timeouts reading from spawned processes

[blank.git] / src / app / proc.cpp

diff --git a/src/app/proc.cpp b/src/app/proc.cpp
index 876eefc0527aaf110d215a3c0ec683c1cae6c966..1373a9107ff8029f1a80ab39adb9f501e02bba70 100644 (file)
--- a/src/app/proc.cpp
+++ b/src/app/proc.cpp
@@ -9,6 +9,7 @@
 #  include <fcntl.h>
 #  include <signal.h>
 #  include <unistd.h>
+#  include <sys/select.h>
 #  include <sys/wait.h>
 #endif
 
@@ -23,18 +24,23 @@ namespace blank {
 struct Process::Impl {
 
        Impl(
-               const string &path_in,
+               const string &path,
                const Arguments &args,
-               const Environment &env);
+               char *const env[]);
        ~Impl();
 
+       static Impl *EnvHelper(
+               const string &path,
+               const Arguments &args,
+               const Environment &env);
+
        size_t WriteIn(const void *buffer, size_t max_len);
        void CloseIn();
 
-       size_t ReadOut(void *buffer, size_t max_len);
+       size_t ReadOut(void *buffer, size_t max_len, int timeout);
        void CloseOut();
 
-       size_t ReadErr(void *buffer, size_t max_len);
+       size_t ReadErr(void *buffer, size_t max_len, int timeout);
        void CloseErr();
 
        void Terminate();
@@ -63,11 +69,18 @@ struct Process::Impl {
 };
 
 
+Process::Process(
+       const string &path,
+       const Arguments &args)
+: impl(new Impl(path, args, nullptr)) {
+
+}
+
 Process::Process(
        const string &path,
        const Arguments &args,
        const Environment &env)
-: impl(new Impl(path, args, env)) {
+: impl(Impl::EnvHelper(path, args, env)) {
 
 }
 
@@ -84,16 +97,16 @@ void Process::CloseIn() {
        impl->CloseIn();
 }
 
-size_t Process::ReadOut(void *buffer, size_t max_len) {
-       return impl->ReadOut(buffer, max_len);
+size_t Process::ReadOut(void *buffer, size_t max_len, int timeout) {
+       return impl->ReadOut(buffer, max_len, timeout);
 }
 
 void Process::CloseOut() {
        impl->CloseOut();
 }
 
-size_t Process::ReadErr(void *buffer, size_t max_len) {
-       return impl->ReadErr(buffer, max_len);
+size_t Process::ReadErr(void *buffer, size_t max_len, int timeout) {
+       return impl->ReadErr(buffer, max_len, timeout);
 }
 
 void Process::CloseErr() {
@@ -112,22 +125,29 @@ int Process::Join() {
        return impl->Join();
 }
 
+Process::Impl *Process::Impl::EnvHelper(
+       const string &path,
+       const Arguments &args,
+       const Environment &env
+) {
+       char *envp[env.size() + 1];
+       for (size_t i = 0; i < env.size(); ++i) {
+               envp[i] = const_cast<char *>(env[i].c_str());
+       }
+       envp[env.size()] = nullptr;
+       return new Impl(path, args, envp);
+}
 
 Process::Impl::Impl(
        const string &path_in,
        const Arguments &args,
-       const Environment &env)
+       char *const envp[])
 : joined(false)
 , status(0)
 , in_closed(false)
 , out_closed(false)
 , err_closed(false) {
        const char *path = path_in.c_str();
-       char *envp[env.size() + 1];
-       for (size_t i = 0; i < env.size(); ++i) {
-               envp[i] = const_cast<char *>(env[i].c_str());
-       }
-       envp[env.size()] = nullptr;
 #ifdef _WIN32
        string cmdline;
        for (const auto &arg : args) {
@@ -222,7 +242,11 @@ Process::Impl::Impl(
                close(fd_err[0]);
                close(fd_err[1]);
 
-               execve(path, argv, envp);
+               if (envp) {
+                       execve(path, argv, envp);
+               } else {
+                       execv(path, argv);
+               }
                // if execve returns, something bad happened
                exit(EXIT_FAILURE);
 
@@ -274,14 +298,35 @@ void Process::Impl::CloseIn() {
        in_closed = true;
 }
 
-size_t Process::Impl::ReadOut(void *buffer, size_t max_len) {
+size_t Process::Impl::ReadOut(void *buffer, size_t max_len, int timeout) {
 #ifdef _WIN32
+       // TODO: timeout implementation for windows child process I/O
        DWORD ret;
        if (!ReadFile(fd_out[0], buffer, max_len, &ret, nullptr)) {
                throw runtime_error("failed to read from child process' output stream");
        }
        return ret;
 #else
+       if (timeout >= 0) {
+               fd_set read_set;
+               fd_set error_set;
+               FD_ZERO(&read_set);
+               FD_ZERO(&error_set);
+               FD_SET(fd_out[0], &read_set);
+               FD_SET(fd_out[0], &error_set);
+               timeval timer;
+               timer.tv_sec = timeout / 1000;
+               timer.tv_usec = (timeout % 1000) * 1000;
+               if (select(fd_out[0] + 1, &read_set, nullptr, &error_set, &timer) == -1) {
+                       throw SysError("error waiting on child process' output stream");
+               }
+               if (FD_ISSET(fd_out[0], &error_set)) {
+                       throw runtime_error("error condition on child process' output stream");
+               }
+               if (!FD_ISSET(fd_out[0], &read_set)) {
+                       throw runtime_error("timeout while waiting on child process' output stream");
+               }
+       }
        int ret = read(fd_out[0], buffer, max_len);
        if (ret < 0) {
                if (errno == EAGAIN) {
@@ -306,14 +351,35 @@ void Process::Impl::CloseOut() {
        out_closed = true;
 }
 
-size_t Process::Impl::ReadErr(void *buffer, size_t max_len) {
+size_t Process::Impl::ReadErr(void *buffer, size_t max_len, int timeout) {
 #ifdef _WIN32
+       // TODO: timeout implementation for windows child process I/O
        DWORD ret;
        if (!ReadFile(fd_err[0], buffer, max_len, &ret, nullptr)) {
                throw runtime_error("failed to read from child process' error stream");
        }
        return ret;
 #else
+       if (timeout >= 0) {
+               fd_set read_set;
+               fd_set error_set;
+               FD_ZERO(&read_set);
+               FD_ZERO(&error_set);
+               FD_SET(fd_err[0], &read_set);
+               FD_SET(fd_err[0], &error_set);
+               timeval timer;
+               timer.tv_sec = timeout / 1000;
+               timer.tv_usec = (timeout % 1000) * 1000;
+               if (select(fd_err[0] + 1, &read_set, nullptr, &error_set, &timer) == -1) {
+                       throw SysError("error waiting on child process' error stream");
+               }
+               if (FD_ISSET(fd_err[0], &error_set)) {
+                       throw runtime_error("error condition on child process' error stream");
+               }
+               if (!FD_ISSET(fd_err[0], &read_set)) {
+                       throw runtime_error("timeout while waiting on child process' error stream");
+               }
+       }
        int ret = read(fd_err[0], buffer, max_len);
        if (ret < 0) {
                if (errno == EAGAIN) {