Initial commit

This includes support to display statistics on a given pid's open file
descriptors. It also can print open file descriptor paths and resolved
paths by type. The current version of this tool has been tested on over
550,000 open file descriptors and performs well (runtime was about 6
seconds).

1 files changed, 190 insertions, 0 deletions

diff --git a/main.c b/main.c
new file mode 100644
index 0000000..1921e14
--- /dev/null
+++ b/main.c
@@ -0,0 +1,190 @@
+/**
+ * Fd-enum is a simple tool to list open file descriptors of a pid by type
+ * Copyright (C) 2021  Aaron Ball <nullspoon@oper.io>
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/stat.h>
+
+struct config {
+  int pid;
+  char dead;
+  char live;
+  char sockets;
+  char inodes;
+  char pipes;
+  char showstats;
+};
+
+int fexists(char* path) {
+  FILE *fd = fopen(path, "r");
+  if(!fd)
+    return 0;
+  fclose(fd);
+  return 1;
+}
+
+void get_help() {
+  puts("Usage: \n\
+  -d, --dead     Print list of dead file descriptors (deleted but still open)\n\
+  -i, --inodes   Print list of inode file descriptors\n\
+  -l, --live     Print list of live file descriptors (open and existing)\n\
+  -p, --pipes    Print list of pipe file descriptors\n\
+  -s, --sockets  Print list of socket file descriptors\n\
+\n\
+  -n, --no-stats Hide file descriptor statistics\n\
+  -h, --help     Print this help text\n\
+");
+}
+
+int parse_args(int argc, char* argv[], struct config* c) {
+  // Initialize config struct
+  c->pid       = -1;
+  c->dead      = 0;
+  c->live      = 0;
+  c->sockets   = 0;
+  c->pipes     = 0;
+  c->inodes    = 0;
+  c->showstats = 1;
+  int i = 1;
+
+  while(i < argc) {
+    if(strcmp(argv[i], "-d") == 0 || strcmp(argv[i], "--dead") == 0) {
+      c->dead = 1;
+    } else if(strcmp(argv[i], "-l") == 0 || strcmp(argv[i], "--live") == 0) {
+      c->live = 1;
+    } else if(strcmp(argv[i], "-s") == 0 || strcmp(argv[i], "--sockets") == 0) {
+      c->sockets = 1;
+    } else if(strcmp(argv[i], "-i") == 0 || strcmp(argv[i], "--inodes") == 0) {
+      c->inodes = 1;
+    } else if(strcmp(argv[i], "-p") == 0 || strcmp(argv[i], "--pipes") == 0) {
+      c->pipes = 1;
+    } else if(strcmp(argv[i], "-n") == 0 || strcmp(argv[i], "--no-stats") == 0) {
+      c->showstats = 0;
+    } else if(strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "--help") == 0) {
+      get_help();
+      exit(1);
+    } else {
+      c->pid = strtol(argv[i], NULL, 10);
+    }
+
+    i++;
+  }
+
+  if(c->pid == -1) {
+    fprintf(stderr, "Must specify valid pid\n");
+    return 2;
+  }
+  return 0;
+}
+
+int main(int argc, char* argv[]) {
+  struct config c;
+
+  char pidpath_fd[32] = {'\0'};
+  char fdpath[289]    = {'\0'};
+  char lnpath[512]    = {'\0'};
+  int retval = 0;
+  int len    = 0;
+  unsigned long unknown  = 0;
+  unsigned long dead    = 0;
+  unsigned long live    = 0;
+  unsigned long sockets = 0;
+  unsigned long inodes  = 0;
+  unsigned long pipes   = 0;
+
+  struct stat sb;
+
+  DIR *dp = NULL;
+  struct dirent *de = NULL;
+
+  if(parse_args(argc, argv, &c) != 0)
+    return 1;
+
+  // Construct the pid path
+  sprintf(pidpath_fd, "/proc/%d/fd", c.pid);
+
+  dp = opendir(pidpath_fd);
+  while((de = readdir(dp)) != NULL) {
+    sprintf(fdpath, "%s/%s%c", pidpath_fd, de->d_name, '\0');
+
+    retval = stat(fdpath, &sb);
+    len = readlink(fdpath, lnpath, 512);
+
+    if(len <= 0)
+      continue;
+    lnpath[len] = '\0';
+
+    // Sockets
+    if(S_ISSOCK(sb.st_mode)) {
+      sockets++;
+      if(c.sockets)
+        printf("%s -> %s\n", fdpath, lnpath);
+
+    // Pipes
+    } else if(S_ISFIFO(sb.st_mode)) {
+      pipes++;
+      if(c.pipes)
+        printf("%s -> %s\n", fdpath, lnpath);
+
+    // Char device links
+    } else if(S_ISCHR(sb.st_mode)) {
+      live++;
+      if(c.live)
+        printf("%s -> %s\n", fdpath, lnpath);
+
+    // File desccriptors
+    } else if(S_ISREG(sb.st_mode)
+        || S_ISDIR(sb.st_mode)) {
+      // Exists
+      if(retval == 0 && fexists(lnpath)) {
+        live++;
+        if(c.live)
+          printf("%s -> %s\n", fdpath, lnpath);
+
+      // Does not exist
+      } else {
+        dead++;
+        if(c.dead)
+          printf("%s -> %s\n", fdpath, lnpath);
+      }
+
+    // Inodes
+    } else if(sb.st_mode == 384) {
+      inodes++;
+      if(c.inodes)
+        printf("%s -> %s\n", fdpath, lnpath);
+
+    } else {
+      unknown++;
+    }
+  }
+  closedir(dp);
+
+  if(c.showstats) {
+    printf("dead:        %ld\n", dead);
+    printf("live:        %ld\n", live);
+    printf("sockets:     %ld\n", sockets);
+    printf("anon_inodes: %ld\n", inodes);
+    printf("pipes:       %ld\n", pipes);
+    printf("unknown:     %ld\n", unknown);
+  }
+
+  return 0;
+}