Switch to new try/with/except/finally structure

Also restructure the errors raised from cpl_errs.

Closes #600

rasterio/_base.pxd

@@ -21,7 +21,7 @@ cdef class DatasetReader:
     cdef public object _read
     cdef object env
 
-    cdef void *band(self, int bidx)
+    cdef void *band(self, int bidx) except NULL
 
 
 cdef void *_osr_from_crs(object crs)

rasterio/_base.pyx

@@ -14,9 +14,11 @@ from libc.stdlib cimport malloc, free
 
 from rasterio cimport _gdal, _ogr
 from rasterio._drivers import driver_count, GDALEnv
-from rasterio._err import cpl_errs, GDALError
+from rasterio._err import (
+    cpl_errs, GDALError, CPLE_IllegalArg, CPLE_OpenFailed)
 from rasterio import dtypes
 from rasterio.coords import BoundingBox
+from rasterio.errors import RasterioIOError
 from rasterio.transform import Affine
 from rasterio.enums import ColorInterp, Compression, Interleaving
 from rasterio.vfs import parse_path, vsi_path
@@ -71,10 +73,13 @@ cdef class DatasetReader(object):
 
         name_b = path.encode('utf-8')
         cdef const char *fname = name_b
-        with cpl_errs:
-            self._hds = _gdal.GDALOpen(fname, 0)
-        if self._hds == NULL:
-            raise ValueError("Null dataset")
+
+        try:
+            with cpl_errs:
+                self._hds = _gdal.GDALOpen(fname, 0)
+        except CPLE_OpenFailed as err:
+            self.env.stop()
+            raise RasterioIOError(str(err))
 
         cdef void *drv
         cdef const char *drv_name
@@ -96,14 +101,26 @@ cdef class DatasetReader(object):
 
         self._closed = False
 
-    cdef void *band(self, int bidx):
-        if self._hds == NULL:
-            raise ValueError("Null dataset")
-        cdef void *hband = _gdal.GDALGetRasterBand(self._hds, bidx)
-        if hband == NULL:
-            raise ValueError("Null band")
+    cdef void *band(self, int bidx) except NULL:
+        cdef void *hband = NULL
+        try:
+            with cpl_errs:
+                hband = _gdal.GDALGetRasterBand(self._hds, bidx)
+        except CPLE_IllegalArg as exc:
+            self.env.stop()
+            raise IndexError(str(exc))
         return hband
 
+    def _has_band(self, bidx):
+        cdef void *hband = NULL
+        try:
+            with cpl_errs:
+                hband = _gdal.GDALGetRasterBand(self._hds, bidx)
+        except CPLE_IllegalArg:
+            self.env.stop()
+            return False
+        return True
+
     def read_crs(self):
         cdef char *proj_c = NULL
         cdef const char * auth_key = NULL
@@ -596,14 +613,9 @@ cdef class DatasetReader(object):
         cdef void *hobj
         cdef const char *domain_c
         cdef char **papszStrList
-        if self._hds == NULL:
-            raise ValueError("can't read closed raster file")
+
         if bidx > 0:
-            if bidx not in self.indexes:
-                raise ValueError("Invalid band index")
-            hobj = _gdal.GDALGetRasterBand(self._hds, bidx)
-            if hobj == NULL:
-                raise ValueError("NULL band")
+            hobj = self.band(bidx)
         else:
             hobj = self._hds
         if ns:
@@ -850,6 +862,8 @@ def tastes_like_gdal(t):
 
 
 cdef void *_osr_from_crs(object crs):
+    """Returns a reference to memory that must be deallocated
+    by the caller."""
     cdef char *proj_c = NULL
     cdef void *osr = _gdal.OSRNewSpatialReference(NULL)
     params = []

rasterio/_err.pyx

@@ -31,6 +31,8 @@ manager raises a more useful and informative error:
 
 from enums import IntEnum
 
+from rasterio.errors import RasterioIOError
+
 
 # CPL function declarations.
 cdef extern from "cpl_error.h":
@@ -39,17 +41,59 @@ cdef extern from "cpl_error.h":
     int CPLGetLastErrorType()
     void CPLErrorReset()
 
+
+class CPLError(Exception):
+    """Base CPL error class"""
+    pass
+
+
+class CPLE_AppDefined(CPLError):
+    pass
+
+
+class CPLE_OutOfMemory(CPLError):
+    pass
+
+
+class CPLE_FileIO(CPLError):
+    pass
+
+
+class CPLE_OpenFailed(CPLError):
+    pass
+
+
+class CPLE_IllegalArg(CPLError):
+    pass
+
+
+class CPLE_NotSupported(CPLError):
+    pass
+
+
+class CPLE_AssertionFailed(CPLError):
+    pass
+
+
+class CPLE_NoWriteAccess(CPLError):
+    pass
+
+
+class CPLE_UserInterrupt(CPLError):
+    pass
+
+
 # Map GDAL error numbers to Python exceptions.
 exception_map = {
-    1: RuntimeError,        # CPLE_AppDefined
-    2: MemoryError,         # CPLE_OutOfMemory
-    3: IOError,             # CPLE_FileIO
-    4: IOError,             # CPLE_OpenFailed
-    5: TypeError,           # CPLE_IllegalArg
-    6: ValueError,          # CPLE_NotSupported
-    7: AssertionError,      # CPLE_AssertionFailed
-    8: IOError,             # CPLE_NoWriteAccess
-    9: KeyboardInterrupt,   # CPLE_UserInterrupt
+    1: CPLE_AppDefined,        # 
+    2: CPLE_OutOfMemory,         # 
+    3: CPLE_FileIO,             # 
+    4: CPLE_OpenFailed,             # 
+    5: CPLE_IllegalArg,           # 
+    6: CPLE_NotSupported,          # 
+    7: CPLE_AssertionFailed,      # 
+    8: CPLE_NoWriteAccess,             # 
+    9: CPLE_UserInterrupt,   # 
     10: ValueError          # ObjectNull
     }
 
@@ -62,11 +106,17 @@ cdef class GDALErrCtxManager:
         return self
 
     def __exit__(self, exc_type=None, exc_val=None, exc_tb=None):
-        cdef int err_type = CPLGetLastErrorType()
-        cdef int err_no = CPLGetLastErrorNo()
-        cdef const char *msg = CPLGetLastErrorMsg()
+        cdef const char *msg_c = NULL
+
+        err_type = CPLGetLastErrorType()
         # TODO: warn for err_type 2?
         if err_type >= 3:
+            err_no = CPLGetLastErrorNo()
+            msg_c = CPLGetLastErrorMsg()
+            msg_b = msg_c
+            msg = msg_b.decode('utf-8')
+            msg = msg.replace("`", "'")
+            msg = msg.replace("\n", " ")
             raise exception_map[err_no](msg)
 
 

rasterio/_io.pyx

@@ -17,10 +17,10 @@ from rasterio cimport _base, _gdal, _ogr, _io
 from rasterio._base import (
     crop_window, eval_window, window_shape, window_index, tastes_like_gdal)
 from rasterio._drivers import driver_count, GDALEnv
-from rasterio._err import cpl_errs, GDALError
+from rasterio._err import cpl_errs, GDALError, CPLE_OpenFailed
 from rasterio import dtypes
 from rasterio.coords import BoundingBox
-from rasterio.errors import DriverRegistrationError
+from rasterio.errors import DriverRegistrationError, RasterioIOError
 from rasterio.five import text_type, string_types
 from rasterio.transform import Affine
 from rasterio.enums import ColorInterp, MaskFlags, Resampling
@@ -1288,9 +1288,13 @@ cdef class RasterUpdater(RasterReader):
             
             driver_b = self.driver.encode('utf-8')
             drv_name = driver_b
-            drv = _gdal.GDALGetDriverByName(drv_name)
-            if drv == NULL:
-                raise ValueError("NULL driver for %s", self.driver)
+            
+            try:
+                with cpl_errs:
+                    drv = _gdal.GDALGetDriverByName(drv_name)
+            except Exception as err:
+                self.env.stop()
+                raise DriverRegistrationError(str(err))
             
             # Find the equivalent GDAL data type or raise an exception
             # We've mapped numpy scalar types to GDAL types so see
@@ -1328,12 +1332,16 @@ cdef class RasterUpdater(RasterReader):
                     "Option: %r\n", 
                     (k, _gdal.CSLFetchNameValue(options, key_c)))
 
-            self._hds = _gdal.GDALCreate(
-                drv, fname, self.width, self.height, self._count,
-                gdal_dtype, options)
-
-            if self._hds == NULL:
-                raise ValueError("NULL dataset")
+            try:
+                with cpl_errs:
+                    self._hds = _gdal.GDALCreate(
+                        drv, fname, self.width, self.height, self._count,
+                        gdal_dtype, options)
+            except Exception as err:
+                self.env.stop()
+                if options != NULL:
+                    _gdal.CSLDestroy(options)
+                raise
 
             if self._init_nodata is not None:
 
@@ -1354,10 +1362,12 @@ cdef class RasterUpdater(RasterReader):
                 self.set_crs(self._crs)
         
         elif self.mode == 'r+':
-            with cpl_errs:
-                self._hds = _gdal.GDALOpen(fname, 1)
-            if self._hds == NULL:
-                raise ValueError("NULL dataset")
+            try:
+                with cpl_errs:
+                    self._hds = _gdal.GDALOpen(fname, 1)
+            except CPLE_OpenFailed as err:
+                self.env.stop()
+                raise RasterioIOError(str(err))
 
         drv = _gdal.GDALGetDatasetDriver(self._hds)
         drv_name = _gdal.GDALGetDriverShortName(drv)
@@ -1659,14 +1669,8 @@ cdef class RasterUpdater(RasterReader):
         cdef void *hobj = NULL
         cdef const char *domain_c = NULL
         cdef char **papszStrList = NULL
-        if self._hds == NULL:
-            raise ValueError("can't read closed raster file")
         if bidx > 0:
-            if bidx not in self.indexes:
-                raise ValueError("Invalid band index")
-            hobj = _gdal.GDALGetRasterBand(self._hds, bidx)
-            if hobj == NULL:
-                raise ValueError("NULL band")
+            hobj = self.band(bidx)
         else:
             hobj = self._hds
         if ns:
@@ -1700,21 +1704,15 @@ cdef class RasterUpdater(RasterReader):
         cdef void *hBand = NULL
         cdef void *hTable
         cdef _gdal.GDALColorEntry color
-        if self._hds == NULL:
-            raise ValueError("can't read closed raster file")
         if bidx > 0:
-            if bidx not in self.indexes:
-                raise ValueError("Invalid band index")
-            hBand = _gdal.GDALGetRasterBand(self._hds, bidx)
-            if hBand == NULL:
-                raise ValueError("NULL band")
+            hBand = self.band(bidx)
+
         # RGB only for now. TODO: the other types.
         # GPI_Gray=0,  GPI_RGB=1, GPI_CMYK=2,     GPI_HLS=3
         hTable = _gdal.GDALCreateColorTable(1)
         vals = range(256)
 
         for i, rgba in colormap.items():
-
             if len(rgba) == 4 and self.driver in ('GTiff'):
                 warnings.warn(
                     "This format doesn't support alpha in colormap entries. "
@@ -1745,18 +1743,18 @@ cdef class RasterUpdater(RasterReader):
 
         specifying a raster subset to write into.
         """
-        cdef void *hband
-        cdef void *hmask
-        if self._hds == NULL:
-            raise ValueError("can't write closed raster file")
-        hband = _gdal.GDALGetRasterBand(self._hds, 1)
-        if hband == NULL:
-            raise ValueError("NULL band mask")
-        if _gdal.GDALCreateMaskBand(hband, 0x02) != 0:
-            raise RuntimeError("Failed to create mask")
-        hmask = _gdal.GDALGetMaskBand(hband)
-        if hmask == NULL:
-            raise ValueError("NULL band mask")
+        cdef void *hband = NULL
+        cdef void *hmask = NULL
+
+        hband = self.band(1)
+        if GDALError.success != _gdal.GDALCreateMaskBand(hband, 0x02):
+            raise RasterioIOError("Failed to create mask.")
+
+        try:
+            with cpl_errs:
+                hmask = _gdal.GDALGetMaskBand(hband)
+        except:
+            raise
         log.debug("Created mask band")
 
         if window:
@@ -1788,23 +1786,20 @@ cdef class RasterUpdater(RasterReader):
         cdef int *factors_c = NULL
         cdef const char *resampling_c = NULL
 
-        if self._hds == NULL:
-            raise ValueError("can't write closed raster file")
-
         # Allocate arrays.
         if factors:
             factors_c = <int *>_gdal.CPLMalloc(len(factors)*sizeof(int))
             for i, factor in enumerate(factors):
                 factors_c[i] = factor
-
-            with cpl_errs:
-                resampling_b = resampling.value.encode('utf-8')
-                resampling_c = resampling_b
-                err = _gdal.GDALBuildOverviews(self._hds, resampling_c,
-                    len(factors), factors_c, 0, NULL, NULL, NULL)
-
-            if factors_c != NULL:
-                _gdal.CPLFree(factors_c)
+            try:
+                with cpl_errs:
+                    resampling_b = resampling.value.encode('utf-8')
+                    resampling_c = resampling_b
+                    err = _gdal.GDALBuildOverviews(self._hds, resampling_c,
+                        len(factors), factors_c, 0, NULL, NULL, NULL)
+            finally:
+                if factors_c != NULL:
+                    _gdal.CPLFree(factors_c)
 
 
 cdef class InMemoryRaster:
@@ -1845,27 +1840,25 @@ cdef class InMemoryRaster:
         cdef int i = 0  # avoids Cython warning in for loop below
         cdef const char *srcwkt = NULL
         cdef void *osr = NULL
+        cdef void *memdriver = NULL
 
         # Several GDAL operations require the array of band IDs as input
         self.band_ids[0] = 1
 
-        cdef void *memdriver = _gdal.GDALGetDriverByName("MEM")
-        if memdriver == NULL:
-            raise DriverRegistrationError(
-                "MEM driver is not registered.")
+        try:
+            with cpl_errs:
+                memdriver = _gdal.GDALGetDriverByName("MEM")
+        except:
+            raise DriverRegistrationError("MEM driver is not registered.")
 
-        self.dataset = _gdal.GDALCreate(
-            memdriver,
-            "output",
-            image.shape[1],
-            image.shape[0],
-            1,
-            <_gdal.GDALDataType>dtypes.dtype_rev[image.dtype.name],
-            NULL
-        )
-
-        if self.dataset == NULL:
-            raise ValueError("NULL output datasource")
+        try:
+            with cpl_errs:
+                self.dataset = _gdal.GDALCreate(
+                    memdriver, "output", image.shape[1], image.shape[0],
+                    1, <_gdal.GDALDataType>dtypes.dtype_rev[image.dtype.name],
+                    NULL)
+        except:
+            raise
 
         if transform is not None:
             for i in range(6):
@@ -1951,14 +1944,19 @@ cdef class IndirectRasterUpdater(RasterUpdater):
                     gdal_dtype = dtypes.dtype_rev.get(tp)
             else:
                 gdal_dtype = dtypes.dtype_rev.get(self._init_dtype)
-            self._hds = _gdal.GDALCreate(
-                memdrv, "temp", self.width, self.height, self._count,
-                gdal_dtype, NULL)
-            if self._hds == NULL:
-                raise ValueError("NULL dataset")
+
+            try:
+                with cpl_errs:
+                    self._hds = _gdal.GDALCreate(
+                        memdrv, "temp", self.width, self.height, self._count,
+                        gdal_dtype, NULL)
+            except:
+                self.env.close()
+                raise
+
             if self._init_nodata is not None:
                 for i in range(self._count):
-                    hband = _gdal.GDALGetRasterBand(self._hds, i+1)
+                    hband = self.band(i+1)
                     success = _gdal.GDALSetRasterNoDataValue(
                                     hband, self._init_nodata)
             if self._transform:
@@ -1967,14 +1965,19 @@ cdef class IndirectRasterUpdater(RasterUpdater):
                 self.set_crs(self._crs)
 
         elif self.mode == 'r+':
-            with cpl_errs:
-                temp = _gdal.GDALOpen(fname, 0)
-            if temp == NULL:
-                raise ValueError("Null dataset")
-            self._hds = _gdal.GDALCreateCopy(
-                                memdrv, "temp", temp, 1, NULL, NULL, NULL)
-            if self._hds == NULL:
-                raise ValueError("NULL dataset")
+            try:
+                with cpl_errs:
+                    temp = _gdal.GDALOpen(fname, 0)
+            except Exception as exc:
+                raise RasterioIOError(str(exc))
+            
+            try:
+                with cpl_errs:
+                    self._hds = _gdal.GDALCreateCopy(
+                        memdrv, "temp", temp, 1, NULL, NULL, NULL)
+            except:
+                raise
+
             drv = _gdal.GDALGetDatasetDriver(temp)
             drv_name = _gdal.GDALGetDriverShortName(drv)
             self.driver = drv_name.decode('utf-8')
@@ -2031,16 +2034,19 @@ cdef class IndirectRasterUpdater(RasterUpdater):
             log.debug(
                 "Option: %r\n", 
                 (k, _gdal.CSLFetchNameValue(options, key_c)))
-        
+
         #self.update_tags(ns='rio_creation_kwds', **kwds)
-        temp = _gdal.GDALCreateCopy(
+        try:
+            with cpl_errs:
+                temp = _gdal.GDALCreateCopy(
                     drv, fname, self._hds, 1, options, NULL, NULL)
-
-        if options != NULL:
-            _gdal.CSLDestroy(options)
-
-        if temp != NULL:
-            _gdal.GDALClose(temp)
+        except:
+            raise
+        finally:
+            if options != NULL:
+                _gdal.CSLDestroy(options)
+            if temp != NULL:
+                _gdal.GDALClose(temp)
 
 
 def writer(path, mode, **kwargs):
@@ -2067,15 +2073,17 @@ def writer(path, mode, **kwargs):
         # driver.
         name_b = path.encode('utf-8')
         fname = name_b
-        with cpl_errs:
-            hds = _gdal.GDALOpen(fname, 0)
-            if hds == NULL:
-                raise ValueError("NULL dataset")
-            drv = _gdal.GDALGetDatasetDriver(hds)
-            drv_name = _gdal.GDALGetDriverShortName(drv)
-            drv_name_b = drv_name
-            driver = drv_name_b.decode('utf-8')
-            _gdal.GDALClose(hds)
+        try:
+            with cpl_errs:
+                hds = _gdal.GDALOpen(fname, 0)
+        except CPLE_OpenFailed as exc:
+            raise RasterioIOError(str(exc))
+
+        drv = _gdal.GDALGetDatasetDriver(hds)
+        drv_name = _gdal.GDALGetDriverShortName(drv)
+        drv_name_b = drv_name
+        driver = drv_name_b.decode('utf-8')
+        _gdal.GDALClose(hds)
 
         if driver == 'GTiff':
             return RasterUpdater(path, mode)
@@ -2091,7 +2099,13 @@ def virtual_file_to_buffer(filename):
      
     filename_b = filename if not isinstance(filename, string_types) else filename.encode('utf-8')
     cfilename = filename_b
-    buff = _gdal.VSIGetMemFileBuffer(cfilename, &buff_len, 0)
+    
+    try:
+        with cpl_errs:
+            buff = _gdal.VSIGetMemFileBuffer(cfilename, &buff_len, 0)
+    except:
+        raise
+
     n = buff_len
     log.debug("Buffer length: %d bytes", n)
     cdef np.uint8_t[:] buff_view = <np.uint8_t[:n]>buff

rasterio/_warp.pyx

@@ -100,8 +100,15 @@ def _transform_geom(
 
     src = _base._osr_from_crs(src_crs)
     dst = _base._osr_from_crs(dst_crs)
-    transform = _gdal.OCTNewCoordinateTransformation(src, dst)
 
+    try:
+        with cpl_errs:
+            transform = _gdal.OCTNewCoordinateTransformation(src, dst)
+    except:
+        _gdal.OSRDestroySpatialReference(src)
+        _gdal.OSRDestroySpatialReference(dst)
+        raise
+        
     # Transform options.
     val_b = str(antimeridian_offset).encode('utf-8')
     val_c = val_b
@@ -110,22 +117,24 @@ def _transform_geom(
     if antimeridian_cutting:
         options = _gdal.CSLSetNameValue(options, "WRAPDATELINE", "YES")
 
-    factory = new OGRGeometryFactory()
-    src_ogr_geom = _features.OGRGeomBuilder().build(geom)
-    dst_ogr_geom = factory.transformWithOptions(
+    try:
+        factory = new OGRGeometryFactory()
+        src_ogr_geom = _features.OGRGeomBuilder().build(geom)
+        with cpl_errs:
+            dst_ogr_geom = factory.transformWithOptions(
                     <const OGRGeometry *>src_ogr_geom,
                     <OGRCoordinateTransformation *>transform,
                     options)
-    del factory
-    g = _features.GeomBuilder().build(dst_ogr_geom)
-
-    _ogr.OGR_G_DestroyGeometry(dst_ogr_geom)
-    _ogr.OGR_G_DestroyGeometry(src_ogr_geom)
-    _gdal.OCTDestroyCoordinateTransformation(transform)
-    if options != NULL:
-        _gdal.CSLDestroy(options)
-    _gdal.OSRDestroySpatialReference(src)
-    _gdal.OSRDestroySpatialReference(dst)
+        g = _features.GeomBuilder().build(dst_ogr_geom)
+    finally:
+        del factory
+        _ogr.OGR_G_DestroyGeometry(dst_ogr_geom)
+        _ogr.OGR_G_DestroyGeometry(src_ogr_geom)
+        _gdal.OCTDestroyCoordinateTransformation(transform)
+        if options != NULL:
+            _gdal.CSLDestroy(options)
+        _gdal.OSRDestroySpatialReference(src)
+        _gdal.OSRDestroySpatialReference(dst)
 
     if precision >= 0:
         if g['type'] == 'Point':
@@ -267,31 +276,39 @@ def _reproject(
             # source is a masked array
             src_nodata = source.fill_value
 
-        hrdriver = _gdal.GDALGetDriverByName("MEM")
-        if hrdriver == NULL:
+        try:
+            with cpl_errs:
+                hrdriver = _gdal.GDALGetDriverByName("MEM")
+        except:
             raise DriverRegistrationError(
                 "'MEM' driver not found. Check that this call is contained "
                 "in a `with rasterio.drivers()` or `with rasterio.open()` "
                 "block.")
 
-        hdsin = _gdal.GDALCreate(
+        try:
+            with cpl_errs:
+                hdsin = _gdal.GDALCreate(
                     hrdriver, "input", cols, rows, 
                     src_count, dtypes.dtype_rev[dtype], NULL)
-        if hdsin == NULL:
-            raise ValueError("NULL input datasource")
+        except:
+            raise
         _gdal.GDALSetDescription(
             hdsin, "Temporary source dataset for _reproject()")
         log.debug("Created temp source dataset")
+
         for i in range(6):
             gt[i] = src_transform[i]
         retval = _gdal.GDALSetGeoTransform(hdsin, gt)
         log.debug("Set transform on temp source dataset: %d", retval)
-        osr = _base._osr_from_crs(src_crs)
-        _gdal.OSRExportToWkt(osr, &srcwkt)
-        _gdal.GDALSetProjection(hdsin, srcwkt)
-        log.debug("Set CRS on temp source dataset: %s", srcwkt)
-        _gdal.CPLFree(srcwkt)
-        _gdal.OSRDestroySpatialReference(osr)
+
+        try:
+            osr = _base._osr_from_crs(src_crs)
+            _gdal.OSRExportToWkt(osr, &srcwkt)
+            _gdal.GDALSetProjection(hdsin, srcwkt)
+            log.debug("Set CRS on temp source dataset: %s", srcwkt)
+        finally:
+            _gdal.CPLFree(srcwkt)
+            _gdal.OSRDestroySpatialReference(osr)
         
         # Copy arrays to the dataset.
         retval = _io.io_auto(source, hdsin, 1)
@@ -315,19 +332,23 @@ def _reproject(
         if destination.shape[0] != src_count:
             raise ValueError("Destination's shape is invalid")
 
-        hrdriver = _gdal.GDALGetDriverByName("MEM")
-        if hrdriver == NULL:
+        try:
+            with cpl_errs:
+                hrdriver = _gdal.GDALGetDriverByName("MEM")
+        except:
             raise DriverRegistrationError(
                 "'MEM' driver not found. Check that this call is contained "
                 "in a `with rasterio.drivers()` or `with rasterio.open()` "
                 "block.")
 
         _, rows, cols = destination.shape
-        hdsout = _gdal.GDALCreate(
-                        hrdriver, "output", cols, rows, src_count, 
-                        dtypes.dtype_rev[np.dtype(destination.dtype).name], NULL)
-        if hdsout == NULL:
-            raise ValueError("Failed to create temp destination dataset.")
+        try:
+            with cpl_errs:
+                hdsout = _gdal.GDALCreate(
+                    hrdriver, "output", cols, rows, src_count, 
+                    dtypes.dtype_rev[np.dtype(destination.dtype).name], NULL)
+        except:
+            raise
         _gdal.GDALSetDescription(
             hdsout, "Temporary destination dataset for _reproject()")
         log.debug("Created temp destination dataset.")
@@ -339,16 +360,16 @@ def _reproject(
             raise ValueError(
                 "Failed to set transform on temp destination dataset.")
 
-        osr = _base._osr_from_crs(dst_crs)
-        _gdal.OSRExportToWkt(osr, &dstwkt)
-        _gdal.OSRDestroySpatialReference(osr)
-        log.debug("CRS for temp destination dataset: %s.", dstwkt)
-
-        if not GDALError.success == _gdal.GDALSetProjection(hdsout, dstwkt):
-            raise ValueError(
-                "Failed to set projection on temp destination dataset.")
-
-        _gdal.CPLFree(dstwkt)
+        try:
+            osr = _base._osr_from_crs(dst_crs)
+            _gdal.OSRExportToWkt(osr, &dstwkt)
+            log.debug("CRS for temp destination dataset: %s.", dstwkt)
+            if not GDALError.success == _gdal.GDALSetProjection(
+                    hdsout, dstwkt):
+                raise ("Failed to set projection on temp destination dataset.")
+        finally:
+            _gdal.OSRDestroySpatialReference(osr)
+            _gdal.CPLFree(dstwkt)
 
         if dst_nodata is None and hasattr(destination, "fill_value"):
             # destination is a masked array
@@ -365,14 +386,18 @@ def _reproject(
     cdef void *hTransformArg = NULL
     cdef _gdal.GDALWarpOptions *psWOptions = NULL
 
-    hTransformArg = _gdal.GDALCreateGenImgProjTransformer(
-                                        hdsin, NULL, hdsout, NULL,
-                                        1, 1000.0, 0)
-    if hTransformArg == NULL:
-        raise ValueError("NULL transformer")
-    log.debug("Created transformer")
-
-    psWOptions = _gdal.GDALCreateWarpOptions()
+    try:
+        with cpl_errs:
+            hTransformArg = _gdal.GDALCreateGenImgProjTransformer(
+                                hdsin, NULL, hdsout, NULL,
+                                1, 1000.0, 0)
+        with cpl_errs:
+            psWOptions = _gdal.GDALCreateWarpOptions()
+        log.debug("Created transformer and options.")
+    except:
+        _gdal.GDALDestroyGenImgProjTransformer(hTransformArg)
+        _gdal.GDALDestroyWarpOptions(psWOptions)
+        raise
 
     # Note: warp_extras is pointed to different memory locations on every
     # call to CSLSetNameValue call below, but needs to be set here to
@@ -534,22 +559,18 @@ def _calculate_default_transform(
 
     with InMemoryRaster(
             img, transform=transform.to_gdal(), crs=src_crs) as temp:
-        hTransformArg = _gdal.GDALCreateGenImgProjTransformer(
-            temp.dataset, NULL, NULL, wkt, 1, 1000.0, 0)
-        if hTransformArg == NULL:
-            if wkt != NULL:
-                _gdal.CPLFree(wkt)
-            raise ValueError("NULL transformer")
-        log.debug("Created transformer")
-
-        # geotransform, npixels, and nlines are modified by the
-        # function called below.
         try:
-            if not GDALError.success == _gdal.GDALSuggestedWarpOutput2(
+            with cpl_errs:
+                hTransformArg = _gdal.GDALCreateGenImgProjTransformer(
+                                    temp.dataset, NULL, NULL, wkt,
+                                    1, 1000.0,0)
+            with cpl_errs:
+                result = _gdal.GDALSuggestedWarpOutput2(
                     temp.dataset, _gdal.GDALGenImgProjTransform, hTransformArg,
-                    geotransform, &npixels, &nlines, extent, 0):
-                raise RuntimeError(
-                    "Failed to compute a suggested warp output.")
+                    geotransform, &npixels, &nlines, extent, 0)
+            log.debug("Created transformer and warp output.")
+        except:
+            raise
         finally:
             if wkt != NULL:
                 _gdal.CPLFree(wkt)

tests/test_err.py

@@ -0,0 +1,28 @@
+# Testing use of cpl_errs
+
+import pytest
+
+import rasterio
+from rasterio.errors import RasterioIOError
+
+
+def test_io_error(tmpdir):
+    with pytest.raises(RasterioIOError) as exc_info:
+        rasterio.open(str(tmpdir.join('foo.tif')))
+    msg = exc_info.value.message
+    assert msg.startswith("'{0}'".format(tmpdir.join('foo.tif')))
+    assert ("does not exist in the file system, and is not recognised as a "
+            "supported dataset name.") in msg
+
+
+def test_io_error_env(tmpdir):
+    with rasterio.drivers() as env:
+        drivers_start = env.drivers()
+        with pytest.raises(RasterioIOError):
+            rasterio.open(str(tmpdir.join('foo.tif')))
+    assert env.drivers() == drivers_start
+
+
+def test_bogus_band_error():
+    with rasterio.open('tests/data/RGB.byte.tif') as src:
+        assert src._has_band(4) is False

tests/test_tags.py

@@ -13,7 +13,7 @@ def test_tags_read():
         assert src.tags(ns='IMAGE_STRUCTURE') == {'INTERLEAVE': 'PIXEL'}
         assert src.tags(ns='bogus') == {}
         assert 'STATISTICS_MAXIMUM' in src.tags(1)
-        with pytest.raises(ValueError):
+        with pytest.raises(IndexError):
             tags = src.tags(4)
 
 def test_tags_update(tmpdir):
@@ -29,7 +29,7 @@ def test_tags_update(tmpdir):
 
         dst.update_tags(a='1', b='2')
         dst.update_tags(1, c=3)
-        with pytest.raises(ValueError):
+        with pytest.raises(IndexError):
             dst.update_tags(4, d=4)
 
         assert dst.tags() == {'a': '1', 'b': '2'}

tests/test_update.py

@@ -15,7 +15,7 @@ def test_update_tags(data):
         with rasterio.open(tiffname, 'r+') as f:
             f.update_tags(a='1', b='2')
             f.update_tags(1, c=3)
-            with pytest.raises(ValueError):
+            with pytest.raises(IndexError):
                 f.update_tags(4, d=4)
             assert f.tags() == {'AREA_OR_POINT': 'Area', 'a': '1', 'b': '2'}
             assert ('c', '3') in f.tags(1).items()