1 | #include <elf.h>
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2 | #include <poll.h>
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3 | #include <fcntl.h>
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4 | #include <signal.h>
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5 | #include "syscall.h"
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6 | #include "atomic.h"
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7 | #include "libc.h"
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8 |
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9 | void __init_tls(size_t *);
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10 |
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11 | static void dummy(void) {}
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12 | weak_alias(dummy, _init);
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13 |
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14 | __attribute__((__weak__, __visibility__("hidden")))
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15 | extern void (*const __init_array_start)(void), (*const __init_array_end)(void);
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16 |
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17 | static void dummy1(void *p) {}
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18 | weak_alias(dummy1, __init_ssp);
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19 |
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20 | #define AUX_CNT 38
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21 |
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22 | void __init_libc(char **envp, char *pn)
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23 | {
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24 | size_t i, *auxv, aux[AUX_CNT] = { 0 };
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25 | __environ = envp;
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26 | for (i=0; envp[i]; i++);
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27 | libc.auxv = auxv = (void *)(envp+i+1);
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28 | for (i=0; auxv[i]; i+=2) if (auxv[i]<AUX_CNT) aux[auxv[i]] = auxv[i+1];
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29 | __hwcap = aux[AT_HWCAP];
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30 | __sysinfo = aux[AT_SYSINFO];
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31 | libc.page_size = aux[AT_PAGESZ];
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32 |
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33 | if (!pn) pn = (void*)aux[AT_EXECFN];
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34 | if (!pn) pn = "";
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35 | __progname = __progname_full = pn;
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36 | for (i=0; pn[i]; i++) if (pn[i]=='/') __progname = pn+i+1;
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37 |
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38 | __init_tls(aux);
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39 | __init_ssp((void *)aux[AT_RANDOM]);
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40 |
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41 | if (aux[AT_UID]==aux[AT_EUID] && aux[AT_GID]==aux[AT_EGID]
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42 | && !aux[AT_SECURE]) return;
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43 |
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44 | struct pollfd pfd[3] = { {.fd=0}, {.fd=1}, {.fd=2} };
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45 | #ifdef SYS_poll
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46 | __syscall(SYS_poll, pfd, 3, 0);
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47 | #else
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48 | __syscall(SYS_ppoll, pfd, 3, &(struct timespec){0}, 0, _NSIG/8);
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49 | #endif
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50 | for (i=0; i<3; i++) if (pfd[i].revents&POLLNVAL)
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51 | if (__sys_open("/dev/null", O_RDWR)<0)
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52 | a_crash();
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53 | libc.secure = 1;
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54 | }
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55 |
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56 | static void libc_start_init(void)
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57 | {
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58 | _init();
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59 | uintptr_t a = (uintptr_t)&__init_array_start;
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60 | for (; a<(uintptr_t)&__init_array_end; a+=sizeof(void(*)()))
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61 | (*(void (**)(void))a)();
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62 | }
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63 |
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64 | weak_alias(libc_start_init, __libc_start_init);
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65 |
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66 | int __libc_start_main(int (*main)(int,char **,char **), int argc, char **argv)
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67 | {
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68 | char **envp = argv+argc+1;
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69 |
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70 | __init_libc(envp, argv[0]);
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71 | __libc_start_init();
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72 |
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73 | /* Pass control to the application */
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74 | exit(main(argc, argv, envp));
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75 | return 0;
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76 | }
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