Matrix: use unix domain socket for unique process file instead

2 files changed, 79 insertions, 81 deletions

diff --git a/plugins/utils/UniqueProcess.hpp b/plugins/utils/UniqueProcess.hpp
index a2145f9..f85704f 100644
--- a/plugins/utils/UniqueProcess.hpp
+++ b/plugins/utils/UniqueProcess.hpp
@@ -1,7 +1,7 @@
 #pragma once
 
 namespace QuickMedia {
-    bool is_quickmedia_instance_already_running(const char *pid_file_dir, const char *plugin_name);
-    bool set_quickmedia_instance_unique(const char *pid_file_dir, const char *plugin_name);
-    void remove_quickmedia_instance_lock(const char *pid_file_dir, const char *plugin_name);
+    bool is_quickmedia_instance_already_running(const char *sock_file_dir, const char *plugin_name);
+    bool set_quickmedia_instance_unique(const char *sock_file_dir, const char *plugin_name);
+    void remove_quickmedia_instance_lock(const char *sock_file_dir, const char *plugin_name);
 }
\ No newline at end of file
diff --git a/src/plugins/utils/UniqueProcess.cpp b/src/plugins/utils/UniqueProcess.cpp
index 76b9cb1..d2025f5 100644
--- a/src/plugins/utils/UniqueProcess.cpp
+++ b/src/plugins/utils/UniqueProcess.cpp
@@ -1,113 +1,111 @@
 #include "../../../plugins/utils/UniqueProcess.hpp"
+#include "../../../include/Storage.hpp"
 #include <stdio.h>
-#include <string.h>
 #include <limits.h>
+#include <sys/socket.h>
+#include <sys/un.h>
 #include <unistd.h>
 #include <fcntl.h>
-#include <stdlib.h>
+#include <errno.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);
+    bool is_quickmedia_instance_already_running(const char *sock_file_dir, const char *plugin_name) {
+        char sock_file[PATH_MAX];
+        snprintf(sock_file, sizeof(sock_file), "%s/quickmedia.%s.sock", sock_file_dir, plugin_name);
 
-        int fd = open(filepath, O_RDONLY);
-        if(fd == -1)
+        std::string resolved_path;
+        if(file_get_content(sock_file, resolved_path) != 0)
             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';
+        resolved_path.resize(108); // sizeof(addr.sun_path) is 108
 
-        char resolved_path[PATH_MAX + 1];
-        if(!realpath(buffer, resolved_path)) {
-            close(fd);
-            return false;
+        int fd = socket(AF_UNIX, SOCK_STREAM, 0);
+        if(fd == -1) {
+            fprintf(stderr, "Error: failed to create unix domain socket, error: %s\n", strerror(errno));
+            return true;
         }
-        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;
+        fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) | O_NONBLOCK);
 
-        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);
+        struct sockaddr_un addr;
+        memset(&addr, 0, sizeof(addr));
+        addr.sun_family = AF_UNIX;
+        strcpy(addr.sun_path, resolved_path.c_str());
+
+        bool running = connect(fd, (struct sockaddr*)&addr, sizeof(addr)) == 0;
+        int err = errno;
+        if(err == EAGAIN)
+            running = true;
+        else if(err == ENOENT)
+            running = false;
         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);
+    bool set_quickmedia_instance_unique(const char *sock_file_dir, const char *plugin_name) {
+        char socket_file[] = "/tmp/quickmedia.XXXXXX";
+        int tmp_file_fd = mkstemp(socket_file);
+        if(tmp_file_fd == -1) {
+            fprintf(stderr, "Error: failed to create temporary file for unix domain socket, error: %s\n", strerror(errno));
+            return false;
+        }
+        unlink(socket_file);
+        close(tmp_file_fd);
 
-        char buffer[256];
-        int fd = open(pid_file, O_RDONLY);
-        if(fd == -1)
+        int fd = socket(AF_UNIX, SOCK_STREAM, 0);
+        if(fd == -1) {
+            fprintf(stderr, "Error: failed to create unix domain socket, error: %s\n", strerror(errno));
             return false;
+        }
 
-        ssize_t bytes_read = read(fd, buffer, sizeof(buffer) - 1);
-        if(bytes_read < 0) {
-            perror("failed to read quickmedia pid file");
+        struct sockaddr_un addr;
+        memset(&addr, 0, sizeof(addr));
+        addr.sun_family = AF_UNIX;
+        strcpy(addr.sun_path, socket_file);
+
+        if(bind(fd, (struct sockaddr*)&addr, sizeof(addr)) == -1) {
+            fprintf(stderr, "Error: failed to bind unix domain socket, error: %s\n", strerror(errno));
+            unlink(socket_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(listen(fd, 0) == -1) {
+            fprintf(stderr, "Error: failed to listen to unix domain socket, error: %s\n", strerror(errno));
+            unlink(socket_file);
+            close(fd);
+            return false;
         }
 
-        if(!running)
-            unlink(pid_file);
-
-        return running;
+        char sock_file[PATH_MAX];
+        snprintf(sock_file, sizeof(sock_file), "%s/quickmedia.%s.sock", sock_file_dir, plugin_name);
+        bool success = file_overwrite(sock_file, socket_file) == 0;
+        if(!success) {
+            fprintf(stderr, "Error: failed to create %s unix domain socket link file\n", sock_file);
+            unlink(socket_file);
+            close(fd);
+        }
+        return success;
     }
 
-    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);
+    void remove_quickmedia_instance_lock(const char *sock_file_dir, const char *plugin_name) {
+        char sock_file[PATH_MAX];
+        snprintf(sock_file, sizeof(sock_file), "%s/quickmedia.%s.sock", sock_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;
+        std::string resolved_path;
+        if(file_get_content(sock_file, resolved_path) != 0) {
+            unlink(sock_file);
+            return;
         }
+        
+        resolved_path.resize(108); // sizeof(addr.sun_path) is 108
 
-        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;
+        if(resolved_path.size() < 4 || memcmp(resolved_path.data(), "/tmp", 4) != 0) {
+            unlink(sock_file);
+            return;
         }
-
-        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);
+        
+        unlink(sock_file);
+        unlink(resolved_path.c_str());
     }
 }
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