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| #include <iostream>
#include <vector>
#include <string>
#include <dirent.h>
#include <limits.h>
#include <string.h>
#include <map>
#define MAX_LINE 1000
struct tree_node
{
pid_t id;
pid_t ppid;
std::string cmd;
std::vector<tree_node*> children;
};
void printTree(tree_node*, int);
int main() {
DIR *dirp;
struct dirent *dp;
char path[PATH_MAX];
char line[MAX_LINE], cmd_str[MAX_LINE];
pid_t ppid;
FILE *fp;
char *p;
bool gotname, gotpid, gotppid;
dirp = opendir("/proc");
if (dirp == NULL)
return -1;
/* Scan entries under /proc directory */
std::map<pid_t, tree_node*> pmap; // id > process, 树结构查找麻烦，建立一个map辅助查找
gotname = false;
gotppid = false;
for (;;) {
errno = 0; /* To distinguish error from end-of-directory */
dp = readdir(dirp);
if (dp == NULL) {
if (errno != 0)
return -1;
else
break;
}
/* Since we are looking for /proc/PID directories, skip entries
that are not directories, or don't begin with a digit. */
if (dp->d_type != DT_DIR || !isdigit((unsigned char) dp->d_name[0]))
continue;
snprintf(path, PATH_MAX, "/proc/%s/status", dp->d_name);
fp = fopen(path, "r");
if (fp == NULL)
continue; /* Ignore errors: fopen() might fail if
process has just terminated */
while (!gotname || !gotppid) {
if (fgets(line, MAX_LINE, fp) == NULL)
break;
/* The "Name:" line contains the name of the command that
this process is running */
if (strncmp(line, "Name:", 5) == 0) {
for (p = line + 5; *p != '\0' && isspace((unsigned char) *p); )
p++;
// 去除最后的换行符
char *pt = p;
while(*pt != '\n' && *pt != '\0')
pt++;
*pt = '\0';
strncpy(cmd_str, p, MAX_LINE - 1);
cmd_str[MAX_LINE -1] = '\0'; /* Ensure null-terminated */
}
if (strncmp(line, "PPid:", 5) == 0) {
ppid = strtol(line + 6, NULL, 10); /* Ensure null-terminated */
}
}
tree_node *pinfo = new tree_node;
pinfo->id = strtol(dp->d_name, NULL, 10);
pinfo->cmd = std::string(cmd_str);
pinfo->ppid = ppid;
pmap[pinfo->id] = pinfo;
fclose(fp);
}
// 构建进程树
for (auto item : pmap) {
if (pmap.count(item.second->ppid) > 0) {
pmap[item.second->ppid]->children.push_back(item.second);
}
}
// 打印
printTree(pmap[1], 0);
}
// 递归的打印出进程的所有子进程
void printTree(tree_node* node, int level) {
for(int i = 0; i < level; i++)
{
printf("|");
printf(" ");
}
printf("|--- ");
printf("[%d]%s\n", node->id, node->cmd.c_str());
for(auto i : node->children) {
printTree(i, level + 1);
}
}
|