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/* RCSid $Id: rtprocess.h,v 3.18 2020/02/28 05:18:49 greg Exp $ */ |
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/* |
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* rtprocess.h |
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* Routines to communicate with separate process via dual pipes |
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* |
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* WARNING: On Windows, there's a system header named <process.h>. |
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*/ |
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#ifndef _RAD_PROCESS_H_ |
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#define _RAD_PROCESS_H_ |
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|
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#include <errno.h> |
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#include <stdio.h> |
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#if defined(_WIN32) || defined(_WIN64) |
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#include <windows.h> /* DWORD etc. */ |
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typedef DWORD RT_PID; |
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#include <process.h> /* getpid() and others */ |
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#define getpid _getpid |
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#define execv _execv |
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#define execvp _execvp |
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#else |
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#include <sys/param.h> |
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#include <sys/types.h> |
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typedef pid_t RT_PID; |
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#endif |
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|
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#include "paths.h" |
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|
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#ifdef __cplusplus |
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extern "C" { |
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#endif |
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|
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/* On Windows, a process ID is a DWORD. That might actually be the |
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same thing as an int, but it's better not to assume anything. |
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|
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This means that we shouldn't rely on PIDs and file descriptors |
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being the same type, so we have to describe processes with a struct, |
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instead of the original int[3]. For that purpose, we typedef a |
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platform independent RT_PID. |
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*/ |
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|
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/* On Unix, we can set flags and assign descriptors before opening a |
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process, coupling an existing input or output to the new process rather |
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than opening both pipes. If PF_FILT_INP is passed in the flags member of |
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SUBPROC, then the given r stream will be attached to the standard input |
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of the child process, and subsequent reads from that descriptor in the |
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parent get data from the standard output of the child, instead. The |
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returned w descriptor is set to -1, since there is no longer any way |
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to write to the input of the child. The default r descriptor of 0 will |
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compel the child to act as a filter on the standard input of the parent. |
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Whatever r handle you specify, the child will filter its read operations. |
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Note that this should be called before anything has been buffered using r. |
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If PF_FILT_OUT is set in flags, then the given w stream will be |
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attached to the standard output of the child, and subsequent writes |
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to that descriptor in the parent send data to the standard input |
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of the child. The returned r descriptor is set to -1, since |
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there is no output to read from any longer in the child. The |
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default w descriptor of 1 will cause the child to act as a filter |
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on the output of the parent. Make sure to call fflush(stdout) first |
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if any data was buffered. It is illegal to set both PF_FILT_INP and |
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PF_FILT_OUT, as a circular process is guaranteed to hang. |
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|
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If you want behavior similar to popen(cmd, "w") (again Unix-only), |
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keeping stdout open in parent, use a duplicate descriptor like so: |
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{ |
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SUBPROC rtp = sp_inactive; |
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FILE *fout; |
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fflush(stdout); |
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rtp.w = dup(fileno(stdout)); |
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rtp.flags |= PF_FILT_OUT; |
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if (open_process(&rtp, cmd_argv) <= 0) { |
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perror(cmd_argv[0]); exit(1); |
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} |
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fout = fdopen(rtp.w, "w"); |
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...write data to filter using fout until finished... |
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fclose(fout); |
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if (close_process(&rtp)) { |
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perror(cmd_argv[0]); exit(1); |
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} |
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...can continue sending data directly to stdout... |
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} |
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We could also have called open_process() after fdopen() above, or after |
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using fopen() on a file if we wanted to insert our filter before it. |
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A similar sequence may be used to filter from stdin without closing |
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it, though process termination becomes more difficult with two readers. |
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Filtering input from a file works better, since the file is then read by |
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the child only, as in: |
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{ |
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SUBPROC rtp = sp_inactive; |
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FILE *fin = fopen(fname, "r"); |
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if (fin == NULL) { |
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open_error(fname); exit(1); |
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} |
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rtp.r = fileno(fin); |
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rtp.flags |= PF_FILT_INP; |
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if (open_process(&rtp, cmd_argv) <= 0) { |
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perror(cmd_argv[0]); fclose(fin); exit(1); |
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} |
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...read filtered file data from fin until EOF... |
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fclose(fin); |
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if (close_process(&rtp)) { |
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perror(cmd_argv[0]); exit(1); |
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} |
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} |
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*/ |
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|
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|
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#ifndef PIPE_BUF |
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#ifdef PIPSIZ |
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#define PIPE_BUF PIPSIZ |
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#else |
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#ifdef PIPE_MAX |
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#define PIPE_BUF PIPE_MAX |
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#else |
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#define PIPE_BUF 512 /* hyperconservative */ |
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#endif |
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#endif |
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#endif |
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/* process flags */ |
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#define PF_RUNNING 1 /* process is running */ |
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#define PF_FILT_INP 2 /* use assigned read descriptor */ |
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#define PF_FILT_OUT 4 /* use assigned write descriptor */ |
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|
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typedef struct { |
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int flags; /* what is being done */ |
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int r; /* read handle */ |
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int w; /* write handle */ |
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RT_PID pid; /* process ID */ |
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} SUBPROC; |
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|
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#define SP_INACTIVE {0,0,1,-1} /* for static initializations */ |
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|
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#define close_process(pd) close_processes(pd,1) |
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|
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extern int open_process(SUBPROC *pd, char *av[]); |
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extern int close_processes(SUBPROC pd[], int nproc); |
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extern int process(SUBPROC *pd, char *recvbuf, char *sendbuf, int nbr, int nbs); |
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extern int readbuf(int fd, char *bpos, int siz); |
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extern int writebuf(int fd, char *bpos, int siz); |
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|
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#if defined(_WIN32) || defined(_WIN64) |
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/* any non-negative increment will send the process to IDLE_PRIORITY_CLASS. */ |
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extern int win_kill(RT_PID pid, int sig /* ignored */); |
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extern int win_nice(int inc); |
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#endif |
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|
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extern SUBPROC sp_inactive; |
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|
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#ifdef __cplusplus |
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} |
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#endif |
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#endif /* _RAD_PROCESS_H_ */ |
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