我在调试中运行代码。一旦父进程收到一个信号，调试器就会在步进时显示我在父处理程序代码中。但从那时起，我无法控制GDB。当我点击“继续”时它会输入一些文件并停止并显示以下消息：
Program received signal SIGTRAP, Trace/breakpoint trap.
_dl_runtime_resolve () at ../sysdeps/x86_64/dl-trampoline.S:34
34 ../sysdeps/x86_64/dl-trampoline.S: No such file or directory.
(gdb) continue
当我尝试继续时，它会重复使用新文件。
show follow-fork-mode的输出和show forkch-on-fork
(gdb) b 78
Breakpoint 1 at 0x400bba: file main.c, line 78.
(gdb) run
Starting program: /home/samkit/Posix_Programming/unix_Simple_prodcon_con_prob/main
Child sending signal
Breakpoint 1, main (argc=1, argv=0x7fffffffdf48) at main.c:79
79 if(cpid==0){
(gdb) show follow-fork-mode
Debugger response to a program call of fork or vfork is "parent".
(gdb) show detach-on-fork
Whether gdb will detach the child of a fork is on.
(gdb)
还尝试在GDB中切换到子进程，在第78行设置断点然后运行。子进程向父进程发送信号并从父进程接收SIGUSR2。因此进入自己的处理程序。之后GDB无法返回（类似于上面）以下是输出：
(gdb) set follow-fork-mode child
(gdb) set detach-on-fork on
(gdb) b 78
Breakpoint 1 at 0x400bba: file main.c, line 78.
(gdb) run
Starting program: /home/samkit/Posix_Programming/unix_Simple_prodcon_con_prob/main
[New process 31109]
[Switching to process 31109]
Breakpoint 1, main (argc=1, argv=0x7fffffffdf48) at main.c:79
79 if(cpid==0){
(gdb) next
83 if((child_sm_id = shmget(key,size*sizeof(char),0))==-1){ // Allocate shared memory
(gdb) next
87 if((child_sm_ptr = shmat(child_sm_id,NULL,0)) == (void *)-1){ // Attach shared memory to your address space
(gdb) next
95 printf("Child sending signal\n");
(gdb) next
Child sending signal
96 kill(getppid(),SIGUSR1);
(gdb) next
Received Signal 10
Sending signal
Program received signal SIGUSR2, User defined signal 2.
0x00007ffff7a4b267 in kill () at ../sysdeps/unix/syscall-template.S:81
81 ../sysdeps/unix/syscall-template.S: No such file or directory.
(gdb) next
childHandler (sig=0) at main.c:25
25 void childHandler(int sig){
(gdb) next
26 printf("Child received Signal %d\n",sig);
(gdb) next
Program received signal SIGTRAP, Trace/breakpoint trap.
0x00000000004006e6 in printf@plt ()
(gdb) next
Single stepping until exit from function printf@plt,
which has no line number information.
0x00000000004006b0 in ?? ()
(gdb) next
Cannot find bounds of current function
(gdb)
我也尝试过继续，但我认为自从GDB看到TRAP后，如果我继续尝试，它会一次又一次地重新执行TRAP。
(gdb) continue
Continuing.
Program received signal SIGTRAP, Trace/breakpoint trap.
0x00000000004006b6 in ?? ()
(gdb) ccontinue
Undefined command: "ccontinue". Try "help".
(gdb) continue
Continuing.
Program received signal SIGTRAP, Trace/breakpoint trap.
_dl_runtime_resolve () at ../sysdeps/x86_64/dl-trampoline.S:34
34 ../sysdeps/x86_64/dl-trampoline.S: No such file or directory.
(gdb) continue
Continuing.
现在我的问题：
Q1）如何让GDB继续执行？ Q2）我有2个进程。如果我在fork之后放置一个断点并执行信息线程，它会显示1个进程和1个进程。它不应该显示2个过程吗？
代码：
# include <signal.h>
# include <stdio.h>
# include <sys/types.h>
# include <sys/fcntl.h>
# include <sys/shm.h>
# include <sys/ipc.h>
# include <unistd.h>
# include <sys/wait.h>
#include <string.h>
#include <stdlib.h>
#define BUFF_SIZE 1024
struct smbuffer{
char buffer[1024];
int count;
};
void parentHandler(int sig){
printf("Received Signal %d\n",sig);
}
void childHandler(int sig){
printf("Child received Signal %d\n",sig);
}
int main( int argc, char* argv[] ) {
/* Child related attributes */
pid_t cpid;
int status;
int retval;
/* Shared memory initialization */
int sm_id;
struct smbuffer *sm_ptr;
key_t key = 1100;
int size = BUFF_SIZE;
if((sm_id = shmget(key , size * sizeof(char) , 0666|IPC_CREAT))== -1){ // Allocate shared memory
perror("SHMGET Failed : \n");
exit(1);
}
if((sm_ptr = shmat(sm_id,NULL,0))==(void *)-1){ // Attach shared memory to your address space
perror("SHMAT Failed : \n");
exit(1);
}
// Intilitialing Signals and handler
struct sigaction childold;
struct sigaction childnew;
childnew.sa_handler = childHandler;
sigset_t childmask ;
sigemptyset(&childmask);
childnew.sa_mask = childmask;
childnew.sa_flags = 0;
sigaction(SIGUSR2,&childnew,&childold);
// Intilitialing Signals and handler
struct sigaction parentold;
struct sigaction parentnew;
parentnew.sa_handler = parentHandler;
sigset_t parentmask ;
sigemptyset(&parentmask);
parentnew.sa_mask = parentmask;
parentnew.sa_flags = 0;
sigaction(SIGUSR1,&parentnew,&parentold);
if((cpid = fork())== -1){
perror("Fork Failed :\n");
}
if(cpid==0){
/* Child code */
struct smbuffer *child_sm_ptr;
int child_sm_id ;
if((child_sm_id = shmget(key,size*sizeof(char),0))==-1){ // Allocate shared memory
perror("Child shmget failed :\n");
exit(2);
}
if((child_sm_ptr = shmat(child_sm_id,NULL,0)) == (void *)-1){ // Attach shared memory to your address space
perror("Child shmat failed :\n");
exit(2);
}
// Signal parent and wait for signal from parent. Loop
while(1){
printf("Child sending signal\n");
kill(getppid(),SIGUSR1);
sigsuspend(&childmask);
sleep(1);
}
if(shmdt(child_sm_ptr)==-1){ // De-attach shared memory
perror("Child shmdt failed :\n");
exit(2);
}
printf("Child exit\n");
return 0;
}
else{
/* Parent code */
// Wait for child signal and signal child. Loop
while(1){
sigsuspend(&parentmask);
printf("Sending signal\n");
kill(cpid,SIGUSR2);
sleep(1);
}
}
if(shmdt(sm_ptr)==-1){ // De-attach shared memory
perror("SHMDT failed :\n");
exit(1);
}
// Free shared memory
if((shmctl(sm_id, IPC_RMID, NULL)) == -1){
perror("Shmctl failed \n");
exit(1);
}
printf("End of code\n");
return 0;
} // End of main