| xj | b04a402 | 2021-11-25 15:01:52 +0800 | [diff] [blame] | 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 | |
| 18 | static int spawned_pager; |
| 19 | static int pager_columns; |
| 20 | |
| 21 | void pager_init(const char *pager_env) |
| 22 | { |
| 23 | subcmd_config.pager_env = pager_env; |
| 24 | } |
| 25 | |
| 26 | static void pager_preexec(void) |
| 27 | { |
| 28 | /* |
| 29 | * Work around bug in "less" by not starting it until we |
| 30 | * have real input |
| 31 | */ |
| 32 | fd_set in; |
| 33 | fd_set exception; |
| 34 | |
| 35 | FD_ZERO(&in); |
| 36 | FD_ZERO(&exception); |
| 37 | FD_SET(0, &in); |
| 38 | FD_SET(0, &exception); |
| 39 | select(1, &in, NULL, &exception, NULL); |
| 40 | |
| 41 | setenv("LESS", "FRSX", 0); |
| 42 | } |
| 43 | |
| 44 | static const char *pager_argv[] = { "sh", "-c", NULL, NULL }; |
| 45 | static struct child_process pager_process; |
| 46 | |
| 47 | static void wait_for_pager(void) |
| 48 | { |
| 49 | fflush(stdout); |
| 50 | fflush(stderr); |
| 51 | /* signal EOF to pager */ |
| 52 | close(1); |
| 53 | close(2); |
| 54 | finish_command(&pager_process); |
| 55 | } |
| 56 | |
| 57 | static void wait_for_pager_signal(int signo) |
| 58 | { |
| 59 | wait_for_pager(); |
| 60 | sigchain_pop(signo); |
| 61 | raise(signo); |
| 62 | } |
| 63 | |
| 64 | void setup_pager(void) |
| 65 | { |
| 66 | const char *pager = getenv(subcmd_config.pager_env); |
| 67 | struct winsize sz; |
| 68 | |
| 69 | if (!isatty(1)) |
| 70 | return; |
| 71 | if (ioctl(1, TIOCGWINSZ, &sz) == 0) |
| 72 | pager_columns = sz.ws_col; |
| 73 | if (!pager) |
| 74 | pager = getenv("PAGER"); |
| 75 | if (!(pager || access("/usr/bin/pager", X_OK))) |
| 76 | pager = "/usr/bin/pager"; |
| 77 | if (!(pager || access("/usr/bin/less", X_OK))) |
| 78 | pager = "/usr/bin/less"; |
| 79 | if (!pager) |
| 80 | pager = "cat"; |
| 81 | if (!*pager || !strcmp(pager, "cat")) |
| 82 | return; |
| 83 | |
| 84 | spawned_pager = 1; /* means we are emitting to terminal */ |
| 85 | |
| 86 | /* spawn the pager */ |
| 87 | pager_argv[2] = pager; |
| 88 | pager_process.argv = pager_argv; |
| 89 | pager_process.in = -1; |
| 90 | pager_process.preexec_cb = pager_preexec; |
| 91 | |
| 92 | if (start_command(&pager_process)) |
| 93 | return; |
| 94 | |
| 95 | /* original process continues, but writes to the pipe */ |
| 96 | dup2(pager_process.in, 1); |
| 97 | if (isatty(2)) |
| 98 | dup2(pager_process.in, 2); |
| 99 | close(pager_process.in); |
| 100 | |
| 101 | /* this makes sure that the parent terminates after the pager */ |
| 102 | sigchain_push_common(wait_for_pager_signal); |
| 103 | atexit(wait_for_pager); |
| 104 | } |
| 105 | |
| 106 | int pager_in_use(void) |
| 107 | { |
| 108 | return spawned_pager; |
| 109 | } |
| 110 | |
| 111 | int pager_get_columns(void) |
| 112 | { |
| 113 | char *s; |
| 114 | |
| 115 | s = getenv("COLUMNS"); |
| 116 | if (s) |
| 117 | return atoi(s); |
| 118 | |
| 119 | return (pager_columns ? pager_columns : 80) - 2; |
| 120 | } |