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#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#include <sys/wait.h>
#include "lift.h"
#define STAGES 2
#define FAIL_PAUSE 0x01
#define FAIL_EXIT 0x02
unsigned failures = 0;
const char* program_name;
void fail
(
const char* source,
int mode,
const char* format,
...
)
{
va_list args;
va_start( args, format );
perror( source );
if( format != NULL )
{
fputs( program_name, stderr );
fputs( ": ", stderr );
vfprintf( stderr, format, args );
fputc( '\n', stderr );
}
va_end( args );
++failures;
if( failures == STAGES || ( mode & FAIL_PAUSE ) )
{
pause();
}
if( failures == STAGES || ( mode & FAIL_EXIT ) )
{
exit( EXIT_FAILURE );
}
}
void checked_take_foreground()
{
signal( SIGTTOU, SIG_IGN );
if( tcsetpgrp( 0, getpgrp() ) < 0 )
{
fail( "tcsetpgrp()", FAIL_EXIT, NULL );
}
signal( SIGTTOU, SIG_DFL );
}
void checked_exec
(
char *const* command_line
)
{
execvp( command_line[ 0 ], command_line );
fail( "execvp()", FAIL_EXIT, "unable to execute %s", command_line[ 0 ] );
}
int main
(
int argc,
char *const argv[]
)
{
program_name = argv[ 0 ];
struct passwd* passwd = getpwuid( getuid() );
if( passwd == NULL )
{
fail( "getpwuid()", FAIL_PAUSE | FAIL_EXIT, NULL );
}
pid_t pid = fork();
if( pid < 0 )
{
fail( "fork()", 0, NULL );
} else if( pid == 0 )
{
if( setpgid( 0, 0 ) < 0 )
{
fail( "setpgid()", FAIL_EXIT, NULL );
}
checked_take_foreground();
char formatted_pid[ 16 ];
snprintf( formatted_pid, sizeof formatted_pid, "%d", getpid() );
setenv( LIFT_PID_ENV, formatted_pid, 1 );
checked_exec( argc > 1 ? &argv[ 1 ] : (char *const[]){ DEFAULT_PATH, NULL } );
} else
{
int status;
pid_t res = wait( &status );
checked_take_foreground();
if( res < 0 )
{
fail( "wait()", FAIL_PAUSE | FAIL_EXIT, NULL );
}
if( WIFEXITED( status ) )
{
if( status == 0 )
{
return 0;
}
fprintf( stderr, "Session unlifted by exit code %d\n", WEXITSTATUS( status ) );
} else if( WIFSIGNALED( status ) )
{
fprintf( stderr, "Session unlifted by %s\n", strsignal( WTERMSIG( status ) ) );
}
}
checked_exec( (char *const[]){ passwd->pw_shell, NULL } );
}
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