diff3: Add support for -A

Diff3 in -A mode generates an ed script to show how the 3 files and
brackets changes that conflict. The ed script generated should when
applied leave familiar merge conflict markers in a patched file.

Diff3 output is not documented, this feature has been arrived at by
comparing bsd diff3 output to gnu diff3 output until they were made to
agree. There are likely to still be differences between these formats.

The gnu diff3 guide is actually quite good at explaining how diff3
output should appear, but it doesn't cover every form of output from
diff3.

https://www.gnu.org/software/diffutils/manual/diffutils.html#Comparing-Three-Files

Discussed with:	pstef, kevans
Sponsored by:	Klara, Inc.
This commit is contained in:
Tom Jones 2022-04-19 15:43:35 +01:00
parent ecbbb0c85e
commit 9ab079c5e8
5 changed files with 157 additions and 8 deletions

View File

@ -30,7 +30,7 @@
.\" @(#)diff3.1 8.2 (Berkeley) 4/18/94
.\" $FreeBSD$
.\"
.Dd August 23, 2021
.Dd April 19, 2022
.Dt DIFF3 1
.Os
.Sh NAME
@ -38,7 +38,7 @@
.Nd 3-way differential file comparison
.Sh SYNOPSIS
.Nm diff3
.Op Fl 3aEeiTXx
.Op Fl 3AaEeiTXx
.Op Fl Fl diff-program Ar program
.Op Fl Fl strip-trailing-cr
.Op Fl L | Fl Fl label Ar label1
@ -71,6 +71,8 @@ Produces an output script suitable for
with changes
specific only to
.Ar file3 .
.It Fl A Fl Fl show-all
Output all changes, bracketing conflicts.
.It Fl a , Fl Fl text
Treat all files as ASCII.
.It Fl E , Fl Fl show-overlap

View File

@ -100,6 +100,14 @@ struct range {
};
struct diff {
#define DIFF_TYPE2 2
#define DIFF_TYPE3 3
int type;
#if DEBUG
char *line;
#endif /* DEBUG */
/* Ranges as lines */
struct range old;
struct range new;
};
@ -129,10 +137,11 @@ static int oflag; /* indicates whether to mark overlaps (-E or -X) */
static int strip_cr;
static char *f1mark, *f2mark, *f3mark;
static const char *oldmark = "<<<<<<<";
static const char *orgmark = "|||||||";
static const char *newmark = ">>>>>>>";
static bool duplicate(struct range *, struct range *);
static int edit(struct diff *, bool, int);
static int edit(struct diff *, bool, int, int);
static char *getchange(FILE *);
static char *get_line(FILE *, size_t *);
static int readin(int fd, struct diff **);
@ -143,6 +152,7 @@ static void merge(int, int);
static void prange(struct range *, bool);
static void repos(int);
static void edscript(int) __dead2;
static void Ascript(int) __dead2;
static void increase(void);
static void usage(void) __dead2;
static void printrange(FILE *, struct range *);
@ -189,6 +199,10 @@ readin(int fd, struct diff **dd)
if (f == NULL)
err(2, "fdopen");
for (i = 0; (p = getchange(f)); i++) {
#if DEBUG
(*dd)[i].line = strdup(p);
#endif /* DEBUG */
if (i >= szchanges - 1)
increase();
a = b = (int)strtoimax(p, &p, 10);
@ -309,6 +323,9 @@ merge(int m1, int m2)
keep(1, &d2->new);
change(3, &d2->new, false);
change(2, &d2->old, false);
} else if (Aflag || mflag) {
// XXX-THJ: What does it mean for the second file to differ?
j = edit(d2, dup, j, DIFF_TYPE2);
}
d2++;
continue;
@ -344,8 +361,10 @@ merge(int m1, int m2)
change(2, &d2->old, false);
d3 = d1->old.to > d1->old.from ? d1 : d2;
change(3, &d3->new, false);
} else
j = edit(d1, dup, j);
} else {
j = edit(d1, dup, j, DIFF_TYPE3);
}
dup = false;
d1++;
d2++;
continue;
@ -369,7 +388,10 @@ merge(int m1, int m2)
d1->new.to = d2->new.to;
}
}
if (eflag)
if (Aflag)
Ascript(j);
else if (eflag)
edscript(j);
}
@ -498,7 +520,7 @@ repos(int nchar)
* collect an editing script for later regurgitation
*/
static int
edit(struct diff *diff, bool dup, int j)
edit(struct diff *diff, bool dup, int j, int difftype)
{
if (((dup + 1) & eflag) == 0)
@ -507,6 +529,12 @@ edit(struct diff *diff, bool dup, int j)
overlap[j] = !dup;
if (!dup)
overlapcnt++;
de[j].type = difftype;
#if DEBUG
de[j].line = diff->line;
#endif /* DEBUG */
de[j].old.from = diff->old.from;
de[j].old.to = diff->old.to;
de[j].new.from = diff->new.from;
@ -574,6 +602,91 @@ edscript(int n)
exit(eflag == 0 ? overlapcnt : 0);
}
/*
* Output an edit script to turn mine into yours, when there is a conflict
* between the 3 files bracket the changes. Regurgitate the diffs in reverse
* order to allow the ed script to track down where the lines are as changes
* are made.
*/
static void
Ascript(int n)
{
int startmark;
bool deletenew;
bool deleteold;
for (; n > 0; n--) {
deletenew = (de[n].new.from == de[n].new.to);
deleteold = (de[n].old.from == de[n].old.to);
startmark = de[n].old.from + (de[n].old.to - de[n].old.from) - 1;
if (de[n].type == DIFF_TYPE2) {
if (!oflag || !overlap[n]) {
prange(&de[n].old, deletenew);
printrange(fp[2], &de[n].new);
} else {
startmark = de[n].new.from +
(de[n].new.to - de[n].new.from);
if (!deletenew)
startmark--;
printf("%da\n", startmark);
printf("%s %s\n", newmark, f3mark);
printf(".\n");
printf("%da\n", startmark -
(de[n].new.to - de[n].new.from));
printf("%s %s\n", oldmark, f2mark);
if (!deleteold)
printrange(fp[1], &de[n].old);
printf("=======\n.\n");
}
} else if (de[n].type == DIFF_TYPE3) {
if (!oflag || !overlap[n]) {
prange(&de[n].old, deletenew);
printrange(fp[2], &de[n].new);
} else {
printf("%da\n", startmark);
printf("%s %s\n", orgmark, f2mark);
if (deleteold) {
struct range r;
r.from = de[n].old.from-1;
r.to = de[n].new.to;
printrange(fp[1], &r);
} else
printrange(fp[1], &de[n].old);
printf("=======\n");
printrange(fp[2], &de[n].new);
}
if (!oflag || !overlap[n]) {
if (!deletenew)
printf(".\n");
} else {
printf("%s %s\n.\n", newmark, f3mark);
/*
* Go to the start of the conflict in original
* file and append lines
*/
printf("%da\n%s %s\n.\n",
startmark - (de[n].old.to - de[n].old.from),
oldmark, f1mark);
}
}
}
if (iflag)
printf("w\nq\n");
exit(overlapcnt > 0);
}
static void
increase(void)
{

View File

@ -21,6 +21,7 @@ ${PACKAGE}FILES+= \
7.out \
8.out \
9.out \
long-ed.out
long-ed.out \
long-A.out
.include <bsd.test.mk>

View File

@ -3,6 +3,7 @@
atf_test_case diff3
atf_test_case diff3_lesssimple
atf_test_case diff3_ed
atf_test_case diff3_A
diff3_body()
{
@ -46,9 +47,19 @@ diff3_ed_body()
diff3 -e $(atf_get_srcdir)/long-m.txt $(atf_get_srcdir)/long-o.txt $(atf_get_srcdir)/long-y.txt
}
diff3_A_body()
{
atf_check -s exit:1 -o file:$(atf_get_srcdir)/8.out \
diff3 -A -L 1 -L 2 -L 3 $(atf_get_srcdir)/1.txt $(atf_get_srcdir)/2.txt $(atf_get_srcdir)/3.txt
atf_check -s exit:1 -o file:$(atf_get_srcdir)/long-A.out \
diff3 -A -L long-m.txt -L long-o.txt -L long-y.txt $(atf_get_srcdir)/long-m.txt $(atf_get_srcdir)/long-o.txt $(atf_get_srcdir)/long-y.txt
}
atf_init_test_cases()
{
atf_add_test_case diff3
# atf_add_test_case diff3_lesssimple
atf_add_test_case diff3_ed
atf_add_test_case diff3_A
}

View File

@ -0,0 +1,22 @@
24d
16a
||||||| long-o.txt
This line is different in yours and mine, but the different in each
=======
This line is different in yours and mine, but the best in yours
>>>>>>> long-y.txt
.
15a
<<<<<<< long-m.txt
.
11a
>>>>>>> long-y.txt
.
10a
<<<<<<< long-o.txt
This line is different in yours and mine, but the same
=======
.
8c
This line is different in yours, much butter
.