1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
|
// file : bpkg/help.cxx -*- C++ -*-
// copyright : Copyright (c) 2014-2015 Code Synthesis Ltd
// license : MIT; see accompanying LICENSE file
#include <bpkg/help>
#ifndef _WIN32
# include <unistd.h> // close()
#else
# include <io.h> // _close()
#endif
#include <chrono>
#include <thread> // this_thread::sleep_for()
#include <iostream>
#include <butl/process>
#include <butl/fdstream>
#include <bpkg/types>
#include <bpkg/utility>
#include <bpkg/diagnostics>
#include <bpkg/bpkg-options>
using namespace std;
using namespace butl;
namespace bpkg
{
struct pager
{
pager (const string& name)
{
// First try less.
//
try
{
string prompt ("-Ps" + name + " (press q to quit, h for help)");
const char* args[] = {
"less",
"-R", // ANSI color
prompt.c_str (),
nullptr
};
p_ = process (args, -1); // Redirect child's stdin to a pipe.
// Wait a bit and see if the pager has exited before reading
// anything (e.g., because exec() couldn't find the program).
// If you know a cleaner way to handle this, let me know (no,
// a select()-based approach doesn't work; the pipe is buffered
// and therefore is always ready for writing).
//
this_thread::sleep_for (chrono::milliseconds (50));
bool r;
if (p_.try_wait (r))
{
#ifndef _WIN32
::close (p_.out_fd);
#else
_close (p_.out_fd);
#endif
}
else
os_.open (p_.out_fd);
}
catch (const process_error& e)
{
if (e.child ())
exit (1);
}
}
std::ostream&
stream ()
{
return os_.is_open () ? os_ : std::cout;
}
bool
wait ()
{
os_.close ();
return p_.wait ();
}
~pager () {wait ();}
private:
process p_;
ofdstream os_;
};
int
help (const help_options&, const string& t, usage_function* usage)
{
if (usage == nullptr) // Not a command.
{
if (t.empty ()) // General help.
usage = &print_bpkg_usage;
else if (t == "common-options") // Help topics.
usage = &print_bpkg_common_options_long_usage;
else
fail << "unknown bpkg command/help topic '" << t << "'" <<
info << "run 'bpkg help' for more information";
}
pager p ("bpkg " + (t.empty () ? "help" : t));
usage (p.stream (), cli::usage_para::none);
// If the pager failed, assume it has issued some diagnostics.
//
return p.wait () ? 0 : 1;
}
}
|
