FreeType2 加载字符因 sigsegv 而崩溃

Question

Breakpoint 1, fruit::FreetypeFontfaceLoader::bitmap (handle=0x5555555c58e0, char_index=65)
    at lib/./freetype_fontface_loader.hpp:42
42                              FT_Load_Char(handle, char_index, FT_LOAD_RENDER);
(gdb) print *handle
 = {num_faces = 1, face_index = 0, face_flags = 2649, style_flags = 0, num_glyphs = 6253, 
  family_name = 0x5555555c6520 "DejaVu Sans", style_name = 0x5555555c6a30 "Book", num_fixed_sizes = 0, 
  available_sizes = 0x0, num_charmaps = 5, charmaps = 0x5555555c6a80, generic = {data = 0x0, finalizer = 0x0}, 
  bbox = {xMin = -2090, yMin = -948, xMax = 3673, yMax = 2524}, units_per_EM = 2048, ascender = 1901, 
  descender = -483, height = 2384, max_advance_width = 3838, max_advance_height = 2384, underline_position = -175, 
  underline_thickness = 90, glyph = 0x5555555ef830, size = 0x5555555f80b0, charmap = 0x5555555c6980, 
  driver = 0x5555555b6100, memory = 0x5555555b5f50, stream = 0x5555555c29b0, sizes_list = {head = 0x5555555c2240, 
    tail = 0x5555555c2240}, autohint = {data = 0x0, finalizer = 0x0}, extensions = 0x0, internal = 0x5555555de5c0}
(gdb) step

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7ed7718 in ?? () from /lib/x86_64-linux-gnu/libfreetype.so.6

==10991== Invalid read of size 4
==10991==    at 0x491B718: ??? (in /usr/lib/x86_64-linux-gnu/libfreetype.so.6.17.1)
==10991==    by 0x491B857: ??? (in /usr/lib/x86_64-linux-gnu/libfreetype.so.6.17.1)
==10991==    by 0x48DBA6F: FT_Get_Char_Index (in /usr/lib/x86_64-linux-gnu/libfreetype.so.6.17.1)
==10991==    by 0x48E1444: FT_Load_Char (in /usr/lib/x86_64-linux-gnu/libfreetype.so.6.17.1)
==10991==    by 0x10D0E5: fruit::FreetypeFontfaceLoader::bitmap(FT_FaceRec_*, unsigned int) (freetype_fontface_loader.hpp:43)

之前的来电：

FT_Face face{};
if(FT_New_Memory_Face(m_handle, reinterpret_cast<FT_Byte const*>(src_buffer.data()), src_buffer.size(), 0, &face) != FT_Err_Ok)
{
    throw FreetypeLoadError{};
}

handle = face;
FT_Set_Pixel_Sizes(handle, 0, 16);

显然，我做错了什么。

Answer 1

显然，我错过了 API 的一个细节：

You must not deallocate the memory before calling FT_Done_Face.

不释放缓冲区解决了问题。

FreeType2 加载字符因 sigsegv 而崩溃

FreeType2 load char crashes with sigsegv

freetype2