//
// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// interpose.c --
//
// Author           : Thierry Delisle
// Created On       : Wed Mar 29 16:10:31 2017
// Last Modified By : Peter A. Buhr
// Last Modified On : Fri Mar 13 17:35:37 2020
// Update Count     : 178
//

#include <stdarg.h>										// va_start, va_end
#include <stdio.h>
#include <string.h>										// strlen
#include <unistd.h>										// _exit, getpid
#define __USE_GNU
#include <signal.h>
#undef __USE_GNU
extern "C" {
#include <dlfcn.h>										// dlopen, dlsym
#include <execinfo.h>									// backtrace, messages
}

#include "bits/debug.hfa"
#include "bits/defs.hfa"
#include "bits/signal.hfa"								// sigHandler_?
#include "startup.hfa"									// STARTUP_PRIORITY_CORE
#include <assert.h>

//=============================================================================================
// Interposing helpers
//=============================================================================================

void preload_libgcc(void) {
	dlopen( "libgcc_s.so.1", RTLD_NOW );
	if ( const char * error = dlerror() ) abort( "interpose_symbol : internal error pre-loading libgcc, %s\n", error );
}

typedef void (* generic_fptr_t)(void);
generic_fptr_t interpose_symbol( const char symbol[], const char version[] ) {
	const char * error;

	static void * library;
	if ( ! library ) {
		#if defined( RTLD_NEXT )
			library = RTLD_NEXT;
		#else
			// missing RTLD_NEXT => must hard-code library name, assuming libstdc++
			library = dlopen( "libc.so.6", RTLD_LAZY );
			error = dlerror();
			if ( error ) {
				abort( "interpose_symbol : failed to open libc, %s\n", error );
			}
		#endif
	} // if

	union { generic_fptr_t fptr; void * ptr; } originalFunc;

	#if defined( _GNU_SOURCE )
		if ( version ) {
			originalFunc.ptr = dlvsym( library, symbol, version );
		} else {
			originalFunc.ptr = dlsym( library, symbol );
		}
	#else
		originalFunc.ptr = dlsym( library, symbol );
	#endif // _GNU_SOURCE

	error = dlerror();
	if ( error ) abort( "interpose_symbol : internal error, %s\n", error );

	return originalFunc.fptr;
}

#define INTERPOSE_LIBC( x, ver ) __cabi_libc.x = (typeof(__cabi_libc.x))interpose_symbol( #x, ver )

//=============================================================================================
// Interposition Startup logic
//=============================================================================================

void sigHandler_segv( __CFA_SIGPARMS__ );
void sigHandler_ill ( __CFA_SIGPARMS__ );
void sigHandler_fpe ( __CFA_SIGPARMS__ );
void sigHandler_abrt( __CFA_SIGPARMS__ );
void sigHandler_term( __CFA_SIGPARMS__ );

struct {
	void (* exit)( int ) __attribute__(( __noreturn__ ));
	void (* abort)( void ) __attribute__(( __noreturn__ ));
} __cabi_libc;

extern "C" {
	void __cfaabi_interpose_startup(void)  __attribute__(( constructor( STARTUP_PRIORITY_CORE ) ));
	void __cfaabi_interpose_startup( void ) {
		const char *version = 0p;

		preload_libgcc();

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdiscarded-qualifiers"
		INTERPOSE_LIBC( abort, version );
		INTERPOSE_LIBC( exit , version );
#pragma GCC diagnostic pop

		// As a precaution (and necessity), errors that result in termination are delivered on a separate stack because
		// task stacks might be very small (4K) and the signal delivery corrupts memory to the point that a clean
		// shutdown is impossible. Also, when a stack overflow encounters the non-accessible sentinel page (debug only)
		// and generates a segment fault, the signal cannot be delivered on the sentinel page. Finally, calls to abort
		// print a stack trace that uses substantial stack space.

		#define MINSTKSZ SIGSTKSZ * 8
		static char stack[MINSTKSZ] __attribute__(( aligned (16) ));
		static stack_t ss;

		ss.ss_sp = stack;
		ss.ss_size = MINSTKSZ;
		ss.ss_flags = 0;
		if ( sigaltstack( &ss, 0p ) == -1 ) {
			abort( "__cfaabi_interpose_startup : internal error, sigaltstack error(%d) %s.", errno, strerror( errno ) );
		} // if

		// Failure handler
		 // internal errors
		__cfaabi_sigaction( SIGSEGV, sigHandler_segv, SA_SIGINFO | SA_ONSTACK ); // Invalid memory reference (default: Core)
		__cfaabi_sigaction( SIGBUS , sigHandler_segv, SA_SIGINFO | SA_ONSTACK ); // Bus error, bad memory access (default: Core)
		__cfaabi_sigaction( SIGILL , sigHandler_ill , SA_SIGINFO | SA_ONSTACK ); // Illegal Instruction (default: Core)
		__cfaabi_sigaction( SIGFPE , sigHandler_fpe , SA_SIGINFO | SA_ONSTACK ); // Floating-point exception (default: Core)

 		// handlers to outside errors
		// reset in-case they insist and send it over and over
		__cfaabi_sigaction( SIGTERM, sigHandler_term, SA_SIGINFO | SA_ONSTACK | SA_RESETHAND ); // Termination signal (default: Term)
		__cfaabi_sigaction( SIGINT , sigHandler_term, SA_SIGINFO | SA_ONSTACK | SA_RESETHAND ); // Interrupt from keyboard (default: Term)
		__cfaabi_sigaction( SIGHUP , sigHandler_term, SA_SIGINFO | SA_ONSTACK | SA_RESETHAND ); // Hangup detected on controlling terminal or death of controlling process (default: Term)
		__cfaabi_sigaction( SIGQUIT, sigHandler_term, SA_SIGINFO | SA_ONSTACK | SA_RESETHAND ); // Quit from keyboard (default: Core)
		__cfaabi_sigaction( SIGABRT, sigHandler_term, SA_SIGINFO | SA_ONSTACK | SA_RESETHAND ); // Abort signal from abort(3) (default: Core)
	}
}

//=============================================================================================
// Terminating Signals logic
//=============================================================================================

// Forward declare abort after the __typeof__ call to avoid ambiguities
void exit( int status, const char fmt[], ... ) __attribute__(( format(printf, 2, 3), __nothrow__, __leaf__, __noreturn__ ));
void abort( const char fmt[], ... ) __attribute__(( format(printf, 1, 2), __nothrow__, __leaf__, __noreturn__ ));
void abort( bool signalAbort, const char fmt[], ... ) __attribute__(( format(printf, 2, 3), __nothrow__, __leaf__, __noreturn__ ));
void __abort( bool signalAbort, const char fmt[], va_list args ) __attribute__(( __nothrow__, __leaf__, __noreturn__ ));

extern "C" {
	void abort( void ) __attribute__(( __nothrow__, __leaf__, __noreturn__ )) {
		abort( false, "%s", "" );
	}

	void __cabi_abort( const char fmt[], ... ) __attribute__(( format(printf, 1, 2), __nothrow__, __leaf__, __noreturn__ )) {
		va_list argp;
		va_start( argp, fmt );
		__abort( false, fmt, argp );
		va_end( argp );
	}

	void exit( int status ) __attribute__(( __nothrow__, __leaf__, __noreturn__ )) {
		__cabi_libc.exit( status );
	}
}

// See concurrency/kernel.cfa and concurrency/preemption.cfa for strong definition used in multi-processor mode.
void __kernel_abort_lock( void ) __attribute__(( __nothrow__, __leaf__, __weak__ )) {}
void __kernel_abort_msg( char buffer[], int size ) __attribute__(( __nothrow__, __leaf__, __weak__ )) {}
int __kernel_abort_lastframe( void ) __attribute__(( __nothrow__, __leaf__, __weak__ )) { return 4; }

enum { abort_text_size = 1024 };
static char abort_text[ abort_text_size ];

static void __cfaabi_backtrace( int start ) {
	enum { Frames = 50, };								// maximum number of stack frames
	int last = __kernel_abort_lastframe();				// skip last N stack frames

	void * array[Frames];
	size_t size = backtrace( array, Frames );
	char ** messages = backtrace_symbols( array, size ); // does not demangle names

	*index( messages[0], '(' ) = '\0';					// find executable name
	__cfaabi_bits_print_nolock( STDERR_FILENO, "Stack back trace for: %s\n", messages[0]);

	for ( unsigned int i = start; i < size - last && messages != 0p; i += 1 ) {
		char * name = 0p, * offset_begin = 0p, * offset_end = 0p;

		for ( char * p = messages[i]; *p; p += 1 ) {	// find parantheses and +offset
			//__cfaabi_bits_print_nolock( "X %s\n", p);
			if ( *p == '(' ) {
				name = p;
			} else if ( *p == '+' ) {
				offset_begin = p;
			} else if ( *p == ')' ) {
				offset_end = p;
				break;
			}
		}

		// if line contains symbol, print it
		int frameNo = i - start;
		if ( name && offset_begin && offset_end && name < offset_begin ) {
			*name++ = '\0';								// delimit strings
			*offset_begin++ = '\0';
			*offset_end++ = '\0';

			__cfaabi_bits_print_nolock( STDERR_FILENO, "(%i) %s : %s + %s %s\n", frameNo, messages[i], name, offset_begin, offset_end);
		} else {										// otherwise, print the whole line
			__cfaabi_bits_print_nolock( STDERR_FILENO, "(%i) %s\n", frameNo, messages[i] );
		}
	}
	free( messages );
}

void exit( int status, const char fmt[], ... ) {
	va_list args;
	va_start( args, fmt );
	vfprintf( stderr, fmt, args );
	va_end( args );
	__cabi_libc.exit( status );
}

static volatile bool __abort_first = 0;

// Cannot forward va_list.
void __abort( bool signalAbort, const char fmt[], va_list args ) {
	// Multiple threads can come here from multiple paths
	// To make sure this is safe any concurrent/subsequent call to abort is redirected to libc-abort
	bool first = ! __atomic_test_and_set( &__abort_first, __ATOMIC_SEQ_CST);

	// Prevent preemption from kicking-in and messing with the abort
	__kernel_abort_lock();

	// first to abort ?
	if ( !first ) {
		// We aren't the first to abort just let C handle it
		signal( SIGABRT, SIG_DFL );	// restore default in case we came here through the function.
		__cabi_libc.abort();
	}

	int len = snprintf( abort_text, abort_text_size, "Cforall Runtime error (UNIX pid:%ld) ", (long int)getpid() ); // use UNIX pid (versus getPid)
	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );

	// print the cause of the error
	assert( fmt );
	len = vsnprintf( abort_text, abort_text_size, fmt, args );
	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );

	// add optional newline if missing at the end of the format text
	if ( fmt[strlen( fmt ) - 1] != '\n' ) {
		__cfaabi_bits_write( STDERR_FILENO, "\n", 1 );
	} // if

	// Give the kernel the chance to add some data in here
	__kernel_abort_msg( abort_text, abort_text_size );

	// print stack trace in handler
	__cfaabi_backtrace( signalAbort ? 4 : 2 );

	// Finally call abort
	__cabi_libc.abort();

}

void abort( const char fmt[], ... ) {
	va_list args;
	va_start( args, fmt );
	__abort( false, fmt, args );
    // CONTROL NEVER REACHES HERE!
	va_end( args );
}

void abort( bool signalAbort, const char fmt[], ... ) {
    va_list args;
    va_start( args, fmt );
    __abort( signalAbort, fmt, args );
    // CONTROL NEVER REACHES HERE!
    va_end( args );
}

void sigHandler_segv( __CFA_SIGPARMS__ ) {
		if ( sfp->si_addr == 0p ) {
			abort( true, "Null pointer (0p) dereference.\n" );
		} else {
			abort( true, "%s at memory location %p.\n"
				   "Possible cause is reading outside the address space or writing to a protected area within the address space with an invalid pointer or subscript.\n",
				   (sig == SIGSEGV ? "Segment fault" : "Bus error"), sfp->si_addr );
		}
}

void sigHandler_ill( __CFA_SIGPARMS__ ) {
	abort( true, "Executing illegal instruction at location %p.\n"
			"Possible cause is stack corruption.\n",
			sfp->si_addr );
}

void sigHandler_fpe( __CFA_SIGPARMS__ ) {
	const char * msg;

	choose( sfp->si_code ) {
	  case FPE_INTDIV, FPE_FLTDIV: msg = "divide by zero";
	  case FPE_FLTOVF: msg = "overflow";
	  case FPE_FLTUND: msg = "underflow";
	  case FPE_FLTRES: msg = "inexact result";
	  case FPE_FLTINV: msg = "invalid operation";
	  default: msg = "unknown";
	} // choose
	abort( true, "Computation error %s at location %p.\n", msg, sfp->si_addr );
}

void sigHandler_term( __CFA_SIGPARMS__ ) {
	abort( true, "Application interrupted by signal: %s.\n", strsignal( sig ) );
}

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