Fix automedia.pid always being overwritten

2 files changed, 47 insertions, 16 deletions

diff --git a/automedia b/automedia
index 3e5fb01..92f3f31 100755
--- a/automedia
+++ b/automedia
diff --git a/src/main.c b/src/main.c
index e5c5321..c9a9bb3 100644
--- a/src/main.c
+++ b/src/main.c
@@ -14,6 +14,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <limits.h>
+#include <assert.h>
 
 #include <dirent.h>
 #include <libgen.h>
@@ -273,6 +274,12 @@ int is_program_running() {
 /* plugin is NULL for rss */
 typedef int (*IterateTrackedItemCallback)(char *title, char *link, char *plugin, char *config_dir, struct json_object_s *json_data, void *userdata);
 static void iterate_tracked_items(char *config_dir, IterateTrackedItemCallback iterate_callback, void *userdata) {
+    /*
+        TODO: Only iterate updated items. To make that work, sync_rss and sync_html need to be updated to update
+        the json_object with new downloaded items (and not only temporary downloaded items) and then also only
+        clean them up!
+    */
+
     char tracked_dir[PATH_MAX];
     strcpy(tracked_dir, config_dir);
     strcat(tracked_dir, "/tracked");
@@ -458,8 +465,9 @@ static void sync_rss_html(char *rss_config_dir, char *html_config_dir, char *pro
     free(unfinished_torrents.items);
 }
 
-static int cmdline_contains_str(const char *cmdline, const char *str) {
-    for(;;) {
+static int cmdline_contains_str(const char *cmdline, int cmdline_len, const char *str) {
+    const char *start = cmdline;
+    while(cmdline - start < cmdline_len) {
         int arg_len = strlen(cmdline);
         if(arg_len == 0)
             return -1;
@@ -467,8 +475,35 @@ static int cmdline_contains_str(const char *cmdline, const char *str) {
         if(strstr(cmdline, str))
             return 0;
 
-        cmdline += arg_len;
+        cmdline += arg_len + 1;
+    }
+    return -1;
+}
+
+/* We can't use file_get_content because reading the size of /proc/<pid>/cmdline fails (returns 0) because its not a regular file */
+static int proc_read_cmdline(const char *pid_str, char *cmdline_data, int cmdline_data_size, int *cmdline_data_size_output) {
+    assert(cmdline_data_size > 0);
+
+    char cmdline_file_path[128];
+    sprintf(cmdline_file_path, "/proc/%s/cmdline", pid_str);
+
+    int cmdline_fd = open(cmdline_file_path, O_RDONLY);
+    if(cmdline_fd == -1) {
+        fprintf(stderr, "Process %s doesn't exist\n", pid_str);
+        return -1;
+    }
+
+    ssize_t bytes_read = read(cmdline_fd, cmdline_data, cmdline_data_size - 1);
+    if(bytes_read == -1) {
+        fprintf(stderr, "Failed to read %s\n", cmdline_file_path);
+        close(cmdline_fd);
+        return -1;
     }
+
+    cmdline_data[bytes_read] = '\0';
+    *cmdline_data_size_output = bytes_read;
+    close(cmdline_fd);
+    return 0;
 }
 
 static void command_sync(int argc, char **argv, char *rss_config_dir, char *html_config_dir, char *program_dir) {
@@ -483,6 +518,7 @@ static void command_sync(int argc, char **argv, char *rss_config_dir, char *html
         exit(1);
     }
     
+    /* Create a pid file because we only want to allow one instance of automedia to run at once */
     int pid_file = open(automedia_pid_path, O_CREAT | O_EXCL | O_SYNC | O_RDWR, 0666);
     if(pid_file == -1 && errno == EEXIST) {
         char *running_automedia_pid;
@@ -492,23 +528,18 @@ static void command_sync(int argc, char **argv, char *rss_config_dir, char *html
                 We have to check the cmdline because another process could theoretically receive the pid
                 that an old automedia process had
             */
-            char cmdline_file_path[128];
-            sprintf(cmdline_file_path, "/proc/%s/cmdline", running_automedia_pid);
-            free(running_automedia_pid);
-
-            char *cmdline;
-            long cmdline_size;
-            if(file_get_content(cmdline_file_path, &cmdline, &cmdline_size) == 0
-                    && cmdline_contains_str(cmdline, "automedia") == 0
-                    && cmdline_contains_str(cmdline, "sync") == 0) {
-                fprintf(stderr, "Automedia is already running with sync");
-                free(cmdline);
+            char cmdline[1024];
+            int cmdline_size;
+            if(proc_read_cmdline(running_automedia_pid, cmdline, sizeof(cmdline), &cmdline_size) == 0
+                && cmdline_contains_str(cmdline, cmdline_size, "automedia") == 0
+                && cmdline_contains_str(cmdline, cmdline_size, "sync") == 0) {
+                fprintf(stderr, "Automedia is already running with sync\n");
+                free(running_automedia_pid);
                 exit(0);
             }
-            free(cmdline);
+            free(running_automedia_pid);
         } else {
             fprintf(stderr, "Failed to get content of %s\n", automedia_pid_path);
-            free(running_automedia_pid);
             exit(1);
         }