<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Lisandro,<div><br></div><div>As a matter of personal taste, I prefer that empty strings be used as initializers for C strings. One of the things I dislike extremely about C (and, one of the reasons I think it is so easy in C to write bad code) is its mixing of integers and pointers and integers and chars. Even though { 0 } is identical to { "" } when initializing C strings, I find the latter more informative. I know the C standard specifies that strings are terminated by the null character, which is elsewhere specified to be a byte with all bits equal to zero. However, "" <i>is</i> the literal empty string, whereas 0 (or '\0') is the underlying implementation of the empty string. This is also why I prefer to use the C99 NULL macro constant to initialize pointers with the <i>nil</i> pointer as opposed to 0 (which gets implicitly cast to a nil pointer of the correct size), the implementation of the nil pointer. As I said, though, this is all just a matter of taste -- there is no difference in the correctness of the code.</div><div><br><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Helvetica Neue'; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; ">Larry Baker<br>US Geological Survey<br>650-329-5608<br><a href="mailto:baker@usgs.gov">baker@usgs.gov</a><br><br><br></span>
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<br><div><div>On 23 Apr 2014, at 3:20 AM, Lisandro Dalcin wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div>On 23 April 2014 00:55, Rob Latham <<a href="mailto:robl@mcs.anl.gov">robl@mcs.anl.gov</a>> wrote:<br><blockquote type="cite"><br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">On 04/22/2014 04:04 AM, Lisandro Dalcin wrote:<br></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">The following simple tests segfaults. A quick fix would be to return<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">an empty string in MPIR_Err_get_dynerr_string() (file dynerrutil.c),<br></blockquote></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">I don't muck around in this code very often, so after thinking about it for<br></blockquote><blockquote type="cite">a bit, and coming up with another way to do it, I opened a ticket so i could<br></blockquote><blockquote type="cite">get a second (third, I guess) opinion:<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><a href="https://trac.mpich.org/projects/mpich/ticket/2067">https://trac.mpich.org/projects/mpich/ticket/2067</a><br></blockquote><blockquote type="cite"><br></blockquote><br>IMHO your patch complicates things too much, I'm still in support of<br>this slightly refined version that removes the usage of empty string<br>constants (Rob, could you upload this patch to the ticket?):<br><br>$ git diff<br>diff --git a/src/mpi/errhan/dynerrutil.c b/src/mpi/errhan/dynerrutil.c<br>index 943e8c3..2e3bb27 100644<br>--- a/src/mpi/errhan/dynerrutil.c<br>+++ b/src/mpi/errhan/dynerrutil.c<br>@@ -48,6 +48,7 @@ static const char<br>*(user_class_msgs[ERROR_MAX_NCLASS]) = { 0 };<br> static const char *(user_code_msgs[ERROR_MAX_NCODE]) = { 0 };<br> static int first_free_class = 0;<br> static int first_free_code = 1; /* code 0 is reserved */<br>+static const char empty_error_string[1] = { 0 };<br><br> /* Forward reference */<br> const char *MPIR_Err_get_dynerr_string( int code );<br>@@ -297,11 +298,13 @@ const char *MPIR_Err_get_dynerr_string( int code )<br> if (errcode) {<br> if (errcode < first_free_code) {<br> errstr = user_code_msgs[errcode];<br>+ if (!errstr) errstr = empty_error_string;<br> }<br> }<br> else {<br> if (errclass < first_free_class) {<br> errstr = user_class_msgs[errclass];<br>+ if (!errstr) errstr = empty_error_string;<br> }<br> }<br><br><br><br>-- <br>Lisandro Dalcin<br>---------------<br>CIMEC (UNL/CONICET)<br>Predio CONICET-Santa Fe<br>Colectora RN 168 Km 472, Paraje El Pozo<br>3000 Santa Fe, Argentina<br>Tel: +54-342-4511594 (ext 1016)<br>Tel/Fax: +54-342-4511169<br><span><error-string.diff></span></div></blockquote></div><br></div></body></html>