Merge remote-tracking branch 'ko/maint' into jc/diff-index-quick-exit-early

* ko/maint: (4352 commits)
  git-submodule.sh: separate parens by a space to avoid confusing some shells
  Documentation/technical/api-diff.txt: correct name of diff_unmerge()
  read_gitfile_gently: use ssize_t to hold read result
  remove tests of always-false condition
  rerere.c: diagnose a corrupt MERGE_RR when hitting EOF between TAB and '\0'
  Git 1.7.5.3
  init/clone: remove short option -L and document --separate-git-dir
  do not read beyond end of malloc'd buffer
  git-svn: Fix git svn log --show-commit
  Git 1.7.5.2
  provide a copy of the LGPLv2.1
  test core.gitproxy configuration
  copy_gecos: fix not adding nlen to len when processing "&"
  Update draft release notes to 1.7.5.2
  Documentation/git-fsck.txt: fix typo: unreadable -> unreachable
  send-pack: avoid deadlock on git:// push with failed pack-objects
  connect: let callers know if connection is a socket
  connect: treat generic proxy processes like ssh processes
  sideband_demux(): fix decl-after-stmt
  t3503: test cherry picking and reverting root commits
  ...

Conflicts:
	diff.c

1 files changed, 49 insertions, 14 deletions

diff --git a/help.c b/help.c
index 6c46d8b494..7654f1bfd6 100644
--- a/help.c
+++ b/help.c
@@ -3,6 +3,7 @@
 #include "exec_cmd.h"
 #include "levenshtein.h"
 #include "help.h"
+#include "common-cmds.h"
 
 /* most GUI terminals set COLUMNS (although some don't export it) */
 static int term_columns(void)
@@ -126,8 +127,8 @@ static int is_executable(const char *name)
 	    !S_ISREG(st.st_mode))
 		return 0;
 
-#ifdef __MINGW32__
-	/* cannot trust the executable bit, peek into the file instead */
+#ifdef WIN32
+{	/* cannot trust the executable bit, peek into the file instead */
 	char buf[3] = { 0 };
 	int n;
 	int fd = open(name, O_RDONLY);
@@ -140,6 +141,7 @@ static int is_executable(const char *name)
 				st.st_mode |= S_IXUSR;
 		close(fd);
 	}
+}
 #endif
 	return st.st_mode & S_IXUSR;
 }
@@ -296,13 +298,17 @@ static void add_cmd_list(struct cmdnames *cmds, struct cmdnames *old)
 	old->names = NULL;
 }
 
+/* An empirically derived magic number */
+#define SIMILARITY_FLOOR 7
+#define SIMILAR_ENOUGH(x) ((x) < SIMILARITY_FLOOR)
+
 const char *help_unknown_cmd(const char *cmd)
 {
 	int i, n, best_similarity = 0;
 	struct cmdnames main_cmds, other_cmds;
 
 	memset(&main_cmds, 0, sizeof(main_cmds));
-	memset(&other_cmds, 0, sizeof(main_cmds));
+	memset(&other_cmds, 0, sizeof(other_cmds));
 	memset(&aliases, 0, sizeof(aliases));
 
 	git_config(git_unknown_cmd_config, NULL);
@@ -315,10 +321,28 @@ const char *help_unknown_cmd(const char *cmd)
 	      sizeof(main_cmds.names), cmdname_compare);
 	uniq(&main_cmds);
 
-	/* This reuses cmdname->len for similarity index */
-	for (i = 0; i < main_cmds.cnt; ++i)
+	/* This abuses cmdname->len for levenshtein distance */
+	for (i = 0, n = 0; i < main_cmds.cnt; i++) {
+		int cmp = 0; /* avoid compiler stupidity */
+		const char *candidate = main_cmds.names[i]->name;
+
+		/* Does the candidate appear in common_cmds list? */
+		while (n < ARRAY_SIZE(common_cmds) &&
+		       (cmp = strcmp(common_cmds[n].name, candidate)) < 0)
+			n++;
+		if ((n < ARRAY_SIZE(common_cmds)) && !cmp) {
+			/* Yes, this is one of the common commands */
+			n++; /* use the entry from common_cmds[] */
+			if (!prefixcmp(candidate, cmd)) {
+				/* Give prefix match a very good score */
+				main_cmds.names[i]->len = 0;
+				continue;
+			}
+		}
+
 		main_cmds.names[i]->len =
-			levenshtein(cmd, main_cmds.names[i]->name, 0, 2, 1, 4);
+			levenshtein(cmd, candidate, 0, 2, 1, 4) + 1;
+	}
 
 	qsort(main_cmds.names, main_cmds.cnt,
 	      sizeof(*main_cmds.names), levenshtein_compare);
@@ -326,15 +350,26 @@ const char *help_unknown_cmd(const char *cmd)
 	if (!main_cmds.cnt)
 		die ("Uh oh. Your system reports no Git commands at all.");
 
-	best_similarity = main_cmds.names[0]->len;
-	n = 1;
-	while (n < main_cmds.cnt && best_similarity == main_cmds.names[n]->len)
-		++n;
-	if (autocorrect && n == 1) {
+	/* skip and count prefix matches */
+	for (n = 0; n < main_cmds.cnt && !main_cmds.names[n]->len; n++)
+		; /* still counting */
+
+	if (main_cmds.cnt <= n) {
+		/* prefix matches with everything? that is too ambiguous */
+		best_similarity = SIMILARITY_FLOOR + 1;
+	} else {
+		/* count all the most similar ones */
+		for (best_similarity = main_cmds.names[n++]->len;
+		     (n < main_cmds.cnt &&
+		      best_similarity == main_cmds.names[n]->len);
+		     n++)
+			; /* still counting */
+	}
+	if (autocorrect && n == 1 && SIMILAR_ENOUGH(best_similarity)) {
 		const char *assumed = main_cmds.names[0]->name;
 		main_cmds.names[0] = NULL;
 		clean_cmdnames(&main_cmds);
-		fprintf(stderr, "WARNING: You called a Git program named '%s', "
+		fprintf(stderr, "WARNING: You called a Git command named '%s', "
 			"which does not exist.\n"
 			"Continuing under the assumption that you meant '%s'\n",
 			cmd, assumed);
@@ -346,9 +381,9 @@ const char *help_unknown_cmd(const char *cmd)
 		return assumed;
 	}
 
-	fprintf(stderr, "git: '%s' is not a git-command. See 'git --help'.\n", cmd);
+	fprintf(stderr, "git: '%s' is not a git command. See 'git --help'.\n", cmd);
 
-	if (best_similarity < 6) {
+	if (SIMILAR_ENOUGH(best_similarity)) {
 		fprintf(stderr, "\nDid you mean %s?\n",
 			n < 2 ? "this": "one of these");