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![Jeff King](/assets/img/avatar_default.png)
If the user specifies a pager of "cat" (or the empty string), whether it is in the environment or from config, we automagically optimize it out to mean "no pager" and avoid forking at all. We treat an empty pager variable similary. However, we did not apply this optimization when DEFAULT_PAGER was set to "cat" (or the empty string). There is no reason to treat DEFAULT_PAGER any differently. The optimization should not be user-visible (unless the user has a bizarre "cat" in their PATH). And even if it is, we are better off behaving consistently between the compile-time default and the environment and config settings. The stray "else" we are removing from this code was introduced by402461a
(pager: do not fork a pager if PAGER is set to empty., 2006-04-16). At that time, the line directly above used: if (!pager) pager = "less"; as a fallback, meaning that it could not possibly trigger the optimization. Later,a3d023d
(Provide a build time default-pager setting, 2009-10-30) turned that constant into a build-time setting which could be anything, but didn't loosen the "else" to let DEFAULT_PAGER use the optimization. Noticed-by: Dale R. Worley <worley@alum.mit.edu> Suggested-by: Matthieu Moy <Matthieu.Moy@grenoble-inp.fr> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
178 lines
3.5 KiB
C
178 lines
3.5 KiB
C
#include "cache.h"
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#include "run-command.h"
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#include "sigchain.h"
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#ifndef DEFAULT_PAGER
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#define DEFAULT_PAGER "less"
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#endif
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struct pager_config {
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const char *cmd;
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int want;
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char *value;
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};
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/*
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* This is split up from the rest of git so that we can do
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* something different on Windows.
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*/
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static const char *pager_argv[] = { NULL, NULL };
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static struct child_process pager_process;
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static void wait_for_pager(void)
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{
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fflush(stdout);
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fflush(stderr);
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/* signal EOF to pager */
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close(1);
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close(2);
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finish_command(&pager_process);
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}
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static void wait_for_pager_signal(int signo)
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{
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wait_for_pager();
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sigchain_pop(signo);
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raise(signo);
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}
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const char *git_pager(int stdout_is_tty)
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{
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const char *pager;
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if (!stdout_is_tty)
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return NULL;
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pager = getenv("GIT_PAGER");
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if (!pager) {
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if (!pager_program)
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git_config(git_default_config, NULL);
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pager = pager_program;
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}
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if (!pager)
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pager = getenv("PAGER");
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if (!pager)
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pager = DEFAULT_PAGER;
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if (!*pager || !strcmp(pager, "cat"))
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pager = NULL;
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return pager;
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}
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void setup_pager(void)
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{
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const char *pager = git_pager(isatty(1));
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if (!pager || pager_in_use())
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return;
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/*
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* force computing the width of the terminal before we redirect
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* the standard output to the pager.
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*/
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(void) term_columns();
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setenv("GIT_PAGER_IN_USE", "true", 1);
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/* spawn the pager */
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pager_argv[0] = pager;
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pager_process.use_shell = 1;
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pager_process.argv = pager_argv;
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pager_process.in = -1;
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if (!getenv("LESS")) {
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static const char *env[] = { "LESS=FRSX", NULL };
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pager_process.env = env;
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}
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if (start_command(&pager_process))
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return;
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/* original process continues, but writes to the pipe */
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dup2(pager_process.in, 1);
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if (isatty(2))
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dup2(pager_process.in, 2);
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close(pager_process.in);
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/* this makes sure that the parent terminates after the pager */
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sigchain_push_common(wait_for_pager_signal);
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atexit(wait_for_pager);
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}
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int pager_in_use(void)
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{
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const char *env;
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env = getenv("GIT_PAGER_IN_USE");
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return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
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}
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/*
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* Return cached value (if set) or $COLUMNS environment variable (if
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* set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
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* and default to 80 if all else fails.
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*/
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int term_columns(void)
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{
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static int term_columns_at_startup;
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char *col_string;
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int n_cols;
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if (term_columns_at_startup)
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return term_columns_at_startup;
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term_columns_at_startup = 80;
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col_string = getenv("COLUMNS");
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if (col_string && (n_cols = atoi(col_string)) > 0)
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term_columns_at_startup = n_cols;
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#ifdef TIOCGWINSZ
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else {
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struct winsize ws;
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if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col)
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term_columns_at_startup = ws.ws_col;
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}
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#endif
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return term_columns_at_startup;
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}
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/*
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* How many columns do we need to show this number in decimal?
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*/
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int decimal_width(int number)
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{
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int i, width;
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for (width = 1, i = 10; i <= number; width++)
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i *= 10;
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return width;
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}
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static int pager_command_config(const char *var, const char *value, void *data)
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{
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struct pager_config *c = data;
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if (!prefixcmp(var, "pager.") && !strcmp(var + 6, c->cmd)) {
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int b = git_config_maybe_bool(var, value);
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if (b >= 0)
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c->want = b;
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else {
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c->want = 1;
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c->value = xstrdup(value);
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}
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}
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return 0;
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}
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/* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
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int check_pager_config(const char *cmd)
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{
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struct pager_config c;
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c.cmd = cmd;
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c.want = -1;
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c.value = NULL;
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git_config(pager_command_config, &c);
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if (c.value)
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pager_program = c.value;
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return c.want;
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}
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