1 //===- SystemUtils.h - Utilities to do low-level system stuff --*- C++ -*--===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains functions used to do a variety of low-level, often
11 // system-specific, tasks.
13 //===----------------------------------------------------------------------===//
15 #include "Support/SystemUtils.h"
20 #include "Config/sys/types.h"
21 #include "Config/sys/stat.h"
22 #include "Config/fcntl.h"
23 #include "Config/sys/wait.h"
24 #include "Config/unistd.h"
25 #include "Config/errno.h"
29 /// isExecutableFile - This function returns true if the filename specified
30 /// exists and is executable.
32 bool isExecutableFile(const std::string &ExeFileName) {
34 if (stat(ExeFileName.c_str(), &Buf))
35 return false; // Must not be executable!
37 if (!(Buf.st_mode & S_IFREG))
38 return false; // Not a regular file?
40 if (Buf.st_uid == getuid()) // Owner of file?
41 return Buf.st_mode & S_IXUSR;
42 else if (Buf.st_gid == getgid()) // In group of file?
43 return Buf.st_mode & S_IXGRP;
44 else // Unrelated to file?
45 return Buf.st_mode & S_IXOTH;
48 /// FindExecutable - Find a named executable, giving the argv[0] of program
49 /// being executed. This allows us to find another LLVM tool if it is built
50 /// into the same directory, but that directory is neither the current
51 /// directory, nor in the PATH. If the executable cannot be found, return an
54 std::string FindExecutable(const std::string &ExeName,
55 const std::string &ProgramPath) {
56 // First check the directory that bugpoint is in. We can do this if
57 // BugPointPath contains at least one / character, indicating that it is a
58 // relative path to bugpoint itself.
60 std::string Result = ProgramPath;
61 while (!Result.empty() && Result[Result.size()-1] != '/')
62 Result.erase(Result.size()-1, 1);
64 if (!Result.empty()) {
66 if (isExecutableFile(Result)) return Result; // Found it?
69 // Okay, if the path to the program didn't tell us anything, try using the
70 // PATH environment variable.
71 const char *PathStr = getenv("PATH");
72 if (PathStr == 0) return "";
74 // Now we have a colon separated list of directories to search... try them...
75 unsigned PathLen = strlen(PathStr);
77 // Find the first colon...
78 const char *Colon = std::find(PathStr, PathStr+PathLen, ':');
80 // Check to see if this first directory contains the executable...
81 std::string FilePath = std::string(PathStr, Colon) + '/' + ExeName;
82 if (isExecutableFile(FilePath))
83 return FilePath; // Found the executable!
85 // Nope it wasn't in this directory, check the next range!
86 PathLen -= Colon-PathStr;
88 while (*PathStr == ':') { // Advance past colons
94 // If we fell out, we ran out of directories in PATH to search, return failure
98 static void RedirectFD(const std::string &File, int FD) {
99 if (File.empty()) return; // Noop
102 int InFD = open(File.c_str(), FD == 0 ? O_RDONLY : O_WRONLY|O_CREAT, 0666);
104 std::cerr << "Error opening file '" << File << "' for "
105 << (FD == 0 ? "input" : "output") << "!\n";
109 dup2(InFD, FD); // Install it as the requested FD
110 close(InFD); // Close the original FD
113 /// RunProgramWithTimeout - This function executes the specified program, with
114 /// the specified null-terminated argument array, with the stdin/out/err fd's
115 /// redirected, with a timeout specified on the command line. This terminates
116 /// the calling program if there is an error executing the specified program.
117 /// It returns the return value of the program, or -1 if a timeout is detected.
119 int RunProgramWithTimeout(const std::string &ProgramPath, const char **Args,
120 const std::string &StdInFile,
121 const std::string &StdOutFile,
122 const std::string &StdErrFile) {
124 // FIXME: install sigalarm handler here for timeout...
129 std::cerr << "ERROR forking!\n";
132 RedirectFD(StdInFile, 0); // Redirect file descriptors...
133 RedirectFD(StdOutFile, 1);
134 RedirectFD(StdErrFile, 2);
136 execv(ProgramPath.c_str(), (char *const *)Args);
137 std::cerr << "Error executing program: '" << ProgramPath;
138 for (; *Args; ++Args)
139 std::cerr << " " << *Args;
146 // Make sure all output has been written while waiting
147 std::cout << std::flush;
150 if (wait(&Status) != Child) {
151 if (errno == EINTR) {
152 static bool FirstTimeout = true;
155 "*** Program execution timed out! This mechanism is designed to handle\n"
156 " programs stuck in infinite loops gracefully. The -timeout option\n"
157 " can be used to change the timeout threshold or disable it completely\n"
158 " (with -timeout=0). This message is only displayed once.\n";
159 FirstTimeout = false;
161 return -1; // Timeout detected
164 std::cerr << "Error waiting for child process!\n";
172 // Function: ExecWait ()
175 // This function executes a program with the specified arguments and
176 // environment. It then waits for the progarm to termiante and then returns
180 // argv - The arguments to the program as an array of C strings. The first
181 // argument should be the name of the program to execute, and the
182 // last argument should be a pointer to NULL.
184 // envp - The environment passes to the program as an array of C strings in
185 // the form of "name=value" pairs. The last element should be a
193 // 1 - The program could not be executed.
194 // 1 - The program returned a non-zero exit status.
195 // 1 - The program terminated abnormally.
198 // The program will inherit the stdin, stdout, and stderr file descriptors
199 // as well as other various configuration settings (umask).
201 // This function should not print anything to stdout/stderr on its own. It is
202 // a generic library function. The caller or executed program should report
203 // errors in the way it sees fit.
205 // This function does not use $PATH to find programs.
208 ExecWait (const char * const old_argv[], const char * const old_envp[])
213 // Status from child process when it exits
217 // Create local versions of the parameters that can be passed into execve()
218 // without creating const problems.
220 char ** const argv = (char ** const) old_argv;
221 char ** const envp = (char ** const) old_envp;
224 // Create a child process.
226 switch (child=fork())
229 // An error occured: Return to the caller.
236 // Child process: Execute the program.
239 execve (argv[0], argv, envp);
242 // If the execve() failed, we should exit and let the parent pick up
243 // our non-zero exit status.
249 // Parent process: Break out of the switch to do our processing.
256 // Parent process: Wait for the child process to termiante.
258 if ((wait (&status)) == -1)
264 // If the program exited normally with a zero exit status, return success!
266 if (WIFEXITED (status) && (WEXITSTATUS(status) == 0))
272 // Otherwise, return failure.
277 } // End llvm namespace