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ioctl(FIONREAD, ...) can block. Switch to non-blocking IO and select(…
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…). Also,

don't assume task will read STDIN in one slurp.

DELTA=150  (101 added, 11 deleted, 38 changed)

git-svn-id: http://google-toolbox-for-mac.googlecode.com/svn/trunk@637 7dc7ac4e-7543-0410-b95c-c1676fc8e2a3
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gtm.daemon committed Sep 27, 2013
1 parent 748c2ac commit b2cc713
Showing 1 changed file with 152 additions and 62 deletions.
214 changes: 152 additions & 62 deletions Foundation/GTMScriptRunner.m
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Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,9 @@
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy
// of the License at
//
//
// http://www.apache.org/licenses/LICENSE-2.0
//
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
Expand All @@ -18,14 +18,14 @@

#import "GTMScriptRunner.h"
#import "GTMDefines.h"

#include <sys/ioctl.h>
#import <unistd.h>
#import <fcntl.h>
#import <sys/select.h>

static BOOL LaunchNSTaskCatchingExceptions(NSTask *task);

@interface GTMScriptRunner (PrivateMethods)
- (NSTask *)interpreterTaskWithAdditionalArgs:(NSArray *)args;
- (unsigned int)availableByteCountNonBlocking:(NSFileHandle *)file;
@end

@implementation GTMScriptRunner
Expand All @@ -39,11 +39,11 @@ + (GTMScriptRunner *)runnerWithBash {
}

+ (GTMScriptRunner *)runnerWithPerl {
return [self runnerWithInterpreter:@"/usr/bin/perl"];
return [self runnerWithInterpreter:@"/usr/bin/perl"];
}

+ (GTMScriptRunner *)runnerWithPython {
return [self runnerWithInterpreter:@"/usr/bin/python"];
return [self runnerWithInterpreter:@"/usr/bin/python"];
}

+ (GTMScriptRunner *)runnerWithInterpreter:(NSString *)interp {
Expand Down Expand Up @@ -92,7 +92,16 @@ - (NSString *)run:(NSString *)cmds {

- (NSString *)run:(NSString *)cmds standardError:(NSString **)err {
if (!cmds) return nil;


// Convert input to data
NSData *inputData = nil;
if ([cmds length]) {
inputData = [cmds dataUsingEncoding:NSUTF8StringEncoding];
if (![inputData length]) {
return nil;
}
}

NSTask *task = [self interpreterTaskWithAdditionalArgs:nil];
NSFileHandle *toTask = [[task standardInput] fileHandleForWriting];
NSFileHandle *fromTask = [[task standardOutput] fileHandleForReading];
Expand All @@ -101,51 +110,142 @@ - (NSString *)run:(NSString *)cmds standardError:(NSString **)err {
if (!LaunchNSTaskCatchingExceptions(task)) {
return nil;
}

[toTask writeData:[cmds dataUsingEncoding:NSUTF8StringEncoding]];
[toTask closeFile];

// Must keep both file handle buffers empty to avoid the deadlock described in
// http://code.google.com/p/google-toolbox-for-mac/issues/detail?id=25
NSMutableString *mutableOutString = [NSMutableString string];
NSMutableString *mutableErrString = [NSMutableString string];
while (true) {
// availableByteCountNonBlocking must be called on both fromTask and errTask
// each time through the loop.
unsigned int bytesFromTask = [self availableByteCountNonBlocking:fromTask];
unsigned int bytesErrTask = [self availableByteCountNonBlocking:errTask];
if (![task isRunning] && (bytesFromTask == 0) && (bytesErrTask == 0)) {
break;

// We're reading an writing to child task via pipes, which is full of
// deadlock dangers. We use non-blocking IO and select() to handle.
// Note that error handling below isn't quite right since
// [task terminate] may not always kill the child. But we want to keep
// this simple.

// Setup for select()
size_t inputOffset = 0;
int toFD = -1;
int fromFD = -1;
int errFD = -1;
int selectMaxFD = -1;
fd_set fdToReadSet, fdToWriteSet;
FD_ZERO(&fdToReadSet);
FD_ZERO(&fdToWriteSet);
if ([inputData length]) {
toFD = [toTask fileDescriptor];
FD_SET(toFD, &fdToWriteSet);
selectMaxFD = MAX(toFD, selectMaxFD);
int flags = fcntl(toFD, F_GETFL);
if ((flags == -1) ||
(fcntl(toFD, F_SETFL, flags | O_NONBLOCK) == -1)) {
[task terminate];
return nil;
}
} else {
[toTask closeFile];
}
fromFD = [fromTask fileDescriptor];
FD_SET(fromFD, &fdToReadSet);
selectMaxFD = MAX(fromFD, selectMaxFD);
errFD = [errTask fileDescriptor];
FD_SET(errFD, &fdToReadSet);
selectMaxFD = MAX(errFD, selectMaxFD);

// Convert to string only at the end, so we don't get partial UTF8 sequences.
NSMutableData *mutableOut = [NSMutableData data];
NSMutableData *mutableErr = [NSMutableData data];

// Communicate till we've removed everything from the select() or timeout
while (([inputData length] && FD_ISSET(toFD, &fdToWriteSet)) ||
((fromFD != -1) && FD_ISSET(fromFD, &fdToReadSet)) ||
((errFD != -1) && FD_ISSET(errFD, &fdToReadSet))) {
// select() on a modifiable copy, we use originals to track state
fd_set selectReadSet;
FD_COPY(&fdToReadSet, &selectReadSet);
fd_set selectWriteSet;
FD_COPY(&fdToWriteSet, &selectWriteSet);
int selectResult = select(selectMaxFD + 1, &selectReadSet, &selectWriteSet,
NULL, NULL);
if (selectResult < 0) {
if ((errno == EAGAIN) || (errno == EINTR)) {
continue; // No change to |fdToReadSet| or |fdToWriteSet|
} else {
[task terminate];
return nil;
}
}
// STDIN
if ([inputData length] && FD_ISSET(toFD, &selectWriteSet)) {
// Use a multiple of PIPE_BUF so that we exercise the non-blocking
// aspect of this IO.
size_t writeSize = PIPE_BUF * 4;
if (([inputData length] - inputOffset) < writeSize) {
writeSize = [inputData length] - inputOffset;
}
if (writeSize > 0) {
// We are non-blocking, so as much as the pipe will take will be
// written.
ssize_t writtenSize = 0;
do {
writtenSize = write(toFD, (char *)[inputData bytes] + inputOffset,
writeSize);
} while ((writtenSize) < 0 && (errno == EINTR));
if ((writtenSize < 0) && (errno != EAGAIN)) {
[task terminate];
return nil;
}
inputOffset += writeSize;
}
if (inputOffset >= [inputData length]) {
FD_CLR(toFD, &fdToWriteSet);
[toTask closeFile];
}
}
if (bytesFromTask > 0) {
NSData *outData = [fromTask availableData];
NSString *dataString =
[[NSString alloc] initWithData:outData encoding:NSUTF8StringEncoding];
[mutableOutString appendString:dataString];
[dataString release];
// STDOUT
if ((fromFD != -1) && FD_ISSET(fromFD, &selectReadSet)) {
char readBuf[1024];
ssize_t readSize = 0;
do {
readSize = read(fromFD, readBuf, 1024);
} while (readSize < 0 && ((errno == EAGAIN) || (errno == EINTR)));
if (readSize < 0) {
[task terminate];
return nil;
} else if (readSize == 0) {
FD_CLR(fromFD, &fdToReadSet); // Hit EOF
} else {
[mutableOut appendBytes:readBuf length:readSize];
}
}
if (bytesErrTask > 0 && err) {
NSData *errData = [errTask availableData];
NSString *dataString =
[[NSString alloc] initWithData:errData encoding:NSUTF8StringEncoding];
[mutableErrString appendString:dataString];
[dataString release];
// STDERR
if ((errFD != -1) && FD_ISSET(errFD, &selectReadSet)) {
char readBuf[1024];
ssize_t readSize = 0;
do {
readSize = read(errFD, readBuf, 1024);
} while (readSize < 0 && ((errno == EAGAIN) || (errno == EINTR)));
if (readSize < 0) {
[task terminate];
return nil;
} else if (readSize == 0) {
FD_CLR(errFD, &fdToReadSet); // Hit EOF
} else {
[mutableErr appendBytes:readBuf length:readSize];
}
}
}

[task terminate];

NSString *outString = mutableOutString;
NSString *errString = mutableErrString;

// All filehandles closed, wait.
[task waitUntilExit];

NSString *outString = [[[NSString alloc] initWithData:mutableOut
encoding:NSUTF8StringEncoding]
autorelease];
NSString *errString = [[[NSString alloc] initWithData:mutableErr
encoding:NSUTF8StringEncoding]
autorelease];;
if (trimsWhitespace_) {
NSCharacterSet *set = [NSCharacterSet whitespaceAndNewlineCharacterSet];
outString = [outString stringByTrimmingCharactersInSet:set];
if (err) {
errString = [errString stringByTrimmingCharactersInSet:set];
}
}

// let folks test for nil instead of @""
if ([outString length] < 1) {
outString = nil;
Expand Down Expand Up @@ -174,19 +274,19 @@ - (NSString *)runScript:(NSString *)path withArgs:(NSArray *)args {

- (NSString *)runScript:(NSString *)path withArgs:(NSArray *)args standardError:(NSString **)err {
if (!path) return nil;

NSArray *scriptPlusArgs = [[NSArray arrayWithObject:path] arrayByAddingObjectsFromArray:args];
NSTask *task = [self interpreterTaskWithAdditionalArgs:scriptPlusArgs];
NSFileHandle *fromTask = [[task standardOutput] fileHandleForReading];

if (!LaunchNSTaskCatchingExceptions(task)) {
return nil;
}

NSData *outData = [fromTask readDataToEndOfFile];
NSString *output = [[[NSString alloc] initWithData:outData
encoding:NSUTF8StringEncoding] autorelease];

// Handle returning standard error if |err| is not nil
if (err) {
NSFileHandle *stderror = [[task standardError] fileHandleForReading];
Expand All @@ -202,18 +302,18 @@ - (NSString *)runScript:(NSString *)path withArgs:(NSArray *)args standardError:
*err = nil;
}
}

[task terminate];

if (trimsWhitespace_) {
output = [output stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
}

// let folks test for nil instead of @""
if ([output length] < 1) {
output = nil;
}

return output;
}

Expand Down Expand Up @@ -245,13 +345,13 @@ - (NSTask *)interpreterTaskWithAdditionalArgs:(NSArray *)args {
[task setStandardInput:[NSPipe pipe]];
[task setStandardOutput:[NSPipe pipe]];
[task setStandardError:[NSPipe pipe]];

// If |environment_| is nil, then use an empty dictionary, otherwise use
// environment_ exactly.
[task setEnvironment:(environment_
? environment_
: [NSDictionary dictionary])];

// Build args to interpreter. The format is:
// interp [args-to-interp] [script-name [args-to-script]]
NSArray *allArgs = nil;
Expand All @@ -264,18 +364,8 @@ - (NSTask *)interpreterTaskWithAdditionalArgs:(NSArray *)args {
if (allArgs){
[task setArguments:allArgs];
}

return task;
}

- (unsigned int)availableByteCountNonBlocking:(NSFileHandle *)file {
int fd = [file fileDescriptor];
int numBytes;
if (ioctl(fd, FIONREAD, (char *) &numBytes) == -1) {
[NSException raise:NSFileHandleOperationException
format:@"ioctl() error %d", errno];
}
return numBytes;
return task;
}

@end
Expand Down

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