Merge branch 'rj/add-p-pager'

A 'P' command to "git add -p" that passes the patch hunk to the
pager has been added.

* rj/add-p-pager:
  add-patch: render hunks through the pager
  pager: introduce wait_for_pager
  pager: do not close fd 2 unnecessarily
  add-patch: test for 'p' command

4 files changed, 107 insertions, 8 deletions

diff --git a/add-patch.c b/add-patch.c
index 46f6bddfe5..1cec4ab67b 100644
--- a/add-patch.c
+++ b/add-patch.c
@@ -7,9 +7,11 @@
 #include "environment.h"
 #include "gettext.h"
 #include "object-name.h"
+#include "pager.h"
 #include "read-cache-ll.h"
 #include "repository.h"
 #include "strbuf.h"
+#include "sigchain.h"
 #include "run-command.h"
 #include "strvec.h"
 #include "pathspec.h"
@@ -1398,7 +1400,7 @@ N_("j - leave this hunk undecided, see next undecided hunk\n"
    "/ - search for a hunk matching the given regex\n"
    "s - split the current hunk into smaller hunks\n"
    "e - manually edit the current hunk\n"
-   "p - print the current hunk\n"
+   "p - print the current hunk, 'P' to use the pager\n"
    "? - print help\n");
 
 static int patch_update_file(struct add_p_state *s,
@@ -1409,7 +1411,7 @@ static int patch_update_file(struct add_p_state *s,
 	struct hunk *hunk;
 	char ch;
 	struct child_process cp = CHILD_PROCESS_INIT;
-	int colored = !!s->colored.len, quit = 0;
+	int colored = !!s->colored.len, quit = 0, use_pager = 0;
 	enum prompt_mode_type prompt_mode_type;
 	enum {
 		ALLOW_GOTO_PREVIOUS_HUNK = 1 << 0,
@@ -1459,9 +1461,18 @@ static int patch_update_file(struct add_p_state *s,
 		strbuf_reset(&s->buf);
 		if (file_diff->hunk_nr) {
 			if (rendered_hunk_index != hunk_index) {
+				if (use_pager) {
+					setup_pager();
+					sigchain_push(SIGPIPE, SIG_IGN);
+				}
 				render_hunk(s, hunk, 0, colored, &s->buf);
 				fputs(s->buf.buf, stdout);
 				rendered_hunk_index = hunk_index;
+				if (use_pager) {
+					sigchain_pop(SIGPIPE);
+					wait_for_pager();
+					use_pager = 0;
+				}
 			}
 
 			strbuf_reset(&s->buf);
@@ -1682,8 +1693,9 @@ soft_increment:
 				hunk->use = USE_HUNK;
 				goto soft_increment;
 			}
-		} else if (s->answer.buf[0] == 'p') {
+		} else if (ch == 'p') {
 			rendered_hunk_index = -1;
+			use_pager = (s->answer.buf[0] == 'P') ? 1 : 0;
 		} else if (s->answer.buf[0] == '?') {
 			const char *p = _(help_patch_remainder), *eol = p;
 
diff --git a/pager.c b/pager.c
index be6f4ee59f..896f40fcd2 100644
--- a/pager.c
+++ b/pager.c
@@ -14,6 +14,7 @@ int pager_use_color = 1;
 
 static struct child_process pager_process;
 static char *pager_program;
+static int old_fd1 = -1, old_fd2 = -1;
 
 /* Is the value coming back from term_columns() just a guess? */
 static int term_columns_guessed;
@@ -23,10 +24,11 @@ static void close_pager_fds(void)
 {
 	/* signal EOF to pager */
 	close(1);
-	close(2);
+	if (old_fd2 != -1)
+		close(2);
 }
 
-static void wait_for_pager_atexit(void)
+static void finish_pager(void)
 {
 	fflush(stdout);
 	fflush(stderr);
@@ -34,8 +36,37 @@ static void wait_for_pager_atexit(void)
 	finish_command(&pager_process);
 }
 
+static void wait_for_pager_atexit(void)
+{
+	if (old_fd1 == -1)
+		return;
+
+	finish_pager();
+}
+
+void wait_for_pager(void)
+{
+	if (old_fd1 == -1)
+		return;
+
+	finish_pager();
+	sigchain_pop_common();
+	unsetenv("GIT_PAGER_IN_USE");
+	dup2(old_fd1, 1);
+	close(old_fd1);
+	old_fd1 = -1;
+	if (old_fd2 != -1) {
+		dup2(old_fd2, 2);
+		close(old_fd2);
+		old_fd2 = -1;
+	}
+}
+
 static void wait_for_pager_signal(int signo)
 {
+	if (old_fd1 == -1)
+		return;
+
 	close_pager_fds();
 	finish_command_in_signal(&pager_process);
 	sigchain_pop(signo);
@@ -111,6 +142,7 @@ void prepare_pager_args(struct child_process *pager_process, const char *pager)
 
 void setup_pager(void)
 {
+	static int once = 0;
 	const char *pager = git_pager(isatty(1));
 
 	if (!pager)
@@ -140,14 +172,20 @@ void setup_pager(void)
 		die("unable to execute pager '%s'", pager);
 
 	/* original process continues, but writes to the pipe */
+	old_fd1 = dup(1);
 	dup2(pager_process.in, 1);
-	if (isatty(2))
+	if (isatty(2)) {
+		old_fd2 = dup(2);
 		dup2(pager_process.in, 2);
+	}
 	close(pager_process.in);
 
-	/* this makes sure that the parent terminates after the pager */
 	sigchain_push_common(wait_for_pager_signal);
-	atexit(wait_for_pager_atexit);
+
+	if (!once) {
+		once++;
+		atexit(wait_for_pager_atexit);
+	}
 }
 
 int pager_in_use(void)
diff --git a/pager.h b/pager.h
index b77433026d..103ecac476 100644
--- a/pager.h
+++ b/pager.h
@@ -5,6 +5,7 @@ struct child_process;
 
 const char *git_pager(int stdout_is_tty);
 void setup_pager(void);
+void wait_for_pager(void);
 int pager_in_use(void);
 int term_columns(void);
 void term_clear_line(void);
diff --git a/t/t3701-add-interactive.sh b/t/t3701-add-interactive.sh
index 9a48933cec..718438ffc7 100755
--- a/t/t3701-add-interactive.sh
+++ b/t/t3701-add-interactive.sh
@@ -575,6 +575,54 @@ test_expect_success 'navigate to hunk via regex / pattern' '
 	test_cmp expect actual.trimmed
 '
 
+test_expect_success 'print again the hunk' '
+	test_when_finished "git reset" &&
+	tr _ " " >expect <<-EOF &&
+	+15
+	 20
+	(1/2) Stage this hunk [y,n,q,a,d,j,J,g,/,e,p,?]? @@ -1,2 +1,3 @@
+	 10
+	+15
+	 20
+	(1/2) Stage this hunk [y,n,q,a,d,j,J,g,/,e,p,?]?_
+	EOF
+	test_write_lines s y g 1 p | git add -p >actual &&
+	tail -n 7 <actual >actual.trimmed &&
+	test_cmp expect actual.trimmed
+'
+
+test_expect_success TTY 'print again the hunk (PAGER)' '
+	test_when_finished "git reset" &&
+	cat >expect <<-EOF &&
+	<GREEN>+<RESET><GREEN>15<RESET>
+	 20<RESET>
+	<BOLD;BLUE>(1/2) Stage this hunk [y,n,q,a,d,j,J,g,/,e,p,?]? <RESET>PAGER <CYAN>@@ -1,2 +1,3 @@<RESET>
+	PAGER  10<RESET>
+	PAGER <GREEN>+<RESET><GREEN>15<RESET>
+	PAGER  20<RESET>
+	<BOLD;BLUE>(1/2) Stage this hunk [y,n,q,a,d,j,J,g,/,e,p,?]? <RESET>
+	EOF
+	test_write_lines s y g 1 P |
+	(
+		GIT_PAGER="sed s/^/PAGER\ /" &&
+		export GIT_PAGER &&
+		test_terminal git add -p >actual
+	) &&
+	tail -n 7 <actual | test_decode_color >actual.trimmed &&
+	test_cmp expect actual.trimmed
+'
+
+test_expect_success TTY 'P handles SIGPIPE when writing to pager' '
+	test_when_finished "rm -f huge_file; git reset" &&
+	printf "\n%2500000s" Y >huge_file &&
+	git add -N huge_file &&
+	test_write_lines P q | (
+		GIT_PAGER="head -n 1" &&
+		export GIT_PAGER &&
+		test_terminal git add -p
+	)
+'
+
 test_expect_success 'split hunk "add -p (edit)"' '
 	# Split, say Edit and do nothing.  Then:
 	#