format-patch --attach/--inline use filename instead of SHA1

index 8af55d2..cc6d663 100644
@@ -519,21 +519,17 @@ static int git_format_config(const char *var, const char *value, void *cb)
 }
 
 
-static const char *get_oneline_for_filename(struct commit *commit,
-					    int keep_subject)
+static const char *get_patch_filename(char* sol, int keep_subject, int nr)
 {
 	static char filename[PATH_MAX];
-	char *sol;
 	int len = 0;
 	int suffix_len = strlen(fmt_patch_suffix) + 1;
 
-	sol = strstr(commit->buffer, "\n\n");
-	if (!sol)
-		filename[0] = '\0';
-	else {
+	if (sol)
+	{
 		int j, space = 0;
 
-		sol += 2;
+		len += sprintf(filename, "%04d-", nr);
 		/* strip [PATCH] or [PATCH blabla] */
 		if (!keep_subject && !prefixcmp(sol, "[PATCH")) {
 			char *eos = strchr(sol + 6, ']');

@@ -564,8 +560,11 @@ static const char *get_oneline_for_filename(struct commit *commit,
 		while (filename[len - 1] == '.'
 		       || filename[len - 1] == '-')
 			len--;
-		filename[len] = '\0';
+		strcpy(filename + len, fmt_patch_suffix);
 	}
+	else
+		sprintf(filename, "%d", nr);
+
 	return filename;
 }
 

@@ -573,7 +572,7 @@ static FILE *realstdout = NULL;
 static const char *output_directory = NULL;
 static int outdir_offset;
 
-static int reopen_stdout(const char *oneline, int nr, struct rev_info *rev)
+static int reopen_stdout(const char *oneline, struct rev_info *rev)
 {
 	char filename[PATH_MAX];
 	int len = 0;

@@ -588,15 +587,7 @@ static int reopen_stdout(const char *oneline, int nr, struct rev_info *rev)
 		if (filename[len - 1] != '/')
 			filename[len++] = '/';
 	}
-
-	if (!oneline)
-		len += sprintf(filename + len, "%d", nr);
-	else {
-		len += sprintf(filename + len, "%04d-", nr);
-		len += snprintf(filename + len, sizeof(filename) - len - 1
-				- suffix_len, "%s", oneline);
-		strcpy(filename + len, fmt_patch_suffix);
-	}
+	strncpy(filename+len, oneline, PATH_MAX-len-1);
 
 	if (!DIFF_OPT_TST(&rev->diffopt, QUIET))
 		fprintf(realstdout, "%s\n", filename + outdir_offset);

@@ -688,8 +679,9 @@ static void make_cover_letter(struct rev_info *rev, int use_stdout,
 	if (rev->commit_format != CMIT_FMT_EMAIL)
 		die("Cover letter needs email format");
 
-	if (!use_stdout && reopen_stdout(numbered_files ?
-				NULL : "cover-letter", 0, rev))
+	if (!use_stdout && reopen_stdout(get_patch_filename(numbered_files ?
+							NULL : "cover-letter",
+							0, 0), rev))
 		return;
 
 	head_sha1 = sha1_to_hex(head->object.sha1);

@@ -802,6 +794,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	struct patch_ids ids;
 	char *add_signoff = NULL;
 	struct strbuf buf = STRBUF_INIT;
+	char *sol = NULL;
 
 	git_config(git_format_config, NULL);
 	init_revisions(&rev, prefix);

@@ -1106,9 +1099,17 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 			}
 			gen_message_id(&rev, sha1_to_hex(commit->object.sha1));
 		}
-		if (!use_stdout && reopen_stdout(numbered_files ? NULL :
-				get_oneline_for_filename(commit, keep_subject),
-				rev.nr, &rev))
+		/*
+		 * If we're outputting numbered files we don't need a subject
+		 * line. Otherwise we want the subject line of the commit
+		 * message which starts after the first double newline
+		 * occurence in the commit buffer.
+		 */
+		if (!numbered_files && (sol = strstr(commit->buffer, "\n\n")))
+			sol += 2;
+		if (!use_stdout && reopen_stdout(get_patch_filename(sol,
+								keep_subject,
+								rev.nr), &rev))
 			die("Failed to create output files");
 		shown = log_tree_commit(&rev, commit);
 		free(commit->buffer);

index cc6d663..8ea25e0 100644
@@ -1107,9 +1107,9 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		 */
 		if (!numbered_files && (sol = strstr(commit->buffer, "\n\n")))
 			sol += 2;
-		if (!use_stdout && reopen_stdout(get_patch_filename(sol,
-								keep_subject,
-								rev.nr), &rev))
+		rev.fmt_patch_filename = get_patch_filename(sol, keep_subject,
+								rev.nr);
+		if (!use_stdout && reopen_stdout(rev.fmt_patch_filename, &rev))
 			die("Failed to create output files");
 		shown = log_tree_commit(&rev, commit);
 		free(commit->buffer);

index 9565c18..dc37d16 100644
@@ -245,14 +245,14 @@ void log_write_email_headers(struct rev_info *opt, const char *name,
 		snprintf(buffer, sizeof(buffer) - 1,
 			 "\n--%s%s\n"
 			 "Content-Type: text/x-patch;"
-			 " name=\"%s.diff\"\n"
+			 " name=\"%s\"\n"
 			 "Content-Transfer-Encoding: 8bit\n"
 			 "Content-Disposition: %s;"
-			 " filename=\"%s.diff\"\n\n",
+			 " filename=\"%s\"\n\n",
 			 mime_boundary_leader, opt->mime_boundary,
-			 name,
+			 opt->fmt_patch_filename,
 			 opt->no_inline ? "attachment" : "inline",
-			 name);
+			 opt->fmt_patch_filename);
 		opt->diffopt.stat_sep = buffer;
 	}
 	*subject_p = subject;

index ad123d7..c34eac9 100644
@@ -86,6 +86,7 @@ struct rev_info {
 	struct log_info *loginfo;
 	int		nr, total;
 	const char	*mime_boundary;
+	const char	*fmt_patch_filename;
 	char		*message_id;
 	struct string_list *ref_message_ids;
 	const char	*add_signoff;

index 8ea25e0..f81d3a3 100644
@@ -951,8 +951,6 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		die ("-n and -k are mutually exclusive.");
 	if (keep_subject && subject_prefix)
 		die ("--subject-prefix and -k are mutually exclusive.");
-	if (numbered_files && use_stdout)
-		die ("--numbered-files and --stdout are mutually exclusive.");
 
 	argc = setup_revisions(argc, argv, &rev, "HEAD");
 	if (argc > 1)

index efa7024..97de415 100644
@@ -493,6 +493,41 @@ static void parse_commit_header(struct format_commit_context *context)
 	context->commit_header_parsed = 1;
 }
 
+static int istitlechar(char c)
+{
+	return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+		(c >= '0' && c <= '9') || c == '.' || c == '_';
+}
+
+static void format_sanitized_subject(struct strbuf *sb, const char *msg)
+{
+	size_t trimlen;
+	int space = 0;
+
+	for (; *msg && *msg != '\n'; msg++) {
+		if (istitlechar(*msg))
+		{
+		    if (space) {
+			strbuf_addch(sb, '-');
+			space = 0;
+		    }
+		    strbuf_addch(sb, *msg);
+		    if (*msg == '.')
+			while (*(msg+1) == '.')
+				msg++;
+		}
+		else
+			space = 1;
+	}
+
+	// trim any trailing '.' or '-' characters
+	trimlen = 0;
+	while (sb->buf[sb->len - 1 - trimlen] == '.'
+		|| sb->buf[sb->len - 1 - trimlen] == '-')
+		trimlen++;
+	strbuf_remove(sb, sb->len - trimlen, trimlen);
+}
+
 const char *format_subject(struct strbuf *sb, const char *msg,
 			   const char *line_separator)
 {

@@ -683,6 +718,9 @@ static size_t format_commit_item(struct strbuf *sb, const char *placeholder,
 	case 's':	/* subject */
 		format_subject(sb, msg + c->subject_off, " ");
 		return 1;
+	case 'f':	/* sanitized subject */
+		format_sanitized_subject(sb, msg + c->subject_off);
+		return 1;
 	case 'b':	/* body */
 		strbuf_addstr(sb, msg + c->body_off);
 		return 1;

index c7a5772..54ef248 100644
@@ -419,12 +419,6 @@ int cmd_log(int argc, const char **argv, const char *prefix)
 /* format-patch */
 #define FORMAT_PATCH_NAME_MAX 64
 
-static int istitlechar(char c)
-{
-	return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
-		(c >= '0' && c <= '9') || c == '.' || c == '_';
-}
-
 static const char *fmt_patch_suffix = ".patch";
 static int numbered = 0;
 static int auto_number = 1;

@@ -519,61 +513,34 @@ static int git_format_config(const char *var, const char *value, void *cb)
 }
 
 
-static const char *get_oneline_for_filename(struct commit *commit,
-					    int keep_subject)
+static void get_patch_filename(struct commit *commit, int nr,
+			       const char *suffix, struct strbuf *buf)
 {
-	static char filename[PATH_MAX];
-	char *sol;
-	int len = 0;
-	int suffix_len = strlen(fmt_patch_suffix) + 1;
-
-	sol = strstr(commit->buffer, "\n\n");
-	if (!sol)
-		filename[0] = '\0';
-	else {
-		int j, space = 0;
-
-		sol += 2;
-		/* strip [PATCH] or [PATCH blabla] */
-		if (!keep_subject && !prefixcmp(sol, "[PATCH")) {
-			char *eos = strchr(sol + 6, ']');
-			if (eos) {
-				while (isspace(*eos))
-					eos++;
-				sol = eos;
-			}
-		}
+	int suffix_len = strlen(suffix) + 1;
+	int start_len = buf->len;
 
-		for (j = 0;
-		     j < FORMAT_PATCH_NAME_MAX - suffix_len - 5 &&
-			     len < sizeof(filename) - suffix_len &&
-			     sol[j] && sol[j] != '\n';
-		     j++) {
-			if (istitlechar(sol[j])) {
-				if (space) {
-					filename[len++] = '-';
-					space = 0;
-				}
-				filename[len++] = sol[j];
-				if (sol[j] == '.')
-					while (sol[j + 1] == '.')
-						j++;
-			} else
-				space = 1;
-		}
-		while (filename[len - 1] == '.'
-		       || filename[len - 1] == '-')
-			len--;
-		filename[len] = '\0';
+	strbuf_addf(buf, commit ? "%04d-" : "%d", nr);
+	if (commit)
+	{
+		format_commit_message(commit, "%f", buf, DATE_NORMAL);
+		/*
+		 * Replace characters at the end with the suffix if the the
+		 * filename is too long
+		 */
+		if (buf->len + suffix_len > FORMAT_PATCH_NAME_MAX + start_len)
+			strbuf_splice(buf,
+				start_len + FORMAT_PATCH_NAME_MAX - suffix_len,
+				suffix_len, suffix, suffix_len);
+		else
+			strbuf_addstr(buf, suffix);
 	}
-	return filename;
 }
 
 static FILE *realstdout = NULL;
 static const char *output_directory = NULL;
 static int outdir_offset;
 
-static int reopen_stdout(const char *oneline, int nr, struct rev_info *rev)
+static int reopen_stdout(const char *oneline, struct rev_info *rev)
 {
 	char filename[PATH_MAX];
 	int len = 0;

@@ -589,14 +556,7 @@ static int reopen_stdout(const char *oneline, int nr, struct rev_info *rev)
 			filename[len++] = '/';
 	}
 
-	if (!oneline)
-		len += sprintf(filename + len, "%d", nr);
-	else {
-		len += sprintf(filename + len, "%04d-", nr);
-		len += snprintf(filename + len, sizeof(filename) - len - 1
-				- suffix_len, "%s", oneline);
-		strcpy(filename + len, fmt_patch_suffix);
-	}
+	strncpy(filename + len, oneline, PATH_MAX - len);
 
 	if (!DIFF_OPT_TST(&rev->diffopt, QUIET))
 		fprintf(realstdout, "%s\n", filename + outdir_offset);

@@ -684,12 +644,17 @@ static void make_cover_letter(struct rev_info *rev, int use_stdout,
 	const char *encoding = "utf-8";
 	struct diff_options opts;
 	int need_8bit_cte = 0;
+	char filename[PATH_MAX];
 
 	if (rev->commit_format != CMIT_FMT_EMAIL)
 		die("Cover letter needs email format");
 
-	if (!use_stdout && reopen_stdout(numbered_files ?
-				NULL : "cover-letter", 0, rev))
+	if (numbered_files)
+	    sprintf(filename, "0");
+	else
+	    sprintf(filename, "%04d-cover-letter%s", 0, fmt_patch_suffix);
+
+	if (!use_stdout && reopen_stdout(filename, rev))
 		return;
 
 	head_sha1 = sha1_to_hex(head->object.sha1);

@@ -802,6 +767,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	struct patch_ids ids;
 	char *add_signoff = NULL;
 	struct strbuf buf = STRBUF_INIT;
+	struct strbuf patch_filename = STRBUF_INIT;
 
 	git_config(git_format_config, NULL);
 	init_revisions(&rev, prefix);

@@ -1104,10 +1070,12 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 			}
 			gen_message_id(&rev, sha1_to_hex(commit->object.sha1));
 		}
-		if (!use_stdout && reopen_stdout(numbered_files ? NULL :
-				get_oneline_for_filename(commit, keep_subject),
-				rev.nr, &rev))
+
+		get_patch_filename(numbered_files ? NULL : commit, rev.nr,
+				    fmt_patch_suffix, &patch_filename);
+		if (!use_stdout && reopen_stdout(patch_filename.buf, &rev))
 			die("Failed to create output files");
+		strbuf_setlen(&patch_filename, 0);
 		shown = log_tree_commit(&rev, commit);
 		free(commit->buffer);
 		commit->buffer = NULL;

@@ -1131,6 +1099,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		if (!use_stdout)
 			fclose(stdout);
 	}
+	strbuf_release(&patch_filename);
 	free(list);
 	if (ignore_if_in_upstream)
 		free_patch_ids(&ids);

index 54ef248..392b16a 100644
@@ -540,30 +540,29 @@ static FILE *realstdout = NULL;
 static const char *output_directory = NULL;
 static int outdir_offset;
 
-static int reopen_stdout(const char *oneline, struct rev_info *rev)
+static int reopen_stdout(struct commit *commit, struct rev_info *rev)
 {
-	char filename[PATH_MAX];
-	int len = 0;
+	struct strbuf filename = STRBUF_INIT;
 	int suffix_len = strlen(fmt_patch_suffix) + 1;
 
 	if (output_directory) {
-		len = snprintf(filename, sizeof(filename), "%s",
-				output_directory);
-		if (len >=
-		    sizeof(filename) - FORMAT_PATCH_NAME_MAX - suffix_len)
+		strbuf_addstr(&filename, output_directory);
+		if (filename.len >=
+		    PATH_MAX - FORMAT_PATCH_NAME_MAX - suffix_len)
 			return error("name of output directory is too long");
-		if (filename[len - 1] != '/')
-			filename[len++] = '/';
+		if (filename.buf[filename.len - 1] != '/')
+			strbuf_addch(&filename, '/');
 	}
 
-	strncpy(filename + len, oneline, PATH_MAX - len);
+	get_patch_filename(commit, rev->nr, fmt_patch_suffix, &filename);
 
 	if (!DIFF_OPT_TST(&rev->diffopt, QUIET))
-		fprintf(realstdout, "%s\n", filename + outdir_offset);
+		fprintf(realstdout, "%s\n", filename.buf + outdir_offset);
 
-	if (freopen(filename, "w", stdout) == NULL)
-		return error("Cannot open patch file %s",filename);
+	if (freopen(filename.buf, "w", stdout) == NULL)
+		return error("Cannot open patch file %s", filename.buf);
 
+	strbuf_release(&filename);
 	return 0;
 }
 

@@ -644,26 +643,43 @@ static void make_cover_letter(struct rev_info *rev, int use_stdout,
 	const char *encoding = "utf-8";
 	struct diff_options opts;
 	int need_8bit_cte = 0;
-	char filename[PATH_MAX];
+	struct commit *commit = NULL;
 
 	if (rev->commit_format != CMIT_FMT_EMAIL)
 		die("Cover letter needs email format");
 
-	if (numbered_files)
-	    sprintf(filename, "0");
-	else
-	    sprintf(filename, "%04d-cover-letter%s", 0, fmt_patch_suffix);
+	committer = git_committer_info(0);
+	head_sha1 = sha1_to_hex(head->object.sha1);
+
+	if (!numbered_files)
+	{
+		/*
+		 * We fake a commit for the cover letter so we get the filename
+		 * desired.
+		 */
+		commit = xcalloc(1, sizeof(*commit));
+		commit->buffer = xmalloc(400);
+		snprintf(commit->buffer, 400,
+			"tree 0000000000000000000000000000000000000000\n"
+			"parent %s\n"
+			"author %s\n"
+			"committer %s\n\n"
+			"cover letter\n",
+			head_sha1, committer, committer);
+	}
 
-	if (!use_stdout && reopen_stdout(filename, rev))
+	if (!use_stdout && reopen_stdout(commit, rev))
 		return;
 
-	head_sha1 = sha1_to_hex(head->object.sha1);
+	if (commit)
+	{
+		free(commit->buffer);
+		free(commit);
+	}
 
 	log_write_email_headers(rev, head_sha1, &subject_start, &extra_headers,
 				&need_8bit_cte);
 
-	committer = git_committer_info(0);
-
 	msg = body;
 	pp_user_info(NULL, CMIT_FMT_EMAIL, &sb, committer, DATE_RFC2822,
 		     encoding);

@@ -767,7 +783,6 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	struct patch_ids ids;
 	char *add_signoff = NULL;
 	struct strbuf buf = STRBUF_INIT;
-	struct strbuf patch_filename = STRBUF_INIT;
 
 	git_config(git_format_config, NULL);
 	init_revisions(&rev, prefix);

@@ -1071,11 +1086,9 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 			gen_message_id(&rev, sha1_to_hex(commit->object.sha1));
 		}
 
-		get_patch_filename(numbered_files ? NULL : commit, rev.nr,
-				    fmt_patch_suffix, &patch_filename);
-		if (!use_stdout && reopen_stdout(patch_filename.buf, &rev))
+		if (!use_stdout && reopen_stdout(numbered_files ? NULL : commit,
+						 &rev))
 			die("Failed to create output files");
-		strbuf_setlen(&patch_filename, 0);
 		shown = log_tree_commit(&rev, commit);
 		free(commit->buffer);
 		commit->buffer = NULL;

@@ -1099,7 +1112,6 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		if (!use_stdout)
 			fclose(stdout);
 	}
-	strbuf_release(&patch_filename);
 	free(list);
 	if (ignore_if_in_upstream)
 		free_patch_ids(&ids);

index 392b16a..a8d6037 100644
@@ -417,7 +417,6 @@ int cmd_log(int argc, const char **argv, const char *prefix)
 }
 
 /* format-patch */
-#define FORMAT_PATCH_NAME_MAX 64
 
 static const char *fmt_patch_suffix = ".patch";
 static int numbered = 0;

@@ -512,30 +511,6 @@ static int git_format_config(const char *var, const char *value, void *cb)
 	return git_log_config(var, value, cb);
 }
 
-
-static void get_patch_filename(struct commit *commit, int nr,
-			       const char *suffix, struct strbuf *buf)
-{
-	int suffix_len = strlen(suffix) + 1;
-	int start_len = buf->len;
-
-	strbuf_addf(buf, commit ? "%04d-" : "%d", nr);
-	if (commit)
-	{
-		format_commit_message(commit, "%f", buf, DATE_NORMAL);
-		/*
-		 * Replace characters at the end with the suffix if the the
-		 * filename is too long
-		 */
-		if (buf->len + suffix_len > FORMAT_PATCH_NAME_MAX + start_len)
-			strbuf_splice(buf,
-				start_len + FORMAT_PATCH_NAME_MAX - suffix_len,
-				suffix_len, suffix, suffix_len);
-		else
-			strbuf_addstr(buf, suffix);
-	}
-}
-
 static FILE *realstdout = NULL;
 static const char *output_directory = NULL;
 static int outdir_offset;

index 9565c18..9a790ab 100644
@@ -179,6 +179,29 @@ static int has_non_ascii(const char *s)
 	return 0;
 }
 
+void get_patch_filename(struct commit *commit, int nr, const char *suffix,
+			struct strbuf *buf)
+{
+	int suffix_len = strlen(suffix) + 1;
+	int start_len = buf->len;
+
+	strbuf_addf(buf, commit ? "%04d-" : "%d", nr);
+	if (commit)
+	{
+		format_commit_message(commit, "%f", buf, DATE_NORMAL);
+		/*
+		 * Replace characters at the end with the suffix if the the
+		 * filename is too long
+		 */
+		if (buf->len + suffix_len > FORMAT_PATCH_NAME_MAX + start_len)
+			strbuf_splice(buf,
+				start_len + FORMAT_PATCH_NAME_MAX - suffix_len,
+				suffix_len, suffix, suffix_len);
+		else
+			strbuf_addstr(buf, suffix);
+	}
+}
+
 void log_write_email_headers(struct rev_info *opt, const char *name,
 			     const char **subject_p,
 			     const char **extra_headers_p,

index f2a9008..78dc5be 100644
@@ -19,4 +19,8 @@ void log_write_email_headers(struct rev_info *opt, const char *name,
 			     int *need_8bit_cte_p);
 void load_ref_decorations(void);
 
+#define FORMAT_PATCH_NAME_MAX 64
+void get_patch_filename(struct commit *commit, int nr, const char *suffix,
+			struct strbuf *buf);
+
 #endif

index a8d6037..83d8c03 100644
@@ -607,7 +607,6 @@ static void make_cover_letter(struct rev_info *rev, int use_stdout,
 			      int nr, struct commit **list, struct commit *head)
 {
 	const char *committer;
-	char *head_sha1;
 	const char *subject_start = NULL;
 	const char *body = "*** SUBJECT HERE ***\n\n*** BLURB HERE ***\n";
 	const char *msg;

@@ -624,7 +623,6 @@ static void make_cover_letter(struct rev_info *rev, int use_stdout,
 		die("Cover letter needs email format");
 
 	committer = git_committer_info(0);
-	head_sha1 = sha1_to_hex(head->object.sha1);
 
 	if (!numbered_files)
 	{

@@ -640,7 +638,7 @@ static void make_cover_letter(struct rev_info *rev, int use_stdout,
 			"author %s\n"
 			"committer %s\n\n"
 			"cover letter\n",
-			head_sha1, committer, committer);
+			sha1_to_hex(head->object.sha1), committer, committer);
 	}
 
 	if (!use_stdout && reopen_stdout(commit, rev))

@@ -652,7 +650,7 @@ static void make_cover_letter(struct rev_info *rev, int use_stdout,
 		free(commit);
 	}
 
-	log_write_email_headers(rev, head_sha1, &subject_start, &extra_headers,
+	log_write_email_headers(rev, head, &subject_start, &extra_headers,
 				&need_8bit_cte);
 
 	msg = body;

@@ -1012,6 +1010,8 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		const char *msgid = clean_message_id(in_reply_to);
 		string_list_append(msgid, rev.ref_message_ids);
 	}
+	rev.numbered_files = numbered_files;
+	rev.patch_suffix = fmt_patch_suffix;
 	if (cover_letter) {
 		if (thread)
 			gen_message_id(&rev, "cover");

index 9a790ab..5c9e2cf 100644
@@ -202,13 +202,14 @@ void get_patch_filename(struct commit *commit, int nr, const char *suffix,
 	}
 }
 
-void log_write_email_headers(struct rev_info *opt, const char *name,
+void log_write_email_headers(struct rev_info *opt, struct commit *commit,
 			     const char **subject_p,
 			     const char **extra_headers_p,
 			     int *need_8bit_cte_p)
 {
 	const char *subject = NULL;
 	const char *extra_headers = opt->extra_headers;
+	const char *name = sha1_to_hex(commit->object.sha1);
 
 	*need_8bit_cte_p = 0; /* unknown */
 	if (opt->total > 0) {

@@ -247,6 +248,7 @@ void log_write_email_headers(struct rev_info *opt, const char *name,
 	if (opt->mime_boundary) {
 		static char subject_buffer[1024];
 		static char buffer[1024];
+		struct strbuf filename =  STRBUF_INIT;
 		*need_8bit_cte_p = -1; /* NEVER */
 		snprintf(subject_buffer, sizeof(subject_buffer) - 1,
 			 "%s"

@@ -265,18 +267,21 @@ void log_write_email_headers(struct rev_info *opt, const char *name,
 			 mime_boundary_leader, opt->mime_boundary);
 		extra_headers = subject_buffer;
 
+		get_patch_filename(opt->numbered_files ? NULL : commit, opt->nr,
+				    opt->patch_suffix, &filename);
 		snprintf(buffer, sizeof(buffer) - 1,
 			 "\n--%s%s\n"
 			 "Content-Type: text/x-patch;"
-			 " name=\"%s.diff\"\n"
+			 " name=\"%s\"\n"
 			 "Content-Transfer-Encoding: 8bit\n"
 			 "Content-Disposition: %s;"
-			 " filename=\"%s.diff\"\n\n",
+			 " filename=\"%s\"\n\n",
 			 mime_boundary_leader, opt->mime_boundary,
-			 name,
+			 filename.buf,
 			 opt->no_inline ? "attachment" : "inline",
-			 name);
+			 filename.buf);
 		opt->diffopt.stat_sep = buffer;
+		strbuf_release(&filename);
 	}
 	*subject_p = subject;
 	*extra_headers_p = extra_headers;

@@ -356,8 +361,7 @@ void show_log(struct rev_info *opt)
 	 */
 
 	if (opt->commit_format == CMIT_FMT_EMAIL) {
-		log_write_email_headers(opt, sha1_to_hex(commit->object.sha1),
-					&subject, &extra_headers,
+		log_write_email_headers(opt, commit, &subject, &extra_headers,
 					&need_8bit_cte);
 	} else if (opt->commit_format != CMIT_FMT_USERFORMAT) {
 		fputs(diff_get_color_opt(&opt->diffopt, DIFF_COMMIT), stdout);

index 78dc5be..20b5caf 100644
@@ -13,7 +13,7 @@ int log_tree_commit(struct rev_info *, struct commit *);
 int log_tree_opt_parse(struct rev_info *, const char **, int);
 void show_log(struct rev_info *opt);
 void show_decorations(struct rev_info *opt, struct commit *commit);
-void log_write_email_headers(struct rev_info *opt, const char *name,
+void log_write_email_headers(struct rev_info *opt, struct commit *commit,
 			     const char **subject_p,
 			     const char **extra_headers_p,
 			     int *need_8bit_cte_p);

index ad123d7..5259ed5 100644
@@ -86,6 +86,8 @@ struct rev_info {
 	struct log_info *loginfo;
 	int		nr, total;
 	const char	*mime_boundary;
+	const char	*patch_suffix;
+	int		numbered_files;
 	char		*message_id;
 	struct string_list *ref_message_ids;
 	const char	*add_signoff;

index c57cef4..a0ef356 100644
@@ -502,6 +502,7 @@ static int istitlechar(char c)
 static void format_sanitized_subject(struct strbuf *sb, const char *msg)
 {
 	size_t trimlen;
+	size_t start_len = sb->len;
 	int space = 2;
 
 	for (; *msg && *msg != '\n'; msg++) {

@@ -519,8 +520,9 @@ static void format_sanitized_subject(struct strbuf *sb, const char *msg)
 
 	/* trim any trailing '.' or '-' characters */
 	trimlen = 0;
-	while (sb->buf[sb->len - 1 - trimlen] == '.'
-		|| sb->buf[sb->len - 1 - trimlen] == '-')
+	while (sb->len - trimlen > start_len &&
+		(sb->buf[sb->len - 1 - trimlen] == '.'
+		|| sb->buf[sb->len - 1 - trimlen] == '-'))
 		trimlen++;
 	strbuf_remove(sb, sb->len - trimlen, trimlen);
 }