Add missing file needed by 79f2e7d3

src/butil/popen.cpp

+// Copyright (c) 2017 Baidu.com, Inc. All Rights Reserved
+// 
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// 
+//     http://www.apache.org/licenses/LICENSE-2.0
+// 
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Author: Zhangyi Chen (chenzhangyi01@baidu.com)
+// Date: 2017/11/04 17:37:43
+
+#include "butil/build_config.h"
+#include "butil/logging.h"
+
+#if defined(OS_LINUX)
+// clone is a linux specific syscall
+#include <sched.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+extern "C" {
+uint64_t BAIDU_WEAK bthread_usleep(uint64_t microseconds);
+}
+
+namespace butil {
+
+const int CHILD_STACK_SIZE = 64 * 1024;
+
+struct ChildArgs {
+    const char* cmd;
+    int pipe_fd0;
+    int pipe_fd1;
+};
+
+int launch_child_process(void* args) {
+    ChildArgs* cargs = (ChildArgs*)args;
+    dup2(cargs->pipe_fd1, STDOUT_FILENO);
+    close(cargs->pipe_fd0);
+    close(cargs->pipe_fd1);
+    execl("/bin/sh", "sh", "-c", cargs->cmd, NULL);
+    _exit(1);
+}
+
+int read_command_output(std::ostream& os, const char* cmd) {
+    int pipe_fd[2];
+    if (pipe(pipe_fd) != 0) {
+        PLOG(ERROR) << "Fail to pipe";
+        return -1;
+    }
+    int saved_errno = 0;
+    int wstatus = 0;
+    pid_t cpid;
+    int rc = 0;
+    ChildArgs args = { cmd, pipe_fd[0], pipe_fd[1] };
+    char buffer[1024];
+
+    char* child_stack = NULL;
+    char* child_stack_mem = (char*)malloc(CHILD_STACK_SIZE);
+    if (!child_stack_mem) {
+        LOG(ERROR) << "Fail to alloc stack for the child process";
+        rc = -1;
+        goto END;
+    }
+    child_stack = child_stack_mem + CHILD_STACK_SIZE;  
+                               // ^ Assume stack grows downward
+    cpid = clone(launch_child_process, child_stack,
+                       __WCLONE | CLONE_VM | SIGCHLD, &args);
+    if (cpid < 0) {
+        PLOG(ERROR) << "Fail to clone child process";
+        rc = -1;
+        goto END;
+    }
+    close(pipe_fd[1]);
+    pipe_fd[1] = -1;
+
+    for (;;) {
+        const ssize_t nr = read(pipe_fd[0], buffer, sizeof(buffer));
+        if (nr > 0) {
+            os.write(buffer, nr);
+            continue;
+        } else if (nr == 0) {
+            break;
+        } else if (errno != EINTR) {
+            LOG(ERROR) << "Encountered error while reading for the pipe";
+            break;
+        }
+    }
+
+    close(pipe_fd[0]);
+    pipe_fd[0] = -1;
+
+    for (;;) {
+        pid_t wpid = waitpid(cpid, &wstatus, WNOHANG);
+        if (wpid > 0) {
+            break;
+        }
+        if (wpid == 0) {
+            if (bthread_usleep != NULL) {
+                bthread_usleep(1000);
+            } else {
+                usleep(1000);
+            }
+            continue;
+        }
+        rc = -1;
+        goto END;
+    }
+
+    if (WIFEXITED(wstatus)) {
+        rc = WEXITSTATUS(wstatus);
+        goto END;
+    }
+
+    if (WIFSIGNALED(wstatus)) {
+        os << "Child process(" << cpid << ") was killed by signal "
+           << WTERMSIG(wstatus);
+    }
+
+    rc = -1;
+    errno = ECHILD;
+
+END:
+    saved_errno = errno;
+    if (child_stack_mem) {
+        free(child_stack_mem);
+    }
+    if (pipe_fd[0] >= 0) {
+        close(pipe_fd[0]);
+    }
+    if (pipe_fd[1] >= 0) {
+        close(pipe_fd[1]);
+    }
+    errno = saved_errno;
+    return rc;
+}
+
+}  // namespace butil 
+
+#else  // OS_LINUX
+
+#include <stdio.h>
+
+namespace butil {
+
+int read_command_output(std::ostream& os, const char* cmd) {
+    FILE* pipe = popen(cmd, "r");
+    if (pipe == NULL) {
+        return -1;
+    }
+    char buffer[1024];
+    for (;;) {
+        size_t nr = fread(buffer, 1, sizeof(buffer), pipe);
+        if (nr != 0) {
+            os.write(buffer, nr);
+        }
+        if (nr != sizeof(buffer)) {
+            if (feof(pipe)) {
+                break;
+            } else if (ferror(pipe)) {
+                LOG(ERROR) << "Encountered error while reading for the pipe";
+                break;
+            }
+            // retry;
+        }
+    }
+    return pclose(pipe);
+}
+
+}  // namespace butil 
+
+#endif  // OS_LINUX

src/butil/popen.h

+// Copyright (c) 2017 Baidu.com, Inc. All Rights Reserved
+// 
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// 
+//     http://www.apache.org/licenses/LICENSE-2.0
+// 
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Author: Zhangyi Chen (chenzhangyi01@baidu.com)
+// Date: 2017/11/04 17:13:18
+
+#ifndef  PUBLIC_COMMON_POPEN_H
+#define  PUBLIC_COMMON_POPEN_H
+
+#include <ostream>
+
+namespace butil {
+
+// Read the stdout of child process executing `cmd'.
+// Returns the exit status(0-255) of cmd and all the output is stored in
+// |os|. -1 otherwise and errno is set appropriately.
+int read_command_output(std::ostream& os, const char* cmd);
+
+}
+
+#endif  //PUBLIC_COMMON_POPEN_H