SYNOPSIS
--------
[verse]
-'git patch-id' < <patch>
+'git patch-id'
[--stable | --unstable] < <patch>
DESCRIPTION
-----------
-A "patch ID" is nothing but a SHA-1 of the diff associated with a patch, with
-whitespace and line numbers ignored. As such, it's "reasonably stable", but at
-the same time also reasonably unique, i.e., two patches that have the same "patch
-ID" are almost guaranteed to be the same thing.
+A "patch ID" is nothing but a sum of SHA-1 of the file diffs associated with a
+patch, with whitespace and line numbers ignored. As such, it's "reasonably
+stable", but at the same time also reasonably unique, i.e., two patches that
+have the same "patch ID" are almost guaranteed to be the same thing.
IOW, you can use this thing to look for likely duplicate commits.
OPTIONS
-------
+
+--stable::
+ Use a "stable" sum of hashes as the patch ID. With this option:
+ - Reordering file diffs that make up a patch does not affect the ID.
+ In particular, two patches produced by comparing the same two trees
+ with two different settings for "-O<orderfile>" result in the same
+ patch ID signature, thereby allowing the computed result to be used
+ as a key to index some meta-information about the change between
+ the two trees;
+
+ - Result is different from the value produced by git 1.9 and older
+ or produced when an "unstable" hash (see --unstable below) is
+ configured - even when used on a diff output taken without any use
+ of "-O<orderfile>", thereby making existing databases storing such
+ "unstable" or historical patch-ids unusable.
+
+ This is the default if patchid.stable is set to true.
+
+--unstable::
+ Use an "unstable" hash as the patch ID. With this option,
+ the result produced is compatible with the patch-id value produced
+ by git 1.9 and older. Users with pre-existing databases storing
+ patch-ids produced by git 1.9 and older (who do not deal with reordered
+ patches) may want to use this option.
+
+ This is the default.
+
<patch>::
The diff to create the ID of.
#include "builtin.h"
-static void flush_current_id(int patchlen, unsigned char *id, git_SHA_CTX *c)
+static void flush_current_id(int patchlen, unsigned char *id, unsigned char *result)
{
- unsigned char result[20];
char name[50];
if (!patchlen)
return;
- git_SHA1_Final(result, c);
memcpy(name, sha1_to_hex(id), 41);
printf("%s %s\n", sha1_to_hex(result), name);
- git_SHA1_Init(c);
}
static int remove_space(char *line)
return 1;
}
-static int get_one_patchid(unsigned char *next_sha1, git_SHA_CTX *ctx, struct strbuf *line_buf)
+static void flush_one_hunk(unsigned char *result, git_SHA_CTX *ctx)
+{
+ unsigned char hash[20];
+ unsigned short carry = 0;
+ int i;
+
+ git_SHA1_Final(hash, ctx);
+ git_SHA1_Init(ctx);
+ /* 20-byte sum, with carry */
+ for (i = 0; i < 20; ++i) {
+ carry += result[i] + hash[i];
+ result[i] = carry;
+ carry >>= 8;
+ }
+}
+
+static int get_one_patchid(unsigned char *next_sha1, unsigned char *result,
+ struct strbuf *line_buf, int stable)
{
int patchlen = 0, found_next = 0;
int before = -1, after = -1;
+ git_SHA_CTX ctx;
+
+ git_SHA1_Init(&ctx);
+ hashclr(result);
while (strbuf_getwholeline(line_buf, stdin, '\n') != EOF) {
char *line = line_buf->buf;
break;
/* Else we're parsing another header. */
+ if (stable)
+ flush_one_hunk(result, &ctx);
before = after = -1;
}
/* Compute the sha without whitespace */
len = remove_space(line);
patchlen += len;
- git_SHA1_Update(ctx, line, len);
+ git_SHA1_Update(&ctx, line, len);
}
if (!found_next)
hashclr(next_sha1);
+ flush_one_hunk(result, &ctx);
+
return patchlen;
}
-static void generate_id_list(void)
+static void generate_id_list(int stable)
{
- unsigned char sha1[20], n[20];
- git_SHA_CTX ctx;
+ unsigned char sha1[20], n[20], result[20];
int patchlen;
struct strbuf line_buf = STRBUF_INIT;
- git_SHA1_Init(&ctx);
hashclr(sha1);
while (!feof(stdin)) {
- patchlen = get_one_patchid(n, &ctx, &line_buf);
- flush_current_id(patchlen, sha1, &ctx);
+ patchlen = get_one_patchid(n, result, &line_buf, stable);
+ flush_current_id(patchlen, sha1, result);
hashcpy(sha1, n);
}
strbuf_release(&line_buf);
}
-static const char patch_id_usage[] = "git patch-id < patch";
+static const char patch_id_usage[] = "git patch-id [--stable | --unstable] < patch";
+
+static int git_patch_id_config(const char *var, const char *value, void *cb)
+{
+ int *stable = cb;
+
+ if (!strcmp(var, "patchid.stable")) {
+ *stable = git_config_bool(var, value);
+ return 0;
+ }
+
+ return git_default_config(var, value, cb);
+}
int cmd_patch_id(int argc, const char **argv, const char *prefix)
{
- if (argc != 1)
+ int stable = -1;
+
+ git_config(git_patch_id_config, &stable);
+
+ /* If nothing is set, default to unstable. */
+ if (stable < 0)
+ stable = 0;
+
+ if (argc == 2 && !strcmp(argv[1], "--stable"))
+ stable = 1;
+ else if (argc == 2 && !strcmp(argv[1], "--unstable"))
+ stable = 0;
+ else if (argc != 1)
usage(patch_id_usage);
- generate_id_list();
+ generate_id_list(stable);
return 0;
}
...
'
+ - test_write_lines <lines>
+
+ Write <lines> on standard output, one line per argument.
+ Useful to prepare multi-line files in a compact form.
+
+ Example:
+
+ test_write_lines a b c d e f g >foo
+
+ Is a more compact equivalent of:
+ cat >foo <<-EOF
+ a
+ b
+ c
+ d
+ e
+ f
+ g
+ EOF
+
+
- test_pause
This command is useful for writing and debugging tests and must be
. ./test-lib.sh
test_expect_success 'setup' '
- test_commit initial foo a &&
- test_commit first foo b &&
- git checkout -b same HEAD^ &&
- test_commit same-msg foo b &&
- git checkout -b notsame HEAD^ &&
- test_commit notsame-msg foo c
+ as="a a a a a a a a" && # eight a
+ test_write_lines $as >foo &&
+ test_write_lines $as >bar &&
+ git add foo bar &&
+ git commit -a -m initial &&
+ test_write_lines $as b >foo &&
+ test_write_lines $as b >bar &&
+ git commit -a -m first &&
+ git checkout -b same master &&
+ git commit --amend -m same-msg &&
+ git checkout -b notsame master &&
+ echo c >foo &&
+ echo c >bar &&
+ git commit --amend -a -m notsame-msg &&
+ test_write_lines bar foo >bar-then-foo &&
+ test_write_lines foo bar >foo-then-bar
'
test_expect_success 'patch-id output is well-formed' '
- git log -p -1 | git patch-id > output &&
+ git log -p -1 | git patch-id >output &&
grep "^[a-f0-9]\{40\} $(git rev-parse HEAD)$" output
'
+#calculate patch id. Make sure output is not empty.
calc_patch_id () {
- git patch-id |
- sed "s# .*##" > patch-id_"$1"
+ name="$1"
+ shift
+ git patch-id "$@" |
+ sed "s/ .*//" >patch-id_"$name" &&
+ test_line_count -gt 0 patch-id_"$name"
+}
+
+get_top_diff () {
+ git log -p -1 "$@" -O bar-then-foo --
}
get_patch_id () {
- git log -p -1 "$1" | git patch-id |
- sed "s# .*##" > patch-id_"$1"
+ get_top_diff "$1" | calc_patch_id "$@"
}
test_expect_success 'patch-id detects equality' '
test_cmp patch-id_master patch-id_same
'
+cmp_patch_id () {
+ if
+ test "$1" = "relevant"
+ then
+ ! test_cmp patch-id_"$2" patch-id_"$3"
+ else
+ test_cmp patch-id_"$2" patch-id_"$3"
+ fi
+}
+
+test_patch_id_file_order () {
+ relevant="$1"
+ shift
+ name="order-${1}-$relevant"
+ shift
+ get_top_diff "master" | calc_patch_id "$name" "$@" &&
+ git checkout same &&
+ git format-patch -1 --stdout -O foo-then-bar |
+ calc_patch_id "ordered-$name" "$@" &&
+ cmp_patch_id $relevant "$name" "ordered-$name"
+
+}
+
+# combined test for options: add more tests here to make them
+# run with all options
+test_patch_id () {
+ test_patch_id_file_order "$@"
+}
+
+# small tests with detailed diagnostic for basic options.
+test_expect_success 'file order is irrelevant with --stable' '
+ test_patch_id_file_order irrelevant --stable --stable
+'
+
+test_expect_success 'file order is relevant with --unstable' '
+ test_patch_id_file_order relevant --unstable --unstable
+'
+
+#Now test various option combinations.
+test_expect_success 'default is unstable' '
+ test_patch_id relevant default
+'
+
+test_expect_success 'patchid.stable = true is stable' '
+ test_config patchid.stable true &&
+ test_patch_id irrelevant patchid.stable=true
+'
+
+test_expect_success 'patchid.stable = false is unstable' '
+ test_config patchid.stable false &&
+ test_patch_id relevant patchid.stable=false
+'
+
+test_expect_success '--unstable overrides patchid.stable = true' '
+ test_config patchid.stable true &&
+ test_patch_id relevant patchid.stable=true--unstable --unstable
+'
+
+test_expect_success '--stable overrides patchid.stable = false' '
+ test_config patchid.stable false &&
+ test_patch_id irrelevant patchid.stable=false--stable --stable
+'
+
test_expect_success 'patch-id supports git-format-patch MIME output' '
get_patch_id master &&
git checkout same &&
fi
}
+# This function writes out its parameters, one per line
+test_write_lines () {
+ printf "%s\n" "$@"
+}
+
perl () {
command "$PERL_PATH" "$@"
}