Changeset 311bc25 in mainline for kernel/generic/src/sysinfo/sysinfo.c

Timestamp:

2011-01-25T17:09:04Z (13 years ago)

Author:

Martin Decky <martin@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

a0ce870

Parents:

8befd0a

Message:

avoid the possibility for infinite looping on fetching sysinfo values
still make the tests in statistical functions more robust
this fixes ticket #237

File:

• kernel/generic/src/sysinfo/sysinfo.c (modified) (4 diffs)

kernel/generic/src/sysinfo/sysinfo.c

@@ -40 +40 @@
 #include <arch/asm.h>
 #include <errno.h>
+#include <macros.h>
 
 /** Maximal sysinfo path length */
@@ -761 +762 @@
  * character must be null).
  *
- * The user space buffer must be sized exactly according
- * to the size of the binary data, otherwise the request
- * fails.
+ * If the user space buffer size does not equal
+ * the actual size of the returned data, the data
+ * is truncated. Whether this is actually a fatal
+ * error or the data can be still interpreted as valid
+ * depends on the nature of the data and has to be
+ * decided by the user space.
+ *
+ * The actual size of data returned is stored to
+ * size_ptr.
  *
  * @param path_ptr    Sysinfo path in the user address space.
@@ -770 +777 @@
  *                    to store the binary data.
  * @param buffer_size User space buffer size.
+ * @param size_ptr    User space pointer where to store the
+ *                    binary data size.
  *
  * @return Error code (EOK in case of no error).
@@ -775 +784 @@
  */
 sysarg_t sys_sysinfo_get_data(void *path_ptr, size_t path_size,
-    void *buffer_ptr, size_t buffer_size)
+    void *buffer_ptr, size_t buffer_size, size_t *size_ptr)
 {
         int rc;
         
         /* Get the item */
-        sysinfo_return_t ret = sysinfo_get_item_uspace(path_ptr, path_size, false);
-
+        sysinfo_return_t ret = sysinfo_get_item_uspace(path_ptr, path_size,
+            false);
+        
         /* Only constant or generated binary data is considered */
-        if ((ret.tag == SYSINFO_VAL_DATA) || (ret.tag == SYSINFO_VAL_FUNCTION_DATA)) {
-                /* Check destination buffer size */
-                if (ret.data.size == buffer_size)
-                        rc = copy_to_uspace(buffer_ptr, ret.data.data,
-                            ret.data.size);
-                else
-                        rc = ENOMEM;
+        if ((ret.tag == SYSINFO_VAL_DATA) ||
+            (ret.tag == SYSINFO_VAL_FUNCTION_DATA)) {
+                size_t size = min(ret.data.size, buffer_size);
+                rc = copy_to_uspace(buffer_ptr, ret.data.data, size);
+                if (rc == EOK)
+                        rc = copy_to_uspace(size_ptr, &size, sizeof(size));
         } else
                 rc = EINVAL;