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am 98957db5: Merge "Test flags before using "info"" into jb-mr1-dev

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* commit '98957db5536e93724c2e9e6bd19d5063f9d4dc2c':
  Test flags before using "info"
This commit is contained in:
Andy McFadden 2012-10-02 15:24:25 -07:00 committed by Android Git Automerger
commit 7c67e4e423
1 changed files with 49 additions and 9 deletions
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52
linker/debugger.c
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@ -29,14 +29,10 @@
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <ctype.h>
#include <stdbool.h>
#include <signal.h>
#include <sys/mman.h>
#include <sys/prctl.h>
#include <errno.h>
#include "linker.h"
#include <sys/socket.h>
#include <sys/un.h>
@ -113,11 +109,15 @@ static int socket_abstract_client(const char *name, int type)
#include <../libc/private/logd.h>
/*
* Writes a summary of the signal to the log file.
* Writes a summary of the signal to the log file. We do this so that, if
* for some reason we're not able to contact debuggerd, there is still some
* indication of the failure in the log.
*
* We could be here as a result of native heap corruption, or while a
* mutex is being held, so we don't want to use any libc functions that
* could allocate memory or hold a lock.
*
* "info" will be NULL if the siginfo_t information was not available.
*/
static void logSignalSummary(int signum, const siginfo_t* info)
{
@ -145,13 +145,45 @@ static void logSignalSummary(int signum, const siginfo_t* info)
// implies that 16 byte names are not.
threadname[MAX_TASK_NAME_LEN] = 0;
}
if (info != NULL) {
format_buffer(buffer, sizeof(buffer),
"Fatal signal %d (%s) at 0x%08x (code=%d), thread %d (%s)",
signum, signame, info->si_addr, info->si_code, gettid(), threadname);
} else {
format_buffer(buffer, sizeof(buffer),
"Fatal signal %d (%s), thread %d (%s)",
signum, signame, gettid(), threadname);
}
__libc_android_log_write(ANDROID_LOG_FATAL, "libc", buffer);
}
/*
* Returns true if the handler for signal "signum" has SA_SIGINFO set.
*/
static bool haveSiginfo(int signum)
{
struct sigaction oldact, newact;
memset(&newact, 0, sizeof(newact));
newact.sa_handler = SIG_DFL;
newact.sa_flags = SA_RESTART;
sigemptyset(&newact.sa_mask);
if (sigaction(signum, &newact, &oldact) < 0) {
__libc_android_log_write(ANDROID_LOG_FATAL, "libc",
"Failed testing for SA_SIGINFO");
return 0;
}
bool ret = (oldact.sa_flags & SA_SIGINFO) != 0;
if (sigaction(signum, &oldact, NULL) < 0) {
__libc_android_log_write(ANDROID_LOG_FATAL, "libc",
"Restore failed in test for SA_SIGINFO");
}
return ret;
}
/*
* Catches fatal signals so we can ask debuggerd to ptrace us before
* we crash.
@ -162,6 +194,14 @@ void debugger_signal_handler(int n, siginfo_t* info, void* unused __attribute__(
unsigned tid;
int s;
/*
* It's possible somebody cleared the SA_SIGINFO flag, which would mean
* our "info" arg holds an undefined value.
*/
if (!haveSiginfo(n)) {
info = NULL;
}
logSignalSummary(n, info);
tid = gettid();