aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/libc_compat/ubuntu_14/glibc.cpp
blob: b2c6098dd86bf0e1a25c2319ca896a5684f7e0f2 (plain) (blame)
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
#include <elf.h> 
#include <errno.h> 
#include <fcntl.h> 
#include <stdlib.h> 
#include <sys/stat.h> 
#include <sys/types.h> 
#include <unistd.h> 
 
#include "glibc.h" 
#include "features.h" 
 
namespace { 
    void ReadAuxVector(Elf64_auxv_t** begin, Elf64_auxv_t** end) noexcept { 
        int fd = open("/proc/self/auxv", O_RDONLY | O_CLOEXEC); 
        if (fd == -1) { 
            return; 
        } 
 
        constexpr size_t item_size = sizeof(Elf64_auxv_t); 
        constexpr size_t block_size = item_size * 32; 
 
        size_t bytes_read = 0; 
        size_t size = 0; 
 
        struct TBuffer { 
            ~TBuffer() { 
                free(Pointer); 
            } 
            char* Pointer = nullptr; 
        } buffer; 
 
        while (true) { 
            size_t bytes_left = size - bytes_read; 
 
            if (!bytes_left) { 
                size += block_size; 
                char* new_buffer = (char*)realloc(buffer.Pointer, size); 
                if (!new_buffer) { 
                    return; 
                } 
                buffer.Pointer = new_buffer; 
                continue; 
            } 
 
            ssize_t r = read(fd, buffer.Pointer + bytes_read, bytes_left); 
            if (!r) { 
                break; 
            } else if (r < 0) { 
                if (errno == EINTR) { 
                    continue; 
                } else { 
                    return; 
                } 
            } 
 
            bytes_read += r; 
        } 
 
        size_t item_count = bytes_read / item_size; 
        *begin = (Elf64_auxv_t*)buffer.Pointer; 
        *end = (Elf64_auxv_t*)(buffer.Pointer + item_count * item_size); 
        buffer.Pointer = nullptr; 
    } 
} 
 
extern "C" { 
    weak unsigned long __getauxval(unsigned long item); 
} 
 
namespace NUbuntuCompat { 
 
    TGlibc::TGlibc() noexcept 
        : AuxVectorBegin(nullptr) 
        , AuxVectorEnd(nullptr) 
    { 
        if (!__getauxval) { 
            ReadAuxVector((Elf64_auxv_t**)&AuxVectorBegin, (Elf64_auxv_t**)&AuxVectorEnd); 
        } 
 
        Secure = (bool)GetAuxVal(AT_SECURE); 
    } 
 
    TGlibc::~TGlibc() noexcept { 
        free(AuxVectorBegin); 
    } 
 
    unsigned long TGlibc::GetAuxVal(unsigned long item) noexcept { 
        if (__getauxval) { 
            return __getauxval(item); 
        } 
 
        for (Elf64_auxv_t* p = (Elf64_auxv_t*)AuxVectorBegin; p < (Elf64_auxv_t*)AuxVectorEnd; ++p) { 
            if (p->a_type == item) { 
                return p->a_un.a_val; 
            } 
        } 
 
        errno = ENOENT; 
        return 0; 
    } 
 
    bool TGlibc::IsSecure() noexcept { 
        return Secure; 
    } 
 
    static TGlibc __attribute__((__init_priority__(101))) GlibcInstance; 
 
    TGlibc& GetGlibc() noexcept { 
        return GlibcInstance; 
    } 
}