[File] [PATCH] of Magdir/images for OS/2 2.x bitmap variant ( *.bmp)

[Jörg Jenderek]

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Hello,
some days ago i handle some OS/2  2.x bitmap variant with file name
extension "bmp". When i run file command version 5.37 for these
examples i get an output like

JUR_OS2.BMP:      PC bitmap, OS/2 2.x format, 640 x 0
pal1huff.bmp:     PC bitmap, OS/2 2.x format, 127 x 0
pal8os2v2-sz.bmp: PC bitmap, OS/2 2.x format, 127 x 0
pal8os2v2.bmp:    PC bitmap, OS/2 2.x format, 127 x 0
TEAMcol-64.bmp:   PC bitmap, OS/2 2.x format, 518 x 0
TOWERBMP.BMP:     PC bitmap, OS/2 2.x format, 58 x 0

Obviously the shown size for height with value 0 is
wrong.Furthermore with -i option deprecated mime type
"image/x-ms-bmp" isshown. With --apple option UNKNUNKN is displayed.
With --extesion option ??? is displayed.

So i add/change lines in Magdir/images. The information about this
variants is found on Wikipedia page about BMP format already
mentioned in magic file.

According to Wikipedia the DIB header use a format named
OS22XBITMAPHEADER. This OS/2 BMP format stores stores 64 bytes in the
DIB header. This variant was recognized by lines starting with
 0	string		BM
 >14	leshort		64		PC bitmap, OS/2 2.x format
Now afterwards show file name extension, apple id and new mime type
for BMP bitmaps by lines
 !:mime		image/bmp
 !:apple	????BMPp
 !:ext		bmp

The image dimensions were shown by lines like
 >>18	leshort		x		\b, %d x
 >>20	leshort		x		%d
The width and height are stored as short variable only for OS/2 1.x
variant, whereas for OS/2 2.x variant dimension values are stored as 4
byte values.

For OS/2 image width and height fields are unsigned integers whereas
for Microsoft Windows variants signed integers are used.
Values for number of bits per pixel (color depth) found are 1 4 8. So
show this values only if not one.
 >>18	ulelong		x		\b, %u x
 >>22	ulelong		x		%u
 >>28	uleshort	>1		x %u


The stored x, y coordinates of the hot spot are often null, but not
for example TOWERBMP.BMP. So show these values if not null by lines
 >>6	uleshort	>0		\b, hotspot %ux
 >>>8	uleshort	x		\b%u

The variable cbSize now contains sometimes the size of the whole file
and sometimes the size of the headers. So show this value by line
 >>2	ulelong		x		\b, cbSize %u

After applying the above mentioned modifications by patch
file-5.37-images-bmp_os2v2.diff then OS/2 2.x bitmap
variants are now described with correct height like

JUR_OS2.BMP:      PC bitmap, OS/2 2.x format, 640 x 400 x 4,
	cbSize 78, bits offset 94
pal1huff.bmp:     PC bitmap, OS/2 2.x format, 127 x 64,
	cbSize 78, bits offset 86
pal8os2v2-sz.bmp: PC bitmap, OS/2 2.x format, 127 x 64 x 8,
	cbSize 78, bits offset 1086
pal8os2v2.bmp:    PC bitmap, OS/2 2.x format, 127 x 64 x 8,
	cbSize 9278, bits offset 1086
TEAMcol-64.bmp:   PC bitmap, OS/2 2.x format, 518 x 412 x 4,
	cbSize 107194, bits offset 201326686
TOWERBMP.BMP:     PC bitmap, OS/2 2.x format, 58 x 79 x 4,
	hotspot 29x39,
	cbSize 78, bits offset 142

I hope my diff file can be applied in future version of file utility.


With best wishes
Jörg Jenderek
- --
Jörg Jenderek










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--- file-5.37/magic/Magdir/images.old	2019-04-19 00:42:27 +0000
+++ file-5.37/magic/Magdir/images	2019-06-28 23:56:19 +0000
@@ -580,5 +580,21 @@
 >14	leshort		64		PC bitmap, OS/2 2.x format
-!:mime	image/x-ms-bmp
->>18	leshort		x		\b, %d x
->>20	leshort		x		%d
+!:mime	image/bmp
+!:apple	????BMPp
+!:ext	bmp
+# image width and height fields are unsigned integers for OS/2
+>>18	ulelong		x		\b, %u x
+>>22	ulelong		x		%u
+# number of bits per pixel (color depth); found 1 4 8
+>>28	uleshort	>1		x %u
+# x, y coordinates of the hotspot
+>>6	uleshort	>0		\b, hotspot %ux
+>>>8	uleshort	x		\b%u
+>>26	uleshort	>1		\b, %u color planes
+# cbSize; size of file or headers
+>>2	ulelong		x		\b, cbSize %u
+#>>2	ulelong		x		\b, cbSize 0x%x
+# offBits; offset to bitmap data like 56h 5Eh 8Eh 43Eh
+>>10	ulelong			x	\b, bits offset %u
+#>>10	ulelong			x	\b, bits offset 0x%x
+#>>(10.l) ubequad		!0	\b, bits 0x%16.16llx
 >14	leshort		40		PC bitmap, Windows 3.x format
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