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compfile.c

/* afio file compresssion code */

#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>

#include <stdlib.h>
#include <sys/signal.h>
#include <sys/types.h>
#include <sys/stat.h>

#include "patchlevel.h"

#include "afio.h"

int matchcompext(char *);
void meminit(void);
void memwrite(char *buf, int count);
int setupgzip(char *name);

int zipfdfd;

/* default value vor gzip 1.2.3 */
int gzipfactor=6;

/* compress all files? */
int forceZflag = 0;

/* this can be set to use something else but gzip: */
char *compressprog = NULL;
int compressargs = 0;


/* max. (virtual) memory usage for -Z option */
off_t maxmem=2*1024*1024;

/* files whose length is below this length won't be compressed */
long compthreshold=0;


/* stuff to build argument list for compression/decompression : */

#define     MAX_ARGS  101

char  * compress_arg_list[MAX_ARGS+1];
/* MAX_ARGS+1 because we need to leave room for a NULL to mark the end */
int   compress_arg_no = 1;

void  add_arg(char *arg)
{
    if((compress_arg_no == 1)&&(*arg=='\0'))
    {
      /* special case: -Q "" means no arguments. */
      return;
    }
    
    if(compress_arg_no < MAX_ARGS )
      compress_arg_list[compress_arg_no++] = arg;
    else
    {
      fprintf (stderr, "afio: Fatal: maximium number of -Q arguments exceeded.\n");
      exit(1);
    }
    
}

/*
 * meminit, memwrite, memreset, memread, memfree.
 */

int memerror;
char *membank=NULL;
size_t allocsize=0;
size_t memsize,membytesread,membytesleft;

void meminit(void)
{
 memerror=0;
 memsize=0;
 /* RWWH: Initialize only the first time */
 if (!allocsize) {
   allocsize=100000;
   membank=(char *)malloc(allocsize);
   if(membank==NULL) 
   {
       warn_nocount("Memory","Low on virtual memory, zipping twice instead.");
       memerror=1;
       allocsize=0;
   }
 }
}

void memwrite(char *buf, int count)
{
 char *oldbank;

 if(memerror) return;

 oldbank=membank;
 /* RWWH: don't increase by linear amount! grow exponentially! */
 if (memsize+count>=allocsize) {
   allocsize=1.25*(memsize+count);
   membank=(char *)realloc(membank,allocsize);
   if(membank==NULL) 
    {
      warn_nocount("Memory","Low on virtual memory, zipping twice instead.");
      /* The free() both works and is necessary.  I can't recall what
         manpage documents this. */
      free(oldbank); 
      memerror=1;
      allocsize=0;
      return;
    }
 }

 memcpy(membank+memsize,buf,(size_t)count);
 memsize+=count;
}

void memreset()
{
 membytesread=0;
 membytesleft=memsize;
} 

int memread(char *buf,int count)
{
 if(membytesleft==0) return 0;

 if ((size_t)count > membytesleft) count=membytesleft;
 memcpy(buf,membank+membytesread,(size_t)count);
 membytesread+=count;
 membytesleft-=count;
 return count; 
}

void memfree()
{
 /* We do not free anymore, this should speed things up. */
#if 0
 if(memerror==0) free(membank);
 allocsize=0;
#endif
}


/*******/

/*
 * Fork a gzip zipping the file name. The zipped version is output through a 
 * pipe, the pipe handle is returned.
 * Returns -1 on failure.
 */
int comppid;

int setupgzip(char *name)
{
 int pipedes[2];
 char farg[3];

 farg[0]='-';
 farg[1]=gzipfactor+'0';
 farg[2]='\0';

 if(pipe(pipedes)==-1) { perror("pipe"); return -1; }

 mayberewind();

 if ((comppid = xfork ("out(), compressing", NODIE)) == 0) 
    {       
      if (arfd != STDIN && arfd != STDOUT) VOID close (arfd);

      dup2(pipedes[1],fileno(stdout));
      close(pipedes[1]);

      VOID close (fileno (stdin));

      if (open (name, O_RDONLY) >= 0)
      { 
        if(! compressargs)
            execlp (compressprog, compressprog, "-c", farg, 0);
        else
            execvp (compressprog, compress_arg_list);
      }
      exit (1);
   }

 close(pipedes[1]);

 /* fprintf(stderr,"pid %d init, pipedes=%d.\n",comppid,pipedes[0]);  */

 return pipedes[0];
}

#include <sys/wait.h> 
#include <sys/types.h>

void waitforgzip()
{
 /* fprintf(stderr,"wait for gzip %d.\n",comppid); */

 xwait (comppid, "out(), wait for gzip child", FALSE);
}

/*
 * compress "name" if we can
 * If we compress we change the statbuf size, the file name, close
 * the old pointer to the file and return the pointer to the compressed
 * version;
 */

#if ( defined(sun) && defined(__svr4__) )
#include <dirent.h>
#else
#include <sys/dir.h>
#endif

void
compressfile (int *fdp, char *name, reg Stat *asb, int *cratio) {
  int compout;
  char *tmpcomp;
  Stat asb2;
  int zipfd;
  ssize_t len;
  char buf[40960];
  off_t ziplen;
  int namelen,usemem;

  if (cratio)
    *cratio = 100;

  /* We need to mark the file as being suitable or not for decompression on
     reading the archive. This is done by adding a .z extension. 

     There is a problem with this: a file that is not suitable for
     compression may already have such an extension. 
     Since this is a regular file, we can use the
     device number to indicate something weird going on here. 

     We look at the bit (asb->sb_rdev)&RDEV_NOTCOMPR:
     If it is 1, it means that the file wasn't suitable for compression,
     and thus that any .z present was there on the original name.
     If it is 0, this does NOT imply that the file was compressed by afio.

     Note that it being 0 doesn't mean `decompress me', it merely
     indicates that a .z extender, _if_ _present_, was added by afio.
     (However, as of version 2.3.6, false does mean that the file was
     compressed by afio and a .z extender added.  In older archives one may
     see filenames with the bit 0 and not ending in .z. Such files 
     have a compressed version larger than the original.)

     In pre-2.4.4 versions, files with size 0 do not have the bit
     set to 1.
  */

  /* indicate unsuitable for compression, may change it later */
   asb->sb_rdev |= RDEV_NOTCOMPR;

  namelen = strlen (name);
  /* Hard link handling code will break if we do compression on the 
     file, so try to compress only if no links or hard link handling.
     Note that if forceZflag==1 than also lflag==1 was set, so this
     test will never return false.

     Also only try to compress if not already compressed,
     or length is >= threshold, or <= maxsizetocompress, 
     but always try if we force compression
  */

  if ( (lflag || (asb->sb_nlink == 1)) 
       &&
       ( ( !matchcompext(name)
           && (asb->sb_size >= compthreshold) 
           && ((maxsizetocompress==0) || ((ulonglong)(asb->sb_size) <= maxsizetocompress))
         )
       || forceZflag
       )
     )
  {  
    /* make sure compress could put on the .Z */
    if ((tmpcomp = strrchr (name, '/')) != NULL)
      tmpcomp++;
    else
      tmpcomp = name;
#ifdef MAXNAMLEN     /* BSD otherwise should be sysV (FFS on sysV?) */
    if (strlen (tmpcomp) + 2 > MAXNAMLEN)
#else
    if (strlen (tmpcomp) + 2 > DIRSIZ)
#endif
      {
#ifndef LONGZFILE
      VOID warn (name, " is too long to tack on .z");
      return;
#endif
      }

  /*  fprintf(stderr,"---nam: %s, len: %d ziplen: ",name,asb->sb_size); */

    usemem=1;
    
    if((zipfd=setupgzip(name))!=-1)
      {
        ziplen=0;
        if(usemem) meminit();
        while((len=read(zipfd,buf,sizeof(buf)))!=0)
          {
           if(len<0) {  fprintf(stderr,
                          "Trouble zipping file, storing uncompressed\n"); 
                        /* read error on pipe, do not use gzip on this file */
                        ziplen=0; break;
                     }    
           if(usemem) memwrite(buf,len);

           ziplen+=len;
           /* too much memory used? */
           if(usemem && ziplen>maxmem)
           { /* prepare to zip twice and free memory */
               usemem=0;
               if (!memerror) memfree();
               /* fprintf(stderr,"zipping twice."); */
           }
        }
        close(zipfd);

        /* wait for child to exit */ 
        if(xwait (comppid, "out(), wait for gzip child", FALSE)!= 0)
            {  fprintf(stderr,
                    "Trouble zipping file, storing uncompressed\n"); 
               ziplen=0;
            }  
  
        if(memerror) usemem=0;

    /*   fprintf(stderr,"%ld\n",ziplen); */
        asb2.sb_size=ziplen;

      if (ziplen>0)
        {
          /* if compressed file is smaller than original, of if forceZflag
             is set, use compressed data */
          if (asb2.sb_size < asb->sb_size || forceZflag )
            {
                if(usemem)
                  { 
                    close (*fdp);
                    strcat (name, ".z");
                    /* was suitable for compression */
                    asb->sb_rdev &= ~RDEV_NOTCOMPR;

                if (cratio)
                  *cratio = (int)((asb2.sb_size * 100.0) / asb->sb_size);
                asb->sb_size = asb2.sb_size;
                *fdp = MEMFD; 
              }
                else
              if ((compout = setupgzip(name)) >= 0)
                    {
                      zipfdfd=compout;
                      compout=ZIPFD;

                      close (*fdp);
                      strcat (name, ".z");
                      /* was suitable for compression */
                  asb->sb_rdev &= ~RDEV_NOTCOMPR;
                       
                  if (cratio)
                  *cratio = (int)((asb2.sb_size * 100.0) / asb->sb_size);
                  asb->sb_size = asb2.sb_size;
                  *fdp = compout;
                }
            }
            else
              {
                if(usemem) memfree();
            }
        }
      }
    
  }
}



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