C fscanf получает мне дубликаты строк

Я пытаюсь отобразить детали каждого процесса, перенаправляя вывод команды "ps". Я перенаправил вывод ps в файл. Я читаю его и выводя Pid и Command с помощью fscanf. Но я вижу, что я получаю дубликаты строк, а в некоторых случаях - отрицательные значения для Pids.

void TR69_DM_GetProcDetails(char *FileName, int32_t *ProcCount, struct ProcessInfo *ProcVar)
{
 char CharBuf[BUF_SIZE] ;
 int32_t i = 0;

 int Pid;
 char Cmd[100];

 FILE *FileDesc;
 FileDesc = fopen (FileName, "r");

 printf("\nFile pointer %ld\n", ftell(FileDesc));
 fscanf (FileDesc, "%[^\n]\n", CharBuf);
 puts(CharBuf);

 printf("\nFile pointer %ld\n", ftell(FileDesc));

 while ( EOF != fscanf (FileDesc, "%*s %lu %*d %*d %*s %*s %*s %s", &Pid, Cmd))
 {
 printf("\n PID is %d and cmd is %s", Pid, Cmd);
 // i++;
 }

}

и я получаю следующий выходной образец:

<pre class="prettyprint linenums"> PID is 2104 and cmd is /usr/lib/indicator-datetime/indicator-datetime-service PID is 2107 and cmd is /usr/lib/indicator-messages/indicator-messages-service PID is 2114 and cmd is /usr/lib/indicator-session/indicator-session-service PID is 2134 and cmd is /usr/lib/geoclue/geoclue-master PID is 2142 and cmd is gnome-screensaver PID is 2145 and cmd is /usr/lib/gnome-disk-utility/gdu-notification-daemon PID is 2342 and cmd is /usr/bin/python PID is 2342 and cmd is /usr/bin/python PID is 4316 and cmd is /sbin/dhclient PID is -4 and cmd is /sbin/dhclient PID is -4 and cmd is /sbin/dhclient PID is -4 and cmd is /sbin/dhclient PID is -4 and cmd is /sbin/dhclient PID is -4 and cmd is /sbin/dhclient PID is -4 and cmd is /sbin/dhclient PID is -4 and cmd is /sbin/dhclient PID is -4 and cmd is /sbin/dhclient PID is -4 and cmd is /sbin/dhclient PID is -4 and cmd is /sbin/dhclient PID is 4444 and cmd is /usr/sbin/ntpd PID is 4444 and cmd is /usr/sbin/ntpd PID is 4444 and cmd is /usr/sbin/ntpd PID is 4444 and cmd is /usr/sbin/ntpd PID is 113 and cmd is /usr/sbin/ntpd PID is 113 and cmd is /usr/sbin/ntpd PID is 5411 and cmd is sshd: PID is 5411 and cmd is sshd: PID is 5411 and cmd is sshd: PID is 5584 and cmd is sshd: PID is 5584 and cmd is sshd: PID is 5585 and cmd is -bash PID is 6790 and cmd is /usr/lib/firefox-4.0.1/firefox-bin PID is 7007 and cmd is /usr/lib/firefox-4.0.1/plugin-container PID is 7007 and cmd is /usr/lib/firefox-4.0.1/plugin-container PID is 7007 and cmd is /usr/lib/firefox-4.0.1/plugin-container PID is 6790 and cmd is /usr/lib/firefox-4.0.1/plugin-container PID is 6790 and cmd is /usr/lib/firefox-4.0.1/plugin-container PID is 6790 and cmd is /usr/lib/firefox-4.0.1/plugin-container PID is 7023 and cmd is /usr/lib/nspluginwrapper/i386/linux/npviewer.bin PID is 7023 and cmd is /usr/lib/nspluginwrapper/i386/linux/npviewer.bin PID is 7023 and cmd is /usr/lib/nspluginwrapper/i386/linux/npviewer.bin PID is 7023 and cmd is /usr/lib/nspluginwrapper/i386/linux/npviewer.bin PID is 7023 and cmd is /usr/lib/nspluginwrapper/i386/linux/npviewer.bin PID is 8390 and cmd is man PID is 8390 and cmd is man PID is 8402 and cmd is pager PID is 8402 and cmd is pager PID is 8827 and cmd is ping PID is 8827 and cmd is ping PID is 8869 and cmd is bash PID is 8907 and cmd is bash PID is 12637 and cmd is cat PID is 12637 and cmd is cat PID is 15164 and cmd is tftp PID is 15185 and cmd is vim PID is 15185 and cmd is vim PID is 16827 and cmd is telnet PID is 16827 and cmd is telnet PID is 17117 and cmd is sshd: PID is 17117 and cmd is sshd: PID is 17117 and cmd is sshd: PID is 17226 and cmd is sshd: PID is 17226 and cmd is sshd: PID is 17227 and cmd is -sh PID is 18120 and cmd is su PID is 18127 and cmd is bash PID is 18896 and cmd is sshd: PID is 18896 and cmd is sshd: PID is 18896 and cmd is sshd: PID is 19069 and cmd is sshd: PID is 19069 and cmd is sshd: PID is 19070 and cmd is -sh PID is 20313 and cmd is gedit PID is 20313 and cmd is gedit PID is 20313 and cmd is gedit PID is 20334 and cmd is ssh PID is 20334 and cmd is ssh PID is 20337 and cmd is [kworker/1:1] PID is 20341 and cmd is su PID is 20349 and cmd is bash PID is 20371 and cmd is [kworker/0:1] PID is 20375 and cmd is [kworker/0:2] PID is 20377 and cmd is [kworker/1:0] PID is 21342 and cmd is [kjournald] PID is 23384 and cmd is /opt/Adobe/Reader9/Reader/intellinux/bin/acroread PID is 23384 and cmd is /opt/Adobe/Reader9/Reader/intellinux/bin/acroread PID is 23495 and cmd is gnome-terminal PID is 23498 and cmd is gnome-pty-helper PID is 23499 and cmd is bash PID is 26446 and cmd is ssh PID is 26446 and cmd is ssh PID is 26733 and cmd is sshd: PID is 26733 and cmd is sshd: PID is 26843 and cmd is -bash PID is 26943 and cmd is sshd: PID is 26943 and cmd is sshd: PID is 27036 and cmd is sshd: PID is 27036 and cmd is sshd: PID is 27036 and cmd is sshd: PID is 27052 and cmd is /usr/lib/openssh/sftp-server PID is 27149 and cmd is sshd: PID is 27149 and cmd is sshd: PID is 27150 and cmd is -bash PID is 27734 and cmd is ssh PID is 27734 and cmd is ssh PID is 28265 and cmd is bin/TR69_DM PID is 0 and cmd is bin/TR69_DM PID is 28266 and cmd is ps PID is 28266 and cmd is ps PID is 29510 and cmd is su PID is 29510 and cmd is su PID is 29517 and cmd is bash PID is 29951 and cmd is minicom PID is 30056 and cmd is bash PID is 30293 and cmd is bash PID is 30329 and cmd is ssh PID is 30329 and cmd is ssh PID is 30597 and cmd is bash PID is 30632 and cmd is ssh PID is 30632 and cmd is ssh PID is 31508 and cmd is bash </pre>

Что, возможно, пошло не так?

1 ответ

fscanf() возвращает количество выполненных заданий. Проверка против EOF недостаточна, поскольку некоторые присвоения могут быть сделаны, а оставшиеся нет, что означает, что последующий код будет обрабатывать устаревшие или неинициализированные значения. Следующий цикл прекратит обработку в первой строке, когда формат будет неожиданным, и избегайте устаревших значений:

while ( 2 == fscanf (FileDesc, "%*s %lu %*d %*d %*s %*s %*s %s", &Pid, Cmd))
{
}

Улучшенное решение будет использовать fgets() для чтения строки, а затем использовать sscanf() для анализа строки чтения. Это позволит вам обнаружить EOF и разрешить несколько попыток разбора строки в разных форматах:

char line[1024];
while (fgets(line, sizeof(line), stdin))
{
 if (2 == sscanf (line, "%*s %lu %*d %*d %*s %*s %*s %s", &Pid, Cmd))
 {
 }
 else if (2 == sscanf (line, "some-other-format", &Pid, Cmd))
 {
 }
 else
 {
 fprintf(stderr, "Unable to parse '%s'\n", line);
 }
}

Кроме того, предотвратите переполнение потенциального буфера, указав максимальное количество символов, которые sscanf() должен написать в Cmd. Это должно быть меньше, чем размер Cmd, оставляя место для прекращающего нулевого символа. Например:

if (2 == sscanf(line, "%lu %255s", &Pid, Cmd))

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