add faq entry, fix windows parsing

Author: planrich

docs/faq.rst

@@ -9,3 +9,6 @@ Frequently Asked Questions
 
 * **What do the colors on vmprof.com mean?**: For plain CPython there is no particular meaning, we might change
   that in the future. For PyPy we have a color coding to show at which state the VM sampled (e.g. JIT, Warmup, ...).
+
+* **My Windows profile is malformed?**: Please ensure that you open the file in binary mode. Otherwise Windows
+  will transform `\n` to `\r\n`.

src/vmprof_common.h

@@ -48,7 +48,13 @@ static struct profbuf_s *volatile current_codes;
  * is 4, but fails on win32
  */
 typedef struct prof_stacktrace_s {
+#ifdef VMPROF_WINDOWS
+    // if padding is 8 bytes, then on both 32bit and 64bit, the
+    // stack field is aligned
+    char padding[sizeof(void*) - 1];
+#else
     char padding[sizeof(long) - 1];
+#endif
     char marker;
     long count, depth;
     void *stack[];

src/vmprof_main_win32.h

@@ -86,10 +86,8 @@ long __stdcall vmprof_mainloop(void *arg)
             continue;
         depth = vmprof_snapshot_thread(tstate->thread_id, tstate, stack);
         if (depth > 0) {
-            // see note in vmprof_common.h on the prof_stacktrace_s struct why
-            // there are two vmpr_write_all calls
-            vmp_write_all((char*)stack + offsetof(prof_stacktrace_s, marker), SIZEOF_PROF_STACKTRACE);
-            vmp_write_all((char*)stack->stack, depth * sizeof(void*));
+            vmp_write_all((char*)stack + offsetof(prof_stacktrace_s, marker),
+                          SIZEOF_PROF_STACKTRACE + depth * sizeof(void*));
         }
     }
 }
@@ -121,4 +119,5 @@ int vmprof_disable(void)
 RPY_EXTERN
 void vmprof_ignore_signals(int ignored)
 {
+    enabled = !ignored;
 }

vmprof/test/cpuburn.py

@@ -1,3 +1,4 @@
+import sys
 import os
 from time import time
 import vmprof
@@ -48,7 +49,10 @@ def test():
 
     PROFILE_FILE = 'vmprof_cpuburn.dat'
 
-    outfd = os.open(PROFILE_FILE, os.O_RDWR | os.O_CREAT | os.O_TRUNC)
+    flags = os.O_RDWR | os.O_CREAT | os.O_TRUNC
+    if sys.platform == 'win32':
+        flags |= os.O_BINARY
+    outfd = os.open(PROFILE_FILE, flags)
     vmprof.enable(outfd, period=0.01)
     test()
     vmprof.disable()