File diff-context-function-width.patch of Package diffutils

---
 src/context.c |    3 ++-
 src/diff.c    |    9 +++++++++
 src/diff.h    |    2 ++
 3 files changed, 13 insertions(+), 1 deletion(-)

--- a/src/context.c
+++ b/src/context.c
@@ -150,10 +150,11 @@ static void
 print_context_function (FILE *out, char const *function)
 {
   int i, j;
+  int limit = context_function_width > 0 ? context_function_width : 40;
   putc (' ', out);
   for (i = 0; c_isspace ((unsigned char) function[i]) && function[i] != '\n'; i++)
     continue;
-  for (j = i; j < i + 40 && function[j] != '\n'; j++)
+  for (j = i; j < i + limit && function[j] != '\n'; j++)
     continue;
   while (i < j && c_isspace ((unsigned char) function[j - 1]))
     j--;
--- a/src/diff.c
+++ b/src/diff.c
@@ -304,6 +304,15 @@ main (int argc, char **argv)
   presume_output_tty = false;
   xstdopen ();
 
+  {
+    char const *t = getenv("DIFF_CFW");
+    if (t) {
+      context_function_width = strtoumax (t, NULL, 10);
+      if (context_function_width < 0)
+	try_help ("invalid context function width '%s'", t);
+    }
+  }
+
   /* Decode the options.  */
 
   while ((c = getopt_long (argc, argv, shortopts, longopts, NULL)) != -1)
--- a/src/diff.h
+++ b/src/diff.h
@@ -230,6 +230,8 @@ XTERN bool minimal;
 
 /* The strftime format to use for time strings.  */
 XTERN char const *time_format;
+
+XTERN int context_function_width;
 
 /* The result of comparison is an "edit script": a chain of 'struct change'.
    Each 'struct change' represents one place where some lines are deleted