Changeset 21448 for trunk/include/excpt.h

Timestamp:

Sep 19, 2010, 8:58:38 PM (15 years ago)

Author:

dmik

Message:

excpt.h: Added support for try/finally/leave SEH statements.

File:

• trunk/include/excpt.h (modified) (3 diffs)

trunk/include/excpt.h

@@ -5 +5 @@
  *
  * Copyright 2010 Dmitry A. Kuminov
+ */
+
+/*
+ * NOTE: This __try/__except and __try/__finally/__leave implementation is not
+ * backed up by the low level compiler support and therefore the following
+ * limitations exist comparing to the MSVC implementation (breaking them will
+ * crash the application):
+ *
+ * 1. You cannot use return, goto and longjmp statements within __try or
+ *    __except or __finally blocks.
+ *
+ * 2. If you use __try and friends inside a do/while/for/switch block, you will
+ *    lose the meaning of break and continue statements and must not use them.
+ *
+ * 3. The scopes of C and C++ exception blocks may not overlap (i.e. you cannot
+ *    use try/catch inside __try/__except and vice versa).
+ *
+ * 4. There may be some other (yet unknown) limitations.
+ *
+ * Fortunately, in most cases, these limitations may be worked around by
+ * slightly changing the original source code.
  */
 
@@ -86 +107 @@
 #define __except(filter_expr) \
             }                                                                  \
+            /* cause the next state to be 3 */                                 \
             __seh_frame.state = 2;                                             \
         }                                                                      \
         else if (__seh_frame.state == 1) {                                     \
+            /* execption caught, call filter expression */                     \
             __seh_frame.filterResult = (filter_expr);                          \
             __asm__("leal %0, %%ebx; jmp *%1"                                  \
@@ -101 +124 @@
                      : :                                                       \
                      : "%eax");                                                \
-        else /* __seh_frame.state == 2 */
+        else /* __seh_frame.state == 2 -> execute except block */
+
+#define __finally \
+            }                                                                  \
+            /* cause the next state to be 2 */                                 \
+            __seh_frame.state = 1;                                             \
+        }                                                                      \
+        else if (__seh_frame.state == 1) {                                     \
+            /* execption caught, handle and proceed to the filally block */    \
+            __seh_frame.filterResult = EXCEPTION_EXECUTE_HANDLER;              \
+            __asm__("leal %0, %%ebx; jmp *%1"                                  \
+                    : : "m"(__seh_frame), "m"(__seh_frame.pHandlerCallback)    \
+                    : "%ebx");                                                 \
+        }                                                                      \
+        else if (__seh_frame.state == 3)                                       \
+            /* remove exception handler */                                     \
+            __asm__ ("movl %%fs:0, %%eax; "                                    \
+                     "movl 0(%%eax), %%eax; "                                  \
+                     "movl %%eax, %%fs:0; "                                    \
+                     : :                                                       \
+                     : "%eax");                                                \
+        else /* __seh_frame.state == 2 -> execute finally block */
+
+#define __leave \
+            /* cause the next state to be 2 */                                 \
+            __seh_frame.state = 1;                                             \
+            continue;
 
 #else /* defined(__GNUC__) */