Re: [PATCH] Add support for host aliases in config files

On Sun, 17 Feb 2008, Junio C Hamano wrote:

Daniel Barkalow [off-list ref] writes:

quoted

..., but I'd like to get the 
code portion out there are reviewed, at least, since I think last time, 
the patch only got as far as a discussion of how I should explain what it 
does.

I actually think that is the most important part to get it right
first.  I usually do not have to read the patch text to reject
an ill-conceived idea if the description is unclear and/or
unconvincing.

I think the documentation (I removed from the quote) shows the
feature is unambiguously good.

What I meant by that was that you'd asked for some change in how this 
feature would get mentioned to people reading man pages on git commands 
that can use it.

quoted

diff --git a/remote.c b/remote.c
index 6b56473..59338a3 100644
--- a/remote.c
+++ b/remote.c

@@ -2,6 +2,15 @@
 #include "remote.h"
 #include "refs.h"
 
+struct host {
+	const char *name;
+
+	const char *base;
+
+	const char **alias;
+	int alias_nr;
+};

Extra blank lines?

I tend to like grouping related fields by having blank lines between 
unrelated ones, but it's not needed here.

quoted

@@ -11,9 +20,32 @@ static int allocated_branches;
 static struct branch *current_branch;
 static const char *default_remote_name;
 
+static struct host **hosts;
+static int allocated_hosts;

The allocation in remote.c file is unusual from the rest of git
that usually follow the technical/api-allocation-growing
convention (the comment unfortunately applies to the code we
already have there).

I think I originally used an older style that never got converted, and 
this time matched the style of the rest of the file. I'll add an initial 
patch to convert the rest of the file to the standard thing, and use that 
style for this patch as well.

quoted

+static const char *alias_url(const char *url)
+{
+	int i, j;
+	for (i = 0; i < allocated_hosts; i++) {
+		if (!hosts[i])
+			continue;
+		for (j = 0; j < hosts[i]->alias_nr; j++) {
+			if (!prefixcmp(url, hosts[i]->alias[j])) {
+				char *ret = malloc(strlen(hosts[i]->base) -
+						   strlen(hosts[i]->alias[j]) +
+						   strlen(url) + 1);
+				strcpy(ret, hosts[i]->base);
+				strcat(ret, url + strlen(hosts[i]->alias[j]));
+				return ret;
+			}

First match semantics is fine during runtime but at some point
we would want a "config file lint" that points out ambiguous
aliases perhaps?

I think first match may actually be useful in dealing with sites where a 
subset of the web-served space is git-served or something. But I'm really 
not sure; maybe we want "longest base" or something.

quoted

@@ -154,7 +233,7 @@ static void read_remotes_file(struct remote *remote)
 
 		switch (value_list) {
 		case 0:
-			add_url(remote, xstrdup(s));
+			add_url_alias(remote, xstrdup(s));
 			break;
 		case 1:
 			add_push_refspec(remote, xstrdup(s));

@@ -206,7 +285,7 @@ static void read_branches_file(struct remote *remote)
 	} else {
 		branch = "refs/heads/master";
 	}
-	add_url(remote, p);
+	add_url_alias(remote, p);
 	add_fetch_refspec(remote, branch);
 	remote->fetch_tags = 1; /* always auto-follow */
 }

These two are logical and clean updates.

quoted

@@ -236,6 +315,20 @@ static int handle_config(const char *key, const char *value)
 		}
 		return 0;
 	}
+	if (!prefixcmp(key, "host.")) {
+		struct host *host;
+		name = key + 5;
+		subkey = strrchr(name, '.');
+		if (!subkey)
+			return 0;

This "ignore this entry" is good.  We might later want to add
host.<var> that is not about a specific host, and we would want
to be able to read a configuration that is written for such a
future version of git.

quoted

+		host = make_host(name, subkey - name);
+		if (!value)
+			return 0;

This is not.

 (1) We should barf saying "host.<this-host>.<var> configuration
     should be a string", for base and rewritebase, instead of
     silently ignoring such a misconfiguration;

True. I'll look up the present best practices for config stuff.

 (2) We should _not_ do such barfing for future variables that
     are not base nor rewritebase, so this "return" is at a
     wrong place.

I was intentionally careful to ignore unknown options.

	-Daniel
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