Leave printf format parsing to glibc if possible.

Call glibc's parse_printf_format() to gather information about
argument types.  This automatically handles positional parameters and
user-defined printf formats for ordinary parameter types; it doesn't
handle user-defined printf parameter types (such as defined by libdfp
for decimal floating-point).

Also add a (non-comprehensive) test.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>
Signed-off-by: Gergely Nagy <algernon@balabit.hu>

2 files changed, 98 insertions, 7 deletions

diff --git a/lib/umberlog.c b/lib/umberlog.c
index b3fadbc..9266c76 100644
--- a/lib/umberlog.c
+++ b/lib/umberlog.c
@@ -28,6 +28,7 @@
 #define _GNU_SOURCE 1
 #define SYSLOG_NAMES 1
 
+#include "config.h"
 #include <stdarg.h>
 #include <sys/types.h>
 #include <unistd.h>
@@ -42,8 +43,10 @@
 #include <time.h>
 #include <errno.h>
 #include <wchar.h>
+#ifdef HAVE_PARSE_PRINTF_FORMAT
+#include <printf.h>
+#endif
 
-#include "config.h"
 #include "umberlog.h"
 #include "buffer.h"
 
@@ -177,8 +180,88 @@ _get_hostname (void)
   return ul_sys_settings.hostname;
 }
 
-static void
-_ul_va_spin (const char *fmt, va_list *pap)
+#ifdef HAVE_PARSE_PRINTF_FORMAT
+
+#define _ul_va_spin _ul_va_spin_glibc
+
+static int
+_ul_va_spin_glibc (const char *fmt, va_list *pap)
+{
+  size_t num_args, i;
+  int *types;
+
+  num_args = parse_printf_format (fmt, 0, NULL);
+  types = malloc (num_args * sizeof (*types));
+  if (types == NULL)
+    goto err;
+  if (parse_printf_format (fmt, num_args, types) != num_args)
+    goto err; /* Should never happen */
+
+  for (i = 0; i < num_args; i++)
+    {
+      switch (types[i])
+        {
+        case PA_CHAR:
+        case PA_INT | PA_FLAG_SHORT:
+        case PA_INT:
+          (void)va_arg (*pap, int);
+          break;
+        case PA_INT | PA_FLAG_LONG:
+          (void)va_arg (*pap, long int);
+          break;
+        case PA_INT | PA_FLAG_LONG_LONG:
+          (void)va_arg (*pap, long long int);
+          break;
+
+        case PA_WCHAR:
+          (void)va_arg (*pap, wint_t);
+          break;
+
+        case PA_STRING:
+          (void)va_arg (*pap, char *);
+          break;
+
+        case PA_WSTRING:
+          (void)va_arg (*pap, wchar_t *);
+          break;
+
+        case PA_POINTER:
+          (void)va_arg (*pap, void *);
+          break;
+
+        case PA_FLOAT:
+        case PA_DOUBLE:
+          (void)va_arg (*pap, double);
+          break;
+        case PA_DOUBLE | PA_FLAG_LONG_DOUBLE:
+          (void)va_arg (*pap, long double);
+          break;
+
+        default:
+          if ((types[i] & PA_FLAG_PTR) != 0)
+            {
+              (void)va_arg (*pap, void *);
+              break;
+            }
+          /* Unknown user-defined parameter type.  Can we log that this
+             happened? */
+          goto err;
+        }
+    }
+
+  free (types);
+  return 0;
+
+ err:
+  free (types);
+  return -1;
+}
+#else /* !HAVE_PARSE_PRINTF_FORMAT */
+
+#define _ul_va_spin _ul_va_spin_legacy
+
+static int
+_ul_va_spin_legacy (const char *fmt, va_list *pap)
 {
   size_t i;
 
@@ -293,7 +376,9 @@ _ul_va_spin (const char *fmt, va_list *pap)
             }
         }
     }
+  return 0;
 }
+#endif /* !HAVE_PARSE_PRINTF_FORMAT */
 
 /* Return a newly allocated string.
    On failure, NULL is returned and it is undefined what PAP points to. */
@@ -314,7 +399,11 @@ _ul_vasprintf_and_advance (const char *fmt, va_list *pap)
   if (res == NULL)
     return NULL;
 
-  _ul_va_spin (fmt, pap);
+  if (_ul_va_spin (fmt, pap) != 0)
+    {
+      free (res);
+      return NULL;
+    }
   return res;
 }
 
diff --git a/lib/umberlog.rst b/lib/umberlog.rst
index 704a5e3..9883de4 100644
--- a/lib/umberlog.rst
+++ b/lib/umberlog.rst
@@ -7,7 +7,7 @@ CEE-enhanced syslog message generation
 --------------------------------------
 
 :Author: Gergely Nagy <algernon@balabit.hu>
-:Date: 2012-04-28
+:Date: 2012-07-19
 :Manual section: 3
 :Manual group: CEE-enhanced syslog Manual
 
@@ -57,8 +57,10 @@ the emitted message. After the *msg_format* format string, and any
 other parameters it refers to, there must be a NULL-terminated list of
 *key*, *value format*, *format parameters*. Each of these pairs,
 constructed from the *key* and the **printf(3)**-style *value format*
-will be added to the generated message.  Note that position specifiers
-(e.g. **%2$**) are not currently supported.
+will be added to the generated message.
+
+Note that user-defined printf types defined by
+**register_printf_type()** are not supported.
 
 **ul_format()** and **ul_vformat()** do the same as the syslog
 variants above, except the formatted payload is not sent to syslog,