unpack-trees: allow Porcelain to give different error messages

diff --git a/unpack-trees.c b/unpack-trees.c
index 1ab28fda45be940b300b504ae029f3fba2c28fa9..0de5a31c0b68f87491e540fdc1978809fee00240 100644 (file)
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -8,6 +8,36 @@
 #include "progress.h"
 #include "refs.h"
 
+/*
+ * Error messages expected by scripts out of plumbing commands such as
+ * read-tree.  Non-scripted Porcelain is not required to use these messages
+ * and in fact are encouraged to reword them to better suit their particular
+ * situation better.  See how "git checkout" replaces not_uptodate_file to
+ * explain why it does not allow switching between branches when you have
+ * local changes, for example.
+ */
+static struct unpack_trees_error_msgs unpack_plumbing_errors = {
+       /* would_overwrite */
+       "Entry '%s' would be overwritten by merge. Cannot merge.",
+
+       /* not_uptodate_file */
+       "Entry '%s' not uptodate. Cannot merge.",
+
+       /* not_uptodate_dir */
+       "Updating '%s' would lose untracked files in it",
+
+       /* would_lose_untracked */
+       "Untracked working tree file '%s' would be %s by merge.",
+
+       /* bind_overlap */
+       "Entry '%s' overlaps with '%s'.  Cannot bind.",
+};
+
+#define ERRORMSG(o,fld) \
+       ( ((o) && (o)->msgs.fld) \
+       ? ((o)->msgs.fld) \
+       : (unpack_plumbing_errors.fld) )
+
 static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
        unsigned int set, unsigned int clear)
 {
@@ -383,10 +413,9 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 
 /* Here come the merge functions */
 
-static int reject_merge(struct cache_entry *ce)
+static int reject_merge(struct cache_entry *ce, struct unpack_trees_options *o)
 {
-       return error("Entry '%s' would be overwritten by merge. Cannot merge.",
-                    ce->name);
+       return error(ERRORMSG(o, would_overwrite), ce->name);
 }
 
 static int same(struct cache_entry *a, struct cache_entry *b)
@@ -430,7 +459,7 @@ static int verify_uptodate(struct cache_entry *ce,
        if (errno == ENOENT)
                return 0;
        return o->gently ? -1 :
-               error("Entry '%s' not uptodate. Cannot merge.", ce->name);
+               error(ERRORMSG(o, not_uptodate_file), ce->name);
 }
 
 static void invalidate_ce_path(struct cache_entry *ce, struct unpack_trees_options *o)
@@ -517,8 +546,7 @@ static int verify_clean_subdirectory(struct cache_entry *ce, const char *action,
        i = read_directory(&d, ce->name, pathbuf, namelen+1, NULL);
        if (i)
                return o->gently ? -1 :
-                       error("Updating '%s' would lose untracked files in it",
-                             ce->name);
+                       error(ERRORMSG(o, not_uptodate_dir), ce->name);
        free(pathbuf);
        return cnt;
 }
@@ -618,8 +646,7 @@ static int verify_absent(struct cache_entry *ce, const char *action,
                }
 
                return o->gently ? -1 :
-                       error("Untracked working tree file '%s' "
-                             "would be %s by merge.", ce->name, action);
+                       error(ERRORMSG(o, would_lose_untracked), ce->name, action);
        }
        return 0;
 }
@@ -751,7 +778,7 @@ int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
        /* #14, #14ALT, #2ALT */
        if (remote && !df_conflict_head && head_match && !remote_match) {
                if (index && !same(index, remote) && !same(index, head))
-                       return o->gently ? -1 : reject_merge(index);
+                       return o->gently ? -1 : reject_merge(index, o);
                return merged_entry(remote, index, o);
        }
        /*
@@ -759,7 +786,7 @@ int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
         * make sure that it matches head.
         */
        if (index && !same(index, head))
-               return o->gently ? -1 : reject_merge(index);
+               return o->gently ? -1 : reject_merge(index, o);
 
        if (head) {
                /* #5ALT, #15 */
@@ -901,11 +928,11 @@ int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o)
                else {
                        /* all other failures */
                        if (oldtree)
-                               return o->gently ? -1 : reject_merge(oldtree);
+                               return o->gently ? -1 : reject_merge(oldtree, o);
                        if (current)
-                               return o->gently ? -1 : reject_merge(current);
+                               return o->gently ? -1 : reject_merge(current, o);
                        if (newtree)
-                               return o->gently ? -1 : reject_merge(newtree);
+                               return o->gently ? -1 : reject_merge(newtree, o);
                        return -1;
                }
        }
@@ -931,7 +958,7 @@ int bind_merge(struct cache_entry **src,
                             o->merge_size);
        if (a && old)
                return o->gently ? -1 :
-                       error("Entry '%s' overlaps with '%s'.  Cannot bind.", a->name, old->name);
+                       error(ERRORMSG(o, bind_overlap), a->name, old->name);
        if (!a)
                return keep_entry(old, o);
        else