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![Jeff King](/assets/img/avatar_default.png)
The diff code represents paths using the diff_filespec struct. This struct has a sha1 to represent the sha1 of the content at that path, as well as a sha1_valid member which indicates whether its sha1 field is actually useful. If sha1_valid is not true, then the filespec represents a working tree file (e.g., for the no-index case, or for when the index is not up-to-date). The diff_filespec is only used internally, though. At the interfaces to the diff subsystem, callers feed the sha1 directly, and we create a diff_filespec from it. It's at that point that we look at the sha1 and decide whether it is valid or not; callers may pass the null sha1 as a sentinel value to indicate that it is not. We should not typically see the null sha1 coming from any other source (e.g., in the index itself, or from a tree). However, a corrupt tree might have a null sha1, which would cause "diff --patch" to accidentally diff the working tree version of a file instead of treating it as a blob. This patch extends the edges of the diff interface to accept a "sha1_valid" flag whenever we accept a sha1, and to use that flag when creating a filespec. In some cases, this means passing the flag through several layers, making the code change larger than would be desirable. One alternative would be to simply die() upon seeing corrupted trees with null sha1s. However, this fix more directly addresses the problem (while bogus sha1s in a tree are probably a bad thing, it is really the sentinel confusion sending us down the wrong code path that is what makes it devastating). And it means that git is more capable of examining and debugging these corrupted trees. For example, you can still "diff --raw" such a tree to find out when the bogus entry was introduced; you just cannot do a "--patch" diff (just as you could not with any other corrupted tree, as we do not have any content to diff). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
293 lines
6.4 KiB
C
293 lines
6.4 KiB
C
/*
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* GIT - The information manager from hell
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*
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* Copyright (C) Linus Torvalds, 2005
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*/
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#include "cache.h"
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#include "exec_cmd.h"
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#include "tag.h"
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#include "tree.h"
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#include "builtin.h"
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#include "parse-options.h"
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#include "diff.h"
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#include "userdiff.h"
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#define BATCH 1
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#define BATCH_CHECK 2
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static void pprint_tag(const unsigned char *sha1, const char *buf, unsigned long size)
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{
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/* the parser in tag.c is useless here. */
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const char *endp = buf + size;
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const char *cp = buf;
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while (cp < endp) {
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char c = *cp++;
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if (c != '\n')
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continue;
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if (7 <= endp - cp && !memcmp("tagger ", cp, 7)) {
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const char *tagger = cp;
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/* Found the tagger line. Copy out the contents
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* of the buffer so far.
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*/
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write_or_die(1, buf, cp - buf);
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/*
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* Do something intelligent, like pretty-printing
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* the date.
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*/
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while (cp < endp) {
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if (*cp++ == '\n') {
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/* tagger to cp is a line
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* that has ident and time.
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*/
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const char *sp = tagger;
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char *ep;
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unsigned long date;
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long tz;
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while (sp < cp && *sp != '>')
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sp++;
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if (sp == cp) {
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/* give up */
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write_or_die(1, tagger,
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cp - tagger);
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break;
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}
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while (sp < cp &&
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!('0' <= *sp && *sp <= '9'))
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sp++;
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write_or_die(1, tagger, sp - tagger);
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date = strtoul(sp, &ep, 10);
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tz = strtol(ep, NULL, 10);
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sp = show_date(date, tz, 0);
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write_or_die(1, sp, strlen(sp));
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xwrite(1, "\n", 1);
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break;
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}
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}
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break;
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}
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if (cp < endp && *cp == '\n')
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/* end of header */
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break;
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}
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/* At this point, we have copied out the header up to the end of
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* the tagger line and cp points at one past \n. It could be the
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* next header line after the tagger line, or it could be another
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* \n that marks the end of the headers. We need to copy out the
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* remainder as is.
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*/
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if (cp < endp)
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write_or_die(1, cp, endp - cp);
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}
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static int cat_one_file(int opt, const char *exp_type, const char *obj_name)
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{
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unsigned char sha1[20];
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enum object_type type;
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char *buf;
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unsigned long size;
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struct object_context obj_context;
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if (get_sha1_with_context(obj_name, sha1, &obj_context))
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die("Not a valid object name %s", obj_name);
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buf = NULL;
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switch (opt) {
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case 't':
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type = sha1_object_info(sha1, NULL);
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if (type > 0) {
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printf("%s\n", typename(type));
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return 0;
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}
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break;
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case 's':
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type = sha1_object_info(sha1, &size);
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if (type > 0) {
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printf("%lu\n", size);
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return 0;
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}
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break;
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case 'e':
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return !has_sha1_file(sha1);
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case 'p':
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type = sha1_object_info(sha1, NULL);
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if (type < 0)
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die("Not a valid object name %s", obj_name);
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/* custom pretty-print here */
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if (type == OBJ_TREE) {
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const char *ls_args[3] = { NULL };
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ls_args[0] = "ls-tree";
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ls_args[1] = obj_name;
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return cmd_ls_tree(2, ls_args, NULL);
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}
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buf = read_sha1_file(sha1, &type, &size);
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if (!buf)
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die("Cannot read object %s", obj_name);
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if (type == OBJ_TAG) {
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pprint_tag(sha1, buf, size);
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return 0;
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}
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/* otherwise just spit out the data */
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break;
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case 'c':
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if (!obj_context.path[0])
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die("git cat-file --textconv %s: <object> must be <sha1:path>",
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obj_name);
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if (!textconv_object(obj_context.path, obj_context.mode, sha1, 1, &buf, &size))
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die("git cat-file --textconv: unable to run textconv on %s",
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obj_name);
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break;
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case 0:
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buf = read_object_with_reference(sha1, exp_type, &size, NULL);
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break;
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default:
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die("git cat-file: unknown option: %s", exp_type);
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}
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if (!buf)
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die("git cat-file %s: bad file", obj_name);
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write_or_die(1, buf, size);
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return 0;
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}
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static int batch_one_object(const char *obj_name, int print_contents)
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{
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unsigned char sha1[20];
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enum object_type type = 0;
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unsigned long size;
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void *contents = contents;
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if (!obj_name)
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return 1;
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if (get_sha1(obj_name, sha1)) {
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printf("%s missing\n", obj_name);
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fflush(stdout);
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return 0;
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}
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if (print_contents == BATCH)
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contents = read_sha1_file(sha1, &type, &size);
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else
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type = sha1_object_info(sha1, &size);
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if (type <= 0) {
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printf("%s missing\n", obj_name);
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fflush(stdout);
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if (print_contents == BATCH)
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free(contents);
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return 0;
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}
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printf("%s %s %lu\n", sha1_to_hex(sha1), typename(type), size);
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fflush(stdout);
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if (print_contents == BATCH) {
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write_or_die(1, contents, size);
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printf("\n");
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fflush(stdout);
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free(contents);
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}
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return 0;
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}
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static int batch_objects(int print_contents)
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{
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struct strbuf buf = STRBUF_INIT;
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while (strbuf_getline(&buf, stdin, '\n') != EOF) {
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int error = batch_one_object(buf.buf, print_contents);
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if (error)
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return error;
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}
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return 0;
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}
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static const char * const cat_file_usage[] = {
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"git cat-file (-t|-s|-e|-p|<type>|--textconv) <object>",
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"git cat-file (--batch|--batch-check) < <list_of_objects>",
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NULL
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};
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static int git_cat_file_config(const char *var, const char *value, void *cb)
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{
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switch (userdiff_config(var, value)) {
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case 0:
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break;
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case -1:
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return -1;
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default:
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return 0;
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}
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return git_default_config(var, value, cb);
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}
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int cmd_cat_file(int argc, const char **argv, const char *prefix)
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{
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int opt = 0, batch = 0;
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const char *exp_type = NULL, *obj_name = NULL;
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const struct option options[] = {
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OPT_GROUP("<type> can be one of: blob, tree, commit, tag"),
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OPT_SET_INT('t', NULL, &opt, "show object type", 't'),
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OPT_SET_INT('s', NULL, &opt, "show object size", 's'),
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OPT_SET_INT('e', NULL, &opt,
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"exit with zero when there's no error", 'e'),
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OPT_SET_INT('p', NULL, &opt, "pretty-print object's content", 'p'),
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OPT_SET_INT(0, "textconv", &opt,
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"for blob objects, run textconv on object's content", 'c'),
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OPT_SET_INT(0, "batch", &batch,
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"show info and content of objects fed from the standard input",
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BATCH),
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OPT_SET_INT(0, "batch-check", &batch,
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"show info about objects fed from the standard input",
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BATCH_CHECK),
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OPT_END()
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};
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git_config(git_cat_file_config, NULL);
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if (argc != 3 && argc != 2)
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usage_with_options(cat_file_usage, options);
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argc = parse_options(argc, argv, prefix, options, cat_file_usage, 0);
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if (opt) {
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if (argc == 1)
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obj_name = argv[0];
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else
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usage_with_options(cat_file_usage, options);
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}
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if (!opt && !batch) {
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if (argc == 2) {
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exp_type = argv[0];
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obj_name = argv[1];
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} else
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usage_with_options(cat_file_usage, options);
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}
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if (batch && (opt || argc)) {
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usage_with_options(cat_file_usage, options);
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}
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if (batch)
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return batch_objects(batch);
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return cat_one_file(opt, exp_type, obj_name);
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}
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