diff --git a/Makefile b/Makefile
index 199fbe8738..164dbcf734 100644
--- a/Makefile
+++ b/Makefile
@@ -260,7 +260,7 @@ LIB_OBJS = \
 	server-info.o setup.o sha1_file.o sha1_name.o strbuf.o \
 	tag.o tree.o usage.o config.o environment.o ctype.o copy.o \
 	fetch-clone.o revision.o pager.o tree-walk.o xdiff-interface.o \
-	write_or_die.o \
+	write_or_die.o trace.o \
 	alloc.o merge-file.o path-list.o help.o unpack-trees.o $(DIFF_OBJS)
 
 BUILTIN_OBJS = \
@@ -514,7 +514,7 @@ ifdef NO_SETENV
 	COMPAT_CFLAGS += -DNO_SETENV
 	COMPAT_OBJS += compat/setenv.o
 endif
-ifdef NO_SETENV
+ifdef NO_UNSETENV
 	COMPAT_CFLAGS += -DNO_UNSETENV
 	COMPAT_OBJS += compat/unsetenv.o
 endif
diff --git a/builtin-unpack-objects.c b/builtin-unpack-objects.c
index ca0ebc2585..0c180b53a3 100644
--- a/builtin-unpack-objects.c
+++ b/builtin-unpack-objects.c
@@ -15,7 +15,7 @@ static const char unpack_usage[] = "git-unpack-objects [-n] [-q] < pack-file";
 
 /* We always read in 4kB chunks. */
 static unsigned char buffer[4096];
-static unsigned long offset, len, eof;
+static unsigned long offset, len;
 static SHA_CTX ctx;
 
 /*
@@ -26,8 +26,6 @@ static void * fill(int min)
 {
 	if (min <= len)
 		return buffer + offset;
-	if (eof)
-		die("unable to fill input");
 	if (min > sizeof(buffer))
 		die("cannot fill %d bytes", min);
 	if (offset) {
diff --git a/cache.h b/cache.h
index 1ff2696456..df5d86fe40 100644
--- a/cache.h
+++ b/cache.h
@@ -401,6 +401,7 @@ extern char git_commit_encoding[MAX_ENCODING_LENGTH];
 
 extern int copy_fd(int ifd, int ofd);
 extern void write_or_die(int fd, const void *buf, size_t count);
+extern int write_or_whine(int fd, const void *buf, size_t count, const char *msg);
 
 /* Finish off pack transfer receiving end */
 extern int receive_unpack_pack(int fd[2], const char *me, int quiet, int);
@@ -426,4 +427,9 @@ extern struct commit *alloc_commit_node(void);
 extern struct tag *alloc_tag_node(void);
 extern void alloc_report(void);
 
+/* trace.c */
+extern int nfvasprintf(char **str, const char *fmt, va_list va);
+extern void trace_printf(const char *format, ...);
+extern void trace_argv_printf(const char **argv, int count, const char *format, ...);
+
 #endif /* CACHE_H */
diff --git a/exec_cmd.c b/exec_cmd.c
index e30936d72c..5d6a1247b4 100644
--- a/exec_cmd.c
+++ b/exec_cmd.c
@@ -97,26 +97,12 @@ int execv_git_cmd(const char **argv)
 		tmp = argv[0];
 		argv[0] = git_command;
 
-		if (getenv("GIT_TRACE")) {
-			const char **p = argv;
-			fputs("trace: exec:", stderr);
-			while (*p) {
-				fputc(' ', stderr);
-				sq_quote_print(stderr, *p);
-				++p;
-			}
-			putc('\n', stderr);
-			fflush(stderr);
-		}
+		trace_argv_printf(argv, -1, "trace: exec:");
 
 		/* execve() can only ever return if it fails */
 		execve(git_command, (char **)argv, environ);
 
-		if (getenv("GIT_TRACE")) {
-			fprintf(stderr, "trace: exec failed: %s\n",
-				strerror(errno));
-			fflush(stderr);
-		}
+		trace_printf("trace: exec failed: %s\n", strerror(errno));
 
 		argv[0] = tmp;
 	}
diff --git a/fsck-objects.c b/fsck-objects.c
index ae0ec8d039..24286de15d 100644
--- a/fsck-objects.c
+++ b/fsck-objects.c
@@ -425,8 +425,23 @@ static int fsck_handle_ref(const char *refname, const unsigned char *sha1)
 static void get_default_heads(void)
 {
 	for_each_ref(fsck_handle_ref);
-	if (!default_refs)
-		die("No default references");
+
+	/*
+	 * Not having any default heads isn't really fatal, but
+	 * it does mean that "--unreachable" no longer makes any
+	 * sense (since in this case everything will obviously
+	 * be unreachable by definition.
+	 *
+	 * Showing dangling objects is valid, though (as those
+	 * dangling objects are likely lost heads).
+	 *
+	 * So we just print a warning about it, and clear the
+	 * "show_unreachable" flag.
+	 */
+	if (!default_refs) {
+		error("No default references");
+		show_unreachable = 0;
+	}
 }
 
 static void fsck_object_dir(const char *path)
diff --git a/git-repack.sh b/git-repack.sh
index 9da92fb061..584a7323ac 100755
--- a/git-repack.sh
+++ b/git-repack.sh
@@ -38,7 +38,7 @@ case ",$all_into_one," in
 	pack_objects=
 
 	# Redundancy check in all-into-one case is trivial.
-	existing=`cd "$PACKDIR" && \
+	existing=`test -d "$PACKDIR" && cd "$PACKDIR" && \
 	    find . -type f \( -name '*.pack' -o -name '*.idx' \) -print`
 	;;
 esac
diff --git a/git.c b/git.c
index bd07289d71..0c8cfa8d34 100644
--- a/git.c
+++ b/git.c
@@ -179,17 +179,9 @@ static int handle_alias(int *argcp, const char ***argv)
 		if (!strcmp(alias_command, new_argv[0]))
 			die("recursive alias: %s", alias_command);
 
-		if (getenv("GIT_TRACE")) {
-			int i;
-			fprintf(stderr, "trace: alias expansion: %s =>",
-				alias_command);
-			for (i = 0; i < count; ++i) {
-				fputc(' ', stderr);
-				sq_quote_print(stderr, new_argv[i]);
-			}
-			fputc('\n', stderr);
-			fflush(stderr);
-		}
+		trace_argv_printf(new_argv, count,
+				  "trace: alias expansion: %s =>",
+				  alias_command);
 
 		new_argv = xrealloc(new_argv, sizeof(char*) *
 				    (count + *argcp + 1));
@@ -292,16 +284,7 @@ static void handle_internal_command(int argc, const char **argv, char **envp)
 			prefix = setup_git_directory();
 		if (p->option & USE_PAGER)
 			setup_pager();
-		if (getenv("GIT_TRACE")) {
-			int j;
-			fprintf(stderr, "trace: built-in: git");
-			for (j = 0; j < argc; ++j) {
-				fputc(' ', stderr);
-				sq_quote_print(stderr, argv[j]);
-			}
-			putc('\n', stderr);
-			fflush(stderr);
-		}
+		trace_argv_printf(argv, argc, "trace: built-in: git");
 
 		exit(p->fn(argc, argv, prefix));
 	}
diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 9324d71ebe..0984e85623 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -152,7 +152,7 @@ sub feature_snapshot {
 our @diff_opts = ('-M'); # taken from git_commit
 
 our $GITWEB_CONFIG = $ENV{'GITWEB_CONFIG'} || "++GITWEB_CONFIG++";
-require $GITWEB_CONFIG if -e $GITWEB_CONFIG;
+do $GITWEB_CONFIG if -e $GITWEB_CONFIG;
 
 # version of the core git binary
 our $git_version = qx($GIT --version) =~ m/git version (.*)$/ ? $1 : "unknown";
@@ -1027,9 +1027,30 @@ sub parse_difftree_raw_line {
 		}
 	}
 	# 'c512b523472485aef4fff9e57b229d9d243c967f'
-	#elsif ($line =~ m/^([0-9a-fA-F]{40})$/) {
-	#	$res{'commit'} = $1;
-	#}
+	elsif ($line =~ m/^([0-9a-fA-F]{40})$/) {
+		$res{'commit'} = $1;
+	}
+
+	return wantarray ? %res : \%res;
+}
+
+# parse line of git-ls-tree output
+sub parse_ls_tree_line ($;%) {
+	my $line = shift;
+	my %opts = @_;
+	my %res;
+
+	#'100644 blob 0fa3f3a66fb6a137f6ec2c19351ed4d807070ffa	panic.c'
+	$line =~ m/^([0-9]+) (.+) ([0-9a-fA-F]{40})\t(.+)$/;
+
+	$res{'mode'} = $1;
+	$res{'type'} = $2;
+	$res{'hash'} = $3;
+	if ($opts{'-z'}) {
+		$res{'name'} = $4;
+	} else {
+		$res{'name'} = unquote($4);
+	}
 
 	return wantarray ? %res : \%res;
 }
@@ -1454,6 +1475,62 @@ sub git_print_simplified_log {
 		-remove_title => $remove_title);
 }
 
+# print tree entry (row of git_tree), but without encompassing <tr> element
+sub git_print_tree_entry {
+	my ($t, $basedir, $hash_base, $have_blame) = @_;
+
+	my %base_key = ();
+	$base_key{hash_base} = $hash_base if defined $hash_base;
+
+	print "<td class=\"mode\">" . mode_str($t->{'mode'}) . "</td>\n";
+	if ($t->{'type'} eq "blob") {
+		print "<td class=\"list\">" .
+		      $cgi->a({-href => href(action=>"blob", hash=>$t->{'hash'},
+		                             file_name=>"$basedir$t->{'name'}", %base_key),
+		              -class => "list"}, esc_html($t->{'name'})) .
+		      "</td>\n" .
+		      "<td class=\"link\">" .
+		      $cgi->a({-href => href(action=>"blob", hash=>$t->{'hash'},
+		                             file_name=>"$basedir$t->{'name'}", %base_key)},
+		              "blob");
+		if ($have_blame) {
+			print " | " .
+				$cgi->a({-href => href(action=>"blame", hash=>$t->{'hash'},
+				                       file_name=>"$basedir$t->{'name'}", %base_key)},
+				        "blame");
+		}
+		if (defined $hash_base) {
+			print " | " .
+			      $cgi->a({-href => href(action=>"history", hash_base=>$hash_base,
+			                             hash=>$t->{'hash'}, file_name=>"$basedir$t->{'name'}")},
+			              "history");
+		}
+		print " | " .
+		      $cgi->a({-href => href(action=>"blob_plain",
+		                             hash=>$t->{'hash'}, file_name=>"$basedir$t->{'name'}")},
+		              "raw") .
+		      "</td>\n";
+
+	} elsif ($t->{'type'} eq "tree") {
+		print "<td class=\"list\">" .
+		      $cgi->a({-href => href(action=>"tree", hash=>$t->{'hash'},
+		                             file_name=>"$basedir$t->{'name'}", %base_key)},
+		              esc_html($t->{'name'})) .
+		      "</td>\n" .
+		      "<td class=\"link\">" .
+		      $cgi->a({-href => href(action=>"tree", hash=>$t->{'hash'},
+		                             file_name=>"$basedir$t->{'name'}", %base_key)},
+		              "tree");
+		if (defined $hash_base) {
+			print " | " .
+			      $cgi->a({-href => href(action=>"history", hash_base=>$hash_base,
+			                             file_name=>"$basedir$t->{'name'}")},
+			              "history");
+		}
+		print "</td>\n";
+	}
+}
+
 ## ......................................................................
 ## functions printing large fragments of HTML
 
@@ -2492,14 +2569,13 @@ sub git_tree {
 	my $refs = git_get_references();
 	my $ref = format_ref_marker($refs, $hash_base);
 	git_header_html();
-	my %base_key = ();
 	my $base = "";
 	my $have_blame = gitweb_check_feature('blame');
 	if (defined $hash_base && (my %co = parse_commit($hash_base))) {
-		$base_key{hash_base} = $hash_base;
 		git_print_page_nav('tree','', $hash_base);
 		git_print_header_div('commit', esc_html($co{'title'}) . $ref, $hash_base);
 	} else {
+		undef $hash_base;
 		print "<div class=\"page_nav\">\n";
 		print "<br/><br/></div>\n";
 		print "<div class=\"title\">$hash</div>\n";
@@ -2512,54 +2588,17 @@ sub git_tree {
 	print "<table cellspacing=\"0\">\n";
 	my $alternate = 0;
 	foreach my $line (@entries) {
-		#'100644	blob	0fa3f3a66fb6a137f6ec2c19351ed4d807070ffa	panic.c'
-		$line =~ m/^([0-9]+) (.+) ([0-9a-fA-F]{40})\t(.+)$/;
-		my $t_mode = $1;
-		my $t_type = $2;
-		my $t_hash = $3;
-		my $t_name = validate_input($4);
+		my %t = parse_ls_tree_line($line, -z => 1);
+
 		if ($alternate) {
 			print "<tr class=\"dark\">\n";
 		} else {
 			print "<tr class=\"light\">\n";
 		}
 		$alternate ^= 1;
-		print "<td class=\"mode\">" . mode_str($t_mode) . "</td>\n";
-		if ($t_type eq "blob") {
-			print "<td class=\"list\">" .
-			      $cgi->a({-href => href(action=>"blob", hash=>$t_hash, file_name=>"$base$t_name", %base_key),
-			              -class => "list"}, esc_html($t_name)) .
-			      "</td>\n" .
-			      "<td class=\"link\">" .
-			      $cgi->a({-href => href(action=>"blob", hash=>$t_hash, file_name=>"$base$t_name", %base_key)},
-			              "blob");
-			if ($have_blame) {
-				print " | " .
-					$cgi->a({-href => href(action=>"blame", hash=>$t_hash, file_name=>"$base$t_name", %base_key)},
-					        "blame");
-			}
-			print " | " .
-			      $cgi->a({-href => href(action=>"history", hash_base=>$hash_base,
-			                             hash=>$t_hash, file_name=>"$base$t_name")},
-			              "history") .
-			      " | " .
-			      $cgi->a({-href => href(action=>"blob_plain",
-			                             hash=>$t_hash, file_name=>"$base$t_name")},
-			              "raw") .
-			      "</td>\n";
-		} elsif ($t_type eq "tree") {
-			print "<td class=\"list\">" .
-			      $cgi->a({-href => href(action=>"tree", hash=>$t_hash, file_name=>"$base$t_name", %base_key)},
-			              esc_html($t_name)) .
-			      "</td>\n" .
-			      "<td class=\"link\">" .
-			      $cgi->a({-href => href(action=>"tree", hash=>$t_hash, file_name=>"$base$t_name", %base_key)},
-			              "tree") .
-			      " | " .
-			      $cgi->a({-href => href(action=>"history", hash_base=>$hash_base, file_name=>"$base$t_name")},
-			              "history") .
-			      "</td>\n";
-		}
+
+		git_print_tree_entry(\%t, $base, $hash_base, $have_blame);
+
 		print "</tr>\n";
 	}
 	print "</table>\n" .
@@ -2778,10 +2817,6 @@ sub git_blobdiff {
 			@difftree
 				or die_error('404 Not Found', "Blob diff not found");
 
-		} elsif (defined $hash) { # try to find filename from $hash
-			if ($hash !~ /[0-9a-fA-F]{40}/) {
-				$hash = git_to_hash($hash);
-			}
 		} elsif (defined $hash &&
 		         $hash =~ /[0-9a-fA-F]{40}/) {
 			# try to find filename from $hash
diff --git a/imap-send.c b/imap-send.c
index 65c71c602d..6a52dbdca4 100644
--- a/imap-send.c
+++ b/imap-send.c
@@ -110,7 +110,6 @@ static char *next_arg( char ** );
 
 static void free_generic_messages( message_t * );
 
-static int nfvasprintf( char **str, const char *fmt, va_list va );
 static int nfsnprintf( char *buf, int blen, const char *fmt, ... );
 
 
@@ -371,21 +370,6 @@ free_generic_messages( message_t *msgs )
 	}
 }
 
-static int
-git_vasprintf( char **strp, const char *fmt, va_list ap )
-{
-	int len;
-	char tmp[1024];
-
-	if ((len = vsnprintf( tmp, sizeof(tmp), fmt, ap )) < 0 || !(*strp = xmalloc( len + 1 )))
-		return -1;
-	if (len >= (int)sizeof(tmp))
-		vsprintf( *strp, fmt, ap );
-	else
-		memcpy( *strp, tmp, len + 1 );
-	return len;
-}
-
 static int
 nfsnprintf( char *buf, int blen, const char *fmt, ... )
 {
@@ -399,15 +383,6 @@ nfsnprintf( char *buf, int blen, const char *fmt, ... )
 	return ret;
 }
 
-static int
-nfvasprintf( char **str, const char *fmt, va_list va )
-{
-	int ret = git_vasprintf( str, fmt, va );
-	if (ret < 0)
-		die( "Fatal: Out of memory\n");
-	return ret;
-}
-
 static struct {
 	unsigned char i, j, s[256];
 } rs;
diff --git a/log-tree.c b/log-tree.c
index 54cdaa4d81..fbe139920a 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -12,10 +12,58 @@ static void show_parents(struct commit *commit, int abbrev)
 	}
 }
 
+/*
+ * Search for "^[-A-Za-z]+: [^@]+@" pattern. It usually matches
+ * Signed-off-by: and Acked-by: lines.
+ */
+static int detect_any_signoff(char *letter, int size)
+{
+	char ch, *cp;
+	int seen_colon = 0;
+	int seen_at = 0;
+	int seen_name = 0;
+	int seen_head = 0;
+
+	cp = letter + size;
+	while (letter <= --cp && (ch = *cp) == '\n')
+		continue;
+
+	while (letter <= cp) {
+		ch = *cp--;
+		if (ch == '\n')
+			break;
+
+		if (!seen_at) {
+			if (ch == '@')
+				seen_at = 1;
+			continue;
+		}
+		if (!seen_colon) {
+			if (ch == '@')
+				return 0;
+			else if (ch == ':')
+				seen_colon = 1;
+			else
+				seen_name = 1;
+			continue;
+		}
+		if (('A' <= ch && ch <= 'Z') ||
+		    ('a' <= ch && ch <= 'z') ||
+		    ch == '-') {
+			seen_head = 1;
+			continue;
+		}
+		/* no empty last line doesn't match */
+		return 0;
+	}
+	return seen_head && seen_name;
+}
+
 static int append_signoff(char *buf, int buf_sz, int at, const char *signoff)
 {
-	int signoff_len = strlen(signoff);
 	static const char signed_off_by[] = "Signed-off-by: ";
+	int signoff_len = strlen(signoff);
+	int has_signoff = 0;
 	char *cp = buf;
 
 	/* Do we have enough space to add it? */
@@ -23,58 +71,26 @@ static int append_signoff(char *buf, int buf_sz, int at, const char *signoff)
 		return at;
 
 	/* First see if we already have the sign-off by the signer */
-	while (1) {
-		cp = strstr(cp, signed_off_by);
-		if (!cp)
-			break;
+	while ((cp = strstr(cp, signed_off_by))) {
+
+		has_signoff = 1;
+
 		cp += strlen(signed_off_by);
-		if ((cp + signoff_len < buf + at) &&
-		    !strncmp(cp, signoff, signoff_len) &&
-		    isspace(cp[signoff_len]))
-			return at; /* we already have him */
+		if (cp + signoff_len >= buf + at)
+			break;
+		if (strncmp(cp, signoff, signoff_len))
+			continue;
+		if (!isspace(cp[signoff_len]))
+			continue;
+		/* we already have him */
+		return at;
 	}
 
-	/* Does the last line already end with "^[-A-Za-z]+: [^@]+@"?
-	 * If not, add a blank line to separate the message from
-	 * the run of Signed-off-by: and Acked-by: lines.
-	 */
-	{
-		char ch;
-		int seen_colon, seen_at, seen_name, seen_head, not_signoff;
-		seen_colon = 0;
-		seen_at = 0;
-		seen_name = 0;
-		seen_head = 0;
-		not_signoff = 0;
-		cp = buf + at;
-		while (buf <= --cp && (ch = *cp) == '\n')
-			;
-		while (!not_signoff && buf <= cp && (ch = *cp--) != '\n') {
-			if (!seen_at) {
-				if (ch == '@')
-					seen_at = 1;
-				continue;
-			}
-			if (!seen_colon) {
-				if (ch == '@')
-					not_signoff = 1;
-				else if (ch == ':')
-					seen_colon = 1;
-				else
-					seen_name = 1;
-				continue;
-			}
-			if (('A' <= ch && ch <= 'Z') ||
-			    ('a' <= ch && ch <= 'z') ||
-			    ch == '-') {
-				seen_head = 1;
-				continue;
-			}
-			not_signoff = 1;
-		}
-		if (not_signoff || !seen_head || !seen_name)
-			buf[at++] = '\n';
-	}
+	if (!has_signoff)
+		has_signoff = detect_any_signoff(buf, at);
+
+	if (!has_signoff)
+		buf[at++] = '\n';
 
 	strcpy(buf + at, signed_off_by);
 	at += strlen(signed_off_by);
diff --git a/peek-remote.c b/peek-remote.c
index 2b30980b04..87f1543fec 100644
--- a/peek-remote.c
+++ b/peek-remote.c
@@ -1,7 +1,6 @@
 #include "cache.h"
 #include "refs.h"
 #include "pkt-line.h"
-#include <sys/wait.h>
 
 static const char peek_remote_usage[] =
 "git-peek-remote [--exec=upload-pack] [host:]directory";
diff --git a/quote.c b/quote.c
index e220dcc280..a38786c177 100644
--- a/quote.c
+++ b/quote.c
@@ -74,6 +74,38 @@ char *sq_quote(const char *src)
 	return buf;
 }
 
+char *sq_quote_argv(const char** argv, int count)
+{
+	char *buf, *to;
+	int i;
+	size_t len = 0;
+
+	/* Count argv if needed. */
+	if (count < 0) {
+		for (count = 0; argv[count]; count++)
+			; /* just counting */
+	}
+
+	/* Special case: no argv. */
+	if (!count)
+		return xcalloc(1,1);
+
+	/* Get destination buffer length. */
+	for (i = 0; i < count; i++)
+		len += sq_quote_buf(NULL, 0, argv[i]) + 1;
+
+	/* Alloc destination buffer. */
+	to = buf = xmalloc(len + 1);
+
+	/* Copy into destination buffer. */
+	for (i = 0; i < count; ++i) {
+		*to++ = ' ';
+		to += sq_quote_buf(to, len, argv[i]);
+	}
+
+	return buf;
+}
+
 char *sq_dequote(char *arg)
 {
 	char *dst = arg;
diff --git a/quote.h b/quote.h
index fc5481e78a..a6c4611c25 100644
--- a/quote.h
+++ b/quote.h
@@ -31,6 +31,7 @@
 extern char *sq_quote(const char *src);
 extern void sq_quote_print(FILE *stream, const char *src);
 extern size_t sq_quote_buf(char *dst, size_t n, const char *src);
+extern char *sq_quote_argv(const char** argv, int count);
 
 /* This unwraps what sq_quote() produces in place, but returns
  * NULL if the input does not look like what sq_quote would have
diff --git a/receive-pack.c b/receive-pack.c
index 201531626c..78f75da5ca 100644
--- a/receive-pack.c
+++ b/receive-pack.c
@@ -2,7 +2,6 @@
 #include "refs.h"
 #include "pkt-line.h"
 #include "run-command.h"
-#include <sys/wait.h>
 
 static const char receive_pack_usage[] = "git-receive-pack <git-dir>";
 
diff --git a/t/t5710-info-alternate.sh b/t/t5710-info-alternate.sh
index 2e1b48a89b..b9f6d96363 100755
--- a/t/t5710-info-alternate.sh
+++ b/t/t5710-info-alternate.sh
@@ -58,6 +58,8 @@ test_expect_failure 'creating too deep nesting' \
 git clone -l -s D E &&
 git clone -l -s E F &&
 git clone -l -s F G &&
+git clone -l -s G H &&
+cd H &&
 test_valid_repo'
 
 cd "$base_dir"
diff --git a/t/test-lib.sh b/t/test-lib.sh
index b6d119af95..695243efad 100755
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -28,7 +28,6 @@ unset GIT_DIR
 unset GIT_EXTERNAL_DIFF
 unset GIT_INDEX_FILE
 unset GIT_OBJECT_DIRECTORY
-unset GIT_TRACE
 unset SHA1_FILE_DIRECTORIES
 unset SHA1_FILE_DIRECTORY
 export GIT_AUTHOR_EMAIL GIT_AUTHOR_NAME
diff --git a/trace.c b/trace.c
new file mode 100644
index 0000000000..90847c3fd8
--- /dev/null
+++ b/trace.c
@@ -0,0 +1,125 @@
+/*
+ * GIT - The information manager from hell
+ *
+ * Copyright (C) 2000-2002 Michael R. Elkins <me@mutt.org>
+ * Copyright (C) 2002-2004 Oswald Buddenhagen <ossi@users.sf.net>
+ * Copyright (C) 2004 Theodore Y. Ts'o <tytso@mit.edu>
+ * Copyright (C) 2006 Mike McCormack
+ * Copyright (C) 2006 Christian Couder
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include "cache.h"
+#include "quote.h"
+
+/* Stolen from "imap-send.c". */
+static int git_vasprintf(char **strp, const char *fmt, va_list ap)
+{
+	int len;
+	char tmp[1024];
+
+	if ((len = vsnprintf(tmp, sizeof(tmp), fmt, ap)) < 0 ||
+	    !(*strp = xmalloc(len + 1)))
+		return -1;
+	if (len >= (int)sizeof(tmp))
+		vsprintf(*strp, fmt, ap);
+	else
+		memcpy(*strp, tmp, len + 1);
+	return len;
+}
+
+/* Stolen from "imap-send.c". */
+int nfvasprintf(char **str, const char *fmt, va_list va)
+{
+	int ret = git_vasprintf(str, fmt, va);
+	if (ret < 0)
+		die("Fatal: Out of memory\n");
+	return ret;
+}
+
+/* Get a trace file descriptor from GIT_TRACE env variable. */
+static int get_trace_fd()
+{
+	char *trace = getenv("GIT_TRACE");
+
+	if (!trace || !strcmp(trace, "0") || !strcasecmp(trace," false"))
+		return 0;
+	if (!strcmp(trace, "1") || !strcasecmp(trace, "true"))
+		return STDERR_FILENO;
+	if (strlen(trace) == 1 && isdigit(*trace))
+		return atoi(trace);
+
+	fprintf(stderr, "What does '%s' for GIT_TRACE means ?\n", trace);
+	fprintf(stderr, "Defaulting to tracing on stderr...\n");
+	return STDERR_FILENO;
+}
+
+static const char err_msg[] = "Could not trace into fd given by "
+	"GIT_TRACE environment variable";
+
+void trace_printf(const char *format, ...)
+{
+	char *trace_str;
+	va_list rest;
+	int fd = get_trace_fd();
+
+	if (!fd)
+		return;
+
+	va_start(rest, format);
+	nfvasprintf(&trace_str, format, rest);
+	va_end(rest);
+
+	write_or_whine(fd, trace_str, strlen(trace_str), err_msg);
+
+	free(trace_str);
+}
+
+void trace_argv_printf(const char **argv, int count, const char *format, ...)
+{
+	char *argv_str, *format_str, *trace_str;
+	size_t argv_len, format_len, trace_len;
+	va_list rest;
+	int fd = get_trace_fd();
+
+	if (!fd)
+		return;
+
+	/* Get the argv string. */
+	argv_str = sq_quote_argv(argv, count);
+	argv_len = strlen(argv_str);
+
+	/* Get the formated string. */
+	va_start(rest, format);
+	nfvasprintf(&format_str, format, rest);
+	va_end(rest);
+
+	/* Allocate buffer for trace string. */
+	format_len = strlen(format_str);
+	trace_len = argv_len + format_len + 1; /* + 1 for \n */
+	trace_str = xmalloc(trace_len + 1);
+
+	/* Copy everything into the trace string. */
+	strncpy(trace_str, format_str, format_len);
+	strncpy(trace_str + format_len, argv_str, argv_len);
+	strcpy(trace_str + trace_len - 1, "\n");
+
+	write_or_whine(fd, trace_str, trace_len, err_msg);
+
+	free(argv_str);
+	free(format_str);
+	free(trace_str);
+}
diff --git a/write_or_die.c b/write_or_die.c
index ab4cb8a69c..bfe4eeb649 100644
--- a/write_or_die.c
+++ b/write_or_die.c
@@ -18,3 +18,28 @@ void write_or_die(int fd, const void *buf, size_t count)
 		p += written;
 	}
 }
+
+int write_or_whine(int fd, const void *buf, size_t count, const char *msg)
+{
+	const char *p = buf;
+	ssize_t written;
+
+	while (count > 0) {
+		written = xwrite(fd, p, count);
+		if (written == 0) {
+			fprintf(stderr, "%s: disk full?\n", msg);
+			return 0;
+		}
+		else if (written < 0) {
+			if (errno == EPIPE)
+				exit(0);
+			fprintf(stderr, "%s: write error (%s)\n",
+				msg, strerror(errno));
+			return 0;
+		}
+		count -= written;
+		p += written;
+	}
+
+	return 1;
+}