patch: implement patch.eol=auto mode

EOLs in patched files are restored to their original value after
patching. We use the first EOL found in the file, files with
inconsistent EOLs will thus be normalized during this process.

doc/hgrc.5.txt

@@ -648,7 +648,10 b' command or with Mercurial Queues extensi'
     When set to 'strict' patch content and patched files end of lines
     are preserved. When set to ``lf`` or ``crlf``, both files end of lines
     are ignored when patching and the result line endings are
-    normalized to either LF (Unix) or CRLF (Windows).
+    normalized to either LF (Unix) or CRLF (Windows). When set to
+    ``auto``, end of lines are again ignored while patching but line
+    endings in patched files are normalized to their original setting
+    on a per-file basis.
     Default: strict.
 
 

mercurial/patch.py

@@ -239,6 +239,7 b' class linereader(object):'
         self.fp = fp
         self.buf = []
         self.textmode = textmode
+        self.eol = None
 
     def push(self, line):
         if line is not None:
@@ -250,6 +251,11 b' class linereader(object):'
             del self.buf[0]
             return l
         l = self.fp.readline()
+        if not self.eol:
+            if l.endswith('\r\n'):
+                self.eol = '\r\n'
+            elif l.endswith('\n'):
+                self.eol = '\n'
         if self.textmode and l.endswith('\r\n'):
             l = l[:-2] + '\n'
         return l
@@ -264,13 +270,13 b' class linereader(object):'
 # @@ -start,len +start,len @@ or @@ -start +start @@ if len is 1
 unidesc = re.compile('@@ -(\d+)(,(\d+))? \+(\d+)(,(\d+))? @@')
 contextdesc = re.compile('(---|\*\*\*) (\d+)(,(\d+))? (---|\*\*\*)')
-eolmodes = ['strict', 'crlf', 'lf']
+eolmodes = ['strict', 'crlf', 'lf', 'auto']
 
 class patchfile(object):
     def __init__(self, ui, fname, opener, missing=False, eolmode='strict'):
         self.fname = fname
         self.eolmode = eolmode
-        self.eol = {'strict': None, 'crlf': '\r\n', 'lf': '\n'}[eolmode]
+        self.eol = None
         self.opener = opener
         self.ui = ui
         self.lines = []
@@ -298,7 +304,10 b' class patchfile(object):'
             return [os.readlink(fname)]
         fp = self.opener(fname, 'r')
         try:
-            return list(linereader(fp, self.eolmode != 'strict'))
+            lr = linereader(fp, self.eolmode != 'strict')
+            lines = list(lr)
+            self.eol = lr.eol
+            return lines
         finally:
             fp.close()
 
@@ -312,10 +321,17 b' class patchfile(object):'
         else:
             fp = self.opener(fname, 'w')
         try:
-            if self.eol and self.eol != '\n':
+            if self.eolmode == 'auto' and self.eol:
+                eol = self.eol
+            elif self.eolmode == 'crlf':
+                eol = '\r\n'
+            else:
+                eol = '\n'
+
+            if self.eolmode != 'strict' and eol != '\n':
                 for l in lines:
                     if l and l[-1] == '\n':
-                        l = l[:-1] + self.eol
+                        l = l[:-1] + eol
                     fp.write(l)
             else:
                 fp.writelines(lines)

tests/test-import-eol

@@ -28,19 +28,35 b" echo '\\.diff' > .hgignore"
 python -c 'file("a", "wb").write("a\nbbb\ncc\n\nd\ne")'
 hg ci -Am adda
 python ../makepatch.py
+
 echo % invalid eol
 hg --config patch.eol='LFCR' import eol.diff
 hg revert -a
+
 echo % force LF
 hg --traceback --config patch.eol='LF' import eol.diff
 python -c 'print repr(file("a","rb").read())'
 hg st
+
 echo % force CRLF
 hg up -C 0
 hg --traceback --config patch.eol='CRLF' import eol.diff
 python -c 'print repr(file("a","rb").read())'
 hg st
 
+echo % auto EOL on LF file
+hg up -C 0
+hg --traceback --config patch.eol='auto' import eol.diff
+python -c 'print repr(file("a","rb").read())'
+hg st
+
+echo % auto EOL on CRLF file
+python -c 'file("a", "wb").write("a\r\nbbb\r\ncc\r\n\r\nd\r\ne")'
+hg commit -m 'switch EOLs in a'
+hg --traceback --config patch.eol='auto' import eol.diff
+python -c 'print repr(file("a","rb").read())'
+hg st
+
 # Test --eol and binary patches
 python -c 'file("b", "wb").write("a\x00\nb")'
 hg ci -Am addb

tests/test-import-eol.out

@@ -10,6 +10,13 b' applying eol.diff'
 1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 applying eol.diff
 'a\r\nyyyy\r\ncc\r\n\r\nd\r\ne'
+% auto EOL on LF file
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+applying eol.diff
+'a\nyyyy\ncc\n\nd\ne'
+% auto EOL on CRLF file
+applying eol.diff
+'a\r\nyyyy\r\ncc\r\n\r\nd\r\ne'
 adding b
 % binary patch with --eol
 applying bin.diff