common/sc_popen.cpp

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4 #include "sc_popen.h"
   5
   6 #ifndef _WIN32
   7
   8 /*      This code is based on popen() and pclose() from Darwin's
   9         libc. The only functional difference is that sc_popen()
  10         places the new process' pid at the pidp address. sc_pclose()
  11         takes this pid which allows the code to be simplified
  12         (maintaining a global linked list of fds to pids and locking
  13         it is no longer necessary). */
  14
  15 #include <sys/cdefs.h>
  16 #include <sys/param.h>
  17 #include <sys/wait.h>
  18 #include <signal.h>
  19 #include <errno.h>
  20 #include <unistd.h>
  21 #include <paths.h>
  22
  23 // allows for linking into a dylib on darwin
  24 #if defined(__APPLE__) && !defined(SC_IPHONE)
  25         #include <crt_externs.h>
  26         #define environ (*_NSGetEnviron())
  27 #else
  28         extern char **environ;
  29 #endif
  30
  31 FILE *
  32 sc_popen(const char *command, pid_t *pidp, const char *type)
  33 {
  34         FILE *iop;
  35         int pdes[2], pid, twoway;
  36         char *argv[4];
  37
  38         /*
  39          * Lite2 introduced two-way popen() pipes using _socketpair().
  40          * FreeBSD's pipe() is bidirectional, so we use that.
  41          */
  42         if (strchr(type, '+')) {
  43                 twoway = 1;
  44                 type = "r+";
  45         } else  {
  46                 twoway = 0;
  47                 if ((*type != 'r' && *type != 'w') || type[1])
  48                         return (NULL);
  49         }
  50         if (pipe(pdes) < 0)
  51                 return (NULL);
  52
  53         argv[0] = (char *)"sh";
  54         argv[1] = (char *)"-c";
  55         argv[2] = (char *)command;
  56         argv[3] = NULL;
  57
  58         switch (pid = fork()) {
  59         case -1:                        /* Error. */
  60                 (void)close(pdes[0]);
  61                 (void)close(pdes[1]);
  62                 return (NULL);
  63                 /* NOTREACHED */
  64         case 0:                         /* Child. */
  65                 if (*type == 'r') {
  66                         /*
  67                          * The _dup2() to STDIN_FILENO is repeated to avoid
  68                          * writing to pdes[1], which might corrupt the
  69                          * parent's copy.  This isn't good enough in
  70                          * general, since the _exit() is no return, so
  71                          * the compiler is free to corrupt all the local
  72                          * variables.
  73                          */
  74                         (void)close(pdes[0]);
  75                         if (pdes[1] != STDOUT_FILENO) {
  76                                 (void)dup2(pdes[1], STDOUT_FILENO);
  77                                 (void)close(pdes[1]);
  78                                 if (twoway)
  79                                         (void)dup2(STDOUT_FILENO, STDIN_FILENO);
  80                         } else if (twoway && (pdes[1] != STDIN_FILENO))
  81                                 (void)dup2(pdes[1], STDIN_FILENO);
  82                 } else {
  83                         if (pdes[0] != STDIN_FILENO) {
  84                                 (void)dup2(pdes[0], STDIN_FILENO);
  85                                 (void)close(pdes[0]);
  86                         }
  87                         (void)close(pdes[1]);
  88                 }
  89
  90                 execve("/bin/sh", argv, environ);
  91                 exit(127);
  92                 /* NOTREACHED */
  93         }
  94
  95         /* Parent; assume fdopen can't fail. */
  96         if (*type == 'r') {
  97                 iop = fdopen(pdes[0], type);
  98                 (void)close(pdes[1]);
  99         } else {
 100                 iop = fdopen(pdes[1], type);
 101                 (void)close(pdes[0]);
 102         }
 103
 104     *pidp = pid;
 105         return iop;
 106 }
 107
 108 /*
 109  * pclose --
 110  *      Pclose returns -1 if stream is not associated with a `popened' command,
 111  *      if already `pclosed', or waitpid returns an error.
 112  */
 113 int
 114 sc_pclose(FILE *iop, pid_t mPid)
 115 {
 116         int pstat = 0;
 117         pid_t pid;
 118
 119         (void)fclose(iop);
 120
 121         do {
 122                 pid = wait4(mPid, &pstat, 0, (struct rusage *)0);
 123         } while (pid == -1 && errno == EINTR);
 124
 125         return (pid == -1 ? -1 : pstat);
 126 }
 127
 128 #else
 129
 130 #include <windows.h>
 131 #include <fcntl.h>
 132 #include <io.h>
 133 #include <errno.h>
 134
 135 /*      The process handle allows us to get the exit code after
 136         the process has died. It must be closed in sc_pclose;
 137         just having the pid as in the unix version is not enough.
 138         Thus this global linked list needs to be maintained and
 139         access to it needs to be locked. */
 140
 141 static struct process {
 142         struct process *next;
 143         FILE *fp;
 144         HANDLE handle;
 145 } *processlist;
 146 static pthread_mutex_t processlist_mutex = PTHREAD_MUTEX_INITIALIZER;
 147
 148 #define THREAD_LOCK()   pthread_mutex_lock(&processlist_mutex)
 149 #define THREAD_UNLOCK() pthread_mutex_unlock(&processlist_mutex)
 150
 151 FILE *
 152 sc_popen(const char *cmd, pid_t *pid, const char *mode)
 153 {
 154         STARTUPINFO si;
 155         PROCESS_INFORMATION pi;
 156         FILE *f = NULL;
 157         int fno;
 158         HANDLE child_in, child_out;
 159         HANDLE father_in, father_out;
 160         HANDLE father_in_dup, father_out_dup;
 161         HANDLE current_pid;
 162         int binary_mode;
 163         char *new_cmd = NULL;
 164         struct process *cur;
 165         BOOL read_mode, write_mode;
 166
 167         if (cmd == NULL) {
 168                 return NULL;
 169         }
 170
 171         new_cmd = (char *)malloc(strlen(cmd) + 10);
 172         sprintf(new_cmd, "cmd /c %s", cmd);
 173
 174         current_pid = GetCurrentProcess();
 175
 176         ZeroMemory( &si, sizeof(STARTUPINFO) );
 177         si.cb = sizeof(STARTUPINFO);
 178         si.dwFlags = STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW;
 179         si.wShowWindow = SW_HIDE;
 180         si.hStdInput = GetStdHandle(STD_INPUT_HANDLE);
 181         si.hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE);
 182         si.hStdError = GetStdHandle(STD_ERROR_HANDLE);
 183
 184         binary_mode = (strchr(mode, 'b') ? _O_BINARY : _O_TEXT);
 185
 186         read_mode = (strchr(mode, 'r') != 0);
 187         write_mode = (strchr(mode, 'w') != 0);
 188
 189         /* Opening the pipe for writing */
 190         if (write_mode) {
 191                 binary_mode |= _O_WRONLY;
 192                 if (CreatePipe(&child_in, &father_out, NULL, 0) == FALSE) {
 193                         fprintf(stderr, "popen: error CreatePipe\n");
 194                         free(new_cmd);
 195                         return NULL;
 196                 }
 197
 198                 if (DuplicateHandle(current_pid, child_in,
 199                                                         current_pid, &father_in_dup,
 200                                                         0, TRUE, DUPLICATE_SAME_ACCESS) == FALSE) {
 201                         fprintf(stderr, "popen: error DuplicateHandle father_out\n");
 202                         free(new_cmd);
 203                         return NULL;
 204                 }
 205                 si.hStdInput = father_in_dup;
 206
 207                 CloseHandle(child_in);
 208                 fno = _open_osfhandle((long)father_out, binary_mode);
 209                 f = _fdopen(fno, mode);
 210         }
 211         /* Opening the pipe for reading */
 212         else if (read_mode) {
 213                 binary_mode |= _O_RDONLY;
 214                 if (CreatePipe(&father_in, &child_out, NULL, 0) == FALSE) {
 215                         fprintf(stderr, "popen: error CreatePipe\n");
 216                         free(new_cmd);
 217                         return NULL;
 218                 }
 219                 if (DuplicateHandle(current_pid, child_out,
 220                                                         current_pid, &father_out_dup,
 221                                                         0, TRUE, DUPLICATE_SAME_ACCESS) == FALSE) {
 222                         fprintf(stderr, "popen: error DuplicateHandle father_in\n");
 223                         free(new_cmd);
 224                         return NULL;
 225                 }
 226                 CloseHandle(child_out);
 227                 si.hStdOutput = father_out_dup;
 228                 fno = _open_osfhandle((long)father_in, binary_mode);
 229                 f = _fdopen(fno, mode);
 230         }
 231         else {
 232                 fprintf(stderr, "popen: invalid mode %s\n", mode);
 233                 free(new_cmd);
 234                 return NULL;
 235         }
 236
 237         /* creating child process */
 238         if (CreateProcess(NULL, /* pointer to name of executable module */
 239                                           new_cmd,      /* pointer to command line string */
 240                                           NULL, /* pointer to process security attributes */
 241                                           NULL, /* pointer to thread security attributes */
 242                                           TRUE, /* handle inheritance flag */
 243                                           0,            /* creation flags */
 244                                           NULL, /* pointer to environment */
 245                                           NULL, /* pointer to current directory */
 246                                           &si,  /* pointer to STARTUPINFO */
 247                                           &pi           /* pointer to PROCESS_INFORMATION */
 248                                           ) == FALSE) {
 249                 fprintf(stderr, "popen: CreateProcess %x\n", GetLastError());
 250                 free(new_cmd);
 251                 fclose(f);
 252                 return NULL;
 253         }
 254
 255         /* Only the process handle is needed, ignore errors */
 256         CloseHandle(pi.hThread);
 257
 258         /* Closing the unnecessary part of the pipe */
 259         if (read_mode)
 260                 CloseHandle(father_out_dup);
 261         else if (write_mode)
 262                 CloseHandle(father_in_dup);
 263
 264         if ((cur = (struct process *)malloc(sizeof(struct process))) == NULL) {
 265                 free(new_cmd);
 266                 fclose(f);
 267                 CloseHandle(pi.hProcess);
 268                 return NULL;
 269         }
 270
 271         cur->fp = f;
 272         cur->handle = pi.hProcess;
 273         THREAD_LOCK();
 274         cur->next = processlist;
 275         processlist = cur;
 276         THREAD_UNLOCK();
 277
 278         if (new_cmd) free(new_cmd);
 279
 280         *pid = pi.dwProcessId;
 281
 282         return f;
 283 }
 284
 285 int
 286 sc_pclose(FILE *f, pid_t pid)
 287 {
 288         struct process *cur, *last;
 289         int exit_code;
 290
 291         THREAD_LOCK();
 292         for (last = NULL, cur = processlist; cur; last = cur, cur = cur->next)
 293                 if (cur->fp == f)
 294                         break;
 295         if (cur == NULL) {
 296                 THREAD_UNLOCK();
 297                 return (-1);
 298         }
 299         if (last == NULL)
 300                 processlist = cur->next;
 301         else
 302                 last->next = cur->next;
 303         THREAD_UNLOCK();
 304
 305         if (WaitForSingleObject(cur->handle, INFINITE) != WAIT_OBJECT_0) {
 306                 fprintf(stderr, "sc_pclose: error, process still active\n");
 307                 free(cur);
 308                 return -1;
 309         }
 310
 311         if (GetExitCodeProcess(cur->handle, (LPDWORD)&exit_code) == 0) {
 312                 fprintf(stderr, "sc_pclose: can't get process exit code\n");
 313                 free(cur);
 314                 return -1;
 315         }
 316
 317         fclose(cur->fp);
 318
 319         if (CloseHandle(cur->handle) == FALSE) {
 320                 fprintf(stderr, "sc_pclose: error closing process handle\n");
 321                 free(cur);
 322                 return -1;
 323         }
 324
 325         free(cur);
 326
 327         return exit_code;
 328 }
 329
 330 #endif