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#include "builtin.h"
#include "tag.h"
/*
* A signature file has a very simple fixed format: four lines
* of "object <sha1>" + "type <typename>" + "tag <tagname>" +
* "tagger <committer>", followed by a blank line, a free-form tag
* message and a signature block that git itself doesn't care about,
* but that can be verified with gpg or similar.
*
* The first four lines are guaranteed to be at least 83 bytes:
* "object <sha1>\n" is 48 bytes, "type tag\n" at 9 bytes is the
* shortest possible type-line, "tag .\n" at 6 bytes is the shortest
* single-character-tag line, and "tagger . <> 0 +0000\n" at 20 bytes is
* the shortest possible tagger-line.
*/
/*
* We refuse to tag something we can't verify. Just because.
*/
static int verify_object(const unsigned char *sha1, const char *expected_type)
{
int ret = -1;
enum object_type type;
unsigned long size;
void *buffer = read_sha1_file(sha1, &type, &size);
const unsigned char *repl = lookup_replace_object(sha1);
if (buffer) {
if (type == type_from_string(expected_type))
ret = check_sha1_signature(repl, buffer, size, expected_type);
free(buffer);
}
return ret;
}
static int verify_tag(char *buffer, unsigned long size)
{
int typelen;
char type[20];
unsigned char sha1[20];
const char *object, *type_line, *tag_line, *tagger_line, *lb, *rb;
size_t len;
if (size < 84)
return error("wanna fool me ? you obviously got the size wrong !");
buffer[size] = 0;
/* Verify object line */
object = buffer;
if (memcmp(object, "object ", 7))
return error("char%d: does not start with \"object \"", 0);
if (get_sha1_hex(object + 7, sha1))
return error("char%d: could not get SHA1 hash", 7);
/* Verify type line */
type_line = object + 48;
if (memcmp(type_line - 1, "\ntype ", 6))
return error("char%d: could not find \"\\ntype \"", 47);
/* Verify tag-line */
tag_line = strchr(type_line, '\n');
if (!tag_line)
return error("char%"PRIuMAX": could not find next \"\\n\"",
(uintmax_t) (type_line - buffer));
tag_line++;
if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n')
return error("char%"PRIuMAX": no \"tag \" found",
(uintmax_t) (tag_line - buffer));
/* Get the actual type */
typelen = tag_line - type_line - strlen("type \n");
if (typelen >= sizeof(type))
return error("char%"PRIuMAX": type too long",
(uintmax_t) (type_line+5 - buffer));
memcpy(type, type_line+5, typelen);
type[typelen] = 0;
/* Verify that the object matches */
if (verify_object(sha1, type))
return error("char%d: could not verify object %s", 7, sha1_to_hex(sha1));
/* Verify the tag-name: we don't allow control characters or spaces in it */
tag_line += 4;
for (;;) {
unsigned char c = *tag_line++;
if (c == '\n')
break;
if (c > ' ')
continue;
return error("char%"PRIuMAX": could not verify tag name",
(uintmax_t) (tag_line - buffer));
}
/* Verify the tagger line */
tagger_line = tag_line;
if (memcmp(tagger_line, "tagger ", 7))
return error("char%"PRIuMAX": could not find \"tagger \"",
(uintmax_t) (tagger_line - buffer));
/*
* Check for correct form for name and email
* i.e. " <" followed by "> " on _this_ line
* No angle brackets within the name or email address fields.
* No spaces within the email address field.
*/
tagger_line += 7;
if (!(lb = strstr(tagger_line, " <")) || !(rb = strstr(lb+2, "> ")) ||
strpbrk(tagger_line, "<>\n") != lb+1 ||
strpbrk(lb+2, "><\n ") != rb)
return error("char%"PRIuMAX": malformed tagger field",
(uintmax_t) (tagger_line - buffer));
/* Check for author name, at least one character, space is acceptable */
if (lb == tagger_line)
return error("char%"PRIuMAX": missing tagger name",
(uintmax_t) (tagger_line - buffer));
/* timestamp, 1 or more digits followed by space */
tagger_line = rb + 2;
if (!(len = strspn(tagger_line, "0123456789")))
return error("char%"PRIuMAX": missing tag timestamp",
(uintmax_t) (tagger_line - buffer));
tagger_line += len;
if (*tagger_line != ' ')
return error("char%"PRIuMAX": malformed tag timestamp",
(uintmax_t) (tagger_line - buffer));
tagger_line++;
/* timezone, 5 digits [+-]hhmm, max. 1400 */
if (!((tagger_line[0] == '+' || tagger_line[0] == '-') &&
strspn(tagger_line+1, "0123456789") == 4 &&
tagger_line[5] == '\n' && atoi(tagger_line+1) <= 1400))
return error("char%"PRIuMAX": malformed tag timezone",
(uintmax_t) (tagger_line - buffer));
tagger_line += 6;
/* Verify the blank line separating the header from the body */
if (*tagger_line != '\n')
return error("char%"PRIuMAX": trailing garbage in tag header",
(uintmax_t) (tagger_line - buffer));
/* The actual stuff afterwards we don't care about.. */
return 0;
}
int cmd_mktag(int argc, const char **argv, const char *prefix)
{
struct strbuf buf = STRBUF_INIT;
unsigned char result_sha1[20];
if (argc != 1)
usage("git mktag < signaturefile");
if (strbuf_read(&buf, 0, 4096) < 0) {
die_errno("could not read from stdin");
}
/* Verify it for some basic sanity: it needs to start with
"object <sha1>\ntype\ntagger " */
if (verify_tag(buf.buf, buf.len) < 0)
die("invalid tag signature file");
if (write_sha1_file(buf.buf, buf.len, tag_type, result_sha1) < 0)
die("unable to write tag file");
strbuf_release(&buf);
printf("%s\n", sha1_to_hex(result_sha1));
return 0;
}
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