[regression] Re: [PATCHv2 10/15] drop length limitations on gecos-derived names and emails

[Jonathan Nieder <jrnieder@gmail.com>]

Hi Jeff,

Jeff King wrote:

> When we pull the user's name from the GECOS field of the
> passwd file (or generate an email address based on their
> username and hostname), we put the result into a
> static buffer.
[...]
> The conversion is mostly mechanical: replace string copies
> with strbuf equivalents, and access the strbuf.buf directly.
> There are a few exceptions:

This broke /etc/mailname handling.  Before:

	$ git var GIT_COMMITTER_IDENT
	Jonathan Nieder <jrn@mailname.example.com> 1359069165 -0800

After:

	$ git var GIT_COMMITTER_IDENT
	Jonathan Nieder <mailname.example.com> 1359069192 -0800

The cause:

[...]
> --- a/ident.c
> +++ b/ident.c
> @@ -19,42 +18,27 @@ int user_ident_explicitly_given;
[...]
> -static int add_mailname_host(char *buf, size_t len)
> +static int add_mailname_host(struct strbuf *buf)
>  {
>  	FILE *mailname;
>  
> @@ -65,7 +49,7 @@ static int add_mailname_host(char *buf, size_t len)
>  				strerror(errno));
>  		return -1;
>  	}
> -	if (!fgets(buf, len, mailname)) {
> +	if (strbuf_getline(buf, mailname, '\n') == EOF) {

This clears the strbuf.

How about something like this as a quick fix?

Reported-by: Mihai Rusu <dizzy@google.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>

diff --git a/ident.c b/ident.c
index 73a06a1..cabd73f 100644
--- a/ident.c
+++ b/ident.c
@@ -41,6 +41,7 @@ static void copy_gecos(const struct passwd *w, struct strbuf *name)
 static int add_mailname_host(struct strbuf *buf)
 {
 	FILE *mailname;
+	struct strbuf mailnamebuf = STRBUF_INIT;
 
 	mailname = fopen("/etc/mailname", "r");
 	if (!mailname) {
@@ -49,14 +50,17 @@ static int add_mailname_host(struct strbuf *buf)
 				strerror(errno));
 		return -1;
 	}
-	if (strbuf_getline(buf, mailname, '\n') == EOF) {
+	if (strbuf_getline(&mailnamebuf, mailname, '\n') == EOF) {
 		if (ferror(mailname))
 			warning("cannot read /etc/mailname: %s",
 				strerror(errno));
+		strbuf_release(&mailnamebuf);
 		fclose(mailname);
 		return -1;
 	}
 	/* success! */
+	strbuf_addbuf(buf, &mailnamebuf);
+	strbuf_release(&mailnamebuf);
 	fclose(mailname);
 	return 0;
 }