X-Git-Url: http://git.annexia.org/?a=blobdiff_plain;f=src%2Fevents.c;h=f707e0bec24ab1096ec3b03493f791d7061f05df;hb=1e35941f62bddafd6b88270b22b3afe4a5d37baa;hp=3894349133b811bb583ed8b2e99ab90517bd53ed;hpb=a53833fdd21cd573fe8fd02d7a11a3a5e9764ce0;p=libguestfs.git

diff --git a/src/events.c b/src/events.c
index 3894349..f707e0b 100644
--- a/src/events.c
+++ b/src/events.c
@@ -28,6 +28,7 @@
 #include <assert.h>
 #include <string.h>
 
+#include "c-ctype.h"
 #include "ignore-value.h"
 
 #include "guestfs.h"
@@ -110,15 +111,17 @@ guestfs___call_callbacks_message (guestfs_h *g, uint64_t event,
       count++;
     }
 
-  /* If nothing was registered and we're verbose or tracing, then we
-   * print the message on stderr.  This essentially emulates the
-   * behaviour of the old-style handlers, while allowing callers to
-   * override print-on-stderr simply by registering a callback.
+  /* Emulate the old-style handlers.  Callers can override
+   * print-on-stderr simply by registering a callback.
    */
-  if (count == 0 && (g->verbose || event == GUESTFS_EVENT_TRACE)) {
-    const char *prefix = "libguestfs: ";
-    const char *trace = "trace: ";
-    const char *nl = "\n";
+  if (count == 0 &&
+      (event == GUESTFS_EVENT_APPLIANCE ||
+       event == GUESTFS_EVENT_LIBRARY ||
+       event == GUESTFS_EVENT_TRACE) &&
+      (g->verbose || event == GUESTFS_EVENT_TRACE)) {
+    int from_appliance = event == GUESTFS_EVENT_APPLIANCE;
+    size_t i;
+    char c;
 
     /* APPLIANCE =>  <buf>
      * LIBRARY =>    libguestfs: <buf>\n
@@ -126,18 +129,47 @@ guestfs___call_callbacks_message (guestfs_h *g, uint64_t event,
      */
 
     if (event != GUESTFS_EVENT_APPLIANCE)
-      ignore_value (write (STDERR_FILENO, prefix, strlen (prefix)));
+      fputs ("libguestfs: ", stderr);
 
     if (event == GUESTFS_EVENT_TRACE)
-      ignore_value (write (STDERR_FILENO, trace, strlen (trace)));
-
-    ignore_value (write (STDERR_FILENO, buf, buf_len));
-
-    /* Messages from the appliance already contain \n characters, others
-     * need this to be appended.
+      fputs ("trace: ", stderr);
+
+    /* Special or non-printing characters in the buffer must be
+     * escaped (RHBZ#731744).  The buffer can contain any 8 bit
+     * character, even \0.
+     *
+     * Handling of \n and \r characters is complex:
+     *
+     * Case 1: Messages from the appliance: These messages already
+     * contain \n and \r characters at logical positions, so we just
+     * echo those out directly.
+     *
+     * Case 2: Messages from other sources: These messages should NOT
+     * contain \n or \r.  If they do, it is escaped.  However we also
+     * need to print a real end of line after these messages.
      */
-    if (event != GUESTFS_EVENT_APPLIANCE)
-      ignore_value (write (STDERR_FILENO, nl, strlen (nl)));
+    for (i = 0; i < buf_len; ++i) {
+      c = buf[i];
+      if (c_isprint (c) || (from_appliance && (c == '\n' || c == '\r')))
+        putc (c, stderr);
+      else {
+        switch (c) {
+        case '\0': fputs ("\\0", stderr); break;
+        case '\a': fputs ("\\a", stderr); break;
+        case '\b': fputs ("\\b", stderr); break;
+        case '\f': fputs ("\\f", stderr); break;
+        case '\n': fputs ("\\n", stderr); break;
+        case '\r': fputs ("\\r", stderr); break;
+        case '\t': fputs ("\\t", stderr); break;
+        case '\v': fputs ("\\v", stderr); break;
+        default:
+          fprintf (stderr, "\\x%x", (unsigned) c);
+        }
+      }
+    }
+
+    if (!from_appliance)
+      putc ('\n', stderr);
   }
 }