Re: Android NDK r26 and utmpx

[Paul Eggert <eggert@cs.ucla.edu>]

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Thanks for reporting that. Would something like the attached Gnulib 
patch fix the Android issue?

This patch assumes that readutmp-like functions have never worked on 
Android (always report nothing); is that the case?

I haven't installed this, or tested it on Android.

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From 60aa07c1ccd5aa18a9f87997a51acc8507515ef1 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sat, 20 Jan 2024 19:01:12 -0800
Subject: [PATCH] readutmp: port to Android NDK r26
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

* lib/readutmp.c (read_utmp_from_file) [__ANDROID__]:
Don’t bother trying to read from a real file, as this
has never worked with Android and the useless code
stops working on Android NDK r26.
---
 ChangeLog      |  8 ++++++++
 lib/readutmp.c | 48 ++++++++++++++++++++++++------------------------
 2 files changed, 32 insertions(+), 24 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index d8d2a13d9e..4533eaceb2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2024-01-20  Paul Eggert  <eggert@cs.ucla.edu>
+
+	readutmp: port to Android NDK r26
+	* lib/readutmp.c (read_utmp_from_file) [__ANDROID__]:
+	Don’t bother trying to read from a real file, as this
+	has never worked with Android and the useless code
+	stops working on Android NDK r26.
+
 2024-01-19  Bruno Haible  <bruno@clisp.org>
 
 	fenv-environment: Fix for NetBSD/powerpc.
diff --git a/lib/readutmp.c b/lib/readutmp.c
index ae2e3ae8c6..59074d68c1 100644
--- a/lib/readutmp.c
+++ b/lib/readutmp.c
@@ -330,7 +330,27 @@ read_utmp_from_file (char const *file, idx_t *n_entries, STRUCT_UTMP **utmp_buf,
 
 # if READUTMP_USE_SYSTEMD || HAVE_UTMPX_H || HAVE_UTMP_H
 
-#  if defined UTMP_NAME_FUNCTION /* glibc, musl, macOS, FreeBSD, NetBSD, Minix, AIX, IRIX, Solaris, Cygwin, Android */
+#  ifdef __ANDROID__
+  /* On Android, there is no /var, and normal processes don't have access
+     to system files.  Therefore use the kernel's uptime counter, although
+     it produces wrong values after the date has been bumped in the running
+     system.  */
+  if ((options & (READ_UTMP_USER_PROCESS | READ_UTMP_NO_BOOT_TIME)) == 0
+      && strcmp (file, UTMP_FILE) == 0
+      && !have_boot_time (a))
+    {
+      struct timespec boot_time;
+      if (get_android_boot_time (&boot_time) >= 0)
+        a = add_utmp (a, options,
+                      "reboot", strlen ("reboot"),
+                      "", 0,
+                      "", 0,
+                      "", 0,
+                      0, BOOT_TIME, boot_time, 0, 0, 0);
+    }
+
+#  elif defined UTMP_NAME_FUNCTION
+  /* glibc, musl, macOS, FreeBSD, NetBSD, Minix, AIX, IRIX, Solaris, Cygwin */
 
   /* Ignore the return value for now.
      Solaris' utmpname returns 1 upon success -- which is contrary
@@ -340,7 +360,7 @@ read_utmp_from_file (char const *file, idx_t *n_entries, STRUCT_UTMP **utmp_buf,
 
   SET_UTMP_ENT ();
 
-#   if (defined __linux__ && !defined __ANDROID__) || defined __minix
+#   if defined __linux__ || defined __minix
   bool file_is_utmp = (strcmp (file, UTMP_FILE) == 0);
   /* Timestamp of the "runlevel" entry, if any.  */
   struct timespec runlevel_ts = {0};
@@ -390,7 +410,7 @@ read_utmp_from_file (char const *file, idx_t *n_entries, STRUCT_UTMP **utmp_buf,
                     #endif
                     UT_EXIT_E_TERMINATION (ut), UT_EXIT_E_EXIT (ut)
                    );
-#   if defined __linux__ && !defined __ANDROID__
+#   ifdef __linux__
       if (file_is_utmp
           && memcmp (UT_USER (ut), "runlevel", strlen ("runlevel") + 1) == 0
           && memcmp (ut->ut_line, "~", strlen ("~") + 1) == 0)
@@ -406,7 +426,7 @@ read_utmp_from_file (char const *file, idx_t *n_entries, STRUCT_UTMP **utmp_buf,
 
   END_UTMP_ENT ();
 
-#   if defined __linux__ && !defined __ANDROID__
+#   ifdef __linux__
   /* On Alpine Linux, UTMP_FILE is not filled.  It is always empty.
      So, fake a BOOT_TIME entry, by getting the time stamp of a file that
      gets touched only during the boot process.
@@ -449,26 +469,6 @@ read_utmp_from_file (char const *file, idx_t *n_entries, STRUCT_UTMP **utmp_buf,
     }
 #   endif
 
-#   if defined __ANDROID__
-  /* On Android, there is no /var, and normal processes don't have access
-     to system files.  Therefore use the kernel's uptime counter, although
-     it produces wrong values after the date has been bumped in the running
-     system.  */
-  if ((options & (READ_UTMP_USER_PROCESS | READ_UTMP_NO_BOOT_TIME)) == 0
-      && strcmp (file, UTMP_FILE) == 0
-      && !have_boot_time (a))
-    {
-      struct timespec boot_time;
-      if (get_android_boot_time (&boot_time) >= 0)
-        a = add_utmp (a, options,
-                      "reboot", strlen ("reboot"),
-                      "", 0,
-                      "", 0,
-                      "", 0,
-                      0, BOOT_TIME, boot_time, 0, 0, 0);
-    }
-#   endif
-
 #   if defined __minix
   /* On Minix, during boot,
        1. an entry gets written into /var/run/utmp, with ut_type = BOOT_TIME,
-- 
2.40.1