Зависает поп-функция C ++ - PullRequest
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Зависает поп-функция C ++

0 голосов
/ 12 февраля 2019

Я работаю над встроенной системой, которая запускает ядро ​​Linux 3.14 на устройстве PowerPC.Мне нужно запустить приложение C ++, которое должно запустить системную команду и получить результат.Я пробовал с popen но зависает.Посмотрите код ниже: 

#define PATH_MAX_MIO 255

...

FILE *fp;
char path[PATH_MAX_MIO];

fp = popen("ll", "r"); // It hangs here. "ll" is the linux command to view files inside a directory
if (fp == NULL){ return; }


while (fgets(path, PATH_MAX_MIO, fp) != NULL)
    std::cout<< path;

pclose(fp);

С помощью отладчика я могу запустить до вызова popen, после чего он зависает, и если я запускаю команду top , я вижу, что процесс занимает почти весь процессор (изменениемежду 90% и 99,9%).

Я не могу понять, почему это происходит.Любой совет?Спасибо.

.: РЕДАКТИРОВАТЬ:. Это вывод strace -f команды 

[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5348] <... select resumed> )      = 15 (in [14], left {0, 0})
[pid  5348] select(15, [], NULL, NULL, {0, 0} <unfinished ...>
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5348] <... select resumed> )      = -1 EINTR (Interrupted system call)
[pid  5348] --- SIGPROF {si_signo=SIGPROF, si_code=SI_KERNEL, si_value={int=14594, ptr=0x3902}} ---
[pid  5348] sigreturn() (mask [])       = -1 EINTR (Interrupted system call)
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL,  <unfinished ...>
[pid  5347] --- SIGPROF {si_signo=SIGPROF, si_code=SI_KERNEL, si_value={int=14594, ptr=0x3902}} ---
[pid  5347] <... rt_sigprocmask resumed> [], 8) = 27
[pid  5347] syscall_671098914(0, 0x1, 0xba4bdeda, 0xcbcb28a, 0xb6f76f8c, 0xb6f76f20) = 0
[pid  5348] select(15, [14], NULL, NULL, {0, 0}) = 0 (Timeout)
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL,  <unfinished ...>
[pid  5348] select(15, [14], NULL, NULL, {0, 0}) = 0 (Timeout)
[pid  5347] <... rt_sigprocmask resumed> [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL,  <unfinished ...>
[pid  5347] --- SIGPROF {si_signo=SIGPROF, si_code=SI_KERNEL, si_value={int=14594, ptr=0x3902}} ---
[pid  5347] <... rt_sigprocmask resumed> [], 8) = 27
[pid  5347] syscall_268774496(0, 0x10052a5c, 0x28002824, 0xb7a2f008, 0x1, 0xb7a379c0) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5348] select(15, [14], NULL, NULL, {0, 0}) = 0 (Timeout)
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL,  <unfinished ...>
[pid  5348] select(15, [14], NULL, NULL, {0, 0}) = 0 (Timeout)
[pid  5347] <... rt_sigprocmask resumed> [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL,  <unfinished ...>
[pid  5347] --- SIGPROF {si_signo=SIGPROF, si_code=SI_KERNEL, si_value={int=14594, ptr=0x3902}} ---
[pid  5347] <... rt_sigprocmask resumed> [], 8) = 27
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid  5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0

Тед Люнгмо предложил запустить трассировку, которая показывает только exec* операции, результат такой: 

strace -f ../runtime/Run6 2>&1 | grep -E 'exec[a-z]+\('
execve("../runtime/Run6", ["../runtime/Run6"], [/* 13 vars */]) = 0
[pid  1068] execve("/bin/sh", ["sh", "-c", "cat /proc/version"], [/* 13 vars */]) = 0
[pid  1069] execve("/bin/cat", ["cat", "/proc/version"], [/* 13 vars */]) = 0

Тогда он висит снова

...