progressbar fd position extraction

1 files changed, 93 insertions, 8 deletions

diff --git a/progressbar.c b/progressbar.c
index a8c183e..8c5900a 100644
--- a/progressbar.c
+++ b/progressbar.c
@@ -4,6 +4,11 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <errno.h>
+#include <string.h>
+#include <stdbool.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+
 
 struct filtered_dir_entries {
     struct dirent ** entries;
@@ -20,7 +25,6 @@ static int search_dir(const char * const dir,
 
     n = scandir(dir, &names, filter_fn, alphasort);
     if (n < 0) {
-        perror("scandir");
         return 1;
     }
 
@@ -75,10 +79,17 @@ int main(int argc, char **argv)
     struct filtered_dir_entries proc_pid_entries = {};
     struct filtered_dir_entries proc_fd_entries = {};
     ssize_t realpath_used;
-    char realpath[BUFSIZ];
-
-    (void) argc;
-    (void) argv;
+    size_t target_filepath_len;
+    char file_realpath[BUFSIZ] = {};
+    char pid[32];
+    char fd[32];
+    bool found_target = false;
+
+    if (argc != 2) {
+        fprintf(stderr, "usage: %s [FILE]\n", (argc > 0 ? argv[0] : "progressbar"));
+        exit(EXIT_FAILURE);
+    }
+    target_filepath_len = strlen(argv[1]);
 
     if (search_dir("/proc", dirent_filter_only_numeric, &proc_pid_entries)) {
         exit(EXIT_FAILURE);
@@ -93,13 +104,87 @@ int main(int argc, char **argv)
             realpath_used = realpath_procfs_fd("/proc",
                                 proc_pid_entries.entries[i]->d_name,
                                 proc_fd_entries.entries[j]->d_name,
-                                &realpath[0], sizeof realpath);
-            if (realpath_used < 0) {
+                                &file_realpath[0], sizeof file_realpath);
+            if (realpath_used <= 0) {
                 continue;
             }
-            printf("%s: __%.*s__\n", proc_pid_entries.entries[i]->d_name, (int)realpath_used, realpath);
+            file_realpath[realpath_used] = '\0';
+            if (realpath_used == target_filepath_len) {
+                if (!strncmp(argv[1], file_realpath, realpath_used)) {
+                    found_target = true;
+                    if (snprintf(pid, sizeof pid, "%s", proc_pid_entries.entries[i]->d_name) <= 0) {
+                        found_target = false;
+                    }
+                    if (snprintf(fd, sizeof fd, "%s", proc_fd_entries.entries[j]->d_name) <= 0) {
+                        found_target = false;
+                    }
+                    break;
+                }
+            }
         }
         free_filtered_dir_entries(&proc_fd_entries);
+
+        if (found_target) {
+            break;
+        }
     }
     free_filtered_dir_entries(&proc_pid_entries);
+
+    if (!found_target) {
+        fprintf(stderr, "%s: file '%s' not found in /proc\n", argv[0], argv[1]);
+        exit(EXIT_FAILURE);
+    }
+
+    printf("PID: %s, FD: %s, FILE: '%.*s'\n", pid, fd, (int)realpath_used, file_realpath);
+
+    char proc_fd_path[BUFSIZ];
+    if (snprintf(proc_fd_path, sizeof proc_fd_path, "%s/%s/fd/%s", "/proc", pid, fd) <= 0) {
+        exit(EXIT_FAILURE);
+    }
+
+    int proc_fd_fd = open(proc_fd_path, 0);
+    if (proc_fd_fd < 0) {
+        perror("open proc_fd");
+        exit(EXIT_FAILURE);
+    }
+
+    struct stat buf = {};
+    if (fstat(proc_fd_fd, &buf)) {
+        perror("stat proc_fd");
+        exit(EXIT_FAILURE);
+    }
+    close(proc_fd_fd);
+
+    printf("Total size: %lld\n", (long long) buf.st_size);
+
+    char proc_fdinfo_path[BUFSIZ];
+    if (snprintf(proc_fdinfo_path, sizeof proc_fdinfo_path, "%s/%s/fdinfo/%s", "/proc", pid, fd) <= 0) {
+        exit(EXIT_FAILURE);
+    }
+
+    int proc_fdinfo_fd = open(proc_fdinfo_path, 0);
+    if (proc_fdinfo_fd < 0) {
+        perror("open proc_fdinfo");
+        exit(EXIT_FAILURE);
+    }
+
+    ssize_t nread;
+    char proc_fdinfo[BUFSIZ];
+    nread = read(proc_fdinfo_fd, &proc_fdinfo[0], sizeof proc_fdinfo);
+    if (nread <= 0) {
+        perror("read proc_fdinfo");
+        exit(EXIT_FAILURE);
+    }
+    proc_fdinfo[nread - 1] = '\0';
+    close(proc_fdinfo_fd);
+
+    static const char needle[] = "pos:\t";
+    char * pospos = strstr(&proc_fdinfo[0], &needle[0]);
+    if (!pospos) {
+        exit(EXIT_FAILURE);
+    }
+    pospos += (sizeof(needle) - 1) / sizeof(needle[0]);
+
+    unsigned long long int current_position = strtoull(pospos, NULL, 10);
+    printf("Current position: %llu\n", current_position);
 }