[PATCH] Fix broken diff-cache output on added files

[git.git] / show-diff.c

diff --git a/show-diff.c b/show-diff.c
index 32d2fce..2ff0bd4 100644 (file)
--- a/show-diff.c
+++ b/show-diff.c
@@ -5,7 +5,25 @@
  */
 #include "cache.h"
 
-static char *diff_cmd = "diff -L 'a/%s' -L 'b/%s' -p -u - '%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 'a/%s' -L 'b/%s' -p -u - '%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)
 {
@@ -47,17 +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) * 2 + 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, 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);
@@ -68,7 +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;
@@ -80,7 +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...]";
@@ -105,11 +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;
@@ -127,6 +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];
@@ -160,7 +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;
                }
@@ -181,7 +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;