mirror of
https://github.com/git/git
synced 2024-08-28 20:20:07 +00:00
![Michael S. Tsirkin](/assets/img/avatar_default.png)
Patch id changes if users reorder file diffs that make up a patch. As the result is functionally equivalent, a different patch id is surprising to many users. In particular, reordering files using diff -O is helpful to make patches more readable (e.g. API header diff before implementation diff). Add an option to change patch-id behaviour making it stable against these kinds of patch change: calculate SHA1 hash for each hunk separately and sum all hashes (using a symmetrical sum) to get patch id We use a 20byte sum and not xor - since xor would give 0 output for patches that have two identical diffs, which isn't all that unlikely (e.g. append the same line in two places). The new behaviour is enabled - when patchid.stable is true - when --stable flag is present Using a new flag --unstable or setting patchid.stable to false force the historical behaviour. In the documentation, clarify that patch ID can now be a sum of hashes, not a hash. Document how command line and config options affect the behaviour. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
202 lines
4 KiB
C
202 lines
4 KiB
C
#include "builtin.h"
|
|
|
|
static void flush_current_id(int patchlen, unsigned char *id, unsigned char *result)
|
|
{
|
|
char name[50];
|
|
|
|
if (!patchlen)
|
|
return;
|
|
|
|
memcpy(name, sha1_to_hex(id), 41);
|
|
printf("%s %s\n", sha1_to_hex(result), name);
|
|
}
|
|
|
|
static int remove_space(char *line)
|
|
{
|
|
char *src = line;
|
|
char *dst = line;
|
|
unsigned char c;
|
|
|
|
while ((c = *src++) != '\0') {
|
|
if (!isspace(c))
|
|
*dst++ = c;
|
|
}
|
|
return dst - line;
|
|
}
|
|
|
|
static int scan_hunk_header(const char *p, int *p_before, int *p_after)
|
|
{
|
|
static const char digits[] = "0123456789";
|
|
const char *q, *r;
|
|
int n;
|
|
|
|
q = p + 4;
|
|
n = strspn(q, digits);
|
|
if (q[n] == ',') {
|
|
q += n + 1;
|
|
n = strspn(q, digits);
|
|
}
|
|
if (n == 0 || q[n] != ' ' || q[n+1] != '+')
|
|
return 0;
|
|
|
|
r = q + n + 2;
|
|
n = strspn(r, digits);
|
|
if (r[n] == ',') {
|
|
r += n + 1;
|
|
n = strspn(r, digits);
|
|
}
|
|
if (n == 0)
|
|
return 0;
|
|
|
|
*p_before = atoi(q);
|
|
*p_after = atoi(r);
|
|
return 1;
|
|
}
|
|
|
|
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;
|
|
char *p = line;
|
|
int len;
|
|
|
|
if (!memcmp(line, "diff-tree ", 10))
|
|
p += 10;
|
|
else if (!memcmp(line, "commit ", 7))
|
|
p += 7;
|
|
else if (!memcmp(line, "From ", 5))
|
|
p += 5;
|
|
else if (!memcmp(line, "\\ ", 2) && 12 < strlen(line))
|
|
continue;
|
|
|
|
if (!get_sha1_hex(p, next_sha1)) {
|
|
found_next = 1;
|
|
break;
|
|
}
|
|
|
|
/* Ignore commit comments */
|
|
if (!patchlen && memcmp(line, "diff ", 5))
|
|
continue;
|
|
|
|
/* Parsing diff header? */
|
|
if (before == -1) {
|
|
if (!memcmp(line, "index ", 6))
|
|
continue;
|
|
else if (!memcmp(line, "--- ", 4))
|
|
before = after = 1;
|
|
else if (!isalpha(line[0]))
|
|
break;
|
|
}
|
|
|
|
/* Looking for a valid hunk header? */
|
|
if (before == 0 && after == 0) {
|
|
if (!memcmp(line, "@@ -", 4)) {
|
|
/* Parse next hunk, but ignore line numbers. */
|
|
scan_hunk_header(line, &before, &after);
|
|
continue;
|
|
}
|
|
|
|
/* Split at the end of the patch. */
|
|
if (memcmp(line, "diff ", 5))
|
|
break;
|
|
|
|
/* Else we're parsing another header. */
|
|
if (stable)
|
|
flush_one_hunk(result, &ctx);
|
|
before = after = -1;
|
|
}
|
|
|
|
/* If we get here, we're inside a hunk. */
|
|
if (line[0] == '-' || line[0] == ' ')
|
|
before--;
|
|
if (line[0] == '+' || line[0] == ' ')
|
|
after--;
|
|
|
|
/* Compute the sha without whitespace */
|
|
len = remove_space(line);
|
|
patchlen += 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(int stable)
|
|
{
|
|
unsigned char sha1[20], n[20], result[20];
|
|
int patchlen;
|
|
struct strbuf line_buf = STRBUF_INIT;
|
|
|
|
hashclr(sha1);
|
|
while (!feof(stdin)) {
|
|
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 [--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)
|
|
{
|
|
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(stable);
|
|
return 0;
|
|
}
|