Testing actual parsing of /proc/<pid>/stat

src/process.h

@@ -0,0 +1,25 @@
+#ifndef PROCESS_MON_H
+#define PROCESS_MON_H
+
+#include <stdint.h>
+
+typedef struct st_process {
+    // For our own purposes
+    struct st_process *next;
+    struct st_process *prev;
+    // attributes identifying thread
+    int lxc;
+    int pid;
+    int ppid;
+    int tgid;
+    int level;
+    char *label;
+    int iskernel;
+    // statistics - each outputs 1 line per process
+    uint64_t cpuTime;
+    uint64_t childCpuTime;
+    uint64_t nThreads;
+    uint64_t resident;
+} Process;
+
+#endif

src/server.c

@@ -1,10 +1,116 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdbool.h>
 #include <string.h>
 #include <unistd.h>
 #include <arpa/inet.h>
 #include <time.h>
+#include <unistd.h>
+#include <stdint.h>
 #include <dirent.h>
+#include "process.h"
+
+static inline uint64_t fast_str2ull(char** str) {
+   uint64_t result = 0;
+   int maxlen = 20; // length of maximum value of 18446744073709551615
+
+   while (maxlen-- && **str >= '0' && **str <= '9') {
+      result *= 10;
+      result += **str - '0';
+      (*str)++;
+   }
+
+   return result;
+}
+
+static int64_t fast_str2ll(char** str) {
+   bool neg = false;
+
+   if (**str == '-') {
+      neg = true;
+      (*str)++;
+   }
+
+   uint64_t res = fast_str2ull(str);
+   int64_t result = (int64_t) res;
+
+   return neg ? -result : result;
+}
+
+#define skipRange(inclusive,exclusive)     \
+    for (int i##inclusive=0; i##inclusive<exclusive-inclusive; i##inclusive++) \
+        location = strchr(location, ' ') + 1;
+
+int parseStatFile(Process *proc, char *filedata) {
+    char *location = filedata;
+    // (1) pid - %d
+    proc->pid = fast_str2ull(&location);
+    location += 2;
+     
+    // (2) comm - %s
+    char *end = strrchr(location, ')');
+    size_t length = end - location;
+    memcpy(proc->label, location, length);
+    proc->label[length] = 0;
+    location = end + 2;
+
+    // (3) State - %c
+    location += 2;
+
+    // (4) ppid - %d
+    proc->ppid = fast_str2ull(&location);
+    location += 1;
+
+    // (5) pgrp - %d
+    proc->tgid = fast_str2ll(&location);
+    location += 1;
+
+    if (proc->tgid != proc->pid) return -1;
+
+    // (6) session - %d
+    location = strchr(location, ' ') + 1;
+
+    // skip [7 - 14)
+    skipRange(7, 9);
+
+    // (9) flags - %u
+    proc->iskernel = fast_str2ull(&location) & PS_KTHREAD;
+    location += 1;
+
+    skipRange(10, 14);
+
+    // (14) utime - %lu
+    proc->cpuTime = fast_str2ull(&location);
+    location += 1;
+
+    // (15) stime - %lu
+    proc->cpuTime += fast_str2ull(&location);
+    location += 1;
+
+    // (16) cutime - %lu
+    proc->childCpuTime = fast_str2ull(&location);
+    location += 1;
+
+    // (17) cstime - %lu
+    proc->childCpuTime += fast_str2ull(&location);
+    location += 1;
+
+    // skip 18-19
+    skipRange(18, 20);
+
+    // (20) - num_threads %ld
+    proc->nThreads = fast_str2ull(&location);
+    location += 1;
+
+    // Skip 21-23
+    skipRange(21,24);
+
+    // (24) - rss %ld
+    proc->resident = fast_str2ull(&location);
+    location += 1;
+
+    return 0;
+}
 
 int main(int argc, char *argv[]) {
     struct dirent *pDirent;
@@ -31,14 +137,24 @@ int main(int argc, char *argv[]) {
     char *fname = malloc(1024);
     FILE *file;
 
+    Process *cur = malloc(sizeof(Process));
+    cur->label = malloc(256);
+    Process *head = cur;
+
     while ((pDirent = readdir(pDir)) != NULL) {
-	char first = pDirent->d_name[0];
-	if (first < '0' || first > '9') continue;
+        char first = pDirent->d_name[0];
+        if (first < '0' || first > '9') continue;
         sprintf(fname, "/proc/%s/stat", pDirent->d_name);
         file = fopen(fname, "rb");
         fread(filedata, 1, 4096, file); 
         fclose(file);
 
+        if (parseStatFile(cur, filedata)) continue;
+        cur->next = malloc(sizeof(Process));
+        cur->next->label = malloc(256);
+        cur->next->prev = cur;
+        cur = cur->next;
+
         strcat(fname, "us");
         file = fopen(fname, "rb");
         fread(filedata, 1, 4096, file);
@@ -47,6 +163,18 @@ int main(int argc, char *argv[]) {
         printf("[%s]\n", filedata);
     }
 
+    cur = cur->prev;
+    free(cur->next);
+    cur->next = NULL;
+
+    int clocks = sysconf(_SC_CLK_TCK);
+
+    cur = head;
+    while (cur != NULL) {
+        printf("proc_cpu_time{pid=\"%d\",ppid=\"%d\",label=\"%s\"} %d\n", cur->pid, cur->ppid, cur->label, cur->cpuTime);
+        cur = cur->next;
+    }
+
     // Close directory and exit.
 
     closedir(pDir);