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/* popen/pclose:
*
* simple MS-DOS piping scheme to imitate UNIX pipes
*/
#include "EXTERN.h"
#include "common.h"
#include <setjmp.h>
#include "util2.h"
#include "util3.h"
#ifndef _NFILE
# define _NFILE 5 /* Number of open files */
#endif _NFILE
#define READIT 1 /* Read pipe */
#define WRITEIT 2 /* Write pipe */
static char* prgname[_NFILE]; /* program name if write pipe */
static int pipetype[_NFILE]; /* 1=read 2=write */
static char* pipename[_NFILE]; /* pipe file name */
/*
*------------------------------------------------------------------------
* run: Execute command via SHELL or COMSPEC
*------------------------------------------------------------------------
*/
static int
run(char* command)
{
jmp_buf panic; /* How to recover from errors */
char* shell; /* Command processor */
char* s = NULL; /* Holds the command */
int s_is_malloced = 0; /* True if need to free 's' */
static char* command_com = "COMMAND.COM";
int status; /* Return codes */
char* shellpath; /* Full command processor path */
char* bp; /* Generic string pointer */
static char dash_c[] = "/c";
s = savestr(command);
/* Determine the command processor */
if ((shell = getenv("SHELL")) == NULL
&& (shell = getenv("COMSPEC")) == NULL)
shell = command_com;
strupr(shell);
shellpath = shell;
/* Strip off any leading backslash directories */
shell = rindex(shellpath, '\\');
if (shell != NULL)
shell++;
else
shell = shellpath;
/* Strip off any leading slash directories */
bp = rindex(shell, '/');
if (bp != NULL)
shell = ++bp;
if (strcmp(shell, command_com) != 0) {
/* MKS Shell needs quoted argument */
char* bp;
bp = s = safemalloc(strlen(command) + 3);
*bp++ = '\'';
while ((*bp++ = *command++) != '\0') ;
*(bp - 1) = '\'';
*bp = '\0';
s_is_malloced = 1;
} else
s = command;
/* Run the program */
status = spawnl(P_WAIT, shellpath, shell, dash_c, s, NULL);
if (s_is_malloced)
free(s);
return status;
}
/*
*------------------------------------------------------------------------
* uniquepipe: returns a unique file name
*------------------------------------------------------------------------
*/
static char*
uniquepipe(void)
{
static char name[14];
static short int num = 0;
(void) sprintf(name, "pipe%04d.tmp", num++);
return name;
}
/*
*------------------------------------------------------------------------
* resetpipe: Private routine to cancel a pipe
*------------------------------------------------------------------------
*/
static void
resetpipe(int fd)
{
char* bp;
if (fd >= 0 && fd < _NFILE) {
pipetype[fd] = 0;
if ((bp = pipename[fd]) != NULL) {
(void) unlink(bp);
free(bp);
pipename[fd] = NULL;
}
if ((bp = prgname[fd]) != NULL) {
free(bp);
prgname[fd] = NULL;
}
}
}
/*
*------------------------------------------------------------------------
* popen: open a pipe
*------------------------------------------------------------------------
*/
FILE* popen(prg, type)
char* prg; /* The command to be run */
char* type; /* "w" or "r" */
{
FILE* p = NULL; /* Where we open the pipe */
int ostdin; /* Where our stdin is now */
int pipefd = -1; /* fileno(p) -- for convenience */
char* tmpfile; /* Holds name of pipe file */
jmp_buf panic; /* Where to go if there's an error */
int lineno; /* Line number where panic happened */
/* Get a unique pipe file name */
tmpfile = filexp("%Y/");
strcat(tmpfile, uniquepipe());
if ((lineno = setjmp(panic)) != 0) {
/* An error has occurred, so clean up */
int E = errno;
if (p != NULL)
(void) fclose(p);
resetpipe(pipefd);
errno = E;
lineno = lineno;
return NULL;
}
if (strcmp(type, "w") == 0) {
/* for write style pipe, pclose handles program execution */
if ((p = fopen(tmpfile, "w")) != NULL) {
pipefd = fileno(p);
pipetype[pipefd] = WRITEIT;
pipename[pipefd] = savestr(tmpfile);
prgname[pipefd] = savestr(prg);
}
} else if (strcmp(type, "r") == 0) {
/* read pipe must create tmp file, set up stdout to point to the temp
* file, and run the program. note that if the pipe file cannot be
* opened, it'll return a condition indicating pipe failure, which is
* fine. */
if ((p = fopen(tmpfile, "w")) != NULL) {
int ostdout;
pipefd = fileno(p);
pipetype[pipefd]= READIT;
pipename[pipefd] = savestr(tmpfile);
/* Redirect stdin for the new command */
ostdout = dup(fileno(stdout));
if (dup2(fileno(stdout), pipefd) < 0) {
int E = errno;
(void) dup2(fileno(stdout), ostdout);
errno = E;
longjmp(panic, __LINE__);
}
if (run(prg) != 0)
longjmp(panic, __LINE__);
if (dup2(fileno(stdout), ostdout) < 0)
longjmp(panic, __LINE__);
if (fclose(p) < 0)
longjmp(panic, __LINE__);
if ((p = fopen(tmpfile, "r")) == NULL)
longjmp(panic, __LINE__);
}
} else {
/* screwy call or unsupported type */
errno = EINVFNC;
longjmp(panic, __LINE__);
}
return p;
}
/* close a pipe */
int
pclose(p)
FILE* p;
{
int pipefd = -1; /* Fildes where pipe is opened */
int ostdout; /* Where our stdout points now */
int ostdin; /* Where our stdin points now */
jmp_buf panic; /* Context to return to if error */
int lineno; /* Line number where panic happened */
if ((lineno = setjmp(panic)) != 0) {
/* An error has occurred, so clean up and return */
int E = errno;
if (p != NULL)
(void) fclose(p);
resetpipe(pipefd);
errno = E;
lineno = lineno;
return -1;
}
pipefd = fileno(p);
if (fclose(p) < 0)
longjmp(panic, __LINE__);
switch (pipetype[pipefd]) {
case WRITEIT:
/* open the temp file again as read, redirect stdin from that
* file, run the program, then clean up. */
if ((p = fopen(pipename[pipefd],"r")) == NULL)
longjmp(panic, __LINE__);
ostdin = dup(fileno(stdin));
if (dup2(fileno(stdin), fileno(p)) < 0)
longjmp(panic, __LINE__);
if (run(prgname[pipefd]) != 0)
longjmp(panic, __LINE__);
if (dup2(fileno(stdin), ostdin) < 0)
longjmp(panic, __LINE__);
if (fclose(p) < 0)
longjmp(panic, __LINE__);
resetpipe(pipefd);
break;
case READIT:
/* close the temp file and remove it */
resetpipe(pipefd);
break;
default:
errno = EINVFNC;
longjmp(panic, __LINE__);
/*NOTREACHED*/
}
return 0;
}
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