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