Merge pull request #739 from kbevers/pipeline-inverse

Pipeline and cct inverse fixes

2 files changed, 38 insertions, 4 deletions

diff --git a/src/PJ_pipeline.c b/src/PJ_pipeline.c
index af9c5394..befc8557 100644
--- a/src/PJ_pipeline.c
+++ b/src/PJ_pipeline.c
@@ -429,14 +429,42 @@ PJ *OPERATION(pipeline,0) {
 
         /* Is this step inverted? */
         for (j = 0;  j < current_argc; j++)
-            if (0==strcmp("inv", current_argv[j]))
-                next_step->inverted = 1;
+            if (0==strcmp("inv", current_argv[j])) {
+                /* if +inv exists in both global and local args the forward operation should be used */
+                next_step->inverted = next_step->inverted == 0 ? 1 : 0;
+            }
 
         P->opaque->pipeline[i+1] = next_step;
 
         proj_log_trace (P, "Pipeline at [%p]:    step at [%p] done", P, next_step);
     }
 
+    /* Require a forward path through the pipeline */
+    for (i = 1; i <= nsteps; i++) {
+        PJ *Q = P->opaque->pipeline[i];
+        if ( ( Q->inverted && (Q->inv || Q->inv3d || Q->fwd4d) ) ||
+             (!Q->inverted && (Q->fwd || Q->fwd3d || Q->fwd4d) ) ) {
+            continue;
+        } else {
+            proj_log_error (P, "Pipeline: A forward operation couldn't be constructed");
+            return destructor (P, PJD_ERR_MALFORMED_PIPELINE);
+        }
+    }
+
+    /* determine if an inverse operation is possible */
+    for (i = 1; i <= nsteps; i++) {
+        PJ *Q = P->opaque->pipeline[i];
+        if ( ( Q->inverted && (Q->fwd || Q->fwd3d || Q->fwd4d) ) ||
+             ( Q->inv || Q->inv3d || Q->inv4d) ) {
+            continue;
+        } else {
+            P->inv   = 0;
+            P->inv3d = 0;
+            P->inv4d = 0;
+            break;
+        }
+    }
+
     proj_log_trace (P, "Pipeline: %d steps built. Determining i/o characteristics", nsteps);
 
     /* Determine forward input (= reverse output) data type */
diff --git a/src/cct.c b/src/cct.c
index f315ae1a..7e48311a 100644
--- a/src/cct.c
+++ b/src/cct.c
@@ -217,9 +217,15 @@ int main(int argc, char **argv) {
         return 1;
     }
 
-    /* We have no API call for inverting an operation, so we brute force it. */
-    if (direction==-1)
+    if (direction==-1) {
+        /* fail if an inverse operation is not available */
+        if (!proj_pj_info(P).has_inverse) {
+            fprintf (stderr, "Inverse operation not available\n");
+            return 1;
+        }
+        /* We have no API call for inverting an operation, so we brute force it. */
         P->inverted = !(P->inverted);
+    }
     direction = 1;
 
     /* Allocate input buffer */