hash-object --literally: fix buffer overrun with extra-long object type
[git] / builtin / hash-object.c
1 /*
2  * GIT - The information manager from hell
3  *
4  * Copyright (C) Linus Torvalds, 2005
5  * Copyright (C) Junio C Hamano, 2005
6  */
7 #include "builtin.h"
8 #include "blob.h"
9 #include "quote.h"
10 #include "parse-options.h"
11 #include "exec_cmd.h"
12
13 /*
14  * This is to create corrupt objects for debugging and as such it
15  * needs to bypass the data conversion performed by, and the type
16  * limitation imposed by, index_fd() and its callees.
17  */
18 static int hash_literally(unsigned char *sha1, int fd, const char *type, unsigned flags)
19 {
20         struct strbuf buf = STRBUF_INIT;
21         int ret;
22
23         if (strbuf_read(&buf, fd, 4096) < 0)
24                 ret = -1;
25         else
26                 ret = hash_sha1_file_literally(buf.buf, buf.len, type, sha1, flags);
27         strbuf_release(&buf);
28         return ret;
29 }
30
31 static void hash_fd(int fd, const char *type, const char *path, unsigned flags,
32                     int literally)
33 {
34         struct stat st;
35         unsigned char sha1[20];
36
37         if (fstat(fd, &st) < 0 ||
38             (literally
39              ? hash_literally(sha1, fd, type, flags)
40              : index_fd(sha1, fd, &st, type_from_string(type), path, flags)))
41                 die((flags & HASH_WRITE_OBJECT)
42                     ? "Unable to add %s to database"
43                     : "Unable to hash %s", path);
44         printf("%s\n", sha1_to_hex(sha1));
45         maybe_flush_or_die(stdout, "hash to stdout");
46 }
47
48 static void hash_object(const char *path, const char *type, const char *vpath,
49                         unsigned flags, int literally)
50 {
51         int fd;
52         fd = open(path, O_RDONLY);
53         if (fd < 0)
54                 die_errno("Cannot open '%s'", path);
55         hash_fd(fd, type, vpath, flags, literally);
56 }
57
58 static void hash_stdin_paths(const char *type, int no_filters, unsigned flags,
59                              int literally)
60 {
61         struct strbuf buf = STRBUF_INIT, nbuf = STRBUF_INIT;
62
63         while (strbuf_getline(&buf, stdin, '\n') != EOF) {
64                 if (buf.buf[0] == '"') {
65                         strbuf_reset(&nbuf);
66                         if (unquote_c_style(&nbuf, buf.buf, NULL))
67                                 die("line is badly quoted");
68                         strbuf_swap(&buf, &nbuf);
69                 }
70                 hash_object(buf.buf, type, no_filters ? NULL : buf.buf, flags,
71                             literally);
72         }
73         strbuf_release(&buf);
74         strbuf_release(&nbuf);
75 }
76
77 int cmd_hash_object(int argc, const char **argv, const char *prefix)
78 {
79         static const char * const hash_object_usage[] = {
80                 N_("git hash-object [-t <type>] [-w] [--path=<file>|--no-filters] [--stdin] [--] <file>..."),
81                 N_("git hash-object  --stdin-paths < <list-of-paths>"),
82                 NULL
83         };
84         const char *type = blob_type;
85         int hashstdin = 0;
86         int stdin_paths = 0;
87         int no_filters = 0;
88         int literally = 0;
89         unsigned flags = HASH_FORMAT_CHECK;
90         const char *vpath = NULL;
91         const struct option hash_object_options[] = {
92                 OPT_STRING('t', NULL, &type, N_("type"), N_("object type")),
93                 OPT_BIT('w', NULL, &flags, N_("write the object into the object database"),
94                         HASH_WRITE_OBJECT),
95                 OPT_COUNTUP( 0 , "stdin", &hashstdin, N_("read the object from stdin")),
96                 OPT_BOOL( 0 , "stdin-paths", &stdin_paths, N_("read file names from stdin")),
97                 OPT_BOOL( 0 , "no-filters", &no_filters, N_("store file as is without filters")),
98                 OPT_BOOL( 0, "literally", &literally, N_("just hash any random garbage to create corrupt objects for debugging Git")),
99                 OPT_STRING( 0 , "path", &vpath, N_("file"), N_("process file as it were from this path")),
100                 OPT_END()
101         };
102         int i;
103         int prefix_length = -1;
104         const char *errstr = NULL;
105
106         argc = parse_options(argc, argv, NULL, hash_object_options,
107                              hash_object_usage, 0);
108
109         if (flags & HASH_WRITE_OBJECT) {
110                 prefix = setup_git_directory();
111                 prefix_length = prefix ? strlen(prefix) : 0;
112                 if (vpath && prefix)
113                         vpath = prefix_filename(prefix, prefix_length, vpath);
114         }
115
116         git_config(git_default_config, NULL);
117
118         if (stdin_paths) {
119                 if (hashstdin)
120                         errstr = "Can't use --stdin-paths with --stdin";
121                 else if (argc)
122                         errstr = "Can't specify files with --stdin-paths";
123                 else if (vpath)
124                         errstr = "Can't use --stdin-paths with --path";
125         }
126         else {
127                 if (hashstdin > 1)
128                         errstr = "Multiple --stdin arguments are not supported";
129                 if (vpath && no_filters)
130                         errstr = "Can't use --path with --no-filters";
131         }
132
133         if (errstr) {
134                 error("%s", errstr);
135                 usage_with_options(hash_object_usage, hash_object_options);
136         }
137
138         if (hashstdin)
139                 hash_fd(0, type, vpath, flags, literally);
140
141         for (i = 0 ; i < argc; i++) {
142                 const char *arg = argv[i];
143
144                 if (0 <= prefix_length)
145                         arg = prefix_filename(prefix, prefix_length, arg);
146                 hash_object(arg, type, no_filters ? NULL : vpath ? vpath : arg,
147                             flags, literally);
148         }
149
150         if (stdin_paths)
151                 hash_stdin_paths(type, no_filters, flags, literally);
152
153         return 0;
154 }