[Python-checkins] python/dist/src/Modules posixmodule.c, 2.329, 2.330

Sun Dec 12 09:30:56 CET 2004

Update of /cvsroot/python/python/dist/src/Modules
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv11850
Modified Files:
	posixmodule.c 
Log Message:
OS/2 specific fixes related to SF bug # 1003471.
Also revise a related function to minimise file handle/pipe leakage
and improve reliability.
Index: posixmodule.c
===================================================================
RCS file: /cvsroot/python/python/dist/src/Modules/posixmodule.c,v
retrieving revision 2.329
retrieving revision 2.330
diff -u -d -r2.329 -r2.330

--- posixmodule.c	13 Oct 2004 15:30:56 -0000	2.329
+++ posixmodule.c	12 Dec 2004 08:30:51 -0000	2.330
@@ -3248,86 +3248,85 @@
 static int
 async_system(const char *command)
 {
- char *p, errormsg[256], args[1024];
- RESULTCODES rcodes;
- APIRET rc;
- char *shell = getenv("COMSPEC");
- if (!shell)
- shell = "cmd";
+	char errormsg[256], args[1024];
+	RESULTCODES rcodes;
+	APIRET rc;
 
- strcpy(args, shell);
- p = &args[ strlen(args)+1 ];
- strcpy(p, "/c ");
- strcat(p, command);
- p += strlen(p) + 1;
- *p = '0円';
+	char *shell = getenv("COMSPEC");
+	if (!shell)
+		shell = "cmd";
 
- rc = DosExecPgm(errormsg, sizeof(errormsg),
- EXEC_ASYNC, /* Execute Async w/o Wait for Results */
- args,
- NULL, /* Inherit Parent's Environment */
- &rcodes, shell);
- return rc;
+	/* avoid overflowing the argument buffer */
+	if (strlen(shell) + 3 + strlen(command) >= 1024)
+		return ERROR_NOT_ENOUGH_MEMORY
+
+	args[0] = '0円';
+	strcat(args, shell);
+	strcat(args, "/c ");
+	strcat(args, command);
+
+	/* execute asynchronously, inheriting the environment */
+	rc = DosExecPgm(errormsg,
+			sizeof(errormsg),
+			EXEC_ASYNC,
+			args,
+			NULL,
+			&rcodes,
+			shell);
+	return rc;
 }
 
 static FILE *
 popen(const char *command, const char *mode, int pipesize, int *err)
 {
- HFILE rhan, whan;
- FILE *retfd = NULL;
- APIRET rc = DosCreatePipe(&rhan, &whan, pipesize);
-
- if (rc != NO_ERROR) {
-	*err = rc;
- return NULL; /* ERROR - Unable to Create Anon Pipe */
- }
-
- if (strchr(mode, 'r') != NULL) { /* Treat Command as a Data Source */
- int oldfd = dup(1); /* Save STDOUT Handle in Another Handle */
-
- DosEnterCritSec(); /* Stop Other Threads While Changing Handles */
- close(1); /* Make STDOUT Available for Reallocation */
-
- if (dup2(whan, 1) == 0) { /* Connect STDOUT to Pipe Write Side */
- DosClose(whan); /* Close Now-Unused Pipe Write Handle */
-
- rc = async_system(command);
- }
-
- dup2(oldfd, 1); /* Reconnect STDOUT to Original Handle */
- DosExitCritSec(); /* Now Allow Other Threads to Run */
-
- if (rc == NO_ERROR)
- retfd = fdopen(rhan, mode); /* And Return Pipe Read Handle */
-
- close(oldfd); /* And Close Saved STDOUT Handle */
- return retfd; /* Return fd of Pipe or NULL if Error */
-
- } else if (strchr(mode, 'w')) { /* Treat Command as a Data Sink */
- int oldfd = dup(0); /* Save STDIN Handle in Another Handle */
+	int oldfd, tgtfd;
+	HFILE pipeh[2];
+	APIRET rc;
 
- DosEnterCritSec(); /* Stop Other Threads While Changing Handles */
- close(0); /* Make STDIN Available for Reallocation */
+	/* mode determines which of stdin or stdout is reconnected to
+	 * the pipe to the child
+	 */
+	if (strchr(mode, 'r') != NULL) {
+		tgt_fd = 1;	/* stdout */
+	} else if (strchr(mode, 'w')) {
+		tgt_fd = 0;	/* stdin */
+	} else {
+		*err = ERROR_INVALID_ACCESS;
+		return NULL;
+	}
 
- if (dup2(rhan, 0) == 0) { /* Connect STDIN to Pipe Read Side */
- DosClose(rhan); /* Close Now-Unused Pipe Read Handle */
+	/* setup the pipe
+	if ((rc = DosCreatePipe(&pipeh[0], &pipeh[1], pipesize)) != NO_ERROR) {
+		*err = rc;
+		return NULL;
+	}
 
- rc = async_system(command);
- }
+	/* prevent other threads accessing stdio */
+	DosEnterCritSec();
 
- dup2(oldfd, 0); /* Reconnect STDIN to Original Handle */
- DosExitCritSec(); /* Now Allow Other Threads to Run */
+	/* reconnect stdio and execute child */
+	oldfd = dup(tgtfd);
+	close(tgtfd);
+	if (dup2(pipeh[tgtfd], tgtfd) == 0) {
+		DosClose(pipeh[tgtfd]);
+		rc = async_system(command);
+	}
 
- if (rc == NO_ERROR)
- retfd = fdopen(whan, mode); /* And Return Pipe Write Handle */
+	/* restore stdio */
+	dup2(oldfd, tgtfd);
+	close(oldfd);
 
- close(oldfd); /* And Close Saved STDIN Handle */
- return retfd; /* Return fd of Pipe or NULL if Error */
+	/* allow other threads access to stdio */
+	DosExitCritSec();
 
- } else {
-	*err = ERROR_INVALID_ACCESS;
- return NULL; /* ERROR - Invalid Mode (Neither Read nor Write) */
- }
+	/* if execution of child was successful return file stream */
+	if (rc == NO_ERROR)
+		return fdopen(pipeh[1 - tgtfd], mode);
+	else {
+		DosClose(pipeh[1 - tgtfd]);
+		*err = rc;
+		return NULL;
+	}
 }
 
 static PyObject *
