Replace .seek() magic numbers with io.SEEK_* constants

A bit more readable.

https://docs.python.org/3/library/io.html#io.IOBase.seek

src/PIL/ContainerIO.py

@@ -18,6 +18,8 @@
 # A file object that provides read access to a part of an existing
 # file (for example a TAR file).
 
+import io
+
 
 class ContainerIO(object):
 
@@ -41,7 +43,7 @@ class ContainerIO(object):
     def isatty(self):
         return 0
 
-    def seek(self, offset, mode=0):
+    def seek(self, offset, mode=io.SEEK_SET):
         """
         Move file pointer.
 

src/PIL/EpsImagePlugin.py

@@ -102,7 +102,7 @@ def Ghostscript(tile, size, fp, scale=1):
         # Copy whole file to read in Ghostscript
         with open(infile_temp, 'wb') as f:
             # fetch length of fp
-            fp.seek(0, 2)
+            fp.seek(0, io.SEEK_END)
             fsize = fp.tell()
             # ensure start position
             # go back
@@ -167,7 +167,7 @@ class PSFile(object):
         self.fp = fp
         self.char = None
 
-    def seek(self, offset, whence=0):
+    def seek(self, offset, whence=io.SEEK_SET):
         self.char = None
         self.fp.seek(offset, whence)
 
@@ -310,7 +310,7 @@ class EpsImageFile(ImageFile.ImageFile):
 
         if s[:4] == b"%!PS":
             # for HEAD without binary preview
-            fp.seek(0, 2)
+            fp.seek(0, io.SEEK_END)
             length = fp.tell()
             offset = 0
         elif i32(s[0:4]) == 0xC6D3D0C5:

src/PIL/IcnsImagePlugin.py

@@ -195,7 +195,7 @@ class IcnsFile(object):
             i += HEADERSIZE
             blocksize -= HEADERSIZE
             dct[sig] = (i, blocksize)
-            fobj.seek(blocksize, 1)
+            fobj.seek(blocksize, io.SEEK_CUR)
             i += blocksize
 
     def itersizes(self):

src/PIL/ImageFile.py

@@ -491,7 +491,7 @@ def _save(im, fp, tile, bufsize=0):
         for e, b, o, a in tile:
             e = Image._getencoder(im.mode, e, a, im.encoderconfig)
             if o > 0:
-                fp.seek(o, 0)
+                fp.seek(o)
             e.setimage(im.im, b)
             if e.pushes_fd:
                 e.setfd(fp)
@@ -510,7 +510,7 @@ def _save(im, fp, tile, bufsize=0):
         for e, b, o, a in tile:
             e = Image._getencoder(im.mode, e, a, im.encoderconfig)
             if o > 0:
-                fp.seek(o, 0)
+                fp.seek(o)
             e.setimage(im.im, b)
             if e.pushes_fd:
                 e.setfd(fp)

src/PIL/Jpeg2KImagePlugin.py

@@ -191,9 +191,9 @@ class Jpeg2KImageFile(ImageFile.ImageFile):
             fd = -1
             try:
                 pos = self.fp.tell()
-                self.fp.seek(0, 2)
+                self.fp.seek(0, io.SEEK_END)
                 length = self.fp.tell()
-                self.fp.seek(pos, 0)
+                self.fp.seek(pos)
             except Exception:
                 length = -1
 

src/PIL/PcfFontFile.py

@@ -16,6 +16,7 @@
 # See the README file for information on usage and redistribution.
 #
 
+import io
 from . import Image, FontFile
 from ._binary import i8, i16le as l16, i32le as l32, i16be as b16, i32be as b32
 
@@ -117,7 +118,7 @@ class PcfFontFile(FontFile.FontFile):
         for i in range(nprops):
             p.append((i32(fp.read(4)), i8(fp.read(1)), i32(fp.read(4))))
         if nprops & 3:
-            fp.seek(4 - (nprops & 3), 1)  # pad
+            fp.seek(4 - (nprops & 3), io.SEEK_CUR)  # pad
 
         data = fp.read(i32(fp.read(4)))
 

src/PIL/PcxImagePlugin.py

@@ -25,6 +25,7 @@
 # See the README file for information on usage and redistribution.
 #
 
+import io
 import logging
 from . import Image, ImageFile, ImagePalette
 from ._binary import i8, i16le as i16, o8, o16le as o16
@@ -80,7 +81,7 @@ class PcxImageFile(ImageFile.ImageFile):
         elif version == 5 and bits == 8 and planes == 1:
             mode = rawmode = "L"
             # FIXME: hey, this doesn't work with the incremental loader !!!
-            self.fp.seek(-769, 2)
+            self.fp.seek(-769, io.SEEK_END)
             s = self.fp.read(769)
             if len(s) == 769 and i8(s[0]) == 12:
                 # check if the palette is linear greyscale

src/PIL/PsdImagePlugin.py

@@ -18,6 +18,7 @@
 
 __version__ = "0.4"
 
+import io
 from . import Image, ImageFile, ImagePalette
 from ._binary import i8, i16be as i16, i32be as i32
 
@@ -214,12 +215,12 @@ def _layerinfo(file):
         if size:
             length = i32(read(4))
             if length:
-                file.seek(length - 16, 1)
+                file.seek(length - 16, io.SEEK_CUR)
             combined += length + 4
 
             length = i32(read(4))
             if length:
-                file.seek(length, 1)
+                file.seek(length, io.SEEK_CUR)
             combined += length + 4
 
             length = i8(read(1))
@@ -229,7 +230,7 @@ def _layerinfo(file):
                 name = read(length).decode('latin-1', 'replace')
             combined += length + 1
 
-        file.seek(size - combined, 1)
+        file.seek(size - combined, io.SEEK_CUR)
         layers.append((name, mode, (x0, y0, x1, y1)))
 
     # get tiles

src/PIL/TarIO.py

@@ -14,6 +14,7 @@
 # See the README file for information on usage and redistribution.
 #
 
+import io
 import sys
 from . import ContainerIO
 
@@ -51,7 +52,7 @@ class TarIO(ContainerIO.ContainerIO):
             if file == name:
                 break
 
-            self.fh.seek((size + 511) & (~511), 1)
+            self.fh.seek((size + 511) & (~511), io.SEEK_CUR)
 
         # Open region
         ContainerIO.ContainerIO.__init__(self, self.fh, self.fh.tell(), size)

src/PIL/TiffImagePlugin.py

@@ -1678,7 +1678,7 @@ class AppendingTiffWriter:
     def tell(self):
         return self.f.tell() - self.offsetOfNewPage
 
-    def seek(self, offset, whence):
+    def seek(self, offset, whence=io.SEEK_SET):
         if whence == os.SEEK_SET:
             offset += self.offsetOfNewPage