/*
 *  sponge.c - read in all available info from stdin, then output it to
 *  file named on the command line
 *
 *  Copyright ©  2006  Tollef Fog Heen
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  version 2 as published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
/* MAX() */
#include <sys/param.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <sys/resource.h>
/* SIZE_MAX */
#include <stdint.h> 
#include <signal.h>
#include <getopt.h>

#include "physmem.c"

#define BUFF_SIZE           8192
#define MIN_SPONGE_SIZE     BUFF_SIZE
char *tmpname = NULL;

void usage() {
	printf("sponge [-a] <file>: soak up all input from stdin and write it "
	       "to <file>\n");
	exit(0);
}

/* all the signal stuff copied from gnu sort */

/* The set of signals that are caught.  */
static sigset_t caught_signals;

/* Critical section status.  */
struct cs_status {
	int valid; // was bool
	sigset_t sigs;
};

/* Enter a critical section.  */
static struct cs_status cs_enter (void) {
	struct cs_status status;
	status.valid = (sigprocmask(SIG_BLOCK, &caught_signals, &status.sigs) == 0);
	return status;
}

/* Leave a critical section.  */
static void cs_leave (struct cs_status status) {
	if (status.valid) {
		/* Ignore failure when restoring the signal mask. */
		sigprocmask(SIG_SETMASK, &status.sigs, NULL);
	}
}

static void cleanup () {
	if (tmpname) {
		unlink(tmpname);
	}
}

static void onexit_cleanup (void) {
	struct cs_status cs = cs_enter();
	cleanup();
	cs_leave(cs);
}

static void sighandler (int sig) {
	if (! SA_NOCLDSTOP)
		signal(sig, SIG_IGN);

	cleanup();

	signal(sig, SIG_DFL);
	raise(sig);
}

/* taken from coreutils sort */
static size_t default_sponge_size (void) {
	/* Let MEM be available memory or 1/8 of total memory, whichever
	   is greater.  */
	double avail = physmem_available();
	double total = physmem_total();
	double mem = MAX(avail, total / 8);
	struct rlimit rlimit;

	/* Let SIZE be MEM, but no more than the maximum object size or
	   system resource limits.  Avoid the MIN macro here, as it is not
	   quite right when only one argument is floating point.  Don't
	   bother to check for values like RLIM_INFINITY since in practice
	   they are not much less than SIZE_MAX.  */
	size_t size = SIZE_MAX;
	if (mem < size)
		size = mem;
	if (getrlimit(RLIMIT_DATA, &rlimit) == 0 && rlimit.rlim_cur < size)
		size = rlimit.rlim_cur;
#ifdef RLIMIT_AS
	if (getrlimit(RLIMIT_AS, &rlimit) == 0 && rlimit.rlim_cur < size)
		size = rlimit.rlim_cur;
#endif

	/* Leave a large safety margin for the above limits, as failure can
	   occur when they are exceeded.  */
	size /= 2;

#ifdef RLIMIT_RSS
	/* Leave a 1/16 margin for RSS to leave room for code, stack, etc.
	   Exceeding RSS is not fatal, but can be quite slow.  */
	if (getrlimit(RLIMIT_RSS, &rlimit) == 0 && rlimit.rlim_cur / 16 * 15 < size)
		size = rlimit.rlim_cur / 16 * 15;
#endif

	/* Use no less than the minimum. */
	return MAX (size, MIN_SPONGE_SIZE);
}

void trapsignals (void) {
	ssize_t i = 0;
	static int const sig[] = {
		/* The usual suspects.  */
		SIGALRM, SIGHUP, SIGINT, SIGPIPE, SIGQUIT, SIGTERM,
#ifdef SIGPOLL
		SIGPOLL,
#endif
#ifdef SIGPROF
		SIGPROF,
#endif
#ifdef SIGVTALRM
		SIGVTALRM,
#endif
#ifdef SIGXCPU
		SIGXCPU,
#endif
#ifdef SIGXFSZ
		SIGXFSZ,
#endif
	};
	int nsigs = sizeof(sig) / sizeof(sig[0]);

#if SA_NOCLDSTOP
	struct sigaction act;

	sigemptyset(&caught_signals);
	for (i = 0; i < nsigs; i++) {
		sigaction(sig[i], NULL, &act);
		if (act.sa_handler != SIG_IGN)
			sigaddset(&caught_signals, sig[i]);
		}
		
		act.sa_handler = sighandler;
		act.sa_mask = caught_signals;
		act.sa_flags = 0;

		for (i = 0; i < nsigs; i++)
			if (sigismember(&caught_signals, sig[i]))
				sigaction(sig[i], &act, NULL);
#else
	for (i = 0; i < nsigs; i++)
		if (signal(sig[i], SIG_IGN) != SIG_IGN) {
			signal(sig[i], sighandler);
			siginterrupt (sig[i], 1);
		}
#endif
}

static void write_buff_tmp(char* buff, size_t length, FILE *fd) {
	if (fwrite(buff, length, 1, fd) < 1) {
		perror("error writing buffer to temporary file");
		fclose(fd);
		exit(1);
	}
}
		
static void write_buff_tmp_finish (char* buff, size_t length, FILE *fd) {
	if (length) 
		write_buff_tmp(buff, length, fd);
	if (fflush(fd) != 0) {
		perror("fflush");
		exit(1);
	}
}

static void write_buff_out (char* buff, size_t length, FILE *fd) {
	if (fwrite(buff, length, 1, fd) < 1) {
		perror("error writing buffer to output file");
		fclose(fd);
		exit(1);
	}
}

static void copy_file (FILE *infile, FILE *outfile, char *buf, size_t size) {
	ssize_t i;
	while ((i = read(fileno(infile), buf, size)) > 0) {
		write_buff_out(buf, i, outfile);
	}
	if (i == -1) {
		perror("read file");
		fclose(infile);
		exit(1);
	}
}

static void copy_tmpfile (FILE *tmpfile, FILE *outfile, char *buf, size_t size) {
	if (lseek(fileno(tmpfile), 0, SEEK_SET)) {
		perror("could to seek to start of file");
		fclose(tmpfile);
		exit(1);
	}
	copy_file(tmpfile, outfile, buf, size);
	if (fclose(tmpfile) != 0) {
		perror("read temporary file");
		exit(1);
	}
	if (fclose(outfile) != 0) {
		perror("error writing buffer to output file");
		exit(1);
	}
}

FILE *open_tmpfile (void) {
	struct cs_status cs;
	int tmpfd;
	FILE *tmpfile;
	mode_t mask;
	char *tmpdir;
	char const * const template="%s/sponge.XXXXXX";

	trapsignals();
	cs = cs_enter();
	tmpdir = getenv("TMPDIR");
	if (tmpdir == NULL)
		tmpdir = "/tmp";
	/* Subtract 2 for `%s' and add 1 for the trailing NULL. */
	tmpname=malloc(strlen(tmpdir) + strlen(template) - 2 + 1);
	if (! tmpname) {
		perror("failed to allocate memory");
		exit(1);
	}
	sprintf(tmpname, template, tmpdir);
	mask=umask(077);
	tmpfd = mkstemp(tmpname);
	umask(mask);
	atexit(onexit_cleanup); // solaris on_exit(onexit_cleanup, 0);
	cs_leave(cs);

	if (tmpfd < 0) {
		perror("mkstemp failed");
		exit(1);
	}
	tmpfile = fdopen(tmpfd, "w+");
	if (! tmpfile) {
		perror("fdopen");
		exit(1);
	}
	return tmpfile;
}

int main (int argc, char **argv) {
	char *buf, *bufstart, *outname = NULL;
	size_t bufsize = BUFF_SIZE;
	size_t bufused = 0;
	FILE *outfile, *tmpfile = 0;
	ssize_t i = 0;
	size_t mem_available = default_sponge_size();
	int tmpfile_used=0;
	int append=0;
	int opt;

	while ((opt = getopt(argc, argv, "ha")) != -1) {
		switch (opt) {
			case 'h':
				usage();
				break;
			case 'a':
				append=1;
		}
	}
	if (optind < argc)
		outname = argv[optind];
	
	tmpfile = open_tmpfile();
	bufstart = buf = malloc(bufsize);
	if (!buf) {
		perror("failed to allocate memory");
		exit(1);
	}
	while ((i = read(0, buf, bufsize - bufused)) > 0) {
		bufused = bufused+i;
		if (bufused == bufsize) {
			if ((bufsize*2) >= mem_available) {
				write_buff_tmp(bufstart, bufused, tmpfile);
				bufused = 0;
				tmpfile_used = 1;
			}
			else {
				bufsize *= 2;
				bufstart = realloc(bufstart, bufsize);
				if (!bufstart) {
					perror("failed to realloc memory");
					exit(1);
				}
			}
		}
		buf = bufstart + bufused;
	}
	if (i < 0) {
		perror("failed to read from stdin");
		exit(1);
	}

	if (outname) {
		mode_t mode;
		struct stat statbuf;
		int exists = (lstat(outname, &statbuf) == 0);
		int regfile = exists && S_ISREG(statbuf.st_mode) && ! S_ISLNK(statbuf.st_mode);

		if (append && regfile) {
			char *tmpbuf = malloc(bufsize);
			if (!tmpbuf) {
				perror("failed to allocate memory");
				exit(1);
			}
			outfile = fopen(outname, "r");
			copy_file(outfile, tmpfile, tmpbuf, bufsize);
			fclose(outfile);
		}
		
		write_buff_tmp_finish(bufstart, bufused, tmpfile);

		/* Set temp file mode to match either
		 * the old file mode, or the default file
		 * mode for a newly created file. */
		if (exists) {
			mode = statbuf.st_mode;
		}
		else {
			mode_t mask = umask(0);
			umask(mask);
			mode = 0666 & ~mask;
		}
		if (chmod(tmpname, mode) != 0) {
			perror("chmod");
			exit(1);
		}

		/* If it's a regular file, or does not yet exist,
		 * attempt a fast rename of the temp file. */
		if ((regfile || ! exists) &&
		    rename(tmpname, outname) == 0) {
			tmpname=NULL; /* don't try to cleanup tmpname */
		}
		else {	
			/* Fall back to slow copy. */
			outfile = fopen(outname, append ? "a" : "w");
			if (!outfile) {
				perror("error opening output file");
				exit(1);
			}
			copy_tmpfile(tmpfile, outfile, bufstart, bufsize);
		}
	}
	else {
		if (tmpfile_used) {
			write_buff_tmp_finish(bufstart, bufused, tmpfile);
			copy_tmpfile(tmpfile, stdout, bufstart, bufsize);
		}
		else if (bufused) {
			/* buffer direct to stdout, no tmpfile */
			write_buff_out(bufstart, bufused, stdout);
		}
	}

	return 0;
}