FreeTDS Development Group

["Castellano, Nicholas" <Nicholas_Castellano AT acml.com>]

I don't like that implementation.  It tries to reinvent the wheel, and won't
behave quite the same as the native stdio calls on any given platform.  In
particular, its handling of floating point numbers makes me really nervous.

Here is my new patch.  It's kind of a cheap trick but it gets the job done.
If you're really worried about complexity, we could use this new approach to
replace the non-threadsafe version too.

It could be made slightly more efficient and robust by not opening and
closing the filehandle each time.  I'm not going to worry about that right
now, until there's a consensus that this is the way to go (there's no point
in putting more effort into this if somebody decides to use Powell's version
despite my concerns).  If this change is accepted and committed, then I'll
go ahead with that.

--nick

-----Original Message-----
From: bounce-freetds-145195 AT franklin.oit.unc.edu
[mailto:bounce-freetds-145195 AT franklin.oit.unc.edu] 
Sent: Thursday, August 29, 2002 10:05 AM
To: TDS Development Group
Subject: [freetds] RE: asprintf vasprintf


> 
> There just doesn't seem to be any way to safely change the
> signal handler on
> the fly in a library function like this, without potentially causing
> undesired behavior in another thread.  In particular, all 
> pthread calls are
> off-limits in signal handlers, which makes it virtually 
> impossible to do
> anything about this.
> 
> I've decided to take another approach and provide a
> completely different
> implementation of vasprintf() that will be used when thread safety is
> enabled.  Stay tuned for another patch later today.
> 

I think we should use Patrick Powell implementation of snprintf/vsnprintf. 
I tought about using pthread keys and other pthread stuff but other problem
raise (portability, complexity).

freddy77

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Index: asprintf.c
===================================================================
RCS file: /cvsroot/freetds/freetds/src/tds/asprintf.c,v
retrieving revision 1.2
diff -u -r1.2 asprintf.c
--- asprintf.c  23 Aug 2002 13:10:15 -0000      1.2
+++ asprintf.c  29 Aug 2002 14:19:08 -0000
@@ -13,15 +13,19 @@
 #include <stdlib.h>
 #include <stdarg.h>
 #include <unistd.h>
+#include <string.h>
+#ifndef _REENTRANT
 #include <sys/mman.h>
 #include <setjmp.h>
 #include <signal.h>
 #include <assert.h>
-#include <string.h>
+#endif
 
 static char  software_version[]   = "$Id: asprintf.c,v 1.2 2002/08/23 
13:10:15 freddy77 Exp $";
 static void *no_unused_var_warn[] = {software_version,
                                      no_unused_var_warn};
+
+#ifndef _REENTRANT
 static jmp_buf env;
 
 static void
@@ -29,10 +33,37 @@
 {
   longjmp(env, 1);
 }
+#endif
 
 int
 vasprintf(char **ret, const char *fmt, va_list ap)
 {
+#ifdef _REENTRANT
+  FILE *fp;
+  int len;
+  char *buf;
+
+  if ((fp = fopen("/dev/null", "w")) == NULL) {
+    *ret = NULL;
+    return -1;
+  }
+  len = vfprintf(fp, fmt, ap);
+  if (fclose(fp) != 0) {
+    *ret = NULL;
+    return -1;
+  }
+  if (len < 0) {
+    *ret = NULL;
+    return len;
+  }
+  if ((buf = malloc(len + 1)) == NULL) {
+    *ret = NULL;
+    return -1;
+  }
+  vsprintf(buf, fmt, ap);
+  *ret = buf;
+  return len;
+#else
   volatile char *buf = NULL;
   volatile unsigned int pgs;
   struct sigaction sa, osa;
@@ -81,6 +112,7 @@
   }
   *ret = (char *) buf;
   return len;
+#endif
 }
 
 int