[PATCH] Split external diff command interface to a separate file.

With this patch, the non-core'ish part of show-diff command that
invokes an external "diff" comand to obtain patches is split
into a separate file.  The next patch will introduce a new
command, diff-tree-helper, which uses this common diff interface
to format diff-tree and diff-cache output into a patch form.

Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 98 deletions

diff --git a/show-diff.c b/show-diff.c
index 2ff0bd4ea6..3e798be303 100644
--- a/show-diff.c
+++ b/show-diff.c
@@ -4,103 +4,7 @@
  * Copyright (C) Linus Torvalds, 2005
  */
 #include "cache.h"
-
-static char *diff_cmd = "diff -L 'a/%s' -L 'b/%s' ";
-static char *diff_opts = "-p -u";
-static char *diff_arg_forward  = " - '%s'";
-static char *diff_arg_reverse  = " '%s' -";
-
-static void prepare_diff_cmd(void)
-{
-	/*
-	 * Default values above are meant to match the
-	 * Linux kernel development style.  Examples of
-	 * alternative styles you can specify via environment
-	 * variables are:
-	 *
-	 * GIT_DIFF_CMD="diff -L '%s' -L '%s'"
-	 * GIT_DIFF_OPTS="-c";
-	 */
-	diff_cmd = getenv("GIT_DIFF_CMD") ? : diff_cmd;
-	diff_opts = getenv("GIT_DIFF_OPTS") ? : diff_opts;
-}
-
-/* Help to copy the thing properly quoted for the shell safety.
- * any single quote is replaced with '\'', and the caller is
- * expected to enclose the result within a single quote pair.
- *
- * E.g.
- *  original     sq_expand     result
- *  name     ==> name      ==> 'name'
- *  a b      ==> a b       ==> 'a b'
- *  a'b      ==> a'\''b    ==> 'a'\''b'
- */
-static char *sq_expand(char *src)
-{
-	static char *buf = NULL;
-	int cnt, c;
-	char *cp;
-
-	/* count bytes needed to store the quoted string. */ 
-	for (cnt = 1, cp = src; *cp; cnt++, cp++)
-		if (*cp == '\'')
-			cnt += 3;
-
-	if (! (buf = malloc(cnt)))
-	    return buf;
-	cp = buf;
-	while ((c = *src++)) {
-		if (c != '\'')
-			*cp++ = c;
-		else {
-			cp = strcpy(cp, "'\\''");
-			cp += 4;
-		}
-	}
-	*cp = 0;
-	return buf;
-}
-
-static void show_differences(char *name, char *label, void *old_contents,
-			     unsigned long long old_size, int reverse)
-{
-	FILE *f;
-	char *name_sq = sq_expand(name);
-	char *label_sq = (name != label) ? sq_expand(label) : name_sq;
-	char *diff_arg = reverse ? diff_arg_reverse : diff_arg_forward;
-	int cmd_size = strlen(name_sq) + strlen(label_sq) * 2 +
-		strlen(diff_cmd) + strlen(diff_opts) + strlen(diff_arg);
-	char *cmd = malloc(cmd_size);
-	int next_at;
-
-	fflush(stdout);
-	next_at = snprintf(cmd, cmd_size, diff_cmd, label_sq, label_sq);
-	next_at += snprintf(cmd+next_at, cmd_size-next_at, "%s", diff_opts);
-	next_at += snprintf(cmd+next_at, cmd_size-next_at, diff_arg, name_sq);
-	f = popen(cmd, "w");
-	if (old_size)
-		fwrite(old_contents, old_size, 1, f);
-	pclose(f);
-	if (label_sq != name_sq)
-		free(label_sq);
-	free(name_sq);
-	free(cmd);
-}
-
-static void show_diff_empty(struct cache_entry *ce, int reverse)
-{
-	char *old;
-	unsigned long int size;
-	unsigned char type[20];
-
-	old = read_sha1_file(ce->sha1, type, &size);
-	if (! old) {
-		error("unable to read blob object for %s (%s)", ce->name,
-		      sha1_to_hex(ce->sha1));
-		return;
-	}
-	show_differences("/dev/null", ce->name, old, size, reverse);
-}
+#include "diff.h"
 
 static const char *show_diff_usage = "show-diff [-q] [-s] [-z] [paths...]";
 
@@ -183,7 +87,8 @@ int main(int argc, char **argv)
 			else {
 				printf("%s: %s\n", ce->name, strerror(errno));
 				if (errno == ENOENT)
-					show_diff_empty(ce, reverse);
+					show_diff_empty(ce->sha1, ce->name,
+							reverse);
 			}
 			continue;
 		}