libsegment: improve error handling (trunk, https://trac.osgeo.org/grass/changeset/62484)

git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@64022 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/segment/init.c

@@ -63,7 +63,9 @@ int Segment_init(SEGMENT *SEG, int fd, int nseg)
     SEG->nseg = nseg;
 
     if (lseek(fd, 0L, SEEK_SET) < 0) {
-	G_warning("Segment_init: %s", strerror(errno));
+	int err = errno;
+
+	G_warning("Segment_init: %s", strerror(err));
 	return -1;
     }
 

lib/segment/open.c

@@ -81,6 +81,7 @@ Segment_open(SEGMENT *SEG, char *fname, off_t nrows, off_t ncols,
     }
     /* re-open for read and write */
     close(SEG->fd);
+    SEG->fd = -1;
     if (-1 == (SEG->fd = open(SEG->fname, 2))) {
 	unlink(SEG->fname);
 	G_warning(_("Unable to re-open segment file"));

lib/segment/pageout.c

@@ -37,8 +37,14 @@
 int seg_pageout(SEGMENT * SEG, int i)
 {
     SEG->seek(SEG, SEG->scb[i].n, 0);
+    errno = 0;
     if (write(SEG->fd, SEG->scb[i].buf, SEG->size) != SEG->size) {
-	G_warning("Segment pageout: %s", strerror(errno));
+	int err = errno;
+
+	if (err)
+	    G_warning("Segment pageout: %s", strerror(err));
+	else
+	    G_warning("Segment pageout: insufficient disk space?");
 	return -1;
     }
     SEG->scb[i].dirty = 0;