG_SCALE_FACTOR_SVG,
                 ARG_DETAILED_SVG,
+                ARG_DRM_CARD_PATH,
         };
 
         static const struct option options[] = {
@@ -371,6 +376,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "mask",             no_argument,       NULL, 'm'                  },
                 { "scale-svg",        required_argument, NULL, ARG_SCALE_FACTOR_SVG },
                 { "detailed",         no_argument,       NULL, ARG_DETAILED_SVG     },
+                { "drm-card",         required_argument, NULL, ARG_DRM_CARD_PATH    },
                 {}
         };
 
@@ -580,6 +586,12 @@ static int parse_argv(int argc, char *argv[]) {
                         arg_detailed_svg = true;
                         break;
 
+                case ARG_DRM_CARD_PATH:
+                        r = parse_path_argument(optarg, /* suppress_root= */ false, &arg_drm_card_path);
+                        if (r < 0)
+                                return r;
+                        break;
+
                 case '?':
                         return -EINVAL;
 
@@ -638,6 +650,9 @@ static int parse_argv(int argc, char *argv[]) {
         if (arg_capability != CAPABILITY_LITERAL && !streq_ptr(argv[optind], "capability"))
                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Option --mask is only supported for capability.");
 
+        if (arg_drm_card_path && !streq_ptr(argv[optind], "chid"))
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Option --drm-card is only supported for chid right now.");
+
         return 1; /* work to do */
 }
 

src/analyze/analyze.h

@@ -51,6 +51,7 @@ extern char *arg_profile;
 extern bool arg_legend;
 extern bool arg_table;
 extern ImagePolicy *arg_image_policy;
+extern char *arg_drm_card_path;
 
 int acquire_bus(sd_bus **bus, bool *use_full_bus);
 

src/boot/chid.c

@@ -16,6 +16,7 @@
 
 #include "chid.h"
 #include "chid-fundamental.h"
+#include "edid.h"
 #include "efi.h"
 #include "sha1-fundamental.h"
 #include "smbios.h"
@@ -72,6 +73,8 @@ static void smbios_info_populate(SmbiosInfo *ret_info) {
         ret_info->smbios_fields[CHID_SMBIOS_FAMILY] = smbios_to_hashable_string(raw.family);
         ret_info->smbios_fields[CHID_SMBIOS_BASEBOARD_PRODUCT] = smbios_to_hashable_string(raw.baseboard_product);
         ret_info->smbios_fields[CHID_SMBIOS_BASEBOARD_MANUFACTURER] = smbios_to_hashable_string(raw.baseboard_manufacturer);
+
+        edid_get_discovered_panel_id(&ret_info->smbios_fields[CHID_EDID_PANEL]);
 }
 
 static void smbios_info_done(SmbiosInfo *info) {
@@ -100,7 +103,7 @@ EFI_STATUS chid_match(const void *hwid_buffer, size_t hwid_length, uint32_t matc
         const Device *devices = ASSERT_PTR(hwid_buffer);
 
         EFI_GUID chids[CHID_TYPES_MAX] = {};
-        static const size_t priority[] = { 3, 6, 8, 10, 4, 5, 7, 9, 11 }; /* From most to least specific. */
+        static const size_t priority[] = { 17, 16, 15, 3, 6, 8, 10, 4, 5, 7, 9, 11 }; /* From most to least specific. */
 
         status = populate_board_chids(chids);
         if (EFI_STATUS_IS_ERROR(status))

src/boot/edid.c

@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "edid.h"
+#include "edid-fundamental.h"
+#include "log.h"
+#include "proto/edid-discovered.h"
+#include "util.h"
+
+EFI_STATUS edid_get_discovered_panel_id(char16_t **ret_panel) {
+        assert(ret_panel);
+        EFI_EDID_DISCOVERED_PROTOCOL *edid_discovered = NULL;
+        EFI_STATUS status = BS->LocateProtocol(MAKE_GUID_PTR(EFI_EDID_DISCOVERED_PROTOCOL), NULL, (void **) &edid_discovered);
+        if (EFI_STATUS_IS_ERROR(status))
+                return status;
+
+        if (!edid_discovered)
+                return EFI_UNSUPPORTED;
+        if (!edid_discovered->Edid)
+                return EFI_UNSUPPORTED;
+        if (edid_discovered->SizeOfEdid == 0)
+                return EFI_UNSUPPORTED;
+
+        /* EDID size is at least 128 as per the specification */
+        if (edid_discovered->SizeOfEdid < 128)
+                return EFI_BUFFER_TOO_SMALL;
+
+        EdidHeader header;
+        if (!edid_parse_blob(edid_discovered->Edid, edid_discovered->SizeOfEdid, &header))
+                return EFI_INCOMPATIBLE_VERSION;
+
+        *ret_panel = xnew0(char16_t, 8);
+        if (!edid_get_panel_id(&header, *ret_panel))
+                return EFI_INVALID_PARAMETER;
+
+        return EFI_SUCCESS;
+}

src/boot/edid.h

@@ -0,0 +1,6 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include "efi.h"
+
+EFI_STATUS edid_get_discovered_panel_id(char16_t **ret_panel);

src/boot/meson.build

@@ -289,6 +289,7 @@ libefi_sources = files(
         'device-path-util.c',
         'devicetree.c',
         'drivers.c',
+        'edid.c',
         'efi-firmware.c',
         'efi-string.c',
         'efivars.c',

src/boot/proto/edid-discovered.h

@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include "efi.h"
+
+#define EFI_EDID_DISCOVERED_PROTOCOL_GUID \
+        GUID_DEF(0x1c0c34f6, 0xd380, 0x41fa, 0xa0, 0x49, 0x8a, 0xd0, 0x6c, 0x1a, 0x66, 0xaa)
+
+typedef struct {
+        uint32_t SizeOfEdid;
+        uint8_t *Edid;
+} EFI_EDID_DISCOVERED_PROTOCOL;

src/boot/test-chid-match.c

@@ -4,6 +4,7 @@
 #include <stdint.h>
 
 #include "chid.h"
+#include "edid.h"
 #include "smbios.h"
 #include "tests.h"
 
@@ -79,6 +80,11 @@ void smbios_raw_info_get_cached(RawSmbiosInfo *ret_info) {
         *ret_info = current_info;
 }
 
+EFI_STATUS edid_get_discovered_panel_id(char16_t **ret_panel) {
+        assert(ret_panel);
+        return EFI_UNSUPPORTED;
+}
+
 TEST(chid_match) {
         for (size_t i = 0; i < ELEMENTSOF(info); i++) {
                 current_info = info[i].smbios_info;

src/boot/util.h

@@ -242,7 +242,10 @@ void *find_configuration_table(const EFI_GUID *guid);
 char16_t *get_extra_dir(const EFI_DEVICE_PATH *file_path);
 
 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#  define be16toh(x) __builtin_bswap16(x)
 #  define be32toh(x) __builtin_bswap32(x)
+#  define le16toh(x) (x)
+#  define le32toh(x) (x)
 #else
 #  error "Unexpected byte order in EFI mode?"
 #endif

src/fundamental/chid-fundamental.c

@@ -147,6 +147,21 @@ const uint32_t chid_smbios_table[CHID_TYPES_MAX] = {
                (UINT32_C(1) << CHID_SMBIOS_BASEBOARD_PRODUCT),
 
         [14] = (UINT32_C(1) << CHID_SMBIOS_MANUFACTURER),
+
+        /* Extra non-standard CHIDs */
+
+        [EXTRA_CHID_BASE + 0] = (UINT32_C(1) << CHID_SMBIOS_MANUFACTURER) |
+                                (UINT32_C(1) << CHID_SMBIOS_FAMILY) |
+                                (UINT32_C(1) << CHID_SMBIOS_PRODUCT_NAME)|
+                                (UINT32_C(1) << CHID_EDID_PANEL),
+
+        [EXTRA_CHID_BASE + 1] = (UINT32_C(1) << CHID_SMBIOS_MANUFACTURER) |
+                                (UINT32_C(1) << CHID_SMBIOS_FAMILY) |
+                                (UINT32_C(1) << CHID_EDID_PANEL),
+
+        [EXTRA_CHID_BASE + 2] = (UINT32_C(1) << CHID_SMBIOS_MANUFACTURER) |
+                                (UINT32_C(1) << CHID_SMBIOS_PRODUCT_SKU) |
+                                (UINT32_C(1) << CHID_EDID_PANEL),
 };
 
 void chid_calculate(const char16_t *const smbios_fields[static _CHID_SMBIOS_FIELDS_MAX], EFI_GUID ret_chids[static CHID_TYPES_MAX]) {

src/fundamental/chid-fundamental.h

@@ -11,7 +11,9 @@
 #include "efi-fundamental.h"
 #include "string-util-fundamental.h"
 
-#define CHID_TYPES_MAX 15
+#define CHID_TYPES_MAX 18
+/* Any chids starting from EXTRA_CHID_BASE are non-standard and are subject to change and renumeration at any time */
+#define EXTRA_CHID_BASE 15
 
 typedef enum ChidSmbiosFields {
         CHID_SMBIOS_MANUFACTURER,
@@ -25,6 +27,7 @@ typedef enum ChidSmbiosFields {
         CHID_SMBIOS_BIOS_MAJOR,
         CHID_SMBIOS_BIOS_MINOR,
         CHID_SMBIOS_ENCLOSURE_TYPE,
+        CHID_EDID_PANEL,
         _CHID_SMBIOS_FIELDS_MAX,
 } ChidSmbiosFields;
 

src/fundamental/edid-fundamental.c

@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "edid-fundamental.h"
+
+#define EDID_FIXED_HEADER_PATTERN "\x00\xFF\xFF\xFF\xFF\xFF\xFF"
+assert_cc(sizeof_field(EdidHeader, pattern) == sizeof(EDID_FIXED_HEADER_PATTERN));
+
+bool edid_parse_blob(const void *blob, size_t blob_size, EdidHeader *ret_header) {
+        assert(ret_header);
+        /* EDID size is at least 128 as per the specification */
+        if (blob_size < 128)
+                return false;
+
+        const EdidHeader *edid_header = ASSERT_PTR(blob);
+        if (memcmp(edid_header->pattern, EDID_FIXED_HEADER_PATTERN, sizeof(EDID_FIXED_HEADER_PATTERN)) != 0)
+                return false;
+
+        *ret_header = (EdidHeader) {
+                .pattern = EDID_FIXED_HEADER_PATTERN,
+                .manufacturer_id = be16toh(edid_header->manufacturer_id),
+                .manufacturer_product_code = le16toh(edid_header->manufacturer_product_code),
+                .serial_number = le32toh(edid_header->serial_number),
+                .week_of_manufacture = edid_header->week_of_manufacture,
+                .year_of_manufacture = edid_header->year_of_manufacture,
+                .edid_version = edid_header->edid_version,
+                .edid_revision = edid_header->edid_revision,
+        };
+        return true;
+}
+
+bool edid_get_panel_id(const EdidHeader *edid_header, char16_t ret_panel[static 8]) {
+        assert(edid_header);
+        assert(ret_panel);
+        static const char hex[] = "0123456789abcdef";
+        for (size_t i = 0; i < 3; i++) {
+                uint8_t letter = (edid_header->manufacturer_id >> (5 * i)) & 0b11111;
+                if (letter > 0b11010)
+                        return false;
+                ret_panel[2 - i] = letter + 'A' - 1;
+        }
+        ret_panel[3] = hex[(edid_header->manufacturer_product_code >> 12) & 0x0F];
+        ret_panel[4] = hex[(edid_header->manufacturer_product_code >>  8) & 0x0F];
+        ret_panel[5] = hex[(edid_header->manufacturer_product_code >>  4) & 0x0F];
+        ret_panel[6] = hex[(edid_header->manufacturer_product_code >>  0) & 0x0F];
+        ret_panel[7] = L'\0';
+        return true;
+}

src/fundamental/edid-fundamental.h

@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#if SD_BOOT
+#  include "efi-string.h"
+#  include "util.h"
+#else
+#  include <endian.h>
+#  include <stddef.h>
+#  include <stdint.h>
+#  include <uchar.h>
+#endif
+
+#include "string-util-fundamental.h"
+
+/* EDID structure, version 1.4 */
+typedef struct EdidHeader {
+        uint8_t pattern[8];                   /* fixed pattern */
+        uint16_t manufacturer_id;             /* big-endian 3-letter code */
+        uint16_t manufacturer_product_code;   /* little-endian */
+        uint32_t serial_number;               /* little-endian */
+        uint8_t week_of_manufacture;          /* week or model year flag (0xFF) */
+        uint8_t year_of_manufacture;          /* year or model if flag is set (0 is 1990) */
+        uint8_t edid_version;                 /* 0x01 for 1.3 and 1.4 */
+        uint8_t edid_revision;                /* 0x03 for 1.3, 0x04 for 1.4 */
+} _packed_ EdidHeader;
+
+bool edid_parse_blob(const void *blob, size_t blob_size, EdidHeader *ret_header);
+bool edid_get_panel_id(const EdidHeader *edid_header, char16_t ret_panel[static 8]);

src/fundamental/meson.build

@@ -5,6 +5,7 @@ fundamental_include = include_directories('.')
 fundamental_sources = files(
         'bootspec-fundamental.c',
         'chid-fundamental.c',
+        'edid-fundamental.c',
         'efivars-fundamental.c',
         'iovec-util-fundamental.h',
         'sha1-fundamental.c',

src/libsystemd/libsystemd.sym

@@ -618,6 +618,7 @@ global:
 
         sd_device_has_tag;
         sd_device_get_property_value;
+        sd_device_get_sysattr_value_full;
         sd_device_get_sysattr_value;
 
         sd_device_set_sysattr_value;

src/libsystemd/sd-device/sd-device.c

@@ -2333,6 +2333,7 @@ void device_clear_sysattr_cache(sd_device *device) {
 typedef struct SysAttrCacheEntry {
         char *key;
         char *value;
+        size_t size;
         int error;
 } SysAttrCacheEntry;
 
@@ -2350,7 +2351,7 @@ DEFINE_PRIVATE_HASH_OPS_WITH_VALUE_DESTRUCTOR(
                 char, path_hash_func, path_compare,
                 SysAttrCacheEntry, sysattr_cache_entry_free);
 
-static int device_cache_sysattr_value_full(sd_device *device, char *key, char *value, int error, bool ignore_uevent) {
+static int device_cache_sysattr_value_full(sd_device *device, char *key, char *value, size_t size, int error, bool ignore_uevent) {
         int r;
 
         assert(device);
@@ -2378,6 +2379,7 @@ static int device_cache_sysattr_value_full(sd_device *device, char *key, char *v
         *entry = (SysAttrCacheEntry) {
                 .key = key,
                 .value = value,
+                .size = size,
                 .error = error,
         };
 
@@ -2390,10 +2392,10 @@ static int device_cache_sysattr_value_full(sd_device *device, char *key, char *v
 }
 
 int device_cache_sysattr_value(sd_device *device, char *key, char *value, int error) {
-        return device_cache_sysattr_value_full(device, key, value, error, /* ignore_uevent = */ true);
+        return device_cache_sysattr_value_full(device, key, value, strlen(value), error, /* ignore_uevent = */ true);
 }
 
-static int device_get_cached_sysattr_value(sd_device *device, const char *key, const char **ret_value) {
+static int device_get_cached_sysattr_value(sd_device *device, const char *key, const char **ret_value, size_t *ret_size) {
         SysAttrCacheEntry *entry;
 
         assert(device);
@@ -2409,6 +2411,8 @@ static int device_get_cached_sysattr_value(sd_device *device, const char *key, c
         }
         if (ret_value)
                 *ret_value = entry->value;
+        if (ret_size)
+                *ret_size = entry->size;
         return 0;
 }
 
@@ -2459,16 +2463,17 @@ int device_chase(sd_device *device, const char *path, ChaseFlags flags, char **r
         return 0;
 }
 
-_public_ int sd_device_get_sysattr_value(sd_device *device, const char *sysattr, const char **ret_value) {
+_public_ int sd_device_get_sysattr_value_full(sd_device *device, const char *sysattr, const char **ret_value, size_t *ret_size) {
         _cleanup_free_ char *resolved = NULL, *value = NULL;
         _cleanup_close_ int fd = -EBADF;
+        size_t size = 0;
         int r;
 
         assert_return(device, -EINVAL);
         assert_return(sysattr, -EINVAL);
 
         /* Look for possibly already cached result. */
-        r = device_get_cached_sysattr_value(device, sysattr, ret_value);
+        r = device_get_cached_sysattr_value(device, sysattr, ret_value, ret_size);
         if (r != -ENOANO)
                 return r;
 
@@ -2496,13 +2501,12 @@ _public_ int sd_device_get_sysattr_value(sd_device *device, const char *sysattr,
                 goto cache_result;
 
         /* Look for cached result again with the resolved path. */
-        r = device_get_cached_sysattr_value(device, resolved, ret_value);
+        r = device_get_cached_sysattr_value(device, resolved, ret_value, ret_size);
         if (r != -ENOANO)
                 return r;
 
         /* Read attribute value, Some attributes contain embedded '\0'. So, it is necessary to also get the
          * size of the result. See issue #20025. */
-        size_t size;
         r = read_virtual_file_fd(fd, SIZE_MAX, &value, &size);
         if (r < 0)
                 goto cache_result;
@@ -2521,7 +2525,7 @@ cache_result:
                         return RET_GATHER(r, -ENOMEM);
         }
 
-        int k = device_cache_sysattr_value_full(device, resolved, value, -r, /* ignore_uevent = */ false);
+        int k = device_cache_sysattr_value_full(device, resolved, value, size, -r, /* ignore_uevent = */ false);
         if (k < 0) {
                 if (r < 0)
                         log_device_debug_errno(device, k,
@@ -2543,6 +2547,8 @@ cache_result:
 
         if (ret_value && r >= 0)
                 *ret_value = value;
+        if (ret_size && r >= 0)
+                *ret_size = size;
 
         /* device_cache_sysattr_value_full() takes 'resolved' and 'value' on success. */
         TAKE_PTR(resolved);
@@ -2550,6 +2556,10 @@ cache_result:
         return r;
 }
 
+_public_ int sd_device_get_sysattr_value(sd_device *device, const char *sysattr, const char **ret_value) {
+        return sd_device_get_sysattr_value_full(device, sysattr, ret_value, NULL);
+}
+
 int device_get_sysattr_int(sd_device *device, const char *sysattr, int *ret_value) {
         const char *value;
         int r;

src/systemd/sd-device.h

@@ -109,7 +109,8 @@ int sd_device_has_tag(sd_device *device, const char *tag);
 int sd_device_has_current_tag(sd_device *device, const char *tag);
 int sd_device_get_property_value(sd_device *device, const char *key, const char **value);
 int sd_device_get_trigger_uuid(sd_device *device, sd_id128_t *ret);
-int sd_device_get_sysattr_value(sd_device *device, const char *sysattr, const char **_value);
+int sd_device_get_sysattr_value_full(sd_device *device, const char *sysattr, const char **ret_value, size_t *ret_size);
+int sd_device_get_sysattr_value(sd_device *device, const char *sysattr, const char **ret_value);
 
 int sd_device_set_sysattr_value(sd_device *device, const char *sysattr, const char *value);
 int sd_device_set_sysattr_valuef(sd_device *device, const char *sysattr, const char *format, ...) _sd_printf_(3, 4);