font-face: Do not reference error font faces directly

Introduce the function _cairo_font_options_create_in_error().

This makes it possible to observe the creation of cairo_font_option_t
error objects by breaking on it and makes the code cleaner by passing
around the status obtained from _cairo_error() instead of throwing the
error.

11 files changed, 106 insertions, 102 deletions

diff --git a/src/cairo-default-context.c b/src/cairo-default-context.c
index 28b268734..bd9994193 100644
--- a/src/cairo-default-context.c
+++ b/src/cairo-default-context.c
@@ -1129,10 +1129,8 @@ _cairo_default_context_get_font_face (void *abstract_cr)
     cairo_status_t status;
 
     status = _cairo_gstate_get_font_face (cr->gstate, &font_face);
-    if (unlikely (status)) {
-	_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	return (cairo_font_face_t *) &_cairo_font_face_nil;
-    }
+    if (unlikely (status))
+	return _cairo_font_face_create_in_error (status);
 
     return font_face;
 }
diff --git a/src/cairo-font-face-private.h b/src/cairo-font-face-private.h
index ebbec7273..2b0805c46 100644
--- a/src/cairo-font-face-private.h
+++ b/src/cairo-font-face-private.h
@@ -65,7 +65,8 @@ struct _cairo_toy_font_face {
     cairo_font_face_t *impl_face; /* The non-toy font face this actually uses */
 };
 
-extern const cairo_private cairo_font_face_t _cairo_font_face_nil;
+cairo_private cairo_font_face_t *
+_cairo_font_face_create_in_error (cairo_status_t status);
 
 cairo_private void
 _cairo_font_face_init (cairo_font_face_t               *font_face,
diff --git a/src/cairo-font-face-twin.c b/src/cairo-font-face-twin.c
index 606a88a18..c914c3009 100644
--- a/src/cairo-font-face-twin.c
+++ b/src/cairo-font-face-twin.c
@@ -727,7 +727,7 @@ _cairo_font_face_twin_create_fallback (void)
     twin_font_face = _cairo_font_face_twin_create_internal ();
     if (! twin_font_face_create_properties (twin_font_face)) {
 	cairo_font_face_destroy (twin_font_face);
-	return (cairo_font_face_t *) &_cairo_font_face_nil;
+	return _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
     }
 
     return twin_font_face;
diff --git a/src/cairo-font-face.c b/src/cairo-font-face.c
index 1f80aa7ea..9c3a9c335 100644
--- a/src/cairo-font-face.c
+++ b/src/cairo-font-face.c
@@ -61,7 +61,7 @@
 
 /* #cairo_font_face_t */
 
-const cairo_font_face_t _cairo_font_face_nil = {
+static const cairo_font_face_t _cairo_font_face_nil = {
     { 0 },				/* hash_entry */
     CAIRO_STATUS_NO_MEMORY,		/* status */
     CAIRO_REFERENCE_COUNT_INVALID,	/* ref_count */
@@ -69,6 +69,58 @@ const cairo_font_face_t _cairo_font_face_nil = {
     NULL
 };
 
+static const cairo_font_face_t _cairo_font_face_null_pointer = {
+    { 0 },                              /* hash_entry */
+    CAIRO_STATUS_NULL_POINTER,          /* status */
+    CAIRO_REFERENCE_COUNT_INVALID,      /* ref_count */
+    { 0, 0, 0, NULL },                  /* user_data */
+    NULL
+};
+
+static const cairo_font_face_t _cairo_font_face_invalid_string = {
+    { 0 },                              /* hash_entry */
+    CAIRO_STATUS_INVALID_STRING,        /* status */
+    CAIRO_REFERENCE_COUNT_INVALID,      /* ref_count */
+    { 0, 0, 0, NULL },                  /* user_data */
+    NULL
+};
+
+static const cairo_font_face_t _cairo_font_face_invalid_slant = {
+    { 0 },                              /* hash_entry */
+    CAIRO_STATUS_INVALID_SLANT,         /* status */
+    CAIRO_REFERENCE_COUNT_INVALID,      /* ref_count */
+    { 0, 0, 0, NULL },                  /* user_data */
+    NULL
+};
+
+static const cairo_font_face_t _cairo_font_face_invalid_weight = {
+    { 0 },                              /* hash_entry */
+    CAIRO_STATUS_INVALID_WEIGHT,        /* status */
+    CAIRO_REFERENCE_COUNT_INVALID,      /* ref_count */
+    { 0, 0, 0, NULL },                  /* user_data */
+    NULL
+};
+
+cairo_font_face_t *
+_cairo_font_face_create_in_error (cairo_status_t status)
+{
+    assert (status != CAIRO_STATUS_SUCCESS);
+
+    if (status == CAIRO_STATUS_NO_MEMORY)
+	return (cairo_font_face_t *) &_cairo_font_face_nil;
+    else if (status == CAIRO_STATUS_NULL_POINTER)
+	return (cairo_font_face_t *) &_cairo_font_face_null_pointer;
+    else if (status == CAIRO_STATUS_INVALID_STRING)
+	return (cairo_font_face_t *) &_cairo_font_face_invalid_string;
+    else if (status == CAIRO_STATUS_INVALID_SLANT)
+	return (cairo_font_face_t *) &_cairo_font_face_invalid_slant;
+    else if (status == CAIRO_STATUS_INVALID_WEIGHT)
+	return (cairo_font_face_t *) &_cairo_font_face_invalid_weight;
+
+    /* XXX use shared error objects */
+    return (cairo_font_face_t *) &_cairo_font_face_nil;
+}
+
 cairo_status_t
 _cairo_font_face_set_error (cairo_font_face_t *font_face,
 	                    cairo_status_t     status)
diff --git a/src/cairo-ft-font.c b/src/cairo-ft-font.c
index c79e0a606..6bdf8aeda 100644
--- a/src/cairo-ft-font.c
+++ b/src/cairo-ft-font.c
@@ -2656,21 +2656,21 @@ static cairo_status_t
 _cairo_ft_font_face_create_for_toy (cairo_toy_font_face_t *toy_face,
 				    cairo_font_face_t **font_face_out)
 {
-    cairo_font_face_t *font_face = (cairo_font_face_t *) &_cairo_font_face_nil;
+    cairo_font_face_t *font_face;
     FcPattern *pattern;
     int fcslant;
     int fcweight;
 
     pattern = FcPatternCreate ();
-    if (!pattern) {
-	_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
+    if (unlikely (pattern == NULL)) {
+	font_face = _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 	return font_face->status;
     }
 
     if (!FcPatternAddString (pattern,
 		             FC_FAMILY, (unsigned char *) toy_face->family))
     {
-	_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
+	font_face = _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 	goto FREE_PATTERN;
     }
 
@@ -2689,7 +2689,7 @@ _cairo_ft_font_face_create_for_toy (cairo_toy_font_face_t *toy_face,
     }
 
     if (!FcPatternAddInteger (pattern, FC_SLANT, fcslant)) {
-	_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
+	font_face = _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 	goto FREE_PATTERN;
     }
 
@@ -2705,7 +2705,7 @@ _cairo_ft_font_face_create_for_toy (cairo_toy_font_face_t *toy_face,
     }
 
     if (!FcPatternAddInteger (pattern, FC_WEIGHT, fcweight)) {
-	_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
+	font_face = _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 	goto FREE_PATTERN;
     }
 
@@ -2812,10 +2812,8 @@ _cairo_ft_font_face_get_implementation (void                     *abstract_face,
 	/* Cache the resolved font whilst the FcConfig remains consistent. */
 	resolved = font_face->resolved_font_face;
 	if (resolved != NULL) {
-	    if (! FcInitBringUptoDate ()) {
-		_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-		return (cairo_font_face_t *) &_cairo_font_face_nil;
-	    }
+	    if (unlikely (! FcInitBringUptoDate ()))
+		return _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 
 	    if (font_face->resolved_config == FcConfigGetCurrent ())
 		return cairo_font_face_reference (resolved);
@@ -2860,10 +2858,8 @@ _cairo_ft_font_face_create_for_pattern (FcPattern *pattern)
     cairo_ft_font_face_t *font_face;
 
     font_face = malloc (sizeof (cairo_ft_font_face_t));
-    if (unlikely (font_face == NULL)) {
-	_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	return (cairo_font_face_t *) &_cairo_font_face_nil;
-    }
+    if (unlikely (font_face == NULL))
+	return _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 
     font_face->unscaled = NULL;
     font_face->next = NULL;
@@ -2871,8 +2867,7 @@ _cairo_ft_font_face_create_for_pattern (FcPattern *pattern)
     font_face->pattern = FcPatternDuplicate (pattern);
     if (unlikely (font_face->pattern == NULL)) {
 	free (font_face);
-	_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	return (cairo_font_face_t *) &_cairo_font_face_nil;
+	return _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
     }
 
     font_face->resolved_font_face = NULL;
@@ -2919,10 +2914,8 @@ _cairo_ft_font_face_create (cairo_ft_unscaled_font_t *unscaled,
 
     /* No match found, create a new one */
     font_face = malloc (sizeof (cairo_ft_font_face_t));
-    if (unlikely (!font_face)) {
-	_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	return (cairo_font_face_t *)&_cairo_font_face_nil;
-    }
+    if (unlikely (font_face == NULL))
+	return _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 
     font_face->unscaled = unscaled;
     _cairo_unscaled_font_reference (&unscaled->base);
@@ -3112,25 +3105,25 @@ _cairo_ft_resolve_pattern (FcPattern		      *pattern,
 
     status = _compute_transform (&sf, &scale);
     if (unlikely (status))
-	return (cairo_font_face_t *)&_cairo_font_face_nil;
+	return _cairo_font_face_create_in_error (status);
 
     pattern = FcPatternDuplicate (pattern);
-    if (pattern == NULL)
-	return (cairo_font_face_t *)&_cairo_font_face_nil;
+    if (unlikely (pattern == NULL))
+	return _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 
-    if (! FcPatternAddDouble (pattern, FC_PIXEL_SIZE, sf.y_scale)) {
-	font_face = (cairo_font_face_t *)&_cairo_font_face_nil;
+    if (unlikely (! FcPatternAddDouble (pattern, FC_PIXEL_SIZE, sf.y_scale))) {
+	font_face = _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 	goto FREE_PATTERN;
     }
 
-    if (! FcConfigSubstitute (NULL, pattern, FcMatchPattern)) {
-	font_face = (cairo_font_face_t *)&_cairo_font_face_nil;
+    if (unlikely (! FcConfigSubstitute (NULL, pattern, FcMatchPattern))) {
+	font_face = _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 	goto FREE_PATTERN;
     }
 
     status = _cairo_ft_font_options_substitute (font_options, pattern);
-    if (status) {
-	font_face = (cairo_font_face_t *)&_cairo_font_face_nil;
+    if (unlikely (status)) {
+	font_face = _cairo_font_face_create_in_error (status);
 	goto FREE_PATTERN;
     }
 
@@ -3138,7 +3131,7 @@ _cairo_ft_resolve_pattern (FcPattern		      *pattern,
 
     status = _cairo_ft_unscaled_font_create_for_pattern (pattern, &unscaled);
     if (unlikely (status)) {
-	font_face = (cairo_font_face_t *)&_cairo_font_face_nil;
+	font_face = _cairo_font_face_create_in_error (status);
 	goto FREE_PATTERN;
     }
 
@@ -3154,8 +3147,12 @@ _cairo_ft_resolve_pattern (FcPattern		      *pattern,
 	}
 
 	status = _cairo_ft_unscaled_font_create_for_pattern (resolved, &unscaled);
-	if (unlikely (status || unscaled == NULL)) {
-	    font_face = (cairo_font_face_t *)&_cairo_font_face_nil;
+	if (unlikely (status)) {
+	    font_face = _cairo_font_face_create_in_error (status);
+	    goto FREE_RESOLVED;
+	}
+	if (unlikely (unscaled == NULL)) {
+	    font_face = _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_NULL_POINTER));
 	    goto FREE_RESOLVED;
 	}
     } else
@@ -3222,7 +3219,7 @@ cairo_ft_font_face_create_for_pattern (FcPattern *pattern)
 
     status = _cairo_ft_unscaled_font_create_for_pattern (pattern, &unscaled);
     if (unlikely (status))
-	return (cairo_font_face_t *) &_cairo_font_face_nil;
+	return _cairo_font_face_create_in_error (status);
     if (unlikely (unscaled == NULL)) {
 	/* Store the pattern.  We will resolve it and create unscaled
 	 * font when creating scaled fonts */
@@ -3294,7 +3291,7 @@ cairo_ft_font_face_create_for_ft_face (FT_Face         face,
 
     status = _cairo_ft_unscaled_font_create_from_face (face, &unscaled);
     if (unlikely (status))
-	return (cairo_font_face_t *)&_cairo_font_face_nil;
+	return _cairo_font_face_create_in_error (status);
 
     ft_options.load_flags = load_flags;
     ft_options.extra_flags = 0;
diff --git a/src/cairo-quartz-font.c b/src/cairo-quartz-font.c
index 32d9bfea9..8beb225ee 100644
--- a/src/cairo-quartz-font.c
+++ b/src/cairo-quartz-font.c
@@ -355,11 +355,8 @@ cairo_quartz_font_face_create_for_cgfont (CGFontRef font)
     quartz_font_ensure_symbols();
 
     font_face = malloc (sizeof (cairo_quartz_font_face_t));
-    if (!font_face) {
-	cairo_status_t ignore_status;
-	ignore_status = _cairo_error (CAIRO_STATUS_NO_MEMORY);
-	return (cairo_font_face_t *)&_cairo_font_face_nil;
-    }
+    if (unlikely (font_face == NULL))
+	return _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 
     font_face->cgFont = CGFontRetain (font);
 
diff --git a/src/cairo-scaled-font.c b/src/cairo-scaled-font.c
index 0bc23f56b..b0afb0995 100644
--- a/src/cairo-scaled-font.c
+++ b/src/cairo-scaled-font.c
@@ -2914,7 +2914,7 @@ cairo_font_face_t *
 cairo_scaled_font_get_font_face (cairo_scaled_font_t *scaled_font)
 {
     if (scaled_font->status)
-	return (cairo_font_face_t*) &_cairo_font_face_nil;
+	return _cairo_font_face_create_in_error (scaled_font->status);
 
     if (scaled_font->original_font_face != NULL)
 	return scaled_font->original_font_face;
diff --git a/src/cairo-toy-font-face.c b/src/cairo-toy-font-face.c
index 54683a37f..9e01039d8 100644
--- a/src/cairo-toy-font-face.c
+++ b/src/cairo-toy-font-face.c
@@ -44,39 +44,6 @@
 #include "cairo-error-private.h"
 #include "cairo-font-face-private.h"
 
-static const cairo_font_face_t _cairo_font_face_null_pointer = {
-    { 0 },				/* hash_entry */
-    CAIRO_STATUS_NULL_POINTER,		/* status */
-    CAIRO_REFERENCE_COUNT_INVALID,	/* ref_count */
-    { 0, 0, 0, NULL },			/* user_data */
-    NULL
-};
-
-static const cairo_font_face_t _cairo_font_face_invalid_string = {
-    { 0 },				/* hash_entry */
-    CAIRO_STATUS_INVALID_STRING,	/* status */
-    CAIRO_REFERENCE_COUNT_INVALID,	/* ref_count */
-    { 0, 0, 0, NULL },			/* user_data */
-    NULL
-};
-
-static const cairo_font_face_t _cairo_font_face_invalid_slant = {
-    { 0 },				/* hash_entry */
-    CAIRO_STATUS_INVALID_SLANT,		/* status */
-    CAIRO_REFERENCE_COUNT_INVALID,	/* ref_count */
-    { 0, 0, 0, NULL },			/* user_data */
-    NULL
-};
-
-static const cairo_font_face_t _cairo_font_face_invalid_weight = {
-    { 0 },				/* hash_entry */
-    CAIRO_STATUS_INVALID_WEIGHT,	/* status */
-    CAIRO_REFERENCE_COUNT_INVALID,	/* ref_count */
-    { 0, 0, 0, NULL },			/* user_data */
-    NULL
-};
-
-
 static const cairo_font_face_backend_t _cairo_toy_font_face_backend;
 
 static int
@@ -260,16 +227,12 @@ cairo_toy_font_face_create (const char          *family,
     cairo_hash_table_t *hash_table;
 
     if (family == NULL)
-	return (cairo_font_face_t*) &_cairo_font_face_null_pointer;
+	return _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_NULL_POINTER));
 
     /* Make sure we've got valid UTF-8 for the family */
     status = _cairo_utf8_to_ucs4 (family, -1, NULL, NULL);
-    if (unlikely (status)) {
-	if (status == CAIRO_STATUS_INVALID_STRING)
-	    return (cairo_font_face_t*) &_cairo_font_face_invalid_string;
-
-	return (cairo_font_face_t*) &_cairo_font_face_nil;
-    }
+    if (unlikely (status))
+	return _cairo_font_face_create_in_error (status);
 
     switch (slant) {
 	case CAIRO_FONT_SLANT_NORMAL:
@@ -277,7 +240,7 @@ cairo_toy_font_face_create (const char          *family,
 	case CAIRO_FONT_SLANT_OBLIQUE:
 	    break;
 	default:
-	    return (cairo_font_face_t*) &_cairo_font_face_invalid_slant;
+	    return _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_INVALID_SLANT));
     }
 
     switch (weight) {
@@ -285,7 +248,7 @@ cairo_toy_font_face_create (const char          *family,
 	case CAIRO_FONT_WEIGHT_BOLD:
 	    break;
 	default:
-	    return (cairo_font_face_t*) &_cairo_font_face_invalid_weight;
+	    return _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_INVALID_WEIGHT));
     }
 
     if (*family == '\0')
@@ -338,7 +301,7 @@ cairo_toy_font_face_create (const char          *family,
  UNWIND_HASH_TABLE_LOCK:
     _cairo_toy_font_face_hash_table_unlock ();
  UNWIND:
-    return (cairo_font_face_t*) &_cairo_font_face_nil;
+    return _cairo_font_face_create_in_error (status);
 }
 slim_hidden_def (cairo_toy_font_face_create);
 
diff --git a/src/cairo-user-font.c b/src/cairo-user-font.c
index 7015eae6b..49c41ad71 100644
--- a/src/cairo-user-font.c
+++ b/src/cairo-user-font.c
@@ -543,10 +543,8 @@ cairo_user_font_face_create (void)
     cairo_user_font_face_t *font_face;
 
     font_face = malloc (sizeof (cairo_user_font_face_t));
-    if (!font_face) {
-	_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	return (cairo_font_face_t *)&_cairo_font_face_nil;
-    }
+    if (unlikely (font_face == NULL))
+	return _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 
     _cairo_font_face_init (&font_face->base, &_cairo_user_font_face_backend);
 
diff --git a/src/cairo-win32-font.c b/src/cairo-win32-font.c
index 866898048..10467a224 100644
--- a/src/cairo-win32-font.c
+++ b/src/cairo-win32-font.c
@@ -2178,10 +2178,8 @@ cairo_win32_font_face_create_for_logfontw_hfont (LOGFONTW *logfont, HFONT font)
     cairo_status_t status;
 
     hash_table = _cairo_win32_font_face_hash_table_lock ();
-    if (unlikely (hash_table == NULL)) {
-        _cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
-	return (cairo_font_face_t *)&_cairo_font_face_nil;
-    }
+    if (unlikely (hash_table == NULL))
+	return _cairo_font_face_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 
     _cairo_win32_font_face_init_key (&key, logfont, font);
 
@@ -2201,8 +2199,8 @@ cairo_win32_font_face_create_for_logfontw_hfont (LOGFONTW *logfont, HFONT font)
 
     /* Otherwise create it and insert into hash table. */
     font_face = malloc (sizeof (cairo_win32_font_face_t));
-    if (!font_face) {
-        _cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
+    if (unlikely (font_face == NULL)) {
+	status = _cairo_error (CAIRO_STATUS_NO_MEMORY);
 	goto FAIL;
     }
 
@@ -2223,7 +2221,7 @@ DONE:
 FAIL:
     _cairo_win32_font_face_hash_table_unlock ();
 
-    return (cairo_font_face_t *)&_cairo_font_face_nil;
+    return _cairo_font_face_create_in_error (status);
 }
 
 /**
diff --git a/src/cairo.c b/src/cairo.c
index 4b034f447..6a7766cef 100644
--- a/src/cairo.c
+++ b/src/cairo.c
@@ -2687,7 +2687,7 @@ cairo_font_face_t *
 cairo_get_font_face (cairo_t *cr)
 {
     if (unlikely (cr->status))
-	return (cairo_font_face_t*) &_cairo_font_face_nil;
+	return _cairo_font_face_create_in_error (cr->status);
 
     return cr->backend->get_font_face (cr);
 }