[mpich-devel] Issue with MPI_Error_string() for user-defined codes/clases

[Lisandro Dalcin]

On 23 April 2014 00:55, Rob Latham <robl at mcs.anl.gov> wrote:
>
>
> On 04/22/2014 04:04 AM, Lisandro Dalcin wrote:
>>
>> The following simple tests segfaults. A quick fix would be to return
>> an empty string in MPIR_Err_get_dynerr_string() (file dynerrutil.c),
>
>
> I don't muck around in this code very often, so after thinking about it for
> a bit, and coming up with another way to do it, I opened a ticket so i could
> get a second (third, I guess) opinion:
>
> https://trac.mpich.org/projects/mpich/ticket/2067
>

IMHO your patch complicates things too much, I'm still in support of
this slightly refined version that removes the usage of empty string
constants (Rob, could you upload this patch to the ticket?):

$ git diff
diff --git a/src/mpi/errhan/dynerrutil.c b/src/mpi/errhan/dynerrutil.c
index 943e8c3..2e3bb27 100644
--- a/src/mpi/errhan/dynerrutil.c
+++ b/src/mpi/errhan/dynerrutil.c
@@ -48,6 +48,7 @@ static const char
*(user_class_msgs[ERROR_MAX_NCLASS]) = { 0 };
 static const char *(user_code_msgs[ERROR_MAX_NCODE]) = { 0 };
 static int  first_free_class = 0;
 static int  first_free_code  = 1;  /* code 0 is reserved */
+static const char empty_error_string[1] = { 0 };

 /* Forward reference */
 const char *MPIR_Err_get_dynerr_string( int code );
@@ -297,11 +298,13 @@ const char *MPIR_Err_get_dynerr_string( int code )
     if (errcode) {
  if (errcode < first_free_code) {
     errstr = user_code_msgs[errcode];
+    if (!errstr) errstr = empty_error_string;
  }
     }
     else {
  if (errclass < first_free_class) {
     errstr = user_class_msgs[errclass];
+    if (!errstr) errstr = empty_error_string;
  }
     }



-- 
Lisandro Dalcin
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diff --git a/src/mpi/errhan/dynerrutil.c b/src/mpi/errhan/dynerrutil.c
index 943e8c3..2e3bb27 100644
--- a/src/mpi/errhan/dynerrutil.c
+++ b/src/mpi/errhan/dynerrutil.c
@@ -48,6 +48,7 @@ static const char *(user_class_msgs[ERROR_MAX_NCLASS]) = { 0 };
 static const char *(user_code_msgs[ERROR_MAX_NCODE]) = { 0 };
 static int  first_free_class = 0;
 static int  first_free_code  = 1;  /* code 0 is reserved */
+static const char empty_error_string[1] = { 0 };
 
 /* Forward reference */
 const char *MPIR_Err_get_dynerr_string( int code );
@@ -297,11 +298,13 @@ const char *MPIR_Err_get_dynerr_string( int code )
     if (errcode) {
 	if (errcode < first_free_code) {
 	    errstr = user_code_msgs[errcode];
+	    if (!errstr) errstr = empty_error_string;
 	}
     }
     else {
 	if (errclass < first_free_class) {
 	    errstr = user_class_msgs[errclass];
+	    if (!errstr) errstr = empty_error_string;
 	}
     }