/*
	File:		MoreUNIX.c

	Contains:	Generic UNIX utilities.

	Written by:	Quinn

	Copyright:	Copyright (c) 2002 by Apple Computer, Inc., All Rights Reserved.

	Disclaimer:	IMPORTANT:  This Apple software is supplied to you by Apple Computer, Inc.
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	Change History (most recent first):

$Log: MoreUNIX.c,v $
Revision 1.4  2002/12/13 00:30:18  eskimo1
10.1 compatibility. futimes isn't available in 10.1. Drat! Also, in NSGetExecutablePathOnTenOneAndEarlierOnly, have to skip over multiple NULLs between the environment and the relative path point, in case someone (like MoreSecDestroyInheritedEnvironment perhaps) has called unsetenv.

Revision 1.3  2002/12/12 23:14:29  eskimo1
C++ compatibility.

Revision 1.2  2002/11/14 20:15:20  eskimo1
In MoreUNIXCopyFile, correctly set the modified and accessed times of the resulting file.

Revision 1.1  2002/11/09 00:15:21  eskimo1
A collection of useful UNIX-level routines.


*/

/////////////////////////////////////////////////////////////////

// Our prototypes

#include "MoreUNIX.h"

// System interfaces

#include <sys/param.h>
#include <mach-o/dyld.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <signal.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <stdbool.h>

// "crt_externs.h" has no C++ guards [3126393], so we have to provide them 
// ourself otherwise we get a link error.

#ifdef __cplusplus
extern "C" {
#endif

#include <crt_externs.h>

#ifdef __cplusplus
}
#endif

// MIB Interfaces

/////////////////////////////////////////////////////////////////

#if MORE_DEBUG

	// There's a macro version of this in the header.
	
	extern int MoreUNIXErrno(int result)
	{
		int err;
		
		err = 0;
		if (result < 0) {
			err = errno;
			assert(err != 0);
		}
		return err;
	}

#endif

/////////////////////////////////////////////////////////////////

static int NSGetExecutablePathOnTenOneAndEarlierOnly(char *execPath, size_t *execPathSize)
{
    int  	err = 0;
    char 	**cursor;
    char 	*possiblyRelativePath;
    char 	absolutePath[MAXPATHLEN];
    size_t 	absolutePathSize;
    
    assert(execPath != NULL);
    assert(execPathSize != NULL);
    
    cursor = (char **) (*(_NSGetArgv()) + *(_NSGetArgc()));
    
    // There should be a NULL after the argv array.
    // If not, error out.
    
    if (*cursor != 0) {
        err = -1;
	}
    
    if (err == 0) {
        // Skip past the NULL after the argv array.
        
        cursor += 1;
        
        // Now, skip over the entire kernel-supplied environment, 
        // which is an array of char * terminated by a NULL.
        
        while (*cursor != 0) {
            cursor += 1;
        }
        
        // Skip over the NULL terminating the environment.  Actually, 
        // there can be multiple NULLs if the program has called 
        // unsetenv, so we skip along until we find a the next non-NULL.
        
        while (*cursor == 0) {
            cursor += 1;
        }

        // Now we have the path that was passed to exec 
        // (not the argv[0] path, but the path that the kernel 
        // actually executed).
        
        possiblyRelativePath = *cursor;

        // Convert the possibly relative path to an absolute 
        // path.  We use realpath for expedience, although 
        // the real implementation of _NSGetExecutablePath
        // uses getcwd and can return a path with symbolic links 
        // etc in it.
        
        if (realpath(possiblyRelativePath, absolutePath) == NULL) {
            err = errno;
		}
    }
    
    // Now copy the path out into the client's buffer, returning 
    // an error if the buffer isn't big enough.
    
    if (err == 0) {
        absolutePathSize = (strlen(absolutePath) + 1);
        
        if (absolutePathSize <= *execPathSize) {
            strcpy(execPath, absolutePath);
        } else {
            err = -1;
        }
        
        *execPathSize = absolutePathSize;
    }

    return err;
}

typedef int (*NSGetExecutablePathProcPtr)(char *buf, size_t *bufsize);

extern int MoreGetExecutablePath(char *execPath, size_t *execPathSize)
{
    if (NSIsSymbolNameDefined("__NSGetExecutablePath")) {
        return ((NSGetExecutablePathProcPtr) NSAddressOfSymbol(NSLookupAndBindSymbol("__NSGetExecutablePath")))(execPath, execPathSize);
    } else {
        // The function _NSGetExecutablePath() is new in Mac OS X 10.2, 
        // so use this custom version when running on 10.1.x and earlier.
        return NSGetExecutablePathOnTenOneAndEarlierOnly(execPath, execPathSize);
    }
}

/////////////////////////////////////////////////////////////////

extern int MoreUNIXRead( int fd,       void *buf, size_t bufSize, size_t *bytesRead   )
	// See comment in header.
{
	int 	err;
	char *	cursor;
	size_t	bytesLeft;
	ssize_t bytesThisTime;

	assert(fd >= 0);
	assert(buf != NULL);
	
	err = 0;
	bytesLeft = bufSize;
	cursor = (char *) buf;
	while ( (err == 0) && (bytesLeft != 0) ) {
		bytesThisTime = read(fd, cursor, bytesLeft);
		if (bytesThisTime > 0) {
			cursor    += bytesThisTime;
			bytesLeft -= bytesThisTime;
		} else if (bytesThisTime == 0) {
			err = EPIPE;
		} else {
			assert(bytesThisTime == -1);
			
			err = errno;
			assert(err != 0);
			if (err == EINTR) {
				err = 0;		// let's loop again
			}
		}
	}
	if (bytesRead != NULL) {
		*bytesRead = bufSize - bytesLeft;
	}
	
	return err;
}

extern int MoreUNIXWrite(int fd, const void *buf, size_t bufSize, size_t *bytesWritten)
	// See comment in header.
{
	int 	err;
	char *	cursor;
	size_t	bytesLeft;
	ssize_t bytesThisTime;
	
	assert(fd >= 0);
	assert(buf != NULL);
	
	// SIGPIPE occurs when you write to pipe or socket 
	// whose other end has been closed.  The default action 
	// for SIGPIPE is to terminate the process.  That's 
	// probably not what you wanted.  So, in the debug build, 
	// we check that you've set the signal action to SIG_IGN 
	// (ignore).  Of course, you could be building a program 
	// that needs SIGPIPE to work in some special way, in 
	// which case you should define MORE_UNIX_WRITE_CHECK_SIGPIPE 
	// to 0 to bypass this check.
	//
	// MoreUNIXIgnoreSIGPIPE, a helper routine defined below, 
	// lets you disable SIGPIPE easily.
	
	#if !defined(MORE_UNIX_WRITE_CHECK_SIGPIPE)
		#define MORE_UNIX_WRITE_CHECK_SIGPIPE 1
	#endif
	#if MORE_DEBUG && MORE_UNIX_WRITE_CHECK_SIGPIPE
		{
			int junk;
			struct sigaction currentSignalState;
			
			junk = sigaction(SIGPIPE, NULL, &currentSignalState);
			assert(junk == 0);
			
			assert( currentSignalState.sa_handler == SIG_IGN );
		}
	#endif

	err = 0;
	bytesLeft = bufSize;
	cursor = (char *) buf;
	while ( (err == 0) && (bytesLeft != 0) ) {
		bytesThisTime = write(fd, cursor, bytesLeft);
		if (bytesThisTime > 0) {
			cursor    += bytesThisTime;
			bytesLeft -= bytesThisTime;
		} else if (bytesThisTime == 0) {
			assert(false);
			err = EPIPE;
		} else {
			assert(bytesThisTime == -1);
			
			err = errno;
			assert(err != 0);
			if (err == EINTR) {
				err = 0;		// let's loop again
			}
		}
	}
	if (bytesWritten != NULL) {
		*bytesWritten = bufSize - bytesLeft;
	}
	
	return err;
}

extern int MoreUNIXIgnoreSIGPIPE(void)
	// See comment in header.
{
	int err;
	struct sigaction signalState;
	
	err = sigaction(SIGPIPE, NULL, &signalState);
	err = MoreUNIXErrno(err);
	if (err == 0) {
		signalState.sa_handler = SIG_IGN;
		
		err = sigaction(SIGPIPE, &signalState, NULL);
		err = MoreUNIXErrno(err);
	}
	
	return err;
}

extern int MoreUNIXCopyDescriptorToDescriptor(int source, int dest)
	// See comment in header.
{
	int		err;
	bool    done;
	char *  buffer;
	static const size_t kBufferSize = 64 * 1024;
	
	assert(source >= 0);
	assert(dest   >= 0);
	
	err = 0;
	buffer = (char *) malloc(kBufferSize);
	if (buffer == NULL) {
		err = ENOMEM;
	}

	if (err == 0) {	
		done = false;
		do {
			size_t bytesRead;
			
			err = MoreUNIXRead(source, buffer, kBufferSize, &bytesRead);
			if (err == EPIPE) {
				done = true;
				err = 0;
			}
			if (err == 0) {
				err = MoreUNIXWrite(dest, buffer, bytesRead, NULL);
			}
		} while (err == 0 && !done);
	}
	
	free(buffer);
	
	return err;
}

extern int MoreUNIXCopyFile(const char *source, const char *dest)
	// See comment in header.
{
	int 		err;
	int 		junk;
	int 		sourceFD;
	int 		destFD;
	struct stat sb;
	
	assert(source != NULL);
	assert(dest   != NULL);
	
	sourceFD = -1;
	destFD   = -1;

	err = stat(source, &sb);
	err = MoreUNIXErrno(err);
	
	if (err == 0) {
		sourceFD = open(source, O_RDONLY, 0);
		err = MoreUNIXErrno(sourceFD);
	}
	
	if (err == 0) {
		destFD = open(dest, O_WRONLY | O_CREAT | O_TRUNC, sb.st_mode & ~(S_ISUID | S_ISGID | S_ISVTX));
		err = MoreUNIXErrno(destFD);
	}
	
	if (err == 0) {
		err = MoreUNIXCopyDescriptorToDescriptor(sourceFD, destFD);
	}

	// Close the descriptors.
	
	if (sourceFD != -1) {
		junk = close(sourceFD);
		assert(junk == 0);
	}
	if (destFD != -1) {
		junk = close(destFD);
		assert(junk == 0);
	}

	// Set the access and modification times of the destination 
	// to match the source.  I originally did this using futimes, 
	// but hey, that's not available on 10.1, so now I do it 
	// using utimes.  *sigh*
	
	if (err == 0) {
		struct timeval times[2];
		
		TIMESPEC_TO_TIMEVAL(&times[0], &sb.st_atimespec);
		TIMESPEC_TO_TIMEVAL(&times[1], &sb.st_mtimespec);
		
		err = utimes(dest, times);
		err = MoreUNIXErrno(err);
	}

	return err;
}