Initial Commit

error.go

@@ -0,0 +1,82 @@
+package pcre
+
+import (
+	"fmt"
+	"unsafe"
+
+	"go.arsenm.dev/pcre/lib"
+
+	"modernc.org/libc"
+	"modernc.org/libc/sys/types"
+)
+
+var pce pcreError
+
+// pcreError is meant to be manually allocated
+// for when pcre requires a pointer to store an error
+// such as for Xpcre2_compile_8().
+type pcreError struct {
+	errCode   int32
+	errOffset lib.Tsize_t
+}
+
+// allocError manually allocates memory for the
+// pcreError struct.
+//
+// libc.Xfree() should be called on the returned
+// pointer once it is no longer needed.
+func allocError(tls *libc.TLS) uintptr {
+	return libc.Xmalloc(tls, types.Size_t(unsafe.Sizeof(pce)))
+}
+
+// addErrCodeOffset adds the offset of the error code
+// within the pcreError struct to a given pointer
+func addErrCodeOffset(p uintptr) uintptr {
+	ptrOffset := unsafe.Offsetof(pce.errCode)
+	return p + ptrOffset
+}
+
+// addErrOffsetOffset adds the offset of the error
+// offset within the pcreError struct to a given pointer
+func addErrOffsetOffset(p uintptr) uintptr {
+	offsetOffset := unsafe.Offsetof(pce.errOffset)
+	return p + offsetOffset
+}
+
+// ptrToError converts the given pointer to a Go error
+func ptrToError(tls *libc.TLS, pe uintptr) *PcreError {
+	eo := *(*pcreError)(unsafe.Pointer(pe))
+
+	err := codeToError(tls, eo.errCode)
+	err.offset = eo.errOffset
+
+	return err
+}
+
+// codeToError converts the given error code into a Go error
+func codeToError(tls *libc.TLS, code int32) *PcreError {
+	errBuf := make([]byte, 256)
+	cErrBuf := uintptr(unsafe.Pointer(&errBuf[0]))
+
+	// Get the textual error message associated with the code,
+	// and store it in errBuf.
+	msgLen := lib.Xpcre2_get_error_message_8(tls, code, cErrBuf, 256)
+
+	return &PcreError{0, string(errBuf[:msgLen])}
+}
+
+// PcreError represents errors returned
+// by underlying pcre2 functions.
+type PcreError struct {
+	offset lib.Tsize_t
+	errStr string
+}
+
+// Error returns the string within the error,
+// prepending the offset if it exists.
+func (pe *PcreError) Error() string {
+	if pe.offset == 0 {
+		return pe.errStr
+	}
+	return fmt.Sprintf("offset %d: %s", pe.offset, pe.errStr)
+}