ENH: Teach KWSys Process basic VMS support
This achieves basic process execution on OpenVMS. We use work-arounds for different fork()/exec() behavior and a lack of select(). VMS emulates fork/exec using setjmp/longjmp to evaluate the child and parent return cases from fork. Therefore both must be invoked from the same function. Since select() works only for sockets we use the BeOS-style polling implementation. However, non-blocking reads on empty pipes cannot be distinguished easily from the last read on a closed pipe. Therefore we identify end of data by an empty read after the child terminates.
This commit is contained in:
Brad King
parent
1eec4fe6ad
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312ca9670f
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@ -67,6 +67,12 @@ do.
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#undef __BEOS__
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#endif
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#if defined(__VMS)
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# define KWSYSPE_VMS_NONBLOCK , O_NONBLOCK
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#else
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# define KWSYSPE_VMS_NONBLOCK
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#endif
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#if defined(KWSYS_C_HAS_PTRDIFF_T) && KWSYS_C_HAS_PTRDIFF_T
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typedef ptrdiff_t kwsysProcess_ptrdiff_t;
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#else
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@ -100,7 +106,7 @@ static inline void kwsysProcess_usleep(unsigned int msec)
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* pipes' file handles to be non-blocking and just poll them directly
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* without select().
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*/
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#if !defined(__BEOS__)
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#if !defined(__BEOS__) && !defined(__VMS)
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# define KWSYSPE_USE_SELECT 1
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#endif
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@ -170,6 +176,7 @@ static void kwsysProcessRestoreDefaultSignalHandlers(void);
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static pid_t kwsysProcessFork(kwsysProcess* cp,
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kwsysProcessCreateInformation* si);
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static void kwsysProcessKill(pid_t process_id);
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static int kwsysProcessSetVMSFeature(char* name, int value);
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static int kwsysProcessesAdd(kwsysProcess* cp);
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static void kwsysProcessesRemove(kwsysProcess* cp);
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#if KWSYSPE_USE_SIGINFO
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@ -720,6 +727,13 @@ void kwsysProcess_Execute(kwsysProcess* cp)
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return;
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}
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/* Make sure pipes behave like streams on VMS. */
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if(!kwsysProcessSetVMSFeature("DECC$STREAM_PIPE", 1))
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{
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kwsysProcessCleanup(cp, 1);
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return;
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}
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/* Save the real working directory of this process and change to
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the working directory for the child processes. This is needed
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to make pipe file paths evaluate correctly. */
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@ -759,7 +773,7 @@ void kwsysProcess_Execute(kwsysProcess* cp)
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{
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/* Create the pipe. */
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int p[2];
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if(pipe(p) < 0)
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if(pipe(p KWSYSPE_VMS_NONBLOCK) < 0)
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{
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kwsysProcessCleanup(cp, 1);
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return;
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@ -1185,11 +1199,24 @@ static int kwsysProcessWaitForPipe(kwsysProcess* cp, char** data, int* length,
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else if (n == 0) /* EOF */
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{
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/* We are done reading from this pipe. */
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kwsysProcessCleanupDescriptor(&cp->PipeReadEnds[i]);
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--cp->PipesLeft;
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#if defined(__VMS)
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if(!cp->CommandsLeft)
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#endif
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{
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kwsysProcessCleanupDescriptor(&cp->PipeReadEnds[i]);
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--cp->PipesLeft;
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}
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}
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else if (n < 0) /* error */
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{
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#if defined(__VMS)
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if(!cp->CommandsLeft)
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{
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kwsysProcessCleanupDescriptor(&cp->PipeReadEnds[i]);
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--cp->PipesLeft;
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}
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else
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#endif
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if((errno != EINTR) && (errno != EAGAIN))
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{
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strncpy(cp->ErrorMessage,strerror(errno),
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@ -1565,6 +1592,11 @@ static int kwsysProcessSetNonBlocking(int fd)
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return flags >= 0;
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}
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/*--------------------------------------------------------------------------*/
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#if defined(__VMS)
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int decc$set_child_standard_streams(int fd1, int fd2, int fd3);
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#endif
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/*--------------------------------------------------------------------------*/
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static int kwsysProcessCreate(kwsysProcess* cp, int prIndex,
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kwsysProcessCreateInformation* si, int* readEnd)
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@ -1616,7 +1648,7 @@ static int kwsysProcessCreate(kwsysProcess* cp, int prIndex,
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{
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/* Create the pipe. */
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int p[2];
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if(pipe(p) < 0)
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if(pipe(p KWSYSPE_VMS_NONBLOCK) < 0)
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{
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return 0;
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}
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@ -1674,7 +1706,14 @@ static int kwsysProcessCreate(kwsysProcess* cp, int prIndex,
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}
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/* Fork off a child process. */
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#if defined(__VMS)
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/* VMS needs vfork and execvp to be in the same function because
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they use setjmp/longjmp to run the child startup code in the
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parent! TODO: OptionDetach. */
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cp->ForkPIDs[prIndex] = vfork();
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#else
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cp->ForkPIDs[prIndex] = kwsysProcessFork(cp, si);
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#endif
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if(cp->ForkPIDs[prIndex] < 0)
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{
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return 0;
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@ -1682,6 +1721,10 @@ static int kwsysProcessCreate(kwsysProcess* cp, int prIndex,
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if(cp->ForkPIDs[prIndex] == 0)
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{
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#if defined(__VMS)
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/* Specify standard pipes for child process. */
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decc$set_child_standard_streams(si->StdIn, si->StdOut, si->StdErr);
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#else
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/* Close the read end of the error reporting pipe. */
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close(si->ErrorPipe[0]);
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@ -1711,14 +1754,21 @@ static int kwsysProcessCreate(kwsysProcess* cp, int prIndex,
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/* Restore all default signal handlers. */
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kwsysProcessRestoreDefaultSignalHandlers();
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#endif
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/* Execute the real process. If successful, this does not return. */
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execvp(cp->Commands[prIndex][0], cp->Commands[prIndex]);
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/* TODO: What does VMS do if the child fails to start? */
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/* Failure. Report error to parent and terminate. */
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kwsysProcessChildErrorExit(si->ErrorPipe[1]);
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}
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#if defined(__VMS)
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/* Restore the standard pipes of this process. */
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decc$set_child_standard_streams(0, 1, 2);
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#endif
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/* A child has been created. */
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++cp->CommandsLeft;
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@ -2266,9 +2316,6 @@ static pid_t kwsysProcessFork(kwsysProcess* cp,
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if(cp->OptionDetach)
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{
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/* Create an intermediate process. */
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#ifdef __VMS
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#define fork vfork
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#endif
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pid_t middle_pid = fork();
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if(middle_pid < 0)
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{
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@ -2436,6 +2483,26 @@ static void kwsysProcessKill(pid_t process_id)
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}
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}
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/*--------------------------------------------------------------------------*/
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#if defined(__VMS)
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int decc$feature_get_index(char *name);
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int decc$feature_set_value(int index, int mode, int value);
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static int kwsysProcessSetVMSFeature(char* name, int value)
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{
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int i;
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errno = 0;
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i = decc$feature_get_index(name);
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return i >= 0 && (decc$feature_set_value(i, 1, value) >= 0 || errno == 0);
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}
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#else
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static int kwsysProcessSetVMSFeature(char* name, int value)
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{
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(void)name;
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(void)value;
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return 1;
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}
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#endif
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/*--------------------------------------------------------------------------*/
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/* Global set of executing processes for use by the signal handler.
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This global instance will be zero-initialized by the compiler. */
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@ -2477,7 +2544,7 @@ static int kwsysProcessesAdd(kwsysProcess* cp)
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{
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/* Create the pipe. */
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int p[2];
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if(pipe(p) < 0)
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if(pipe(p KWSYSPE_VMS_NONBLOCK) < 0)
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{
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return 0;
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}
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