[SCM] GNU M4 source repository branch, stackovf, updated. v1.5.89a-29-g0b2dea6

[Eric Blake]

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- Log -----------------------------------------------------------------
commit 0b2dea68c4f3e2f6cca84291536b80b3c4eac058
Author: Eric Blake <address@hidden>
Date:   Fri Jun 6 16:37:21 2008 -0600

    Inform users what to do in case of programmer error.
    
    * src/m4.h (EXIT_INTERNAL_ERROR): New macro.
    * configure.ac (AC_TYPE_SIGNAL): Delete, now that we assume C89.
    * src/m4.c (fault_handler): New method.
    (program_error_message): New variable, for async-safety.
    (main): Print bug reporting address rather than dump core on any
    failed assertions or detected non-stack-overflow faults.
    
    Signed-off-by: Eric Blake <address@hidden>

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog    |    8 ++++++++
 configure.ac |    2 --
 src/m4.c     |   31 ++++++++++++++++++++++++++++++-
 src/m4.h     |    3 +++
 4 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 18c8301..6dc4932 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
 2008-06-06  Eric Blake  <address@hidden>
 
+       Inform users what to do in case of programmer error.
+       * src/m4.h (EXIT_INTERNAL_ERROR): New macro.
+       * configure.ac (AC_TYPE_SIGNAL): Delete, now that we assume C89.
+       * src/m4.c (fault_handler): New method.
+       (program_error_message): New variable, for async-safety.
+       (main): Print bug reporting address rather than dump core on any
+       failed assertions or detected non-stack-overflow faults.
+
        Replace stackovf with gnulib c-stack.
        * m4/gnulib.cache.m4: Import c-stack module.
        * configure.ac (AC_CHECK_HEADERS_ONCE): Remove check for
diff --git a/configure.ac b/configure.ac
index 3fb059b..3456d8f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -32,8 +32,6 @@ AC_CONFIG_HEADERS([lib/config.h:lib/config.hin])
 AC_PROG_CC
 M4_EARLY
 
-AC_TYPE_SIGNAL
-
 # Tandem/NSK is broken - it has 'long long int' but not
 # 'unsigned long long int', which confuses assumptions made by gnulib.
 # Simply pretend that neither type exists if both do not work.
diff --git a/src/m4.c b/src/m4.c
index 63dcc20..f2c7c61 100644
--- a/src/m4.c
+++ b/src/m4.c
@@ -177,6 +177,28 @@ m4_warn (int errnum, const call_info *caller, const char 
*format, ...)
       va_end (args);
     }
 }
+
+/* Translated message for program errors.  Do not translate it in the
+   signal handler, since gettext is not async-signal-safe.  */
+static const char * volatile program_error_message;
+
+/* Print a nicer message about any programmer errors, then exit.  This
+   must be aysnc-signal safe, since it is executed as a signal
+   handler.  If SIGNO is zero, this represents a stack overflow; in
+   that case, we return to allow c_stack_action to handle things.  */
+static void
+fault_handler (int signo)
+{
+  if (signo)
+    {
+      write (STDERR_FILENO, program_name, strlen (program_name));
+      write (STDERR_FILENO, ": ", 2);
+      write (STDERR_FILENO, program_error_message,
+             strlen (program_error_message));
+      write (STDERR_FILENO, "\n", 1);
+      _exit (EXIT_INTERNAL_ERROR);
+    }
+}
 
 
 /*---------------------------------------------.
@@ -415,8 +437,15 @@ main (int argc, char *const *argv, char *const *envp)
   debug_init ();
   set_quoting_style (NULL, escape_quoting_style);
   set_char_quoting (NULL, ':', 1);
-  if (c_stack_action (NULL) == 0)
+
+  /* Stack overflow and program error handling.  */
+  if (c_stack_action (fault_handler) == 0)
     nesting_limit = 0;
+  program_error_message
+    = xasprintf (_("internal error detected; please report this bug to <%s>"),
+                 PACKAGE_BUGREPORT);
+  /* FIXME - use sigaction.  */
+  signal (SIGABRT, fault_handler);
 
   /* First, we decode the arguments, to size up tables and stuff.  */
 
diff --git a/src/m4.h b/src/m4.h
index 6290122..a38a2f8 100644
--- a/src/m4.h
+++ b/src/m4.h
@@ -73,6 +73,9 @@
 # undef UNIX
 #endif
 
+/* Used if any programmer error is detected (not possible, right?)  */
+#define EXIT_INTERNAL_ERROR 2
+
 /* Used for version mismatch, when -R detects a frozen file it can't parse.  */
 #define EXIT_MISMATCH 63
 


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