| 1 |
/* RCSid $Id: rtprocess.h,v 3.24 2024/06/03 18:55:51 greg Exp $ */ |
| 2 |
/* |
| 3 |
* rtprocess.h |
| 4 |
* Routines to communicate with separate process via dual pipes |
| 5 |
* |
| 6 |
* WARNING: On Windows, there's a system header named <process.h>. |
| 7 |
*/ |
| 8 |
#ifndef _RAD_PROCESS_H_ |
| 9 |
#define _RAD_PROCESS_H_ |
| 10 |
|
| 11 |
#include <errno.h> |
| 12 |
#include "paths.h" |
| 13 |
#if defined(_WIN32) || defined(_WIN64) |
| 14 |
#include <windows.h> /* DWORD etc. */ |
| 15 |
typedef DWORD RT_PID; |
| 16 |
#include <process.h> /* getpid() and others */ |
| 17 |
#define getpid _getpid |
| 18 |
#define execv _execv |
| 19 |
#define execvp _execvp |
| 20 |
#ifdef _MSC_VER |
| 21 |
#include <BaseTsd.h> |
| 22 |
typedef SSIZE_T ssize_t; |
| 23 |
#endif |
| 24 |
#else |
| 25 |
typedef pid_t RT_PID; |
| 26 |
#endif |
| 27 |
|
| 28 |
|
| 29 |
#ifdef __cplusplus |
| 30 |
extern "C" { |
| 31 |
#endif |
| 32 |
|
| 33 |
/* On Windows, a process ID is a DWORD. That might actually be the |
| 34 |
same thing as an int, but it's better not to assume anything. |
| 35 |
|
| 36 |
This means that we shouldn't rely on PIDs and file descriptors |
| 37 |
being the same type, so we have to describe processes with a struct, |
| 38 |
instead of the original int[3]. For that purpose, we typedef a |
| 39 |
platform independent RT_PID. |
| 40 |
*/ |
| 41 |
|
| 42 |
/* On Unix, we can set flags and assign descriptors before opening a |
| 43 |
process, coupling an existing input or output to the new process rather |
| 44 |
than opening both pipes. If PF_FILT_INP is passed in the flags member of |
| 45 |
SUBPROC, then the given r stream will be attached to the standard input |
| 46 |
of the child process, and subsequent reads from that descriptor in the |
| 47 |
parent get data from the standard output of the child, instead. The |
| 48 |
returned w descriptor is set to -1, since there is no longer any way |
| 49 |
to write to the input of the child. The default r descriptor of 0 will |
| 50 |
compel the child to act as a filter on the standard input of the parent. |
| 51 |
Whatever r handle you specify, the child will filter its read operations. |
| 52 |
Note that this should be called before anything has been buffered using r. |
| 53 |
If PF_FILT_OUT is set in flags, then the given w stream will be |
| 54 |
attached to the standard output of the child, and subsequent writes |
| 55 |
to that descriptor in the parent send data to the standard input |
| 56 |
of the child. The returned r descriptor is set to -1, since |
| 57 |
there is no longer any output to read from the child. The |
| 58 |
default w descriptor of 1 will cause the child to act as a filter |
| 59 |
on the output of the parent. Make sure to call fflush(stdout) first |
| 60 |
if any data was buffered. It is illegal to set both PF_FILT_INP and |
| 61 |
PF_FILT_OUT, as a circular process is guaranteed to hang. |
| 62 |
|
| 63 |
If you want behavior similar to popen(cmd, "w") (again Unix-only), |
| 64 |
keeping stdout open in parent, use a duplicate descriptor like so: |
| 65 |
{ |
| 66 |
SUBPROC rtp = sp_inactive; |
| 67 |
FILE *fout; |
| 68 |
fflush(stdout); |
| 69 |
rtp.w = dup(fileno(stdout)); |
| 70 |
rtp.flags |= PF_FILT_OUT; |
| 71 |
if (open_process(&rtp, cmd_argv) <= 0) { |
| 72 |
perror(cmd_argv[0]); exit(1); |
| 73 |
} |
| 74 |
fout = fdopen(rtp.w, "w"); |
| 75 |
...write data to filter using fout until finished... |
| 76 |
fclose(fout); |
| 77 |
if (close_process(&rtp)) { |
| 78 |
perror(cmd_argv[0]); exit(1); |
| 79 |
} |
| 80 |
...can continue sending data directly to stdout... |
| 81 |
} |
| 82 |
We could also have called open_process() after fdopen() above, or after |
| 83 |
using fopen() on a file if we wanted to insert our filter before it. |
| 84 |
A similar sequence may be used to filter from stdin without closing |
| 85 |
it, though process termination becomes more difficult with two readers. |
| 86 |
Filtering input from a file works better, since the file is then read by |
| 87 |
the child only, as in: |
| 88 |
{ |
| 89 |
SUBPROC rtp = sp_inactive; |
| 90 |
FILE *fin = fopen(fname, "r"); |
| 91 |
if (fin == NULL) { |
| 92 |
open_error(fname); exit(1); |
| 93 |
} |
| 94 |
rtp.r = fileno(fin); |
| 95 |
rtp.flags |= PF_FILT_INP; |
| 96 |
if (open_process(&rtp, cmd_argv) <= 0) { |
| 97 |
perror(cmd_argv[0]); fclose(fin); exit(1); |
| 98 |
} |
| 99 |
...read filtered file data from fin until EOF... |
| 100 |
fclose(fin); |
| 101 |
if (close_process(&rtp)) { |
| 102 |
perror(cmd_argv[0]); exit(1); |
| 103 |
} |
| 104 |
} |
| 105 |
*/ |
| 106 |
|
| 107 |
|
| 108 |
#ifndef PIPE_BUF |
| 109 |
#ifdef PIPSIZ |
| 110 |
#define PIPE_BUF PIPSIZ |
| 111 |
#else |
| 112 |
#ifdef PIPE_MAX |
| 113 |
#define PIPE_BUF PIPE_MAX |
| 114 |
#else |
| 115 |
#define PIPE_BUF 512 /* hyperconservative */ |
| 116 |
#endif |
| 117 |
#endif |
| 118 |
#endif |
| 119 |
/* process flags */ |
| 120 |
#define PF_RUNNING 1 /* process is running */ |
| 121 |
#define PF_FILT_INP 2 /* use assigned read descriptor */ |
| 122 |
#define PF_FILT_OUT 4 /* use assigned write descriptor */ |
| 123 |
|
| 124 |
typedef struct { |
| 125 |
int flags; /* what is being done */ |
| 126 |
int r; /* read handle */ |
| 127 |
int w; /* write handle */ |
| 128 |
RT_PID pid; /* process ID */ |
| 129 |
} SUBPROC; |
| 130 |
|
| 131 |
#define SP_INACTIVE {0,0,1,-1} /* for static initializations */ |
| 132 |
|
| 133 |
#define close_process(pd) close_processes(pd,1) |
| 134 |
|
| 135 |
extern int open_process(SUBPROC *pd, char *av[]); |
| 136 |
extern int close_processes(SUBPROC pd[], int nproc); |
| 137 |
extern int process(SUBPROC *pd, void *recvbuf, void *sendbuf, int nbr, int nbs); |
| 138 |
extern ssize_t readbuf(int fd, void *bpos, ssize_t siz); |
| 139 |
extern ssize_t writebuf(int fd, const void *bpos, ssize_t siz); |
| 140 |
|
| 141 |
#if defined(_WIN32) || defined(_WIN64) |
| 142 |
/* any non-negative increment will send the process to IDLE_PRIORITY_CLASS. */ |
| 143 |
extern int win_kill(RT_PID pid, int sig /* ignored */); |
| 144 |
extern int win_nice(int inc); |
| 145 |
#endif |
| 146 |
|
| 147 |
extern SUBPROC sp_inactive; |
| 148 |
|
| 149 |
#ifdef __cplusplus |
| 150 |
} |
| 151 |
#endif |
| 152 |
#endif /* _RAD_PROCESS_H_ */ |
| 153 |
|
