Revise error codes to have a reduced set exposed in the public API.

Fixes #2482

And also add proj_context_errno_string()

Revise gie 'expect failure errno XXXX' strings

1 files changed, 24 insertions, 9 deletions

diff --git a/src/projections/sconics.cpp b/src/projections/sconics.cpp
index c12b05a2..9084404c 100644
--- a/src/projections/sconics.cpp
+++ b/src/projections/sconics.cpp
@@ -48,15 +48,28 @@ static int phi12(PJ *P, double *del) {
     double p1, p2;
     int err = 0;
 
-    if (!pj_param(P->ctx, P->params, "tlat_1").i ||
-        !pj_param(P->ctx, P->params, "tlat_2").i) {
-        err = -41;
-    } else {
+    if (!pj_param(P->ctx, P->params, "tlat_1").i )
+    {
+        proj_log_error(P, _("Missing parameter: lat_1 should be specified"));
+        err = PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE;
+    }
+    else if ( !pj_param(P->ctx, P->params, "tlat_2").i)
+    {
+        proj_log_error(P, _("Missing parameter: lat_2 should be specified"));
+        err = PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE;
+    }
+    else
+    {
         p1 = pj_param(P->ctx, P->params, "rlat_1").f;
         p2 = pj_param(P->ctx, P->params, "rlat_2").f;
         *del = 0.5 * (p2 - p1);
-        static_cast<struct pj_opaque*>(P->opaque)->sig = 0.5 * (p2 + p1);
-        err = (fabs(*del) < EPS || fabs(static_cast<struct pj_opaque*>(P->opaque)->sig) < EPS) ? PJD_ERR_ABS_LAT1_EQ_ABS_LAT2 : 0;
+        const double sig = 0.5 * (p2 + p1);
+        static_cast<struct pj_opaque*>(P->opaque)->sig = sig;
+        err = (fabs(*del) < EPS || fabs(sig) < EPS) ? PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE : 0;
+        if( err )
+        {
+            proj_log_error(P, _("Illegal value for lat_1 and lat_2: |lat_1 - lat_2| and |lat_1 + lat_2| should be > 0"));
+        }
     }
     return err;
 }
@@ -119,7 +132,7 @@ static PJ *setup(PJ *P, enum Type type) {
     int err;
     struct pj_opaque *Q = static_cast<struct pj_opaque*>(calloc (1, sizeof (struct pj_opaque)));
     if (nullptr==Q)
-        return pj_default_destructor (P, ENOMEM);
+        return pj_default_destructor (P, PROJ_ERR_INVALID_OP /*ENOMEM*/);
     P->opaque = Q;
     Q->type = type;
 
@@ -167,8 +180,10 @@ static PJ *setup(PJ *P, enum Type type) {
         Q->c1 = 1./tan (Q->sig);
         del = P->phi0 - Q->sig;
         if (fabs (del) - EPS10 >= M_HALFPI)
-            return pj_default_destructor(P, PJD_ERR_LAT_0_HALF_PI_FROM_MEAN);
-
+        {
+            proj_log_error(P, _("Invalid value for lat_0/lat_1/lat_2: |lat_0 - 0.5 * (lat_1 + lat_2)| should be < 90°"));
+            return pj_default_destructor(P, PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
+        }
         Q->rho_0 = Q->c2 * (Q->c1 - tan (del));
         break;