builtin-merge: allow using a custom strategy

Allow using a custom strategy, as long as it's named git-merge-foo. The
error handling is now done using is_git_command(). The list of available
strategies is now shown by list_commands().

If an invalid strategy is supplied, like -s foobar, then git-merge would
list all git-merge-* commands. This is not perfect, since for example
git-merge-index is not a valid strategy.

These are removed from the output by scanning the list of main commands;
if the git-merge-foo command is listed in the all_strategy list, then
it's shown, otherwise excluded. This does not exclude commands somewhere
else in the PATH, where custom strategies are expected.

Signed-off-by: Miklos Vajna <vmiklos@frugalware.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-merge.c b/builtin-merge.c
index e78fa18b3a68e2b7f041beab0524ce1a2b7e9365..1f9389bfd7913208b4149b6e6a104949b8d10252 100644 (file)
--- a/builtin-merge.c
+++ b/builtin-merge.c
@@ -22,6 +22,7 @@
 #include "log-tree.h"
 #include "color.h"
 #include "rerere.h"
+#include "help.h"
 
 #define DEFAULT_TWOHEAD (1<<0)
 #define DEFAULT_OCTOPUS (1<<1)
@@ -77,7 +78,9 @@ static int option_parse_message(const struct option *opt,
 static struct strategy *get_strategy(const char *name)
 {
        int i;
-       struct strbuf err;
+       struct strategy *ret;
+       static struct cmdnames main_cmds, other_cmds;
+       static int longest;
 
        if (!name)
                return NULL;
@@ -86,12 +89,37 @@ static struct strategy *get_strategy(const char *name)
                if (!strcmp(name, all_strategy[i].name))
                        return &all_strategy[i];
 
-       strbuf_init(&err, 0);
-       for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
-               strbuf_addf(&err, " %s", all_strategy[i].name);
-       fprintf(stderr, "Could not find merge strategy '%s'.\n", name);
-       fprintf(stderr, "Available strategies are:%s.\n", err.buf);
-       exit(1);
+       if (!longest) {
+               struct cmdnames not_strategies;
+
+               memset(&main_cmds, 0, sizeof(struct cmdnames));
+               memset(&other_cmds, 0, sizeof(struct cmdnames));
+               memset(&not_strategies, 0, sizeof(struct cmdnames));
+               longest = load_command_list("git-merge-", &main_cmds,
+                               &other_cmds);
+               for (i = 0; i < main_cmds.cnt; i++) {
+                       int j, found = 0;
+                       struct cmdname *ent = main_cmds.names[i];
+                       for (j = 0; j < ARRAY_SIZE(all_strategy); j++)
+                               if (!strncmp(ent->name, all_strategy[j].name, ent->len)
+                                               && !all_strategy[j].name[ent->len])
+                                       found = 1;
+                       if (!found)
+                               add_cmdname(&not_strategies, ent->name, ent->len);
+                       exclude_cmds(&main_cmds, &not_strategies);
+               }
+       }
+       if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
+
+               fprintf(stderr, "Could not find merge strategy '%s'.\n\n", name);
+               list_commands("strategies", longest, &main_cmds, &other_cmds);
+               exit(1);
+       }
+
+       ret = xmalloc(sizeof(struct strategy));
+       memset(ret, 0, sizeof(struct strategy));
+       ret->name = xstrdup(name);
+       return ret;
 }
 
 static void append_strategy(struct strategy *s)