On NetBSD/macppc, if you call g_log() with multiple log levels *and* with a log message format string that has arguments (%s or whatever), it will crash.

It looks like the problem is that g_logv() will use its va_list more than once without calling va_copy(). On many ppc systems this fails because va_list is defined as

 struct {
   stuff...
 } va_list[1];

meaning that it is, in effect, passed by reference in cases where an i386's simple pointer-to-the-stack va_list would be passed by value. As a result, the second invocation of *vprintf() picks up where the previous one left off, instead of starting at the beginning.

Using va_copy() will portably make an independent copy of the va_list state, though.

On the other hand, it doesn't look like g_logv() actually *needs* to traverse the argument list more than once: instead of calling *vprintf() for each log level, it could call it just once and use the resulting string for each log message.

Here's a short program demonstrating the crash. Notice how it prints the message from the first of the multiple log levels, but fails trying to format it again for the next log level.

$ cat ./valog2.c

#include <glib.h>

int main()
{
  int foo1 = 42;
  char *foo2 = "fortytwo";
  char *foo3 = "blah";

  g_log("wargha", G_LOG_LEVEL_INFO, "A message at only one log level (%d %s %s)", foo1, foo2, foo3);
 
  g_log("wargha", G_LOG_LEVEL_INFO|G_LOG_LEVEL_MESSAGE,
        "A message at multiple log levels (%d %s %s)", foo1, foo2, foo3);
}
$ cc valog2.c `/usr/pkg/bin/pkg-config glib-2.0 --cflags --libs`
$ ./a.out
wargha-INFO: A message at only one log level (42 fortytwo blah)
wargha-INFO: A message at multiple log levels (42 fortytwo blah)
[2]   Segmentation fault (core dumped) ./a.out
$ gdb ./a.out
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This GDB was configured as "powerpc--netbsd"...(no debugging symbols found)

(gdb) run
Starting program: /home/wiml/bad_glib/a.out 
wargha-INFO: A message at only one log level (42 fortytwo blah)
wargha-INFO: A message at multiple log levels (42 fortytwo blah)

Program received signal SIGSEGV, Segmentation fault.
0xefea53a8 in strlen () from /usr/lib/libc.so.12
(gdb) bt

+ Trace 213949