Mechanical conversion to use prefixcmp()

This mechanically converts strncmp() to use prefixcmp(), but only when
the parameters match specific patterns, so that they can be verified
easily.  Leftover from this will be fixed in a separate step, including
idiotic conversions like

    if (!strncmp("foo", arg, 3))

  =>

    if (!(-prefixcmp(arg, "foo")))

This was done by using this script in px.perl

   #!/usr/bin/perl -i.bak -p
   if (/strncmp\(([^,]+), "([^\\"]*)", (\d+)\)/ && (length($2) == $3)) {
           s|strncmp\(([^,]+), "([^\\"]*)", (\d+)\)|prefixcmp($1, "$2")|;
   }
   if (/strncmp\("([^\\"]*)", ([^,]+), (\d+)\)/ && (length($1) == $3)) {
           s|strncmp\("([^\\"]*)", ([^,]+), (\d+)\)|(-prefixcmp($2, "$1"))|;
   }

and running:

   $ git grep -l strncmp -- '*.c' | xargs perl px.perl

Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/builtin-read-tree.c b/builtin-read-tree.c
index 8ba436dbac..e47715538b 100644
--- a/builtin-read-tree.c
+++ b/builtin-read-tree.c
@@ -133,7 +133,7 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 		 *  entries and put the entries from the tree under the
 		 * given subdirectory.
 		 */
-		if (!strncmp(arg, "--prefix=", 9)) {
+		if (!prefixcmp(arg, "--prefix=")) {
 			if (stage || opts.merge || opts.prefix)
 				usage(read_tree_usage);
 			opts.prefix = arg + 9;
@@ -179,7 +179,7 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 			continue;
 		}
 
-		if (!strncmp(arg, "--exclude-per-directory=", 24)) {
+		if (!prefixcmp(arg, "--exclude-per-directory=")) {
 			struct dir_struct *dir;
 
 			if (opts.dir)