Allow non-developer to clone, checkout and fetch more easily.

The code that uses committer_info() in reflog can barf and die
whenever it is asked to update a ref.  And I do not think
calling ignore_missing_committer_name() upfront like recent
receive-pack did in the aplication is a reasonable workaround.

What the patch does.

 - git_committer_info() takes one parameter.  It used to be "if
   this is true, then die() if the name is not available due to
   bad GECOS, otherwise issue a warning once but leave the name
   empty".  The reason was because we wanted to prevent bad
   commits from being made by git-commit-tree (and its
   callers).  The value 0 is only used by "git var -l".

   Now it takes -1, 0 or 1.  When set to -1, it does not
   complain but uses the pw->pw_name when name is not
   available.  Existing 0 and 1 values mean the same thing as
   they used to mean before.  0 means issue warnings and leave
   it empty, 1 means barf and die.

 - ignore_missing_committer_name() and its existing caller
   (receive-pack, to set the reflog) have been removed.

 - git-format-patch, to come up with the phoney message ID when
   asked to thread, now passes -1 to git_committer_info().  This
   codepath uses only the e-mail part, ignoring the name.  It
   used to barf and die.  The other call in the same program
   when asked to add signed-off-by line based on committer
   identity still passes 1 to make sure it barfs instead of
   adding a bogus s-o-b line.

 - log_ref_write in refs.c, to come up with the name to record
   who initiated the ref update in the reflog, passes -1.  It
   used to barf and die.

The last change means that git-update-ref, git-branch, and
commit walker backends can now be used in a repository with
reflog by somebody who does not have the user identity required
to make a commit.  They all used to barf and die.

I've run tests and all of them seem to pass, and also tried "git
clone" as a user whose GECOS is empty -- git clone works again
now (it was broken when reflog was enabled by default).

But this definitely needs extra sets of eyeballs.

Signed-off-by: Junio C Hamano <junkio@cox.net>

builtin-log.c

@@ -352,7 +352,7 @@ static void get_patch_ids(struct rev_info *rev, struct diff_options *options, co
 
 static void gen_message_id(char *dest, unsigned int length, char *base)
 {
-	const char *committer = git_committer_info(1);
+	const char *committer = git_committer_info(-1);
 	const char *email_start = strrchr(committer, '<');
 	const char *email_end = strrchr(committer, '>');
 	if(!email_start || !email_end || email_start > email_end - 1)

cache.h

@@ -320,7 +320,6 @@ void datestamp(char *buf, int bufsize);
 unsigned long approxidate(const char *);
 
 extern int setup_ident(void);
-extern void ignore_missing_committer_name(void);
 extern const char *git_author_info(int);
 extern const char *git_committer_info(int);
 

ident.c

@@ -180,12 +180,21 @@ static const char *get_ident(const char *name, const char *email,
 		email = git_default_email;
 
 	if (!*name) {
-		if (name == git_default_name && env_hint) {
+		struct passwd *pw;
+
+		if (0 <= error_on_no_name &&
+		    name == git_default_name && env_hint) {
 			fprintf(stderr, env_hint, au_env, co_env);
 			env_hint = NULL; /* warn only once, for "git-var -l" */
 		}
-		if (error_on_no_name)
+		if (0 < error_on_no_name)
 			die("empty ident %s <%s> not allowed", name, email);
+		pw = getpwuid(getuid());
+		if (!pw)
+			die("You don't exist. Go away!");
+		strlcpy(git_default_name, pw->pw_name,
+			sizeof(git_default_name));
+		name = git_default_name;
 	}
 
 	strcpy(date, git_default_date);
@@ -218,18 +227,3 @@ const char *git_committer_info(int error_on_no_name)
 			 getenv("GIT_COMMITTER_DATE"),
 			 error_on_no_name);
 }
-
-void ignore_missing_committer_name()
-{
-	/* If we did not get a name from the user's gecos entry then
-	 * git_default_name is empty; so instead load the username
-	 * into it as a 'good enough for now' approximation of who
-	 * this user is.
-	 */
-	if (!*git_default_name) {
-		struct passwd *pw = getpwuid(getuid());
-		if (!pw)
-			die("You don't exist. Go away!");
-		strlcpy(git_default_name, pw->pw_name, sizeof(git_default_name));
-	}
-}

receive-pack.c

@@ -430,8 +430,6 @@ int main(int argc, char **argv)
 		die("attempt to push into a shallow repository");
 
 	setup_ident();
-	/* don't die if gecos is empty */
-	ignore_missing_committer_name();
 	git_config(receive_pack_config);
 
 	if (0 <= transfer_unpack_limit)

refs.c

@@ -958,7 +958,7 @@ static int log_ref_write(struct ref_lock *lock,
 				     lock->log_file, strerror(errno));
 	}
 
-	committer = git_committer_info(1);
+	committer = git_committer_info(-1);
 	if (msg) {
 		maxlen = strlen(committer) + strlen(msg) + 2*40 + 5;
 		logrec = xmalloc(maxlen);