git.itanic.dy.fi Git - scan-pagemap/blob - pidlib.c

   1 #include <stdlib.h>
   2 #include <stdio.h>
   3 #include <libgen.h>
   4 #include <errno.h>
   5 #include <string.h>
   6
   7 #include "pidlib.h"
   8
   9 char *get_name_by_pid(int pid)
  10 {
  11         static int last_pid;
  12         static char cmdline[128];
  13         static char *bname;
  14
  15         if (last_pid == pid)
  16                 return bname;
  17
  18         if (read_cmdline(pid, pid, cmdline, sizeof(cmdline))) {
  19                 bname = NULL;
  20                 return NULL;
  21         }
  22
  23         bname = basename(cmdline);
  24
  25         last_pid = pid;
  26         return bname;
  27 }
  28
  29 static int parse_pid(DIR **dir)
  30 {
  31         struct dirent *dirent;
  32         int error;
  33
  34 restart:
  35         dirent = readdir(*dir);
  36         if (!dirent) {
  37                 if (errno == 0) {
  38                         closedir(*dir);
  39                         *dir = NULL;
  40                         return 0;
  41                 }
  42                 error = errno;
  43                 printf("Failed to read /proc directory: %s\n", strerror(error));
  44                 return -1;
  45         }
  46
  47         if (dirent->d_name[0] < '0' || dirent->d_name[0] > '9')
  48                 goto restart;
  49
  50         return atoi(dirent->d_name);
  51 }
  52
  53 static int opendir_check(DIR **dir, const char *path)
  54 {
  55         int error;
  56
  57         if (!*dir) {
  58                 *dir = opendir(path);
  59                 if (!dir) {
  60                         error = errno;
  61                         fprintf(stderr, "Failed to open %s directory: %s\n",
  62                                 path, strerror(error));
  63                         return -1;
  64                 }
  65         }
  66
  67         return 0;
  68 }
  69
  70 int get_next_tid(int pid, DIR **dir)
  71 {
  72         if (*dir == NULL) {
  73                 char path[64];
  74
  75                 snprintf(path, sizeof(path), "/proc/%d/task/", pid);
  76                 if (opendir_check(dir, path))
  77                         return -1;
  78         }
  79
  80         return parse_pid(dir);
  81 }
  82
  83 int get_next_pid(DIR **dir)
  84 {
  85         if (opendir_check(dir, "/proc"))
  86                 return -1;
  87
  88         return parse_pid(dir);
  89 }
  90
  91 int get_next_pid_by_name(DIR **dir, char *name)
  92 {
  93         int pid;
  94         char *pname;
  95
  96         if (opendir_check(dir, "/proc"))
  97                 return -1;
  98
  99         while (1) {
 100                 pid = parse_pid(dir);
 101                 if (pid <= 0)
 102                         break;
 103
 104                 pname = get_name_by_pid(pid);
 105                 if (pname == NULL)
 106                         continue;
 107                 if (strcmp(pname, name))
 108                         continue;
 109
 110                 return pid;
 111         }
 112
 113         return 0;
 114 }
 115
 116 int read_cmdline(int pid, int tid, char *cmdline, size_t len)
 117 {
 118         FILE *file;
 119         char path[512];
 120         int ret;
 121
 122         snprintf(path, sizeof(path), "/proc/%d/task/%d/cmdline", pid, tid);
 123         file = fopen(path, "rb");
 124
 125         if (!file)
 126                 return -1;
 127
 128         ret = fread(cmdline, 1, len, file);
 129         if (ret > 0)
 130                 cmdline[ret - 1] = 0;
 131         fclose(file);
 132
 133         return ret > 0 ? 0 : -1;
 134 }
 135