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/index-pack.c b/index-pack.c
index 72e096241..fa9a0e748 100644
--- a/index-pack.c
+++ b/index-pack.c
@@ -849,9 +849,9 @@ int main(int argc, char **argv)
 				fix_thin_pack = 1;
 			} else if (!strcmp(arg, "--keep")) {
 				keep_msg = "";
-			} else if (!strncmp(arg, "--keep=", 7)) {
+			} else if (!prefixcmp(arg, "--keep=")) {
 				keep_msg = arg + 7;
-			} else if (!strncmp(arg, "--pack_header=", 14)) {
+			} else if (!prefixcmp(arg, "--pack_header=")) {
 				struct pack_header *hdr;
 				char *c;