SysIII/usr/src/cmd/sccs/src/bdiff.c
# include "../hdr/defines.h"
SCCSID(@(#)bdiff 5.1);
/*
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.
*/
int seglim; /* limit of size of file segment to be generated */
char diff[] = "diff";
char tempskel[] = "/tmp/bdXXXXX"; /* used to generate temp file names */
char tempfile[32];
char otmp[32], ntmp[32];
int linenum;
main(argc,argv)
int argc;
char *argv[];
{
FILE *poldfile, *pnewfile, *tptr;
char oline[BUFSIZ], nline[BUFSIZ], diffline[BUFSIZ];
char *olp, *nlp, *dp;
int i, otcnt, ntcnt;
int pfd[2];
FILE *poldtemp, *pnewtemp, *pipeinp;
int status;
/*
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 (bd1)");
if (equal(argv[1],"-") && equal(argv[2],"-"))
fatal("both files standard input (bd2)");
if (equal(argv[1],"-"))
poldfile = stdin;
else
poldfile = xfopen(argv[1],0);
if (equal(argv[2],"-"))
pnewfile = stdin;
else
pnewfile = xfopen(argv[2],0);
seglim = 3500;
if (argc > 3) {
if (argv[3][0] == '-' && argv[3][1] == 's')
Fflags &= ~FTLMSG;
else {
if ((seglim = patoi(argv[3])) == -1)
fatal("non-numeric limit (bd4)");
if (argc == 5 && argv[4][0] == '-' &&
argv[4][1] == 's')
Fflags &= ~FTLMSG;
}
}
linenum = 0;
/*
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.
*/
while (1) {
olp = fgets(oline,BUFSIZ,poldfile);
nlp = fgets(nline,BUFSIZ,pnewfile);
if (!olp && !nlp) /* files are equal */
exit(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,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,poldfile);
}
if (equal(olp,nlp))
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.
*/
while (1) {
/*
If both files are at EOF, everything is done.
*/
if (!olp && !nlp) /* finished */
exit(0);
if (!olp) {
/*
Generate appropriate "append"
output without executing 'diff'.
*/
addgen(nline,pnewfile);
}
if (!nlp) {
/*
Generate appropriate "delete"
output without executing 'diff'.
*/
delgen(oline,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) {
fputs(oline,poldtemp);
olp = fgets(oline,BUFSIZ,poldfile);
otcnt++;
}
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) {
fputs(nline,pnewtemp);
nlp = fgets(nline,BUFSIZ,pnewfile);
ntcnt++;
}
fclose(pnewtemp);
/*
Create pipes and fork.
*/
xpipe(pfd);
if ((i = fork()) < 0) {
close(pfd[0]);
close(pfd[1]);
fatal("cannot fork, try again (bd3)");
}
else if (i == 0) { /* child process */
close(pfd[0]);
close(1);
dup(pfd[1]);
close(pfd[1]);
/*
Execute 'diff' on the segment files.
*/
execlp(diff,diff,otmp,ntmp,0);
close(1);
sprintf(Error,"cannot execute '%s' (bd5)",diff);
fatal(Error);
}
else { /* parent process */
close(pfd[1]);
pipeinp = fdfopen(pfd[0],0);
/*
Process 'diff' output.
*/
while ((dp = fgets(diffline,BUFSIZ,pipeinp))) {
if (numeric(*dp))
fixnum(diffline);
else
printf("%s",diffline);
}
fclose(pipeinp);
/*
EOF on pipe.
*/
wait(&status);
if (status&~0x100) {
sprintf(Error,"'%s' failed (bd6)",diff);
fatal(Error);
}
}
linenum += seglim;
/*
Remove temporary files.
*/
unlink(otmp);
unlink(ntmp);
}
}
/*
Routine to save remainder of a file.
*/
saverest(line,iptr)
char *line;
FILE *iptr;
{
register char *lp;
FILE *temptr;
temptr = maket(tempfile);
lp = line;
while (lp) {
fputs(line,temptr);
linenum++;
lp = fgets(line,BUFSIZ,iptr);
}
fclose(temptr);
}
/*
Routine to write out data saved by
'saverest' routine and to remove the file.
*/
putsave(line,type)
char *line;
char type;
{
FILE *temptr;
temptr = xfopen(tempfile,0);
while (fgets(line,BUFSIZ,temptr))
printf("%c %s",type,line);
fclose(temptr);
xunlink(tempfile);
}
fixnum(lp)
char *lp;
{
int num;
while (*lp) {
switch (*lp) {
case 'a':
case 'c':
case 'd':
case ',':
case '\n':
printf("%c",*lp);
lp++;
break;
default:
lp = satoi(lp,&num);
num += linenum;
printf("%d",num);
}
}
}
addgen(lp,fp)
char *lp;
FILE *fp;
{
printf("%da%d,",linenum,linenum+1);
/*
Save lines of new file.
*/
saverest(lp,fp);
printf("%d\n",linenum);
/*
Output saved lines, as 'diff' would.
*/
putsave(lp,'>');
exit(0);
}
delgen(lp,fp)
char *lp;
FILE *fp;
{
int savenum;
printf("%d,",linenum+1);
savenum = linenum;
/*
Save lines of old file.
*/
saverest(lp,fp);
printf("%dd%d\n",linenum,savenum);
/*
Output saved lines, as 'diff' would.
*/
putsave(lp,'<');
exit(0);
}
clean_up()
{
unlink(tempfile);
unlink(otmp);
unlink(ntmp);
}
maket(file)
char *file;
{
FILE *iop;
copy(tempskel,file);
iop = xfcreat(mktemp(file),0644);
return(iop);
}