From 3f7ba603500a5dec43a062da5235c69e10d29da6 Mon Sep 17 00:00:00 2001
From: Matheus Tavares <matheus.bernardino@usp.br>
Date: Tue, 16 Feb 2021 11:06:52 -0300
Subject: checkout-index: omit entries with no tempname from --temp output

With --temp (or --stage=all, which implies --temp), checkout-index
writes a list to stdout associating temporary file names to the entries'
names. But if it fails to write an entry, and the failure happens before
even assigning a temporary filename to that entry, we get an odd output
line. This can be seen when trying to check out a symlink whose blob is
missing:

$ missing_blob=$(git hash-object --stdin </dev/null)
$ git update-index --add --cacheinfo 120000,$missing_blob,foo
$ git checkout-index --temp foo
error: unable to read sha1 file of foo (e69de29bb2d1d6434b8b29ae775ad8c2e48c5391)
        foo

The 'TAB foo' line is not much useful and it might break scripts that
expect the 'tempname TAB foo' output. So let's omit such entries from
the stdout list (but leaving the error message on stderr).

We could also consider omitting _all_ failed entries from the output
list, but that's probably not a good idea as the associated tempfiles
may have been created even when checkout failed, so scripts may want to
use the output list for cleanup.

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/checkout-index.c b/builtin/checkout-index.c
index 4bbfc92..023e49e 100644
--- a/builtin/checkout-index.c
+++ b/builtin/checkout-index.c
@@ -23,22 +23,35 @@ static struct checkout state = CHECKOUT_INIT;
 static void write_tempfile_record(const char *name, const char *prefix)
 {
 	int i;
+	int have_tempname = 0;
 
 	if (CHECKOUT_ALL == checkout_stage) {
-		for (i = 1; i < 4; i++) {
-			if (i > 1)
-				putchar(' ');
-			if (topath[i][0])
-				fputs(topath[i], stdout);
-			else
-				putchar('.');
+		for (i = 1; i < 4; i++)
+			if (topath[i][0]) {
+				have_tempname = 1;
+				break;
+			}
+
+		if (have_tempname) {
+			for (i = 1; i < 4; i++) {
+				if (i > 1)
+					putchar(' ');
+				if (topath[i][0])
+					fputs(topath[i], stdout);
+				else
+					putchar('.');
+			}
 		}
-	} else
+	} else if (topath[checkout_stage][0]) {
+		have_tempname = 1;
 		fputs(topath[checkout_stage], stdout);
+	}
 
-	putchar('\t');
-	write_name_quoted_relative(name, prefix, stdout,
-				   nul_term_line ? '\0' : '\n');
+	if (have_tempname) {
+		putchar('\t');
+		write_name_quoted_relative(name, prefix, stdout,
+					   nul_term_line ? '\0' : '\n');
+	}
 
 	for (i = 0; i < 4; i++) {
 		topath[i][0] = 0;
-- 
cgit v0.10.2-6-g49f6