Attachment 17913 Details for Bug 16727 – Use sysconf to get initial buf size, then try exponential backoff if we get ERANGE

[patch] Use sysconf to get initial buf size, then try exponential backoff if we get ERANGE

dbus_ERANGE_handling.patch (text/plain), 5.56 KB, created by Marc Brockschmidt on 2008-07-27 04:55:35 UTC

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Creator: Marc Brockschmidt

Created: 2008-07-27 04:55:35 UTC

Size: 5.56 KB

patch

obsolete

>--- dbus-1.2.1/dbus/dbus-sysdeps-unix.c	2008-04-04 15:24:08.000000000 +0000
>+++ dbus-1.2.1.patched/dbus/dbus-sysdeps-unix.c	2008-07-27 11:44:35.000000000 +0000
>@@ -1452,28 +1452,59 @@
>   {
>     struct passwd *p;
>     int result;
>-    char buf[1024];
>+    size_t buflen;
>+    char *buf;
>     struct passwd p_str;
> 
>-    p = NULL;
>+    /* retrieve maximum needed size for buf */
>+    buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
>+
>+    if (buflen <= 0)
>+      buflen = 1024;
>+
>+    result = -1;
>+    while(1)
>+      {
>+        buf = dbus_malloc(buflen);
>+        if (buf == NULL)
>+          {
>+            dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
>+            return FALSE;
>+          }
>+
>+        p = NULL;
> #ifdef HAVE_POSIX_GETPWNAM_R
>-    if (uid != DBUS_UID_UNSET)
>-      result = getpwuid_r (uid, &p_str, buf, sizeof (buf),
>-                           &p);
>-    else
>-      result = getpwnam_r (username_c, &p_str, buf, sizeof (buf),
>-                           &p);
>+        if (uid != DBUS_UID_UNSET)
>+          result = getpwuid_r (uid, &p_str, buf, buflen,
>+                               &p);
>+        else
>+          result = getpwnam_r (username_c, &p_str, buf, buflen,
>+                               &p);
> #else
>-    if (uid != DBUS_UID_UNSET)
>-      p = getpwuid_r (uid, &p_str, buf, sizeof (buf));
>-    else
>-      p = getpwnam_r (username_c, &p_str, buf, sizeof (buf));
>-    result = 0;
>+        if (uid != DBUS_UID_UNSET)
>+          p = getpwuid_r (uid, &p_str, buf, buflen);
>+        else
>+          p = getpwnam_r (username_c, &p_str, buf, buflen);
>+        result = 0;
> #endif /* !HAVE_POSIX_GETPWNAM_R */
>+        //Try a bigger buffer if ERANGE was returned
>+        if (result == ERANGE && buflen < 512 * 1024)
>+          {
>+            dbus_free(buf);
>+            buflen *= 2;
>+          }
>+        else
>+          {
>+            break;
>+          }
>+      }
>     if (result == 0 && p == &p_str)
>       {
>         if (!fill_user_info_from_passwd (p, info, error))
>-          return FALSE;
>+          {
>+            dbus_free(buf);
>+            return FALSE;
>+          }
>       }
>     else
>       {
>@@ -1481,6 +1512,7 @@
>                         "User \"%s\" unknown or no memory to allocate password entry\n",
>                         username_c ? username_c : "???");
>         _dbus_verbose ("User %s unknown\n", username_c ? username_c : "???");
>+        dbus_free(buf);
>         return FALSE;
>       }
>   }
>@@ -1497,7 +1529,10 @@
>     if (p != NULL)
>       {
>         if (!fill_user_info_from_passwd (p, info, error))
>-          return FALSE;
>+          {
>+            dbus_free(buf);
>+            return FALSE;
>+          }
>       }
>     else
>       {
>@@ -1505,6 +1540,7 @@
>                         "User \"%s\" unknown or no memory to allocate password entry\n",
>                         username_c ? username_c : "???");
>         _dbus_verbose ("User %s unknown\n", username_c ? username_c : "???");
>+        dbus_free(buf);
>         return FALSE;
>       }
>   }
>--- dbus-1.2.1/dbus/dbus-sysdeps-util-unix.c	2008-04-04 15:24:08.000000000 +0000
>+++ dbus-1.2.1.patched/dbus/dbus-sysdeps-util-unix.c	2008-07-27 11:50:53.000000000 +0000
>@@ -828,31 +828,64 @@
>   {
>     struct group *g;
>     int result;
>-    char buf[1024];
>+    size_t buflen;
>+    char *buf;
>     struct group g_str;
>+    dbus_bool_t b;
> 
>-    g = NULL;
>+    /* retrieve maximum needed size for buf */
>+    buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
>+
>+    if (buflen <= 0)
>+      buflen = 1024;
>+
>+    result = -1;
>+    while (1)
>+      {
>+        buf = dbus_malloc(buflen);
>+        if (buf == NULL)
>+          {
>+            dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
>+            return FALSE;
>+          }
>+
>+        g = NULL;
> #ifdef HAVE_POSIX_GETPWNAM_R
> 
>-    if (group_c_str)
>-      result = getgrnam_r (group_c_str, &g_str, buf, sizeof (buf),
>-                           &g);
>-    else
>-      result = getgrgid_r (gid, &g_str, buf, sizeof (buf),
>-                           &g);
>+        if (group_c_str)
>+          result = getgrnam_r (group_c_str, &g_str, buf, buflen,
>+                               &g);
>+        else
>+          result = getgrgid_r (gid, &g_str, buf, buflen,
>+                               &g);
> #else
>-    g = getgrnam_r (group_c_str, &g_str, buf, sizeof (buf));
>-    result = 0;
>+        g = getgrnam_r (group_c_str, &g_str, buf, buflen);
>+        result = 0;
> #endif /* !HAVE_POSIX_GETPWNAM_R */
>+        //Try a bigger buffer if ERANGE was returned
>+        if (result == ERANGE && buflen < 512 * 1024)
>+          {
>+            dbus_free(buf);
>+            buflen *= 2;
>+          }
>+        else
>+          {
>+            break;
>+          }
>+      }
>+
>     if (result == 0 && g == &g_str)
>       {
>-        return fill_user_info_from_group (g, info, error);
>+        b = fill_user_info_from_group (g, info, error);
>+        dbus_free(buf);
>+        return b;
>       }
>     else
>       {
>         dbus_set_error (error, _dbus_error_from_errno (errno),
>                         "Group %s unknown or failed to look it up\n",
>                         group_c_str ? group_c_str : "???");
>+        dbus_free(buf);
>         return FALSE;
>       }
>   }
>@@ -865,13 +898,16 @@
> 
>     if (g != NULL)
>       {
>-        return fill_user_info_from_group (g, info, error);
>+        b = fill_user_info_from_group (g, info, error);
>+        dbus_free(buf);
>+        return b;
>       }
>     else
>       {
>         dbus_set_error (error, _dbus_error_from_errno (errno),
>                         "Group %s unknown or failed to look it up\n",
>                         group_c_str ? group_c_str : "???");
>+        dbus_free(buf);
>         return FALSE;
>       }
>   }

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Attachments on bug 16727: 17838 | 17913

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