aboutsummaryrefslogtreecommitdiff
path: root/abspath.c
blob: 64adbe2a1b5e5679fb0dc772452b4aca1865ee4c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
#include "cache.h"

/*
 * Do not use this for inspecting *tracked* content.  When path is a
 * symlink to a directory, we do not want to say it is a directory when
 * dealing with tracked content in the working tree.
 */
int is_directory(const char *path)
{
	struct stat st;
	return (!stat(path, &st) && S_ISDIR(st.st_mode));
}

/* We allow "recursive" symbolic links. Only within reason, though. */
#define MAXDEPTH 5

/*
 * Return the real path (i.e., absolute path, with symlinks resolved
 * and extra slashes removed) equivalent to the specified path.  (If
 * you want an absolute path but don't mind links, use
 * absolute_path().)  The return value is a pointer to a static
 * buffer.
 *
 * The input and all intermediate paths must be shorter than MAX_PATH.
 * The directory part of path (i.e., everything up to the last
 * dir_sep) must denote a valid, existing directory, but the last
 * component need not exist.  If die_on_error is set, then die with an
 * informative error message if there is a problem.  Otherwise, return
 * NULL on errors (without generating any output).
 *
 * If path is our buffer, then return path, as it's already what the
 * user wants.
 */
static const char *real_path_internal(const char *path, int die_on_error)
{
	static char bufs[2][PATH_MAX + 1], *buf = bufs[0], *next_buf = bufs[1];
	char *retval = NULL;

	/*
	 * If we have to temporarily chdir(), store the original CWD
	 * here so that we can chdir() back to it at the end of the
	 * function:
	 */
	char cwd[1024] = "";

	int buf_index = 1;

	int depth = MAXDEPTH;
	char *last_elem = NULL;
	struct stat st;

	/* We've already done it */
	if (path == buf || path == next_buf)
		return path;

	if (!*path) {
		if (die_on_error)
			die("The empty string is not a valid path");
		else
			goto error_out;
	}

	if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX) {
		if (die_on_error)
			die("Too long path: %.*s", 60, path);
		else
			goto error_out;
	}

	while (depth--) {
		if (!is_directory(buf)) {
			char *last_slash = find_last_dir_sep(buf);
			if (last_slash) {
				last_elem = xstrdup(last_slash + 1);
				last_slash[1] = '\0';
			} else {
				last_elem = xstrdup(buf);
				*buf = '\0';
			}
		}

		if (*buf) {
			if (!*cwd && !getcwd(cwd, sizeof(cwd))) {
				if (die_on_error)
					die_errno("Could not get current working directory");
				else
					goto error_out;
			}

			if (chdir(buf)) {
				if (die_on_error)
					die_errno("Could not switch to '%s'", buf);
				else
					goto error_out;
			}
		}
		if (!getcwd(buf, PATH_MAX)) {
			if (die_on_error)
				die_errno("Could not get current working directory");
			else
				goto error_out;
		}

		if (last_elem) {
			size_t len = strlen(buf);
			if (len + strlen(last_elem) + 2 > PATH_MAX) {
				if (die_on_error)
					die("Too long path name: '%s/%s'",
					    buf, last_elem);
				else
					goto error_out;
			}
			if (len && !is_dir_sep(buf[len-1]))
				buf[len++] = '/';
			strcpy(buf + len, last_elem);
			free(last_elem);
			last_elem = NULL;
		}

		if (!lstat(buf, &st) && S_ISLNK(st.st_mode)) {
			ssize_t len = readlink(buf, next_buf, PATH_MAX);
			if (len < 0) {
				if (die_on_error)
					die_errno("Invalid symlink '%s'", buf);
				else
					goto error_out;
			}
			if (PATH_MAX <= len) {
				if (die_on_error)
					die("symbolic link too long: %s", buf);
				else
					goto error_out;
			}
			next_buf[len] = '\0';
			buf = next_buf;
			buf_index = 1 - buf_index;
			next_buf = bufs[buf_index];
		} else
			break;
	}

	retval = buf;
error_out:
	free(last_elem);
	if (*cwd && chdir(cwd))
		die_errno ("Could not change back to '%s'", cwd);

	return retval;
}

const char *real_path(const char *path)
{
	return real_path_internal(path, 1);
}

const char *real_path_if_valid(const char *path)
{
	return real_path_internal(path, 0);
}

static const char *get_pwd_cwd(void)
{
	static char cwd[PATH_MAX + 1];
	char *pwd;
	struct stat cwd_stat, pwd_stat;
	if (getcwd(cwd, PATH_MAX) == NULL)
		return NULL;
	pwd = getenv("PWD");
	if (pwd && strcmp(pwd, cwd)) {
		stat(cwd, &cwd_stat);
		if ((cwd_stat.st_dev || cwd_stat.st_ino) &&
		    !stat(pwd, &pwd_stat) &&
		    pwd_stat.st_dev == cwd_stat.st_dev &&
		    pwd_stat.st_ino == cwd_stat.st_ino) {
			strlcpy(cwd, pwd, PATH_MAX);
		}
	}
	return cwd;
}

/*
 * Use this to get an absolute path from a relative one. If you want
 * to resolve links, you should use real_path.
 *
 * If the path is already absolute, then return path. As the user is
 * never meant to free the return value, we're safe.
 */
const char *absolute_path(const char *path)
{
	static char buf[PATH_MAX + 1];

	if (!*path) {
		die("The empty string is not a valid path");
	} else if (is_absolute_path(path)) {
		if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
			die("Too long path: %.*s", 60, path);
	} else {
		size_t len;
		const char *fmt;
		const char *cwd = get_pwd_cwd();
		if (!cwd)
			die_errno("Cannot determine the current working directory");
		len = strlen(cwd);
		fmt = (len > 0 && is_dir_sep(cwd[len-1])) ? "%s%s" : "%s/%s";
		if (snprintf(buf, PATH_MAX, fmt, cwd, path) >= PATH_MAX)
			die("Too long path: %.*s", 60, path);
	}
	return buf;
}

/*
 * Unlike prefix_path, this should be used if the named file does
 * not have to interact with index entry; i.e. name of a random file
 * on the filesystem.
 */
const char *prefix_filename(const char *pfx, int pfx_len, const char *arg)
{
	static char path[PATH_MAX];
#ifndef GIT_WINDOWS_NATIVE
	if (!pfx_len || is_absolute_path(arg))
		return arg;
	memcpy(path, pfx, pfx_len);
	strcpy(path + pfx_len, arg);
#else
	char *p;
	/* don't add prefix to absolute paths, but still replace '\' by '/' */
	if (is_absolute_path(arg))
		pfx_len = 0;
	else if (pfx_len)
		memcpy(path, pfx, pfx_len);
	strcpy(path + pfx_len, arg);
	for (p = path + pfx_len; *p; p++)
		if (*p == '\\')
			*p = '/';
#endif
	return path;
}