~nabijaczleweli/klapki

ref: 92bd266682eb2df69b39bb2fa529c913ac050a64 klapki/src/context_wisen.cpp -rw-r--r-- 5.1 KiB
92bd2666наб This is kinda releasablish 1 year, 26 days ago
                                                                                
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
119
120
121
122
123
124
125
126
127
128
129
130
131
// The MIT License (MIT)

// Copyright (c) 2020 наб <nabijaczleweli@nabijaczleweli.xyz>

// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.


#include "config.hpp"
#include "context.hpp"
#include "context_detail.hpp"
#include "quickscope_wrapper.hpp"
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>


#define TRY(...)                                       \
	({                                                   \
		auto ret = __VA_ARGS__;                            \
		if(auto err = std::get_if<std::string>(&ret); err) \
			return std::move(*err);                          \
		std::move(std::get<0>(ret));                       \
	})


namespace {
	struct mapped_chunk {
		std::string_view data;
		std::shared_ptr<void> data_cont;

		static std::variant<mapped_chunk, std::string> from_fd(const char * for_whom, int fd) {
			struct stat sb;
			if(fstat(fd, &sb) < 0)
				return fmt::format("{} file stat(): {}", for_whom, strerror(errno));

			auto map = mmap(nullptr, sb.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
			if(map == MAP_FAILED)
				return fmt::format("{} file mmap(): {}", for_whom, strerror(errno));

			return mapped_chunk{{static_cast<char *>(map), static_cast<std::size_t>(sb.st_size)}, {map, [size = sb.st_size](auto map) { munmap(map, size); }}};
		}
	};

	static std::variant<mapped_chunk, std::string> gain_wisdom(const klapki::config & cfg, const char * from, const char * version, const char * variant) {
		auto fd = memfd_create(from, MFD_CLOEXEC);
		if(fd < 0)
			return fmt::format("opening {} {} {} file: {}", from, version, variant, strerror(errno));
		klapki::quickscope_wrapper cmdline_fd_del{[&] { close(fd); }};

		switch(auto pid = fork()) {
			case -1:
				return fmt::format("forking for {} {} {}: {}", from, version, variant, strerror(errno));

			case 0: {  // child
				if(dup2(fd, 1) < 0)
					exit(0x6B);

				const auto hook = fmt::format("{}{}", cfg.wisdom_root(), from);
				execl(hook.c_str(), from, version, variant, (char *)NULL);
				fmt::print(stderr, "exec {} {} {}: {}\n", hook, version, variant, strerror(errno));
				exit(0x6B);
			}

			default:  // parent
				int result;
				waitpid(pid, &result, 0);
				if(WIFEXITED(result) && WEXITSTATUS(result) != 0)
					return fmt::format("{} child returned {}", from, WEXITSTATUS(result));
				else if(WIFSIGNALED(result))
					return fmt::format("{} child killed by signal {}", from, WTERMSIG(result));

				return mapped_chunk::from_fd("cmdline", fd);
		}
	}

	static void trim(std::string_view & str) {
		// Character set stolen from isspace()
		str.remove_prefix(std::min(str.find_first_not_of(" \f\n\r\t\v"), str.size()));
		str.remove_suffix(std::min(str.size() - str.find_last_not_of(" \f\n\r\t\v") - 1, str.size()));
	}

	static void denewline(std::string_view & str) { std::replace(const_cast<char *>(std::begin(str)), const_cast<char *>(std::end(str)), '\n', ' '); }

	static void validate_cmdline(const std::string_view & cmdline) {
		klapki::context::detail::tokenise_cmdline(cmdline, [&](auto && arg) {
			if(arg.substr(0, std::strlen("initrd=")) == "initrd=") {  // string_view::starts_with() is C++20
				fmt::print(stderr, "Stray {} in cmdline, things might not work as planned\n", arg);
				return false;
			} else
				return true;
		});
	}
}

std::optional<std::string> klapki::context::context::wisen(const config & cfg, state::state & state) {
	for(auto && [bootnum, kern] : this->our_kernels) {
		auto skern = std::find_if(std::begin(state.statecfg.wanted_entries), std::end(state.statecfg.wanted_entries),
		                          [bn = bootnum](auto && skern) { return skern.bootnum_hint == bn; });
		if(skern == std::end(state.statecfg.wanted_entries))
			throw __func__;

		auto description = TRY(gain_wisdom(cfg, "description", skern->version.c_str(), skern->variant.c_str()));
		auto cmdline     = TRY(gain_wisdom(cfg, "cmdline", skern->version.c_str(), skern->variant.c_str()));
		trim(description.data);
		trim(cmdline.data);
		denewline(description.data);
		denewline(cmdline.data);
		validate_cmdline(cmdline.data);

		kern.description = description.data;
		kern.cmdline     = cmdline.data;
	}

	return {};
}