1// SPDX-License-Identifier: GPL-2.0 2#include <sys/select.h> 3#include <stdlib.h> 4#include <stdio.h> 5#include <string.h> 6#include <signal.h> 7#include <sys/ioctl.h> 8#include "pager.h" 9#include "run-command.h" 10#include "sigchain.h" 11#include "subcmd-config.h" 12 13/* 14 * This is split up from the rest of git so that we can do 15 * something different on Windows. 16 */ 17 18static int spawned_pager; 19static int pager_columns; 20 21void pager_init(const char *pager_env) 22{ 23 subcmd_config.pager_env = pager_env; 24} 25 26static const char *forced_pager; 27 28void force_pager(const char *pager) 29{ 30 forced_pager = pager; 31} 32 33static void pager_preexec(void) 34{ 35 /* 36 * Work around bug in "less" by not starting it until we 37 * have real input 38 */ 39 fd_set in; 40 fd_set exception; 41 42 FD_ZERO(&in); 43 FD_ZERO(&exception); 44 FD_SET(0, &in); 45 FD_SET(0, &exception); 46 select(1, &in, NULL, &exception, NULL); 47 48 setenv("LESS", "FRSX", 0); 49} 50 51static const char *pager_argv[] = { "sh", "-c", NULL, NULL }; 52static struct child_process pager_process; 53 54static void wait_for_pager(void) 55{ 56 fflush(stdout); 57 fflush(stderr); 58 /* signal EOF to pager */ 59 close(1); 60 close(2); 61 finish_command(&pager_process); 62} 63 64static void wait_for_pager_signal(int signo) 65{ 66 wait_for_pager(); 67 sigchain_pop(signo); 68 raise(signo); 69} 70 71void setup_pager(void) 72{ 73 const char *pager = getenv(subcmd_config.pager_env); 74 struct winsize sz; 75 76 if (forced_pager) 77 pager = forced_pager; 78 if (!isatty(1) && !forced_pager) 79 return; 80 if (ioctl(1, TIOCGWINSZ, &sz) == 0) 81 pager_columns = sz.ws_col; 82 if (!pager) 83 pager = getenv("PAGER"); 84 if (!(pager || access("/usr/bin/pager", X_OK))) 85 pager = "/usr/bin/pager"; 86 if (!(pager || access("/usr/bin/less", X_OK))) 87 pager = "/usr/bin/less"; 88 if (!pager) 89 pager = "cat"; 90 if (!*pager || !strcmp(pager, "cat")) 91 return; 92 93 spawned_pager = 1; /* means we are emitting to terminal */ 94 95 /* spawn the pager */ 96 pager_argv[2] = pager; 97 pager_process.argv = pager_argv; 98 pager_process.in = -1; 99 pager_process.preexec_cb = pager_preexec; 100 101 if (start_command(&pager_process)) 102 return; 103 104 /* original process continues, but writes to the pipe */ 105 dup2(pager_process.in, 1); 106 if (isatty(2)) 107 dup2(pager_process.in, 2); 108 close(pager_process.in); 109 110 /* this makes sure that the parent terminates after the pager */ 111 sigchain_push_common(wait_for_pager_signal); 112 atexit(wait_for_pager); 113} 114 115int pager_in_use(void) 116{ 117 return spawned_pager; 118} 119 120int pager_get_columns(void) 121{ 122 char *s; 123 124 s = getenv("COLUMNS"); 125 if (s) 126 return atoi(s); 127 128 return (pager_columns ? pager_columns : 80) - 2; 129} 130