forks
/
arsd
mirror of https://github.com/adamdruppe/arsd.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

hack to help a user load a corrupted file

This commit is contained in:
Adam D. Ruppe 2020-12-21 12:45:23 -05:00
parent afbb2f144c
commit d7d904ba85
1 changed files with 26 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
bmp.d
View File

@ -48,8 +48,22 @@ MemoryImage readBmp(in ubyte[] data, bool lookForFileHeader = true) {
History:
The `lookForFileHeader` param was added in July 2020.
+/
MemoryImage readBmpIndirect(scope void delegate(void*, size_t) fread, bool lookForFileHeader = true) {
MemoryImage readBmpIndirect(scope void delegate(void*, size_t) fread, bool lookForFileHeader = true, bool hackAround64BitLongs = false) {
uint read4() { uint what; fread(&what, 4); return what; }
uint readLONG() {
auto le = read4();
/++
A user on discord encountered a file in the wild that wouldn't load
by any other bmp viewer. After looking at the raw bytes, it appeared it
wrote out the LONG fields on the bitmap info header as 64 bit values when
they are supposed to always be 32 bit values. This hack gives a chance to work
around that and load the file anyway.
+/
if(hackAround64BitLongs)
if(read4() != 0)
throw new Exception("hackAround64BitLongs is true, but the file doesn't appear to use 64 bit longs");
return le;
}
ushort read2(){ ushort what; fread(&what, 2); return what; }
ubyte read1(){ ubyte what; fread(&what, 1); return what; }
@ -58,8 +72,11 @@ MemoryImage readBmpIndirect(scope void delegate(void*, size_t) fread, bool lookF
throw new Exception("didn't get expected byte value", __FILE__, line);
}
void require2(ushort t) {
if(read2() != t)
auto got = read2();
if(got != t) {
version(arsd_debug_bitmap_loader) { import core.stdc.stdio; printf("expected: %d, got %d\n", cast(int) t, cast(int) got); }
throw new Exception("didn't get expected short value");
}
}
void require4(uint t, size_t line = __LINE__) {
auto got = read4();
@ -83,6 +100,8 @@ MemoryImage readBmpIndirect(scope void delegate(void*, size_t) fread, bool lookF
auto sizeOfBitmapInfoHeader = read4();
if (sizeOfBitmapInfoHeader < 12) throw new Exception("invalid bitmap header size");
version(arsd_debug_bitmap_loader) { import core.stdc.stdio; printf("size of bitmap info header: %d\n", cast(uint)sizeOfBitmapInfoHeader); }
int width, height, rdheight;
if (sizeOfBitmapInfoHeader == 12) {
@ -91,13 +110,14 @@ MemoryImage readBmpIndirect(scope void delegate(void*, size_t) fread, bool lookF
} else {
if (sizeOfBitmapInfoHeader < 16) throw new Exception("invalid bitmap header size");
sizeOfBitmapInfoHeader -= 4; // hack!
width = read4();
rdheight = cast(int)read4();
width = readLONG();
rdheight = cast(int)readLONG();
}
height = (rdheight < 0 ? -rdheight : rdheight);
rdheight = (rdheight < 0 ? 1 : -1); // so we can use it as delta (note the inverted sign)
version(arsd_debug_bitmap_loader) { import core.stdc.stdio; printf("size: %dx%d\n", cast(int)width, cast(int) height); }
if (width < 1 || height < 1) throw new Exception("invalid bitmap dimensions");
require2(1); // planes
@ -127,8 +147,8 @@ MemoryImage readBmpIndirect(scope void delegate(void*, size_t) fread, bool lookF
sizeOfBitmapInfoHeader -= 6*4;
compression = read4();
sizeOfUncompressedData = read4();
xPixelsPerMeter = read4();
yPixelsPerMeter = read4();
xPixelsPerMeter = readLONG();
yPixelsPerMeter = readLONG();
colorsUsed = read4();
colorsImportant = read4();
}