[PATCH 1/2] pager: introduce wait_for_pager
- From
Rubén Justo <rjusto@gmail.com>
- Date
- Jul 25, 2024, 16:43 UTC
- Message-ID
- <2ec2a894-a173-469c-8211-ac5f49a82a27@gmail.com>
- In-Reply-To
- <24e83a0f-b0c8-4cd5-b321-1d7702b844ce@gmail.com>
Since f67b45f862 (Introduce trivial new pager.c helper infrastructure, 2006-02-28) we have the machinery to send our output to a pager.
That machinery, once set up, does not allow us to regain the original stdio streams.
In the interactive commands (i.e.: add -p) we want to use the pager for some output, while maintaining the interaction with the user.
Modify the pager machinery so that we can use `setup_pager()` and, once we've finished sending the desired output for the pager, wait for the pager termination using a new function `wait_for_pager()`. Make this function reset the pager machinery before returning.
One specific point to note is that we avoid forking the pager in `setup_pager()` if the configured pager is an empty string [*1*] or simply "cat" [*2*]. In these cases, `setup_pager()` does nothing and therefore `wait_for_pager()` should not be called.
We could modify `setup_pager()` to return an indication of these situations, so we could avoid calling `wait_for_pager()`.
However, let's avoid transferring that responsibility to the caller and instead treat the call to `wait_for_pager()` as a no-op when we know we haven't forked the pager.
1.- 402461aab1 (pager: do not fork a pager if PAGER is set to empty.,
2006-04-16)2.- caef71a535 (Do not fork PAGER=cat, 2006-04-16)
Signed-off-by: Rubén Justo <rjusto@gmail.com> --- pager.c | 46 ++++++++++++++++++++++++++++++++++++++++------ pager.h | 1 + 2 files changed, 41 insertions(+), 6 deletions(-)
diff --git a/pager.c b/pager.c index 251adfc2ad..896f40fcd2 100644 --- a/pager.c +++ b/pager.c @@ -14,7 +14,7 @@ int pager_use_color = 1; static struct child_process pager_process; static char *pager_program; -static int close_fd2; +static int old_fd1 = -1, old_fd2 = -1; /* Is the value coming back from term_columns() just a guess? */ static int term_columns_guessed; @@ -24,11 +24,11 @@ static void close_pager_fds(void) { /* signal EOF to pager */ close(1); - if (close_fd2) + if (old_fd2 != -1) close(2); } -static void wait_for_pager_atexit(void) +static void finish_pager(void) { fflush(stdout); fflush(stderr); @@ -36,8 +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); @@ -113,6 +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) @@ -142,16 +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)) { - close_fd2 = 1; + 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);
-- 2.46.0.rc0.4.g6f4990c0d4