#!/usr/bin/python
import os
from pathlib import Path

__doc__ ="""procuall.py: enumerate all processes run by the user who runs the
script.

usage: python procuall.py
"""

def search_proc():
    """for each process under /proc
       parse the status file and try to match uid
       if there is a match, the process belongs to the user"""
    uid = os.getuid()
    all = Path("/proc")
    procs = all.glob("[0-9]*")
    processes = [p for p in procs]
    info = {}
    for proc in processes:
        status = proc.joinpath("status")
        with open(status) as f:
            lines = f.readlines()
            cmd = lines[0].split("\t")
            name = cmd[1].strip("\n")
            uidl = lines[8].split("\t")
            puid = uidl[1].strip("\n")
            if int(puid) == uid:
                info.update({name: proc.stem})
    return info


def main():
    """Get info about running processes
    output the command being run and the pid"""
    info = search_proc()
    for k, v in info.items():
        print(f"cmd: {k}, pid: {v}")


if __name__ == '__main__':
    main()

# output of strace python procuall.py
...
910 getuid()                                = 1000
911 newfstatat(AT_FDCWD, "/proc", {st_mode=S_IFDIR|0555, st_size=0, ...}, 0) = 0
912 openat(AT_FDCWD, "/proc", O_RDONLY|O_NONBLOCK|O_CLOEXEC|O_DIRECTORY) = 3
913 newfstatat(3, "", {st_mode=S_IFDIR|0555, st_size=0, ...}, AT_EMPTY_PATH) = 0
914 getdents64(3, 0x560cbd19e900 /* 416 entries */, 32768) = 11232
915 getdents64(3, 0x560cbd19e900 /* 0 entries */, 32768) = 0
916 close(3)                                = 0
...

# output of strace ./procuall adam
...
97 openat(AT_FDCWD, "/proc", O_RDONLY|O_NONBLOCK|O_CLOEXEC|O_DIRECTORY) = 3
98 newfstatat(3, "", {st_mode=S_IFDIR|0555, st_size=0, ...}, AT_EMPTY_PATH) = 0
99 getdents64(3, 0x7d3db0 /* 438 entries */, 32768) = 12552
...

/* Function to read a line from file */
char* fgetLine(size_t size, FILE* fd)
{
	char* input = NULL;
	char* buf;
	buf = malloc(size);  /* allocate the min number of bytes */
	if (buf == NULL) {
		fprintf(stderr, "malloc error\n");
		exit(1);
	}
    size_t len = 0, newlen = 0;
	do {
		/* read at most size bytes */
		if(!fgets(buf, size, fd))
		{
			/* read null bytes */
			buf[0] = '\0';
			return buf;
		}
		newlen = strlen(buf); /* check length of string to be copied */
		if (newlen > 0 && buf[newlen-1] == '\n') {
			buf[--newlen] = '\0'; /* remove the trailing newline if present */
		}
		if (newlen == size-1) { /* we're not finished */
			size *= 2;   /* Double the size    */
		} 		
		input = realloc(input, size);
		if (input == NULL) {
			fprintf(stderr, "realloc error\n");
			exit(1);
		}
		memcpy(input + len, buf, newlen+1); /* begin to write at byte 0, else */
		len += newlen;
		size += newlen;
	} while (buf[newlen] && buf[newlen-1]!='\n' && buf[newlen-1]!=EOF);
	return input;
}

#include <dirent.h>
#include <stdarg.h>
#include <sys/stat.h>

#include "adio.h"
#include "cscratch_common.h"
#include "ugid_info.h"


/* procuall.c: all process being run by a user 
 *
 * usage: procuall <username>
 * */

#define MAXLINE 512
#define LPID 5

int s_isdigit(const char* s) {
    int result = 0;
    while (*s != '\0') {
        if (('0' <= *s) && ('9' >= *s)) {
            result = 1;
        }
        s++;
    }
    return result;
}

char*
make_filename(const char* pid) {
    char* fname;
    if (s_isdigit(pid)) {
        sprintf(fname, "/proc/%s/status", pid);
        return fname;
    }
    return NULL;
}

int
main (int argc, char* argv[])
{
    char* uname = argv[1];
    uid_t uid = uidFromName(uname);
    printf("user: %s\tuid: %d\n", uname, uid);

    DIR* dirp;
    char* proc = "/proc";
    dirp = opendir(proc);
    struct dirent* dp;
    char* fname;
    int size = 0;
    FILE* fp;
    int fd;
    char* lone;

    struct stat sb;

    if (dirp) {
        errno = 0;
        while ((dp = readdir(dirp)) != NULL) {
            fname = make_filename(dp->d_name);
            if (fname) {
                fp = fopen(fname, "r");
                fd = fileno(fp);
                if (fstat(fd, &sb) == -1) {
                    return -1; /* just cheese it! */
                }
                if (uid == sb.st_uid) {
                    lone = fgetLine(MAXLINE, fp);
                    printf("%-24s pid:%-30.30s\n", lone, dp->d_name);
                }
            }
        }
        closedir(dirp);
    }
    return 0;
}

    dirp = opendir(PROC);
    if (dirp) {
        errno = 0;
        while ((dp = readdir(dirp)) != NULL) {
            fname = make_filename(dp->d_name);
            if (access(fname, F_OK) == 0) {
                fp = fopen(fname, "r");
                if (fp == NULL) { /* Entered a bad state */
                    fprintf(stderr, "Error: fopen attempted read on %s, returned %d", fname, errno);
                } else {
                    fd = fileno(fp);
                    if (fstat(fd, &sb) == -1) {
                        return -1; /* just cheese it! */
                    }
                    if (uid == sb.st_uid) {
                        lone = fgetLine(MAXLINE, fp);
                        printf("%-24s pid:%-30.30s\n", lone, dp->d_name);
                    }
                }
            } else {
                fprintf(stderr, "Error: %s failed before fopen\n", dp->d_name);
            }
        }
        closedir(dirp);
    }

/* check that string s is a contiguous array of integer characters */
bool s_isinteger(const char* s) {
    bool result = (*s != '\0');
    while (*s != '\0') {
        if ((*s < '0') || (*s > '9')) {
            return false;
        }
        s++;
    }
    return result;
}

proc % hyperfine --warmup=100 --shell=none "python scripts/procuall.py" "./procuall adam
Benchmark 1: python scripts/procuall.py
  Time (mean ± σ):      32.2 ms ±   0.3 ms    [User: 24.3 ms, System: 7.6 ms]
  Range (min … max):    31.5 ms …  33.2 ms    92 runs

Benchmark 2: ./procuall adam
  Time (mean ± σ):       2.5 ms ±   0.1 ms    [User: 0.3 ms, System: 2.1 ms]
  Range (min … max):     2.3 ms …   3.5 ms    989 runs

Summary
  ./procuall adam ran
   12.97 ± 0.72 times faster than python scripts/procuall.py

#include <dirent.h>
#include <stdarg.h>
#include <sys/stat.h>

#include "cscratch_common.h"
#include "ugid_info.h"


/* procuall.c: all process being run by a user
 *
 * usage: procuall <username>
 * */

#define MAXLINE 4096
#define PROC "/proc"

/* check that string s is a contiguous array of integer characters */
bool s_isinteger(const char* s) {
    bool result = (*s != '\0');
    while (*s != '\0') {
        if ((*s < '0') || (*s > '9')) {
            return false;
        }
        s++;
    }
    return result;
}

int
make_filename(char fname[MAXLINE], const char* pid) {
    if (s_isinteger(pid)) {
        snprintf(fname, MAXLINE, "/proc/%s/status", pid);
        return 0;
    }
    return -1;
}

int
main (int argc, char* argv[]) {
    if (argc != 2) {
        printf("usage: procuall <username>\n");
        exit(EPERM);
    }
    char* uname = argv[1];
    uid_t uid = uidFromName(uname);
    printf("user: %s\tuid: %d\n", uname, uid);

    DIR* dirp;
    struct dirent* dp;
    FILE* fp;
    int fd;

    char* line = NULL;
    ssize_t rread = 0;
    size_t len = 0;
    struct stat sb;

    dirp = opendir(PROC);
    if (dirp) {
        errno = 0;
        while ((dp = readdir(dirp)) != NULL) {

            int rc;
            char fname[MAXLINE];
            if ((rc = make_filename(fname, dp->d_name)) == -1) {
                fprintf(stderr, "Error make_filename\n");
                goto err_fname;
            }

            if (access(fname, F_OK) != 0) {
                fprintf(stderr, "Error: %s failed before fopen\n", dp->d_name);
                goto err_file;
            }

            if ((fp = fopen(fname, "r")) == NULL) { /* Entered a bad state */
                fprintf(stderr, "Error: fopen attempted read on %s, returned %d", fname, errno);
                goto err_file;
            }

            if ((fd = fileno(fp)) == -1) {
                fprintf(stderr, "Error fileno %d\n", errno);
                fclose(fp);
                goto err_proc;
            }

            if (fstat(fd, &sb) == -1) {
                fprintf(stderr, "Error fstat %d\n", errno);
                goto err_proc;
            }

            if (uid == sb.st_uid) {
                if ((rread = getline(&line, &len, fp)) != -1) {
                    fprintf(stderr, "%spid:\t%s\n", line, dp->d_name);
                } else {
                    fprintf(stderr, "Error getline %d\n", errno);
                }
            }
err_proc:
            fclose(fp);
        }
err_fname:
err_file:
        /* cleanup directory stuff */
        closedir(dirp);
    }
    return 0;
}