[PATCH v1 1/8] compat/terminal: let prompt accept input from pipe

[Firmin Martin <firminmartin24@gmail.com>]

Currently, git_prompt ignores input coming from anywhere other than
terminal (pipe, redirection etc.) meaning that standard prompt
auto-answering methods would have no effect:

        echo 'Y' | git ...
        yes 'Y' | git ...
        git ... <input.txt

It also prevents git subcommands using git_prompt to be tested using
such methods.

This patch fixes this issue by considering standard input when !isatty(0).
It also rearranges the control flow to close input and output file handlers.

Signed-off-by: Firmin Martin <firminmartin24@gmail.com>
---
 compat/terminal.c | 47 ++++++++++++++++++++++++++++-------------------
 1 file changed, 28 insertions(+), 19 deletions(-)

diff --git a/compat/terminal.c b/compat/terminal.c
index 43b73ddc75..c12e0b9ab9 100644
--- a/compat/terminal.c
+++ b/compat/terminal.c
@@ -202,41 +202,50 @@ static int mingw_getchar(void)
 char *git_terminal_prompt(const char *prompt, int echo)
 {
 	static struct strbuf buf = STRBUF_INIT;
-	int r;
-	FILE *input_fh, *output_fh;
+	int r, input_not_from_tty = !isatty(STDIN_FILENO);
+	FILE *input_fh = NULL, *output_fh = NULL;
+	char* ret = NULL;
+
+	if (input_not_from_tty) 
+		input_fh = stdin;
+	else
+		input_fh = fopen(INPUT_PATH, "r" FORCE_TEXT);
 
-	input_fh = fopen(INPUT_PATH, "r" FORCE_TEXT);
 	if (!input_fh)
-		return NULL;
+		goto done;
 
 	output_fh = fopen(OUTPUT_PATH, "w" FORCE_TEXT);
-	if (!output_fh) {
-		fclose(input_fh);
-		return NULL;
-	}
 
-	if (!echo && disable_echo()) {
-		fclose(input_fh);
-		fclose(output_fh);
-		return NULL;
-	}
+	if (!output_fh) 
+		goto done;
+
+	if (!echo && disable_echo()) 
+		goto done;
 
 	fputs(prompt, output_fh);
 	fflush(output_fh);
 
 	r = strbuf_getline_lf(&buf, input_fh);
-	if (!echo) {
+
+	if (input_not_from_tty) 
+		fputs(buf.buf, output_fh);
+
+	if (!echo || input_not_from_tty) {
 		putc('\n', output_fh);
 		fflush(output_fh);
 	}
 
 	restore_term();
-	fclose(input_fh);
-	fclose(output_fh);
 
-	if (r == EOF)
-		return NULL;
-	return buf.buf;
+	if (r != EOF)
+		ret = buf.buf;
+done:
+	if (input_fh && input_fh != stdin) 
+		fclose(input_fh);
+	if (output_fh)
+		fclose(output_fh);
+
+	return ret;
 }
 
 /*
-- 
2.31.1.449.g4a44fa8106