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dir: fix checks on common prefix directory

Many years ago, the directory traversing logic had an optimization that would always recurse into any directory that was a common prefix of all the pathspecs without walking the leading directories to get down to the desired directory. Thus, git ls-files -o .git/ # case A would notice that .git/ was a common prefix of all pathspecs (since it is the only pathspec listed), and then traverse into it and start showing unknown files under that directory. Unfortunately, .git/ is not a directory we should be traversing into, which made this optimization problematic. This also affected cases like git ls-files -o --exclude-standard t/ # case B where t/ was in the .gitignore file and thus isn't interesting and shouldn't be recursed into. It also affected cases like git ls-files -o --directory untracked_dir/ # case C where untracked_dir/ is indeed untracked and thus interesting, but the --directory flag means we only want to show the directory itself, not recurse into it and start listing untracked files below it. The case B class of bugs were noted and fixed in commits 16e2cfa90993 ("read_directory(): further split treat_path()", 2010-01-08) and 48ffef966c76 ("ls-files: fix overeager pathspec optimization", 2010-01-08), with the idea being that we first wanted to check whether the common prefix was interesting. The former patch noted that treat_path() couldn't be used when checking the common prefix because treat_path() requires a dir_entry() and we haven't read any directories at the point we are checking the common prefix. So, that patch split treat_one_path() out of treat_path(). The latter patch then created a new treat_leading_path() which duplicated by hand the bits of treat_path() that couldn't be broken out and then called treat_one_path() for the remainder. There were three problems with this approach: * The duplicated logic in treat_leading_path() accidentally missed the check for special paths (such as is_dot_or_dotdot and matching ".git"), causing case A types of bugs to continue to be an issue. * The treat_leading_path() logic assumed we should traverse into anything where path_treatment was not path_none, i.e. it perpetuated class C types of bugs. * It meant we had split logic that needed to kept in sync, running the risk that people introduced new inconsistencies (such as in commit be8a84c52669, which we reverted earlier in this series, or in commit df5bcdf83ae which we'll fix in a subsequent commit) Fix most these problems by making treat_leading_path() not only loop over each leading path component, but calling treat_path() directly on each. To do so, we have to create a synthetic dir_entry, but that only takes a few lines. Then, pay attention to the path_treatment result we get from treat_path() and don't treat path_excluded, path_untracked, and path_recurse all the same as path_recurse. This leaves one remaining problem, the new inconsistency from commit df5bcdf83ae. That will be addressed in a subsequent commit. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Elijah Newren committed Dec 19, 2019 at 21:28 UTC b9670c1f5e6b98837c489a03ac0d343d30e08505

2 files changed +59 -14

dir.c

+56 -11

@@ -2102,37 +2102,82 @@ static int treat_leading_path(struct dir_struct *dir,

2102 const struct pathspec *pathspec)

2103 {

2104 struct strbuf sb = STRBUF_INIT;

2105 - int baselen, rc = 0;

2105 + int prevlen, baselen;

2106 const char *cp;

2107 + struct cached_dir cdir;

2108 + struct dirent *de;

2109 + enum path_treatment state = path_none;

2110 +

2111 + /*

2112 + * For each directory component of path, we are going to check whether

2113 + * that path is relevant given the pathspec. For example, if path is

2114 + * foo/bar/baz/

2115 + * then we will ask treat_path() whether we should go into foo, then

2116 + * whether we should go into bar, then whether baz is relevant.

2117 + * Checking each is important because e.g. if path is

2118 + * .git/info/

2119 + * then we need to check .git to know we shouldn't traverse it.

2120 + * If the return from treat_path() is:

2121 + * * path_none, for any path, we return false.

2122 + * * path_recurse, for all path components, we return true

2123 + * * <anything else> for some intermediate component, we make sure

2124 + * to add that path to the relevant list but return false

2125 + * signifying that we shouldn't recurse into it.

2126 + */

2127

2128 while (len && path[len - 1] == '/')

2129 len--;

2130 if (!len)

2131 return 1;

2132 +

2133 + /*

2134 + * We need a manufactured dirent with sufficient space to store a

2135 + * leading directory component of path in its d_name. Here, we

2136 + * assume that the dirent's d_name is either declared as

2137 + * char d_name[BIG_ENOUGH]

2138 + * or that it is declared at the end of the struct as

2139 + * char d_name[]

2140 + * For either case, padding with len+1 bytes at the end will ensure

2141 + * sufficient storage space.

2142 + */

2143 + de = xcalloc(1, sizeof(struct dirent)+len+1);

2144 + memset(&cdir, 0, sizeof(cdir));

2145 + cdir.de = de;

2146 +#if defined(DT_UNKNOWN) && !defined(NO_D_TYPE_IN_DIRENT)

2147 + de->d_type = DT_DIR;

2148 +#endif

2149 baselen = 0;

2150 + prevlen = 0;

2151 while (1) {

2114 - cp = path + baselen + !!baselen;

2152 + prevlen = baselen + !!baselen;

2153 + cp = path + prevlen;

2154 cp = memchr(cp, '/', path + len - cp);

2155 if (!cp)

2156 baselen = len;

2157 else

2158 baselen = cp - path;

2120 - strbuf_setlen(&sb, 0);

2159 + strbuf_reset(&sb);

2160 strbuf_add(&sb, path, baselen);

2161 if (!is_directory(sb.buf))

2162 break;

2124 - if (simplify_away(sb.buf, sb.len, pathspec))

2125 - break;

2126 - if (treat_one_path(dir, NULL, istate, &sb, baselen, pathspec,

2127 - DT_DIR, NULL) == path_none)

2163 + strbuf_reset(&sb);

2164 + strbuf_add(&sb, path, prevlen);

2165 + memcpy(de->d_name, path+prevlen, baselen-prevlen);

2166 + de->d_name[baselen-prevlen] = '\0';

2167 + state = treat_path(dir, NULL, &cdir, istate, &sb, prevlen,

2168 + pathspec);

2169 + if (state != path_recurse)

2170 break; /* do not recurse into it */

2129 - if (len <= baselen) {

2130 - rc = 1;

2171 + if (len <= baselen)

2172 break; /* finished checking */

2132 - }

2173 }

2174 + add_path_to_appropriate_result_list(dir, NULL, &cdir, istate,

2175 + &sb, baselen, pathspec,

2176 + state);

2177 +

2178 + free(de);

2179 strbuf_release(&sb);

2135 - return rc;

2180 + return state == path_recurse;

2181 }

2182

2183 static const char *get_ident_string(void)

t/t3011-common-prefixes-and-directory-traversal.sh

+3 -3

@@ -74,7 +74,7 @@ test_expect_success 'git ls-files -o --directory untracked_dir does not recurse'

74 test_cmp expect actual

75 '

77 -test_expect_failure 'git ls-files -o --directory untracked_dir/ does not recurse' '

77 +test_expect_success 'git ls-files -o --directory untracked_dir/ does not recurse' '

78 echo untracked_dir/ >expect &&

79 git ls-files -o --directory untracked_dir/ >actual &&

80 test_cmp expect actual

@@ -86,7 +86,7 @@ test_expect_success 'git ls-files -o untracked_repo does not recurse' '

86 test_cmp expect actual

87 '

89 -test_expect_failure 'git ls-files -o untracked_repo/ does not recurse' '

89 +test_expect_success 'git ls-files -o untracked_repo/ does not recurse' '

90 echo untracked_repo/ >expect &&

91 git ls-files -o untracked_repo/ >actual &&

92 test_cmp expect actual

@@ -133,7 +133,7 @@ test_expect_success 'git ls-files -o .git shows nothing' '

133 test_must_be_empty actual

134 '

135

136 -test_expect_failure 'git ls-files -o .git/ shows nothing' '

136 +test_expect_success 'git ls-files -o .git/ shows nothing' '

137 git ls-files -o .git/ >actual &&

138 test_must_be_empty actual

139 '