implement proc status parsing

include/process.h

@@ -1,4 +1,33 @@
 #ifndef __PROCESS_H
 #define __PROCESS_H
 
+#include <sys/types.h>
+
+typedef enum {
+    UNINTERRUPTABLE_SLEEP   = 'D',
+    IDLE_KERNEL_THREAD      = 'I',
+    RUNNING                 = 'R',
+    INTERRUPTIBLE_SLEEP     = 'S',
+    STOPPED                 = 'T',
+    STOPPED_BY_DEBUGGER     = 't',
+    DEAD                    = 'X',
+    ZOMBIE                  = 'Z'
+} process_state_t;
+
+#define MAX_PROCESS_NAME 256
+typedef struct {
+    char name[MAX_PROCESS_NAME];
+    mode_t umask;
+    process_state_t state;
+    pid_t tgid;
+    pid_t ngid;
+    pid_t pid;
+    pid_t ppid;
+    pid_t tracer_pid;
+    uid_t uid;
+    gid_t gid;
+} process_status_t;
+
+int process_parse_status(pid_t pid, process_status_t* status);
+
 #endif

src/main.c

@@ -3,6 +3,19 @@
 
 int main(int argc, char** argv)
 {
+    process_status_t status = {};
+    process_parse_status(getpid(), &status);
+
+    printf("name: %s\n", status.name);
+    printf("umask: %d\n", status.umask);
+    printf("state: %d\n", status.state);
+    printf("tgid: %d\n", status.tgid);
+    printf("ngid: %d\n", status.ngid);
+    printf("pid: %d\n", status.pid);
+    printf("ppid: %d\n", status.ppid);
+    printf("tracer_pid: %d\n", status.tracer_pid);
+    printf("uid: %d\n", status.uid);
+    printf("gid: %d\n", status.gid);
 
     return 0;
 }

src/process.c

@@ -1 +1,54 @@
 #include "process.h"
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+int process_parse_status(pid_t pid, process_status_t* status)
+{
+    char statusPath[256] = {0};
+    snprintf(statusPath, sizeof(statusPath), "/proc/%d/status", pid);
+
+    int statusFd = open(statusPath, O_RDONLY);
+    if (statusFd < 0) return 1;
+
+    char buffer[4096] = {0};
+    int rd = read(statusFd, buffer, sizeof(buffer));
+    close(statusFd);
+
+    if (rd < 1) return 1;
+
+    char* lineptr = NULL, *line = strtok_r(buffer, "\n", &lineptr);
+    while (line != NULL)
+    {
+        char* fieldptr = NULL;
+        const char* key = (const char*)strtok_r(line, ":\t", &fieldptr);
+        const char* value = (const char*)strtok_r(NULL, ":\t", &fieldptr);
+
+        if (!strcmp(key, "Name"))
+            strncpy(status->name, value, MAX_PROCESS_NAME);
+        else if (!strcmp(key, "Umask"))
+            status->umask = (unsigned int)strtoul(value, NULL, 8);
+        else if (!strcmp(key, "State"))
+            status->state = (process_state_t)value[0];
+        else if (!strcmp(key, "Tgid"))
+            status->tgid = atoi(value);
+        else if (!strcmp(key, "Ngid"))
+            status->ngid = atoi(value);
+        else if (!strcmp(key, "Pid"))
+            status->pid = atoi(value);
+        else if (!strcmp(key, "PPid"))
+            status->ppid = atoi(value);
+        else if (!strcmp(key, "TracerPid"))
+            status->tracer_pid = atoi(value);
+        else if (!strcmp(key, "Uid"))
+            status->uid = atoi(value);
+        else if (!strcmp(key, "Gid"))
+            status->gid = atoi(value);
+
+        line = strtok_r(NULL, "\n", &lineptr);
+    }
+
+    return 0;
+}