1 files changed, 113 insertions, 0 deletions
diff --git a/src/plugins/utils/UniqueProcess.cpp b/src/plugins/utils/UniqueProcess.cpp
new file mode 100644
index 0000000..76b9cb1
--- /dev/null
+++ b/src/plugins/utils/UniqueProcess.cpp
@@ -0,0 +1,113 @@
+#include "../../../plugins/utils/UniqueProcess.hpp"
+#include <stdio.h>
+#include <string.h>
+#include <limits.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdlib.h>
+
+namespace QuickMedia {
+    static bool is_process_running_program(pid_t pid, const char *program_name) {
+        char filepath[256];
+        snprintf(filepath, sizeof(filepath), "/proc/%ld/cmdline", (long)pid);
+
+        int fd = open(filepath, O_RDONLY);
+        if(fd == -1)
+            return false;
+        
+        char buffer[PATH_MAX + 1];
+        ssize_t bytes_read = read(fd, buffer, sizeof(buffer) - 1);
+        if(bytes_read == -1) {
+            close(fd);
+            return false;
+        }
+        buffer[bytes_read] = '\0';
+
+        char resolved_path[PATH_MAX + 1];
+        if(!realpath(buffer, resolved_path)) {
+            close(fd);
+            return false;
+        }
+        bytes_read = strlen(resolved_path);
+        resolved_path[bytes_read] = '\0';
+
+        const char *end = resolved_path + bytes_read;
+        const char *start = (const char*)memrchr(resolved_path, '/', bytes_read);
+        if(start)
+            start += 1;
+        else
+            start = buffer;
+
+        const size_t cmd_arg0_len = end - start;
+        const size_t program_name_len = strlen(program_name);
+        bool running = (cmd_arg0_len == program_name_len && memcmp(start, program_name, program_name_len) == 0);
+        close(fd);
+        return running;
+    }
+
+    bool is_quickmedia_instance_already_running(const char *pid_file_dir, const char *plugin_name) {
+        char pid_file[PATH_MAX];
+        snprintf(pid_file, sizeof(pid_file), "%s/quickmedia.%s.pid", pid_file_dir, plugin_name);
+
+        char buffer[256];
+        int fd = open(pid_file, O_RDONLY);
+        if(fd == -1)
+            return false;
+
+        ssize_t bytes_read = read(fd, buffer, sizeof(buffer) - 1);
+        if(bytes_read < 0) {
+            perror("failed to read quickmedia pid file");
+            close(fd);
+            return false;
+        }
+        buffer[bytes_read] = '\0';
+        close(fd);
+
+        bool running = false;
+        long pid = 0;
+        if(sscanf(buffer, "%ld", &pid) == 1) {
+            if(is_process_running_program(pid, "quickmedia")) {
+                fprintf(stderr, "Error: quickmedia %s is already running\n", plugin_name);
+                running = true;
+            }
+        } else {
+            fprintf(stderr, "Warning: quickmedia pid file is in incorrect format, it's possible that its corrupt. Replacing file and continuing...\n");
+            running = false;
+        }
+
+        if(!running)
+            unlink(pid_file);
+
+        return running;
+    }
+
+    bool set_quickmedia_instance_unique(const char *pid_file_dir, const char *plugin_name) {
+        char pid_file[PATH_MAX];
+        snprintf(pid_file, sizeof(pid_file), "%s/quickmedia.%s.pid", pid_file_dir, plugin_name);
+
+        int fd = open(pid_file, O_WRONLY|O_CREAT|O_TRUNC, 0777);
+        if(fd == -1) {
+            perror("failed to create quickmedia pid file");
+            return false;
+        }
+
+        bool success = true;
+        char buffer[256];
+        const int buffer_size = snprintf(buffer, sizeof(buffer), "%ld", (long)getpid());
+        if(write(fd, buffer, buffer_size) == -1) {
+            perror("failed to write quickmedia pid file");
+            success = false;
+        }
+
+        close(fd);
+        if(!success)
+            unlink(pid_file);
+        return success;
+    }
+
+    void remove_quickmedia_instance_lock(const char *pid_file_dir, const char *plugin_name) {
+        char pid_file[PATH_MAX];
+        snprintf(pid_file, sizeof(pid_file), "%s/quickmedia.%s.pid", pid_file_dir, plugin_name);
+        unlink(pid_file);
+    }
+}
+\ No newline at end of file