From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Sat, 26 Jun 2021 01:40:07 +0000 (+0900)
Subject: sd-device: allow to read sysattr which contains embedded NUL
X-Git-Tag: v249-rc3~30^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=70160c6eeee07ac6aa817826d13e8eff9563ce1e;p=thirdparty%2Fsystemd.git

sd-device: allow to read sysattr which contains embedded NUL

This effectively reverts the commit 2a394d0bf2f0afd8b9ed5faeb33f23459e3c6504.

But drop trailing '\r' of the read value, as sd_device_set_sysattr_value() drops it.

Fixes #20025.
---

diff --git a/src/libsystemd/sd-device/sd-device.c b/src/libsystemd/sd-device/sd-device.c
index 0d04e16818a..388128bf330 100644
--- a/src/libsystemd/sd-device/sd-device.c
+++ b/src/libsystemd/sd-device/sd-device.c
@@ -2022,13 +2022,17 @@ _public_ int sd_device_get_sysattr_value(sd_device *device, const char *sysattr,
                 /* skip non-readable files */
                 return -EPERM;
         else {
-                /* read attribute value */
-                r = read_full_virtual_file(path, &value, NULL);
+                size_t size;
+
+                /* Read attribute value, Some attributes contain embedded '\0'. So, it is necessary to
+                 * also get the size of the result. See issue #20025. */
+                r = read_full_virtual_file(path, &value, &size);
                 if (r < 0)
                         return r;
 
                 /* drop trailing newlines */
-                delete_trailing_chars(value, "\n");
+                while (size > 0 && strchr(NEWLINE, value[--size]))
+                        value[size] = '\0';
         }
 
         /* Unfortunately, we need to return 'const char*' instead of 'char*'. Hence, failure in caching