elf.h: add ELFCOMPRESS_ZSTD

[musl] / src / env / __libc_start_main.c

diff --git a/src/env/__libc_start_main.c b/src/env/__libc_start_main.c
index c10a3f3..c5b277b 100644 (file)
--- a/src/env/__libc_start_main.c
+++ b/src/env/__libc_start_main.c
@@ -2,29 +2,23 @@
 #include <poll.h>
 #include <fcntl.h>
 #include <signal.h>
+#include <unistd.h>
 #include "syscall.h"
 #include "atomic.h"
 #include "libc.h"
 
-void __init_tls(size_t *);
-
-#ifndef SHARED
-static void dummy() {}
+static void dummy(void) {}
 weak_alias(dummy, _init);
-extern void (*const __init_array_start)() __attribute__((weak));
-extern void (*const __init_array_end)() __attribute__((weak));
-#endif
+
+extern weak hidden void (*const __init_array_start)(void), (*const __init_array_end)(void);
 
 static void dummy1(void *p) {}
 weak_alias(dummy1, __init_ssp);
 
 #define AUX_CNT 38
 
-extern size_t __hwcap, __sysinfo;
-extern char *__progname, *__progname_full;
-
-#ifndef SHARED
-static
+#ifdef __GNUC__
+__attribute__((__noinline__))
 #endif
 void __init_libc(char **envp, char *pn)
 {
@@ -34,13 +28,13 @@ void __init_libc(char **envp, char *pn)
        libc.auxv = auxv = (void *)(envp+i+1);
        for (i=0; auxv[i]; i+=2) if (auxv[i]<AUX_CNT) aux[auxv[i]] = auxv[i+1];
        __hwcap = aux[AT_HWCAP];
-       __sysinfo = aux[AT_SYSINFO];
+       if (aux[AT_SYSINFO]) __sysinfo = aux[AT_SYSINFO];
        libc.page_size = aux[AT_PAGESZ];
 
-       if (pn) {
-               __progname = __progname_full = pn;
-               for (i=0; pn[i]; i++) if (pn[i]=='/') __progname = pn+i+1;
-       }
+       if (!pn) pn = (void*)aux[AT_EXECFN];
+       if (!pn) pn = "";
+       __progname = __progname_full = pn;
+       for (i=0; pn[i]; i++) if (pn[i]=='/') __progname = pn+i+1;
 
        __init_tls(aux);
        __init_ssp((void *)aux[AT_RANDOM]);
@@ -49,30 +43,55 @@ void __init_libc(char **envp, char *pn)
                && !aux[AT_SECURE]) return;
 
        struct pollfd pfd[3] = { {.fd=0}, {.fd=1}, {.fd=2} };
+       int r =
 #ifdef SYS_poll
        __syscall(SYS_poll, pfd, 3, 0);
 #else
        __syscall(SYS_ppoll, pfd, 3, &(struct timespec){0}, 0, _NSIG/8);
 #endif
+       if (r<0) a_crash();
        for (i=0; i<3; i++) if (pfd[i].revents&POLLNVAL)
                if (__sys_open("/dev/null", O_RDWR)<0)
                        a_crash();
        libc.secure = 1;
 }
 
-int __libc_start_main(int (*main)(int,char **,char **), int argc, char **argv)
+static void libc_start_init(void)
 {
-       char **envp = argv+argc+1;
-
-#ifndef SHARED
-       __init_libc(envp, argv[0]);
        _init();
        uintptr_t a = (uintptr_t)&__init_array_start;
        for (; a<(uintptr_t)&__init_array_end; a+=sizeof(void(*)()))
-               (*(void (**)())a)();
-#endif
+               (*(void (**)(void))a)();
+}
+
+weak_alias(libc_start_init, __libc_start_init);
+
+typedef int lsm2_fn(int (*)(int,char **,char **), int, char **);
+static lsm2_fn libc_start_main_stage2;
+
+int __libc_start_main(int (*main)(int,char **,char **), int argc, char **argv,
+       void (*init_dummy)(), void(*fini_dummy)(), void(*ldso_dummy)())
+{
+       char **envp = argv+argc+1;
+
+       /* External linkage, and explicit noinline attribute if available,
+        * are used to prevent the stack frame used during init from
+        * persisting for the entire process lifetime. */
+       __init_libc(envp, argv[0]);
+
+       /* Barrier against hoisting application code or anything using ssp
+        * or thread pointer prior to its initialization above. */
+       lsm2_fn *stage2 = libc_start_main_stage2;
+       __asm__ ( "" : "+r"(stage2) : : "memory" );
+       return stage2(main, argc, argv);
+}
+
+static int libc_start_main_stage2(int (*main)(int,char **,char **), int argc, char **argv)
+{
+       char **envp = argv+argc+1;
+       __libc_start_init();
 
-       /* Pass control to to application */
+       /* Pass control to the application */
        exit(main(argc, argv, envp));
        return 0;
 }