X-Git-Url: https://git.verplant.org/?a=blobdiff_plain;f=show-diff.c;h=2ff0bd4ea636db2ad54e9ff34e1d70ac7a9a98f0;hb=93256315b2444601a35484f4fb76cd5723284201;hp=40bc187bdc201c6d5b7df0eb7144d98760b72bdd;hpb=8f3671dcd93b8c5ab21582752f736646c66e2249;p=git.git

diff --git a/show-diff.c b/show-diff.c
index 40bc187b..2ff0bd4e 100644
--- a/show-diff.c
+++ b/show-diff.c
@@ -5,7 +5,25 @@
  */
 #include "cache.h"
 
-static char *diff_cmd = "diff -L '%s' -u -N  - '%s'";
+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
@@ -16,9 +34,6 @@ static char *diff_cmd = "diff -L '%s' -u -N  - '%s'";
  *  name     ==> name      ==> 'name'
  *  a b      ==> a b       ==> 'a b'
  *  a'b      ==> a'\''b    ==> 'a'\''b'
- *
- * NOTE! The returned memory belongs to this function so
- * do not free it.
  */
 static char *sq_expand(char *src)
 {
@@ -47,16 +62,21 @@ static char *sq_expand(char *src)
 }
 
 static void show_differences(char *name, char *label, void *old_contents,
-			     unsigned long long old_size)
+			     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;
-	int cmd_size = strlen(name_sq) + strlen(label_sq) + strlen(diff_cmd);
+	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);
-	snprintf(cmd, cmd_size, diff_cmd, label_sq, name_sq);
+	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);
@@ -67,7 +87,7 @@ static void show_differences(char *name, char *label, void *old_contents,
 	free(cmd);
 }
 
-static void show_diff_empty(struct cache_entry *ce)
+static void show_diff_empty(struct cache_entry *ce, int reverse)
 {
 	char *old;
 	unsigned long int size;
@@ -79,7 +99,7 @@ static void show_diff_empty(struct cache_entry *ce)
 		      sha1_to_hex(ce->sha1));
 		return;
 	}
-	show_differences("/dev/null", ce->name, old, size);
+	show_differences("/dev/null", ce->name, old, size, reverse);
 }
 
 static const char *show_diff_usage = "show-diff [-q] [-s] [-z] [paths...]";
@@ -104,11 +124,14 @@ int main(int argc, char **argv)
 	int silent = 0;
 	int silent_on_nonexisting_files = 0;
 	int machine_readable = 0;
+	int reverse = 0;
 	int entries = read_cache();
 	int i;
 
 	while (1 < argc && argv[1][0] == '-') {
-		if (!strcmp(argv[1], "-s"))
+		if  (!strcmp(argv[1], "-R"))
+			reverse = 1;
+		else if (!strcmp(argv[1], "-s"))
 			silent_on_nonexisting_files = silent = 1;
 		else if (!strcmp(argv[1], "-q"))
 			silent_on_nonexisting_files = 1;
@@ -126,6 +149,7 @@ int main(int argc, char **argv)
 		perror("read_cache");
 		exit(1);
 	}
+	prepare_diff_cmd();
 	for (i = 0; i < entries; i++) {
 		struct stat st;
 		struct cache_entry *ce = active_cache[i];
@@ -159,7 +183,7 @@ int main(int argc, char **argv)
 			else {
 				printf("%s: %s\n", ce->name, strerror(errno));
 				if (errno == ENOENT)
-					show_diff_empty(ce);
+					show_diff_empty(ce, reverse);
 			}
 			continue;
 		}
@@ -180,7 +204,8 @@ int main(int argc, char **argv)
 			error("unable to read blob object for %s (%s)",
 			      ce->name, sha1_to_hex(ce->sha1));
 		else
-			show_differences(ce->name, ce->name, old, size);
+			show_differences(ce->name, ce->name, old, size,
+					 reverse);
 		free(old);
 	}
 	return 0;