From b1c915155606da48678c124f2a1bde4a95a9ee61 Mon Sep 17 00:00:00 2001
From: Krzysztof Konopko <krzysztof.konopko@youview.com>
Date: Thu, 28 Feb 2013 22:33:55 +0000
Subject: [PATCH] _dbus_file_get_contents() - support reading from procfs files

For most procfs files (including process status file) fstat() returns size
0.  See Notes on stat() manual page [1].

This can be addressed but at least trying to read from a file that looks
like an empty one and give up if no data is read.

[1] http://man7.org/linux/man-pages/man2/stat.2.html
---
 dbus/dbus-file-unix.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/dbus/dbus-file-unix.c b/dbus/dbus-file-unix.c
index 1975933..f82f78b 100644
--- a/dbus/dbus-file-unix.c
+++ b/dbus/dbus-file-unix.c
@@ -60,6 +60,7 @@ _dbus_file_get_contents (DBusString       *str,
   struct stat sb;
   int orig_len;
   int total;
+  int bytes_read;
   const char *filename_c;
 
   _DBUS_ASSERT_ERROR_IS_CLEAR (error);
@@ -104,11 +105,10 @@ _dbus_file_get_contents (DBusString       *str,
     }
   
   total = 0;
+  bytes_read = 0;
   orig_len = _dbus_string_get_length (str);
   if (sb.st_size > 0 && S_ISREG (sb.st_mode))
     {
-      int bytes_read;
-
       while (total < (int) sb.st_size)
         {
           bytes_read = _dbus_read (fd, str,
@@ -145,6 +145,34 @@ _dbus_file_get_contents (DBusString       *str,
     }
   else
     {
+      /* Special file case when fstat() returns 0, e. g. a file in procfs */
+      const size_t buffer_size = 512;
+
+      while ((bytes_read = _dbus_read (fd, str, buffer_size)))
+        {
+          if (bytes_read < 0)
+            {
+              dbus_set_error (error, _dbus_error_from_errno (errno),
+                              "Error reading \"%s\": %s",
+                              filename_c,
+                              _dbus_strerror (errno));
+
+              _dbus_verbose ("read() failed: %s",
+                             _dbus_strerror (errno));
+
+              _dbus_close (fd, NULL);
+              _dbus_string_set_length (str, orig_len);
+              return FALSE;
+            }
+          else
+            total += bytes_read;
+        }
+
+      /* OK, it was truly an empty file */
+      if (total == 0)
+        {
+          _dbus_string_set_length (str, orig_len);
+        }
       _dbus_close (fd, NULL);
       return TRUE;
     }
-- 
1.8.1.2