doc: Add comments for socket descriptor handling when forking

TheCharlatan · TheCharlatan · commit b56bf218c7d5 · 2024-08-21T09:59:59.000+02:00
diff --git a/src/mp/util.cpp b/src/mp/util.cpp
@@ -110,10 +110,12 @@ int SpawnProcess(int& pid, FdToArgsFn&& fd_to_args)
     if (pid == -1) {
         throw std::system_error(errno, std::system_category(), "fork");
     }
+    // Parent process closes the descriptor for socket 0, child closes the descriptor for socket 1.
     if (close(fds[pid ? 0 : 1]) != 0) {
         throw std::system_error(errno, std::system_category(), "close");
     }
     if (!pid) {
+        // Child process must close all potentially open descriptors, except socket 0.
         int maxFd = MaxFd();
         for (int fd = 3; fd < maxFd; ++fd) {
             if (fd != fds[0]) {

Original file line number	Diff line number	Diff line change
`@@ -110,10 +110,12 @@ int SpawnProcess(int& pid, FdToArgsFn&& fd_to_args)`
`110`	`110`	`if (pid == -1) {`
`111`	`111`	`throw std::system_error(errno, std::system_category(), "fork");`
`112`	`112`	`}`
	`113`	`+ // Parent process closes the descriptor for socket 0, child closes the descriptor for socket 1.`
`113`	`114`	`if (close(fds[pid ? 0 : 1]) != 0) {`
`114`	`115`	`throw std::system_error(errno, std::system_category(), "close");`
`115`	`116`	`}`
`116`	`117`	`if (!pid) {`
	`118`	`+ // Child process must close all potentially open descriptors, except socket 0.`
`117`	`119`	`int maxFd = MaxFd();`
`118`	`120`	`for (int fd = 3; fd < maxFd; ++fd) {`
`119`	`121`	`if (fd != fds[0]) {`