git/pager.c
Junio C Hamano 4e18cd5ef7 Merge branch 'rj/pager-die-upon-exec-failure'
When GIT_PAGER failed to spawn, depending on the code path taken,
we failed immediately (correct) or just spew the payload to the
standard output (incorrect).  The code now always fail immediately
when GIT_PAGER fails.

* rj/pager-die-upon-exec-failure:
  pager: die when paging to non-existing command
2024-07-08 14:53:08 -07:00

267 lines
5.5 KiB
C

#include "git-compat-util.h"
#include "config.h"
#include "editor.h"
#include "pager.h"
#include "run-command.h"
#include "sigchain.h"
#include "alias.h"
int pager_use_color = 1;
#ifndef DEFAULT_PAGER
#define DEFAULT_PAGER "less"
#endif
static struct child_process pager_process;
static char *pager_program;
/* Is the value coming back from term_columns() just a guess? */
static int term_columns_guessed;
static void close_pager_fds(void)
{
/* signal EOF to pager */
close(1);
close(2);
}
static void wait_for_pager_atexit(void)
{
fflush(stdout);
fflush(stderr);
close_pager_fds();
finish_command(&pager_process);
}
static void wait_for_pager_signal(int signo)
{
close_pager_fds();
finish_command_in_signal(&pager_process);
sigchain_pop(signo);
raise(signo);
}
static int core_pager_config(const char *var, const char *value,
const struct config_context *ctx UNUSED,
void *data UNUSED)
{
if (!strcmp(var, "core.pager"))
return git_config_string(&pager_program, var, value);
return 0;
}
const char *git_pager(int stdout_is_tty)
{
const char *pager;
if (!stdout_is_tty)
return NULL;
pager = getenv("GIT_PAGER");
if (!pager) {
if (!pager_program)
read_early_config(core_pager_config, NULL);
pager = pager_program;
}
if (!pager)
pager = getenv("PAGER");
if (!pager)
pager = DEFAULT_PAGER;
if (!*pager || !strcmp(pager, "cat"))
pager = NULL;
return pager;
}
static void setup_pager_env(struct strvec *env)
{
const char **argv;
int i;
char *pager_env = xstrdup(PAGER_ENV);
int n = split_cmdline(pager_env, &argv);
if (n < 0)
die("malformed build-time PAGER_ENV: %s",
split_cmdline_strerror(n));
for (i = 0; i < n; i++) {
char *cp = strchr(argv[i], '=');
if (!cp)
die("malformed build-time PAGER_ENV");
*cp = '\0';
if (!getenv(argv[i])) {
*cp = '=';
strvec_push(env, argv[i]);
}
}
free(pager_env);
free(argv);
}
void prepare_pager_args(struct child_process *pager_process, const char *pager)
{
strvec_push(&pager_process->args, pager);
pager_process->use_shell = 1;
setup_pager_env(&pager_process->env);
pager_process->trace2_child_class = "pager";
}
void setup_pager(void)
{
const char *pager = git_pager(isatty(1));
if (!pager)
return;
/*
* After we redirect standard output, we won't be able to use an ioctl
* to get the terminal size. Let's grab it now, and then set $COLUMNS
* to communicate it to any sub-processes.
*/
{
char buf[64];
xsnprintf(buf, sizeof(buf), "%d", term_columns());
if (!term_columns_guessed)
setenv("COLUMNS", buf, 0);
}
setenv("GIT_PAGER_IN_USE", "true", 1);
child_process_init(&pager_process);
/* spawn the pager */
prepare_pager_args(&pager_process, pager);
pager_process.in = -1;
strvec_push(&pager_process.env, "GIT_PAGER_IN_USE");
if (start_command(&pager_process))
die("unable to execute pager '%s'", pager);
/* original process continues, but writes to the pipe */
dup2(pager_process.in, 1);
if (isatty(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);
}
int pager_in_use(void)
{
return git_env_bool("GIT_PAGER_IN_USE", 0);
}
/*
* Return cached value (if set) or $COLUMNS environment variable (if
* set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
* and default to 80 if all else fails.
*/
int term_columns(void)
{
static int term_columns_at_startup;
char *col_string;
int n_cols;
if (term_columns_at_startup)
return term_columns_at_startup;
term_columns_at_startup = 80;
term_columns_guessed = 1;
col_string = getenv("COLUMNS");
if (col_string && (n_cols = atoi(col_string)) > 0) {
term_columns_at_startup = n_cols;
term_columns_guessed = 0;
}
#ifdef TIOCGWINSZ
else {
struct winsize ws;
if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col) {
term_columns_at_startup = ws.ws_col;
term_columns_guessed = 0;
}
}
#endif
return term_columns_at_startup;
}
/*
* Clear the entire line, leave cursor in first column.
*/
void term_clear_line(void)
{
if (is_terminal_dumb())
/*
* Fall back to print a terminal width worth of space
* characters (hoping that the terminal is still as wide
* as it was upon the first call to term_columns()).
*/
fprintf(stderr, "\r%*s\r", term_columns(), "");
else
/*
* On non-dumb terminals use an escape sequence to clear
* the whole line, no matter how wide the terminal.
*/
fputs("\r\033[K", stderr);
}
/*
* How many columns do we need to show this number in decimal?
*/
int decimal_width(uintmax_t number)
{
int width;
for (width = 1; number >= 10; width++)
number /= 10;
return width;
}
struct pager_command_config_data {
const char *cmd;
int want;
char *value;
};
static int pager_command_config(const char *var, const char *value,
const struct config_context *ctx UNUSED,
void *vdata)
{
struct pager_command_config_data *data = vdata;
const char *cmd;
if (skip_prefix(var, "pager.", &cmd) && !strcmp(cmd, data->cmd)) {
int b = git_parse_maybe_bool(value);
if (b >= 0)
data->want = b;
else {
data->want = 1;
data->value = xstrdup(value);
}
}
return 0;
}
/* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
int check_pager_config(const char *cmd)
{
struct pager_command_config_data data;
data.cmd = cmd;
data.want = -1;
data.value = NULL;
read_early_config(pager_command_config, &data);
if (data.value)
pager_program = data.value;
return data.want;
}