1 //===- SystemUtils.h - Utilities to do low-level system stuff --*- C++ -*--===//
2 //
3 // This file contains functions used to do a variety of low-level, often
4 // system-specific, tasks.
5 //
6 //===----------------------------------------------------------------------===//
7 
8 #include "SystemUtils.h"
9 #include <algorithm>
10 #include <fstream>
11 #include <iostream>
12 #include <stdlib.h>
13 #include <sys/types.h>
14 #include <sys/stat.h>
15 #include <fcntl.h>
16 #include <sys/wait.h>
17 #include <unistd.h>
18 #include <errno.h>
19 
20 /// removeFile - Delete the specified file
21 ///
22 void removeFile(const std::string &Filename) {
23   unlink(Filename.c_str());
24 }
25 
26 /// getUniqueFilename - Return a filename with the specified prefix.  If the
27 /// file does not exist yet, return it, otherwise add a suffix to make it
28 /// unique.
29 ///
30 std::string getUniqueFilename(const std::string &FilenameBase) {
31   if (!std::ifstream(FilenameBase.c_str()))
32     return FilenameBase;    // Couldn't open the file? Use it!
33 
34   // Create a pattern for mkstemp...
35   char *FNBuffer = (char*)alloca(FilenameBase.size()+8);
36   strcpy(FNBuffer, FilenameBase.c_str());
37   strcpy(FNBuffer+FilenameBase.size(), "-XXXXXX");
38 
39   // Agree on a temporary file name to use....
40   int TempFD;
41   if ((TempFD = mkstemp(FNBuffer)) == -1) {
42     std::cerr << "bugpoint: ERROR: Cannot create temporary file in the current "
43 	      << " directory!\n";
44     exit(1);
45   }
46 
47   // We don't need to hold the temp file descriptor... we will trust that noone
48   // will overwrite/delete the file while we are working on it...
49   close(TempFD);
50   return FNBuffer;
51 }
52 
53 /// isExecutableFile - This function returns true if the filename specified
54 /// exists and is executable.
55 ///
56 bool isExecutableFile(const std::string &ExeFileName) {
57   struct stat Buf;
58   if (stat(ExeFileName.c_str(), &Buf))
59     return false;  // Must not be executable!
60 
61   if (!(Buf.st_mode & S_IFREG))
62     return false;                    // Not a regular file?
63 
64   if (Buf.st_uid == getuid())        // Owner of file?
65     return Buf.st_mode & S_IXUSR;
66   else if (Buf.st_gid == getgid())   // In group of file?
67     return Buf.st_mode & S_IXGRP;
68   else                               // Unrelated to file?
69     return Buf.st_mode & S_IXOTH;
70 }
71 
72 
73 // FindExecutable - Find a named executable, giving the argv[0] of bugpoint.
74 // This assumes the executable is in the same directory as bugpoint itself.
75 // If the executable cannot be found, return an empty string.
76 //
77 std::string FindExecutable(const std::string &ExeName,
78 			   const std::string &BugPointPath) {
79   // First check the directory that bugpoint is in.  We can do this if
80   // BugPointPath contains at least one / character, indicating that it is a
81   // relative path to bugpoint itself.
82   //
83   std::string Result = BugPointPath;
84   while (!Result.empty() && Result[Result.size()-1] != '/')
85     Result.erase(Result.size()-1, 1);
86 
87   if (!Result.empty()) {
88     Result += ExeName;
89     if (isExecutableFile(Result)) return Result; // Found it?
90   }
91 
92   // Okay, if the path to bugpoint didn't tell us anything, try using the PATH
93   // environment variable.
94   const char *PathStr = getenv("PATH");
95   if (PathStr == 0) return "";
96 
97   // Now we have a colon seperated list of directories to search... try them...
98   unsigned PathLen = strlen(PathStr);
99   while (PathLen) {
100     // Find the first colon...
101     const char *Colon = std::find(PathStr, PathStr+PathLen, ':');
102 
103     // Check to see if this first directory contains the executable...
104     std::string FilePath = std::string(PathStr, Colon) + '/' + ExeName;
105     if (isExecutableFile(FilePath))
106       return FilePath;                    // Found the executable!
107 
108     // Nope it wasn't in this directory, check the next range!
109     PathLen -= Colon-PathStr;
110     PathStr = Colon;
111     while (*PathStr == ':') {   // Advance past colons
112       PathStr++;
113       PathLen--;
114     }
115   }
116 
117   // If we fell out, we ran out of directories in PATH to search, return failure
118   return "";
119 }
120 
121 static void RedirectFD(const std::string &File, int FD) {
122   if (File.empty()) return;  // Noop
123 
124   // Open the file
125   int InFD = open(File.c_str(), FD == 0 ? O_RDONLY : O_WRONLY|O_CREAT, 0666);
126   if (InFD == -1) {
127     std::cerr << "Error opening file '" << File << "' for "
128 	      << (FD == 0 ? "input" : "output") << "!\n";
129     exit(1);
130   }
131 
132   dup2(InFD, FD);   // Install it as the requested FD
133   close(InFD);      // Close the original FD
134 }
135 
136 /// RunProgramWithTimeout - This function executes the specified program, with
137 /// the specified null-terminated argument array, with the stdin/out/err fd's
138 /// redirected, with a timeout specified on the commandline.  This terminates
139 /// the calling program if there is an error executing the specified program.
140 /// It returns the return value of the program, or -1 if a timeout is detected.
141 ///
142 int RunProgramWithTimeout(const std::string &ProgramPath, const char **Args,
143 			  const std::string &StdInFile,
144 			  const std::string &StdOutFile,
145 			  const std::string &StdErrFile) {
146 
147   // FIXME: install sigalarm handler here for timeout...
148 
149   int Child = fork();
150   switch (Child) {
151   case -1:
152     std::cerr << "ERROR forking!\n";
153     exit(1);
154   case 0:               // Child
155     RedirectFD(StdInFile, 0);      // Redirect file descriptors...
156     RedirectFD(StdOutFile, 1);
157     RedirectFD(StdErrFile, 2);
158 
159     execv(ProgramPath.c_str(), (char *const *)Args);
160     std::cerr << "Error executing program '" << ProgramPath;
161     for (; *Args; ++Args)
162       std::cerr << " " << *Args;
163     exit(1);
164 
165   default: break;
166   }
167 
168   // Make sure all output has been written while waiting
169   std::cout << std::flush;
170 
171   int Status;
172   if (wait(&Status) != Child) {
173     if (errno == EINTR) {
174       static bool FirstTimeout = true;
175       if (FirstTimeout) {
176 	std::cout <<
177  "*** Program execution timed out!  This mechanism is designed to handle\n"
178  "    programs stuck in infinite loops gracefully.  The -timeout option\n"
179  "    can be used to change the timeout threshold or disable it completely\n"
180  "    (with -timeout=0).  This message is only displayed once.\n";
181 	FirstTimeout = false;
182       }
183       return -1;   // Timeout detected
184     }
185 
186     std::cerr << "Error waiting for child process!\n";
187     exit(1);
188   }
189   return Status;
190 }
191