ref: 479a31ae8f4a361b101aa203aa1c0822137708d7
dir: /sys/src/cmd/diff/diffio.c/
#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ctype.h>
#include "diff.h"
static Biobuf *input[2];
static char *file1, *file2;
static int firstchange;
#define MAXLINELEN 4096
#define MIN(x, y) ((x) < (y) ? (x): (y))
static int
readline(Biobuf *bp, char *buf)
{
int c;
char *p, *e;
p = buf;
e = p + MAXLINELEN-1;
do {
c = Bgetc(bp);
if (c < 0) {
if (p == buf)
return -1;
break;
}
if (c == '\n')
break;
*p++ = c;
} while (p < e);
*p = 0;
if (c != '\n' && c >= 0) {
do c = Bgetc(bp);
while (c >= 0 && c != '\n');
}
return p - buf;
}
#define HALFLONG 16
#define low(x) (x&((1L<<HALFLONG)-1))
#define high(x) (x>>HALFLONG)
/*
* hashing has the effect of
* arranging line in 7-bit bytes and then
* summing 1-s complement in 16-bit hunks
*/
static int
readhash(Biobuf *bp, char *buf)
{
long sum;
unsigned shift;
char *p;
int len, space;
sum = 1;
shift = 0;
if ((len = readline(bp, buf)) == -1)
return 0;
p = buf;
switch(bflag) /* various types of white space handling */
{
case 0:
while (len--) {
sum += (long)*p++ << (shift &= (HALFLONG-1));
shift += 7;
}
break;
case 1:
/*
* coalesce multiple white-space
*/
for (space = 0; len--; p++) {
if (isspace(*p)) {
space++;
continue;
}
if (space) {
shift += 7;
space = 0;
}
sum += (long)*p << (shift &= (HALFLONG-1));
shift += 7;
}
break;
default:
/*
* strip all white-space
*/
while (len--) {
if (isspace(*p)) {
p++;
continue;
}
sum += (long)*p++ << (shift &= (HALFLONG-1));
shift += 7;
}
break;
}
sum = low(sum) + high(sum);
return ((short)low(sum) + (short)high(sum));
}
Biobuf *
prepare(int i, char *arg, char *orig)
{
Line *p;
int j, h;
Biobuf *bp;
char *cp, buf[MAXLINELEN];
int nbytes;
Rune r;
bp = Bopen(arg, OREAD);
if (!bp) {
panic(mflag ? 0: 2, "cannot open %s: %r\n", arg);
return 0;
}
if (binary)
return bp;
nbytes = Bread(bp, buf, MIN(1024, MAXLINELEN));
if (nbytes > 0) {
cp = buf;
while (cp < buf+nbytes-UTFmax) {
/*
* heuristic for a binary file in the
* brave new UNICODE world
*/
cp += chartorune(&r, cp);
if (r == 0 || (r > 0x7f && r <= 0xa0)) {
binary++;
return bp;
}
}
Bseek(bp, 0, 0);
}
p = emalloc(3*sizeof(Line));
for (j = 0; h = readhash(bp, buf); p[j].value = h)
p = erealloc(p, (++j+3)*sizeof(Line));
len[i] = j;
file[i] = p;
input[i] = bp;
if (i == 0) {
file1 = orig;
firstchange = 0;
} else
file2 = orig;
return bp;
}
static int
squishspace(char *buf)
{
char *p, *q;
int space;
for (space = 0, q = p = buf; *q; q++) {
if (isspace(*q)) {
space++;
continue;
}
if (space && bflag == 1) {
*p++ = ' ';
space = 0;
}
*p++ = *q;
}
*p = 0;
return p - buf;
}
/*
* need to fix up for unexpected EOF's
*/
void
check(Biobuf *bf, Biobuf *bt)
{
int f, t, flen, tlen;
char fbuf[MAXLINELEN], tbuf[MAXLINELEN];
ixold[0] = ixnew[0] = 0;
for (f = t = 1; f < len[0]; f++) {
flen = readline(bf, fbuf);
ixold[f] = ixold[f-1] + flen + 1; /* ftell(bf) */
if (J[f] == 0)
continue;
do {
tlen = readline(bt, tbuf);
ixnew[t] = ixnew[t-1] + tlen + 1; /* ftell(bt) */
} while (t++ < J[f]);
if (bflag) {
flen = squishspace(fbuf);
tlen = squishspace(tbuf);
}
if (flen != tlen || strcmp(fbuf, tbuf))
J[f] = 0;
}
while (t < len[1]) {
tlen = readline(bt, tbuf);
ixnew[t] = ixnew[t-1] + tlen + 1; /* fseek(bt) */
t++;
}
}
static void
range(int a, int b, char *separator)
{
Bprint(&stdout, "%d", a > b ? b: a);
if (a < b)
Bprint(&stdout, "%s%d", separator, b);
}
static void
fetch(long *f, int a, int b, Biobuf *bp, char *s)
{
char buf[MAXLINELEN];
int maxb;
if(a <= 1)
a = 1;
if(bp == input[0])
maxb = len[0];
else
maxb = len[1];
if(b > maxb)
b = maxb;
if(a > maxb)
return;
Bseek(bp, f[a-1], 0);
while (a++ <= b) {
readline(bp, buf);
Bprint(&stdout, "%s%s\n", s, buf);
}
}
typedef struct Change Change;
struct Change
{
int a;
int b;
int c;
int d;
};
Change *changes;
int nchanges;
void
change(int a, int b, int c, int d)
{
char verb;
char buf[4];
Change *ch;
if (a > b && c > d)
return;
anychange = 1;
if (mflag && firstchange == 0) {
if(mode) {
buf[0] = '-';
buf[1] = mode;
buf[2] = ' ';
buf[3] = '\0';
} else {
buf[0] = '\0';
}
Bprint(&stdout, "diff %s%s %s\n", buf, file1, file2);
firstchange = 1;
}
verb = a > b ? 'a': c > d ? 'd': 'c';
switch(mode) {
case 'e':
range(a, b, ",");
Bputc(&stdout, verb);
break;
case 0:
range(a, b, ",");
Bputc(&stdout, verb);
range(c, d, ",");
break;
case 'n':
Bprint(&stdout, "%s:", file1);
range(a, b, ",");
Bprint(&stdout, " %c ", verb);
Bprint(&stdout, "%s:", file2);
range(c, d, ",");
break;
case 'f':
Bputc(&stdout, verb);
range(a, b, " ");
break;
case 'c':
case 'a':
case 'u':
if(nchanges%1024 == 0)
changes = erealloc(changes, (nchanges+1024)*sizeof(changes[0]));
ch = &changes[nchanges++];
ch->a = a;
ch->b = b;
ch->c = c;
ch->d = d;
return;
}
Bputc(&stdout, '\n');
if (mode == 0 || mode == 'n') {
fetch(ixold, a, b, input[0], "< ");
if (a <= b && c <= d)
Bprint(&stdout, "---\n");
}
fetch(ixnew, c, d, input[1], mode == 0 || mode == 'n' ? "> ": "");
if (mode != 0 && mode != 'n' && c <= d)
Bprint(&stdout, ".\n");
}
enum
{
Lines = 3, /* number of lines of context shown */
};
int
changeset(int i)
{
while(i<nchanges && changes[i].b+1+2*Lines > changes[i+1].a)
i++;
if(i<nchanges)
return i+1;
return nchanges;
}
void
flushchanges(void)
{
int a, b, c, d, at, hdr;
int i, j;
if(nchanges == 0)
return;
hdr = 0;
for(i=0; i<nchanges; ){
j = changeset(i);
a = changes[i].a-Lines;
b = changes[j-1].b+Lines;
c = changes[i].c-Lines;
d = changes[j-1].d+Lines;
if(a < 1)
a = 1;
if(c < 1)
c = 1;
if(b > len[0])
b = len[0];
if(d > len[1])
d = len[1];
if(mode == 'a'){
a = 1;
b = len[0];
c = 1;
d = len[1];
j = nchanges;
}
if(mode == 'u'){
if(!hdr){
Bprint(&stdout, "--- %s\n", file1);
Bprint(&stdout, "+++ %s\n", file2);
hdr = 1;
}
Bprint(&stdout, "@@ -%d,%d +%d,%d @@\n", a, b-a+1, c, d-c+1);
}else{
Bprint(&stdout, "%s:", file1);
range(a, b, ",");
Bprint(&stdout, " - ");
Bprint(&stdout, "%s:", file2);
range(c, d, ",");
Bputc(&stdout, '\n');
}
at = a;
for(; i<j; i++){
fetch(ixold, at, changes[i].a-1, input[0], mode == 'u' ? " " : " ");
fetch(ixold, changes[i].a, changes[i].b, input[0], mode == 'u' ? "-" : "- ");
fetch(ixnew, changes[i].c, changes[i].d, input[1], mode == 'u' ? "+" : "+ ");
at = changes[i].b+1;
}
fetch(ixold, at, b, input[0], mode == 'u' ? " " : " ");
}
nchanges = 0;
}