cmd/bdiff/bdiff.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*  Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*    All Rights Reserved   */


/*
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <fatal.h>
#include <signal.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdlib.h>
#include <wait.h>

#define ONSIG   16

/*
 *  This program segments two files into pieces of <= seglim lines
 *  (which is passed as a third argument or defaulted to some number)
 *  and then executes diff upon the pieces. The output of
 *  'diff' is then processed to make it look as if 'diff' had
 *  processed the files whole. The reason for all this is that seglim
 *  is a reasonable upper limit on the size of files that diff can
 *  process.
 *  NOTE -- by segmenting the files in this manner, it cannot be
 *  guaranteed that the 'diffing' of the segments will generate
 *  a minimal set of differences.
 *  This process is most definitely not equivalent to 'diffing'
 *  the files whole, assuming 'diff' could handle such large files.
 *
 *  'diff' is executed by a child process, generated by forking,
 *  and communicates with this program through pipes.
 */

static char Error[128];

static int seglim;  /* limit of size of file segment to be generated */

static char diff[]  =  "/usr/bin/diff";
static char tempskel[] = "/tmp/bdXXXXXX"; /* used to generate temp file names */
static char tempfile[32];
static char otmp[32], ntmp[32];
static int  fflags;
static int  fatal_num = 1;      /* exit number for fatal exit */
static offset_t linenum;
static size_t obufsiz, nbufsiz, dbufsiz;
static char *readline(char **, size_t *, FILE *);
static void addgen(char **, size_t *, FILE *);
static void delgen(char **, size_t *, FILE *);
static void fixnum(char *);
static void fatal(char *);
static void setsig(void);
static void setsig1(int);
static char *satoi(char *, offset_t *);
static FILE *maket(char *);

static char *prognam;

int
main(int argc, char *argv[])
{
    FILE *poldfile, *pnewfile;
    char *oline, *nline, *diffline;
    char *olp, *nlp, *dp;
    int otcnt, ntcnt;
    pid_t i;
    int pfd[2];
    FILE *poldtemp, *pnewtemp, *pipeinp;
    int status;

    prognam = argv[0];
    /*
     * Set flags for 'fatal' so that it will clean up,
     * produce a message, and terminate.
     */
    fflags = FTLMSG | FTLCLN | FTLEXIT;

    setsig();

    if (argc < 3 || argc > 5)
        fatal("arg count");

    if (strcmp(argv[1], "-") == 0 && strcmp(argv[2], "-") == 0)
        fatal("both files standard input");
    if (strcmp(argv[1], "-") == 0)
        poldfile = stdin;
    else
        if ((poldfile = fopen(argv[1], "r")) == NULL) {
            (void) snprintf(Error, sizeof (Error),
                "Can not open '%s'", argv[1]);
            fatal(Error);
        }
    if (strcmp(argv[2], "-") == 0)
        pnewfile = stdin;
    else
        if ((pnewfile = fopen(argv[2], "r")) == NULL) {
            (void) snprintf(Error, sizeof (Error),
                "Can not open '%s'", argv[2]);
            fatal(Error);
        }

    seglim = 3500;

    if (argc > 3) {
        if (argv[3][0] == '-' && argv[3][1] == 's')
            fflags &= ~FTLMSG;
        else {
            if ((seglim = atoi(argv[3])) == 0)
                fatal("non-numeric limit");
            if (argc == 5 && argv[4][0] == '-' &&
                    argv[4][1] == 's')
                fflags &= ~FTLMSG;
        }
    }

    linenum = 0;

    /* Allocate the buffers and initialize their lengths */

    obufsiz = BUFSIZ;
    nbufsiz = BUFSIZ;
    dbufsiz = BUFSIZ;

    if ((oline = (char *)malloc(obufsiz)) == NULL ||
        (nline = (char *)malloc(nbufsiz)) == NULL ||
        (diffline = (char *)malloc(dbufsiz)) == NULL)
        fatal("Out of memory");

    /*
     * The following while-loop will prevent any lines
     * common to the beginning of both files from being
     * sent to 'diff'. Since the running time of 'diff' is
     * non-linear, this will help improve performance.
     * If, during this process, both files reach EOF, then
     * the files are equal and the program will terminate.
     * If either file reaches EOF before the other, the
     * program will generate the appropriate 'diff' output
     * itself, since this can be easily determined and will
     * avoid executing 'diff' completely.
     */
    for (;;) {
        olp = readline(&oline, &obufsiz, poldfile);
        nlp = readline(&nline, &nbufsiz, pnewfile);

        if (!olp && !nlp)   /* EOF found on both:  files equal */
            return (0);

        if (!olp) {
            /*
             * The entire old file is a prefix of the
             * new file. Generate the appropriate "append"
             * 'diff'-like output, which is of the form:
             *      nan, n
             * where 'n' represents a line-number.
             */
            addgen(&nline, &nbufsiz, pnewfile);
        }

        if (!nlp) {
            /*
             * The entire new file is a prefix of the
             * old file. Generate the appropriate "delete"
             * 'diff'-like output, which is of the form:
             *      n, ndn
             * where 'n' represents a line-number.
             */
            delgen(&oline, &obufsiz, poldfile);
        }

        if (strcmp(olp, nlp) == 0)
            linenum++;
        else
            break;
    }

    /*
     * Here, first 'linenum' lines are equal.
     * The following while-loop segments both files into
     * seglim segments, forks and executes 'diff' on the
     * segments, and processes the resulting output of
     * 'diff', which is read from a pipe.
     */
    for (;;) {
        /* If both files are at EOF, everything is done. */
        if (!olp && !nlp)   /* finished */
            return (0);

        if (!olp) {
            /*
             * Generate appropriate "append"
             * output without executing 'diff'.
             */
            addgen(&nline, &nbufsiz, pnewfile);
        }

        if (!nlp) {
            /*
             * Generate appropriate "delete"
             * output without executing 'diff'.
             */
            delgen(&oline, &obufsiz, poldfile);
        }

        /*
         * Create a temporary file to hold a segment
         * from the old file, and write it.
         */
        poldtemp = maket(otmp);
        otcnt = 0;
        while (olp && otcnt < seglim) {
            (void) fputs(oline, poldtemp);
            if (ferror(poldtemp) != 0) {
                fflags |= FTLMSG;
                fatal("Can not write to temporary file");
            }
            olp = readline(&oline, &obufsiz, poldfile);
            otcnt++;
        }
        (void) fclose(poldtemp);

        /*
         * Create a temporary file to hold a segment
         * from the new file, and write it.
         */
        pnewtemp = maket(ntmp);
        ntcnt = 0;
        while (nlp && ntcnt < seglim) {
            (void) fputs(nline, pnewtemp);
            if (ferror(pnewtemp) != 0) {
                fflags |= FTLMSG;
                fatal("Can not write to temporary file");
            }
            nlp = readline(&nline, &nbufsiz, pnewfile);
            ntcnt++;
        }
        (void) fclose(pnewtemp);

        /* Create pipes and fork.  */
        if ((pipe(pfd)) == -1)
            fatal("Can not create pipe");
        if ((i = fork()) < (pid_t)0) {
            (void) close(pfd[0]);
            (void) close(pfd[1]);
            fatal("Can not fork, try again");
        } else if (i == (pid_t)0) { /* child process */
            (void) close(pfd[0]);
            (void) close(1);
            (void) dup(pfd[1]);
            (void) close(pfd[1]);

            /* Execute 'diff' on the segment files. */
            (void) execlp(diff, diff, otmp, ntmp, 0);

            /*
             * Exit code here must be > 1.
             * Parent process treats exit code of 1 from the child
             * as non-error because the child process "diff" exits
             * with a status of 1 when a difference is encountered.
             * The error here is a true error--the parent process
             * needs to detect it and exit with a non-zero status.
             */
            (void) close(1);
            (void) snprintf(Error, sizeof (Error),
                "Can not execute '%s'", diff);
            fatal_num = 2;
            fatal(Error);
        } else {            /* parent process */
            (void) close(pfd[1]);
            pipeinp = fdopen(pfd[0], "r");

            /* Process 'diff' output. */
            while ((dp = readline(&diffline, &dbufsiz, pipeinp))) {
                if (isdigit(*dp))
                    fixnum(diffline);
                else
                    (void) printf("%s", diffline);
            }

            (void) fclose(pipeinp);

            /* EOF on pipe. */
            (void) wait(&status);
            if (status&~0x100) {
                (void) snprintf(Error, sizeof (Error),
                    "'%s' failed", diff);
                fatal(Error);
            }
        }
        linenum += seglim;

        /* Remove temporary files. */
        (void) unlink(otmp);
        (void) unlink(ntmp);
    }
}

/* Routine to save remainder of a file. */
static void
saverest(char **linep, size_t *bufsizp, FILE *iptr)
{
    char *lp;
    FILE *temptr;

    temptr = maket(tempfile);

    lp = *linep;

    while (lp) {
        (void) fputs(*linep, temptr);
        linenum++;
        lp = readline(linep, bufsizp, iptr);
    }
    (void) fclose(temptr);
}

/* Routine to write out data saved by 'saverest' and to remove the file. */
static void
putsave(char **linep, size_t *bufsizp, char type)
{
    FILE *temptr;

    if ((temptr = fopen(tempfile, "r")) == NULL) {
        (void) snprintf(Error, sizeof (Error),
            "Can not open tempfile ('%s')", tempfile); fatal(Error);
    }

    while (readline(linep, bufsizp, temptr))
        (void) printf("%c %s", type, *linep);

    (void) fclose(temptr);

    (void) unlink(tempfile);
}

static void
fixnum(char *lp)
{
    offset_t num;

    while (*lp) {
        switch (*lp) {

        case 'a':
        case 'c':
        case 'd':
        case ',':
        case '\n':
            (void) printf("%c", *lp);
            lp++;
            break;

        default:
            lp = satoi(lp, &num);
            num += linenum;
            (void) printf("%lld", num);
        }
    }
}

static void
addgen(char **lpp, size_t *bufsizp, FILE *fp)
{
    offset_t oldline;
    (void) printf("%llda%lld", linenum, linenum+1);

    /* Save lines of new file. */
    oldline = linenum + 1;
    saverest(lpp, bufsizp, fp);

    if (oldline < linenum)
        (void) printf(",%lld\n", linenum);
    else
        (void) printf("\n");

    /* Output saved lines, as 'diff' would. */
    putsave(lpp, bufsizp, '>');

    exit(0);
}

static void
delgen(char **lpp, size_t *bufsizp, FILE *fp)
{
    offset_t savenum;

    (void) printf("%lld", linenum+1);
    savenum = linenum;

    /* Save lines of old file. */
    saverest(lpp, bufsizp, fp);

    if (savenum +1 != linenum)
        (void) printf(",%lldd%lld\n", linenum, savenum);
    else
        (void) printf("d%lld\n", savenum);

    /* Output saved lines, as 'diff' would.  */
    putsave(lpp, bufsizp, '<');

    exit(0);
}

static void
clean_up()
{
    (void) unlink(tempfile);
    (void) unlink(otmp);
    (void) unlink(ntmp);
}

static FILE *
maket(char *file)
{
    FILE *iop;
    int fd;

    (void) strcpy(file, tempskel);
    if ((fd = mkstemp(file)) == -1 ||
        (iop = fdopen(fd, "w+")) == NULL) {
        (void) snprintf(Error, sizeof (Error),
            "Can not open/create temp file ('%s')", file);
        fatal(Error);
    }
    return (iop);
}

static void
fatal(char *msg)
/*
 *  General purpose error handler.
 *
 *  The argument to fatal is a pointer to an error message string.
 *  The action of this routine is driven completely from
 *  the "fflags" global word (see <fatal.h>).
 *
 *  The FTLMSG bit controls the writing of the error
 *  message on file descriptor 2.  A newline is written
 *  after the user supplied message.
 *
 *  If the FTLCLN bit is on, clean_up is called.
 */
{
    if (fflags & FTLMSG)
        (void) fprintf(stderr, "%s: %s\n", prognam, msg);
    if (fflags & FTLCLN)
        clean_up();
    if (fflags & FTLEXIT)
        exit(fatal_num);
}

static void
setsig()
/*
 *  General-purpose signal setting routine.
 *  All non-ignored, non-caught signals are caught.
 *  If a signal other than hangup, interrupt, or quit is caught,
 *  a "user-oriented" message is printed on file descriptor 2.
 *  If hangup, interrupt or quit is caught, that signal
 *  is set to ignore.
 *  Termination is like that of "fatal",
 *  via "clean_up()"
 */
{
    void (*act)(int);
    int j;

    for (j = 1; j < ONSIG; j++) {
        act = signal(j, setsig1);
        if (act == SIG_ERR)
            continue;
        if (act == SIG_DFL)
            continue;
        (void) signal(j, act);
    }
}

static void
setsig1(int sig)
{

    (void) signal(sig, SIG_IGN);
    clean_up();
    exit(1);
}

static char *
satoi(char *p, offset_t *ip)
{
    offset_t sum;

    sum = 0;
    while (isdigit(*p))
        sum = sum * 10 + (*p++ - '0');
    *ip = sum;
    return (p);
}

/*
 * Read a line of data from a file.  If the current buffer is not large enough
 * to contain the line, double the size of the buffer and continue reading.
 * Loop until either the entire line is read or until there is no more space
 * to be malloc'd.
 */

static char *
readline(char **bufferp, size_t *bufsizp, FILE *filep)
{
    char *bufp;
    size_t newsize;     /* number of bytes to make buffer */
    size_t oldsize;

    (*bufferp)[*bufsizp - 1] = '\t'; /* arbitrary non-zero character */
    (*bufferp)[*bufsizp - 2] = ' '; /* arbitrary non-newline char */
    bufp = fgets(*bufferp, *bufsizp, filep);
    if (bufp == NULL)
        return (bufp);
    while ((*bufferp)[*bufsizp -1] == '\0' &&
        (*bufferp)[*bufsizp - 2] != '\n' &&
        strlen(*bufferp) == *bufsizp - 1) {
        newsize = 2 * (*bufsizp);
        bufp = (char *)realloc((void *)*bufferp, newsize);
        if (bufp == NULL)
            fatal("Out of memory");
        oldsize = *bufsizp;
        *bufsizp = newsize;
        *bufferp = bufp;
        (*bufferp)[*bufsizp - 1] = '\t';
        (*bufferp)[*bufsizp - 2] = ' ';
        bufp = fgets(*bufferp + oldsize -1, oldsize + 1, filep);
        if (bufp == NULL) {
            if (filep->_flag & _IOEOF) {
                bufp = *bufferp;
                break;
            } else
                fatal("Read error");
        } else
            bufp = *bufferp;
    }
    return (bufp);
}